CADENCE DESIGN SYSTEMS INC
S-4, 1998-12-23
PREPACKAGED SOFTWARE
Previous: DESIGNS INC, DEFA14A, 1998-12-23
Next: ESSEF CORP, DEF 14A, 1998-12-23



<PAGE>
 
  AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 23, 1998.
 
                                                       REGISTRATION NO. 333-
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
 
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549
 
                               ----------------
 
                                   FORM S-4
 
                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933
 
                               ----------------
 
                         CADENCE DESIGN SYSTEMS, INC.
            (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
        DELAWARE                     7372                    77-0148231
     (STATE OR OTHER           (PRIMARY STANDARD            (IRS EMPLOYER
     JURISDICTION OF              INDUSTRIAL           IDENTIFICATION NUMBER)
    INCORPORATION OR          CLASSIFICATION CODE
      ORGANIZATION)                 NUMBER)
 
           2655 SEELY AVENUE, BUILDING 5, SAN JOSE, CALIFORNIA 95134
                                (408) 943-1234
   (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
                 OF REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
 
                             R.L. SMITH MCKEITHEN
             SENIOR VICE PRESIDENT, GENERAL COUNSEL AND SECRETARY
                         CADENCE DESIGN SYSTEMS, INC.
           2655 SEELY AVENUE, BUILDING 5, SAN JOSE, CALIFORNIA 95134
                                (408) 943-1234
           (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER,
                  INCLUDING AREA CODE, OF AGENT FOR SERVICE)
 
                                  COPIES TO:
           KENNETH R. LAMB                            LARRY SONSINI
         GREGORY J. CONKLIN                        HERBERT P. FOCKLER
     GIBSON, DUNN & CRUTCHER LLP            WILSON SONSINI GOODRICH & ROSATI
ONE MONTGOMERY STREET, TELESIS TOWER               650 PAGE MILL ROAD
   SAN FRANCISCO, CALIFORNIA 94104             PALO ALTO, CALIFORNIA 94303
           (415) 393-8200                            (650) 493-9300
 
                        CALCULATION OF REGISTRATION FEE
<TABLE>
- ------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------
<CAPTION>
                                                                PROPOSED
                                                 PROPOSED        MAXIMUM
                                                  MAXIMUM       AGGREGATE
    TITLE OF EACH CLASS OF      AMOUNT TO BE  OFFERING PRICE    OFFERING          AMOUNT OF
SECURITIES TO BE REGISTERED(1)  REGISTERED(2)   PER SHARE       PRICE(3)     REGISTRATION FEE(3)
- ------------------------------------------------------------------------------------------------
<S>                             <C>           <C>            <C>             <C>
        Common Stock,
         par value
         $.01 per
         share......             11,800,000      $14.4375    $330,522,711.75     $91,885.31
- ------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------
</TABLE>
(1) Also includes associated Rights to purchase shares of the Registrant's
    common stock, which Rights are not currently separable from the shares of
    common stock and not currently exercisable.
(2) The number of shares to be registered pursuant to this Registration
    Statement is based upon the aggregate number of shares of Quickturn Design
    Systems, Inc. ("Quickturn") common stock, par value $.001 per share
    ("Quickturn Common Stock"), and the number of shares of Quickturn Common
    Stock issuable upon exercise of outstanding options and warrants to
    acquire shares of Quickturn Common Stock currently outstanding, multiplied
    by an assumed exchange ratio (representing a value of $14 per share of
    Quickturn Common Stock) of 0.58 shares of common stock, par value $.01 per
    share, of the Registrant ("Cadence Common Stock"), based on a per share
    price of Cadence Common Stock of approximately $25.
(3) The registration fee was computed pursuant to Rules 457(f) and 457(c)
    under the Securities Act of 1933, as amended (the "Securities Act"), based
    on the average of the high and low sales prices of Quickturn Common Stock,
    as reported by the Nasdaq National Market System on December 16, 1998.
 
  APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after the effective date of this Registration Statement and the
satisfaction or waiver of all other conditions to the Merger described in the
Proxy Statement/Prospectus.
 
  If the securities being registered on this form are being offered in
connection with the formation of a holding company and there is compliance
with General Instruction G, check the following box. [_]
 
                               ----------------
 
  THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT
SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS
REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH
SECTION 8(A) OF THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION,
ACTING PURSUANT TO SAID SECTION 8(A), MAY DETERMINE.
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
<PAGE>
 
                         QUICKTURN DESIGN SYSTEMS, INC.
                               55 W. TRIMBLE ROAD
                           SAN JOSE, CALIFORNIA 95131
 
                                                                          , 1999
 
Dear Stockholder:
 
  You are cordially invited to attend a Special Meeting of Stockholders of
Quickturn Design Systems, Inc. ("QUICKTURN") on      , 1999, at  .m., local
time (the "SPECIAL MEETING"). The Special Meeting will be held at Quickturn's
principal executive offices located at 55 W. Trimble Road, San Jose,
California. Your Board of Directors and management look forward to greeting
those stockholders able to attend in person.
 
  At the Special Meeting, you will be asked to consider and vote upon the
combination of Quickturn and Cadence Design Systems, Inc. ("CADENCE") through
the merger (the "MERGER") of CDSI Acquisition, Inc., a wholly-owned subsidiary
of Cadence ("MERGER SUB"), with and into Quickturn, pursuant to a merger
agreement, dated December 8, 1998, among Quickturn, Cadence and Merger Sub, as
amended on December 16, 1998 (the "MERGER AGREEMENT"). As a result, Quickturn
will become a wholly-owned subsidiary of Cadence.
 
  In the Merger, each share of Quickturn common stock will be converted into
$14 worth of Cadence common stock.
 
  The Merger is intended to constitute a tax-free reorganization. Quickturn
stockholders will incur no federal income tax as the result of the exchange of
Quickturn common stock for Cadence common stock.
 
  THE QUICKTURN BOARD OF DIRECTORS (THE "BOARD") UNANIMOUSLY (I) DEEMS THE
MERGER TO BE ADVISABLE, FAIR TO AND IN THE BEST INTERESTS OF QUICKTURN AND ITS
STOCKHOLDERS, (II) APPROVES AND ADOPTS THE MERGER AGREEMENT AND (III)
RECOMMENDS THAT QUICKTURN STOCKHOLDERS VOTE "FOR" THE APPROVAL OF THE MERGER
AGREEMENT AND THE CONSUMMATION OF THE MERGER.
 
  The Board has received a written opinion, dated December 8, 1998 (the "H&Q
OPINION"), from Hambrecht & Quist LLC, Quickturn's financial advisor, that, as
of such date, based upon and subject to the factors and assumptions set forth
in such written opinion, the consideration to be received by the holders of
Quickturn common stock pursuant to the Merger Agreement was fair from a
financial point of view. A copy of the H&Q Opinion is attached to the Proxy
Statement/Prospectus as Appendix C.
 
  The Merger Agreement and the consummation of the Merger must be approved by
the holders of a majority of the outstanding Quickturn common stock. Your vote
on this matter is very important. We urge you to review carefully the enclosed
material and to return your proxy card promptly.
 
  Whether or not you plan to attend the Special Meeting, please sign, date, and
return the enclosed proxy card promptly in the envelope provided. Your shares
will then be represented at the Special Meeting, and Quickturn will be able to
avoid the expense of further solicitation. If you attend the Special Meeting,
you may, at your discretion, withdraw your proxy and vote in person.
 
  On behalf of the Board, thank you for your cooperation and continued support.
 
                                          Sincerely,
 
                                          Keith R. Lobo
                                          President and Chief Executive
                                           Officer
<PAGE>
 
                         QUICKTURN DESIGN SYSTEMS, INC.
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
 
                           TO BE HELD ON      , 1999
 
TO THE STOCKHOLDERS OF
QUICKTURN DESIGN SYSTEMS, INC.:
 
  NOTICE IS HEREBY GIVEN that a Special Meeting of Stockholders of Quickturn
Design Systems, Inc., a Delaware corporation ("Quickturn"), will be held on
     ,  , 1999, at  .m., local time, at the principal executive offices of
Quickturn, 55 W. Trimble Road, San Jose, California, for the following
purposes:
 
    1. To consider and vote upon a proposal to adopt the Agreement and Plan
  of Merger, dated as of December 8, 1998, as amended on December 16, 1998
  (the "Merger Agreement"), by and among Quickturn, Cadence Design Systems,
  Inc., a Delaware corporation ("Cadence"), and CDSI Acquisition, Inc., a
  Delaware corporation and a wholly-owned subsidiary of Cadence ("Merger
  Sub"), pursuant to which, among other things, Merger Sub will merge with
  and into Quickturn upon the terms and subject to the conditions set forth
  in the Merger Agreement, as more fully described in the enclosed Proxy
  Statement/Prospectus.
 
    2. To consider and vote upon the postponement or adjournment of the
  Special Meeting in order to solicit additional votes to approve the Merger
  Agreement if the Secretary of the Special Meeting determines that there are
  not sufficient votes to approve the Merger Agreement.
 
  The close of business on      , 1999 has been fixed as the record date for
determining those stockholders entitled to vote at the special meeting of
Quickturn stockholders and any adjournments or postponements of the Special
Meeting. Accordingly, only stockholders of record on such date are entitled to
notice of, and to vote at, the Special Meeting and any adjournments or
postponements of the Special Meeting.
 
                                          By Order of the Board of Directors
 
                                          Raymond K. Ostby
                                          Vice President Finance and
                                          Administration, Chief Financial
                                          Officer and Secretary
 
       , 1999
 
  WHETHER OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING IN PERSON, PLEASE
COMPLETE, DATE, SIGN AND RETURN THE ENCLOSED PROXY CARD IN THE ENCLOSED
ENVELOPE, WHICH REQUIRES NO POSTAGE IF MAILED IN THE UNITED STATES. IF YOU
ATTEND THE SPECIAL MEETING, YOU MAY VOTE IN PERSON IF YOU WISH, EVEN IF YOU
HAVE PREVIOUSLY RETURNED YOUR PROXY CARD.
 
  THE BOARD OF DIRECTORS OF QUICKTURN UNANIMOUSLY RECOMMENDS THAT STOCKHOLDERS
VOTE FOR ADOPTION OF THE MERGER AGREEMENT.
<PAGE>
 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY +
+NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE     +
+SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN    +
+OFFER TO SELL THESE SECURITIES AND IT IS NOT SOLICITING AN OFFER TO BUY THESE +
+SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.             +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
                                PROXY STATEMENT
                                       OF
                         QUICKTURN DESIGN SYSTEMS, INC.
 
                                  -----------
 
                                   PROSPECTUS
                                       OF
                          CADENCE DESIGN SYSTEMS, INC.
 
  Cadence Design Systems, Inc. and Quickturn Design Systems, Inc. have entered
into a merger agreement providing for a wholly-owned subsidiary of Cadence to
merge with Quickturn. After the merger, Quickturn will continue as the
surviving corporation and will be a wholly-owned subsidiary of Cadence.
Quickturn stockholders will receive $14 worth of Cadence common stock for each
outstanding share of Quickturn common stock (determined based on the average
closing price of Cadence common stock over a short period immediately prior to
the date the merger is completed).
 
  This Proxy Statement/Prospectus is being furnished to Quickturn stockholders
in connection with the solicitation by Quickturn's Board of Directors of
proxies for use at the special meeting of stockholders to be held at
Quickturn's principal executive offices located at 55 W. Trimble Road, San
Jose, California, at    .m., local time, on      ,   , 1999. At this meeting,
Quickturn stockholders will vote on the proposed merger. This Proxy
Statement/Prospectus also constitutes the prospectus of Cadence with respect to
the shares of Cadence common stock to be issued to Quickturn stockholders in
the merger.
 
  Share Information:
 
  Cadence ("CDN")New York Stock Exchange closing price on December 22, 1998:
$28.00
 
  Quickturn ("QKTN")Nasdaq National Market System
closing price on December 22, 1998: $14.625
 
  All information concerning Cadence contained in this Proxy
Statement/Prospectus has been furnished by Cadence, and all information
concerning Quickturn contained in this Proxy Statement/Prospectus has been
furnished by Quickturn. Quickturn stockholders are encouraged to read all
information contained in this Proxy Statement/Prospectus carefully and
understand it before they vote.
 
  SEE "RISK FACTORS" BEGINNING ON PAGE 16 FOR A DISCUSSION OF CERTAIN RISKS
THAT YOU SHOULD CONSIDER IN DETERMINING HOW TO VOTE UPON THE PROPOSED MERGER.
 
  NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED THE SECURITIES TO BE ISSUED IN THIS TRANSACTION OR
DETERMINED THAT THIS PROXY STATEMENT/PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
  THIS PROXY STATEMENT/PROSPECTUS IS DATED DECEMBER 23, 1998, AND IS FIRST
BEING MAILED TO QUICKTURN STOCKHOLDERS ON OR ABOUT      , 1999.
<PAGE>
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
SUMMARY....................................................................   3
RISK FACTORS...............................................................  16
  Risk Factors Relating to the Merger......................................  16
    Unsuccessful Integration of Business Operations........................  16
    Potentially Significant Integration Costs..............................  16
    Reduced Returns for Quickturn Stockholders.............................  16
    Tax Risks Associated with the Merger...................................  16
    Certain Accounting Issues..............................................  16
    Conflicts of Interest..................................................  17
    Unsolicited Tender Offer for Quickturn.................................  17
    Potential Volatility of Stock Price....................................  18
    Dependence on Key Quickturn Personnel..................................  18
    Conditions to the Closing of the Merger................................  18
    Risk of Failure to Complete Merger.....................................  19
  Risk Factors Relating to Cadence.........................................  19
    Rapid Technological Change; Dependence on New Products.................  19
    Fluctuations in Quarterly Results of Operations........................  19
    Cadence's Industry is Highly Competitive...............................  20
    Risks Relating to Design and Consulting Services Businesses............  20
    Risks Associated with Mergers and Acquisitions.........................  21
    Dependence on Key Personnel............................................  21
    Risks Relating to International Operations.............................  21
    Dependence on Proprietary Technology; Risks of Infringement............  22
    Risk of Failure to Obtain Export Licenses..............................  23
    Year 2000 Compliance Risk..............................................  23
    Stock Repurchase Program Risks.........................................  23
    Risks Relating to Anti-Takeover Defenses...............................  24
  Risk Factors Relating to Quickturn.......................................  24
    Risks of Fluctuations In Quarterly Results of Operations...............  24
    Customer Concentration.................................................  24
    New Product Transition.................................................  24
    International Sales....................................................  25
    Dependence Upon Certain Suppliers......................................  25
    Gross Margins..........................................................  26
    Quickturn's Industry is Highly Competitive.............................  26
    Year 2000 Compliance Risk..............................................  27
QUICKTURN SPECIAL MEETING..................................................  28
  General..................................................................  28
  Matters to be Considered.................................................  28
  Proxies..................................................................  28
  Solicitation of Proxies..................................................  28
  Record Date and Voting Rights............................................  28
  Recommendation of Quickturn Board........................................  29
THE MERGER.................................................................  30
  General..................................................................  30
  Background of the Merger.................................................  30
</TABLE>
 
                                       i
<PAGE>
 
<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<S>                                                                        <C>
  Recommendation of the Quickturn Board and Quickturn's Reasons for the
   Merger ................................................................  34
  Opinion of Quickturn's Financial Advisor................................  36
  The Merger..............................................................  40
  Conversion of Quickturn Stock; Treatment of Quickturn Stock Options and
   Warrants...............................................................  40
  Exchange of Certificates; Fractional Shares.............................  41
  Effective Time..........................................................  42
  Representations and Warranties..........................................  42
  Conduct of Business Pending the Merger and Other Agreements.............  42
  Conditions to Consummation of the Merger................................  46
  Regulatory Approvals Required for the Merger............................  48
  Material Federal Income Tax Consequences................................  49
  Accounting Treatment....................................................  50
  Termination of the Merger Agreement.....................................  51
  Extension, Waiver and Amendment of the Merger Agreement.................  53
  Employee Benefits and Plans.............................................  54
  Stock Exchange Listing..................................................  54
  Interests of Certain Persons in the Merger..............................  54
  Option Agreement........................................................  56
  Restrictions on Resales by Affiliates...................................  60
MANAGEMENT AFTER THE MERGER...............................................  62
PRICE RANGE OF COMMON STOCK...............................................  63
INFORMATION ABOUT CADENCE.................................................  64
  General.................................................................  64
  Management and Additional Information...................................  64
INFORMATION ABOUT QUICKTURN...............................................  65
  General.................................................................  65
  Management and Additional Information...................................  65
CADENCE CAPITAL STOCK AND COMPARISON OF STOCKHOLDER RIGHTS................  66
  Description of Cadence Capital Stock....................................  66
  Cadence Rights Plan.....................................................  67
  Comparison of Rights of Cadence Stockholders and Quickturn
   Stockholders...........................................................  69
DISSENTERS' APPRAISAL RIGHTS..............................................  73
LEGAL MATTERS.............................................................  73
EXPERTS...................................................................  73
STOCKHOLDER PROPOSALS.....................................................  73
OTHER MATTERS.............................................................  73
WHERE YOU CAN FIND MORE INFORMATION.......................................  74
UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION..............  77
<CAPTION>
<S>                                                                        <C>
APPENDICES
Appendix A Merger Agreement
Appendix B Option Agreement
Appendix C Opinion of Hambrecht & Quist
Appendix D Form of Proxy Card
</TABLE>
 
                                       ii
<PAGE>
 
  TO FIND ANY ONE OF THE PRINCIPAL SECTIONS IDENTIFIED BELOW, SIMPLY BEND THE
DOCUMENT SLIGHTLY TO EXPOSE THE BLACK TABS AND OPEN THE DOCUMENT TO THE TAB
WHICH CORRESPONDS TO THE TITLE OF THE SECTION YOU WISH TO READ. FOR YOUR
CONVENIENCE, WE HAVE INCLUDED AN INDEX OF FREQUENTLY USED CAPITALIZED TERMS IN
THIS PROXY STATEMENT/PROSPECTUS IN AN INDEX OF DEFINED TERMS, WHICH IS PRINTED
ON GOLD PAPER TOWARD THE BACK OF THIS PROXY STATEMENT/PROSPECTUS.
 
                                                               TABLE OF CONTENTS
 
                                                                         SUMMARY
 
                                                                    RISK FACTORS
 
                                                       QUICKTURN SPECIAL MEETING
 
                                                                      THE MERGER
 
                                                     MANAGEMENT AFTER THE MERGER
 
                                                       INFORMATION ABOUT CADENCE
 
                                                     INFORMATION ABOUT QUICKTURN
 
                                                     PRICE RANGE OF COMMON STOCK
 
                      CADENCE CAPITAL STOCK AND COMPARISON OF STOCKHOLDER RIGHTS
 
                                                    DISSENTERS' APPRAISAL RIGHTS
 
                                                                   LEGAL MATTERS
 
                                                                         EXPERTS
 
                                                           STOCKHOLDER PROPOSALS
 
                                                                   OTHER MATTERS
 
                                             WHERE YOU CAN FIND MORE INFORMATION
 
                                                           FINANCIAL INFORMATION
 
                                                          INDEX OF DEFINED TERMS
 
                                                                      APPENDICES
 
                                       2
<PAGE>
 
                                    SUMMARY
 
  This brief summary highlights selected information from the Proxy
Statement/Prospectus. It does not contain all of the information that is
important to you. We urge you to carefully read the entire Proxy
Statement/Prospectus and the other documents to which this document refers to
fully understand the merger. See "Where You Can Find More Information."
 
THE MERGER (PAGE 30)
 
  We've attached the merger agreement to this document as Appendix A. Please
read the merger agreement. It is the legal document that governs the merger.
 
 General
 
  We propose that Cadence and Quickturn combine by way of merging a wholly-
owned subsidiary of Cadence with Quickturn. After the merger is completed,
Quickturn will be a wholly-owned subsidiary of Cadence. We expect to complete
the merger no later than March 2, 1999.
 
 Exchange of Shares (page 41)
 
  At the effective time of the merger, each of your shares of Quickturn common
stock will automatically become the right to receive from Cadence $14 worth of
Cadence common stock. For this purpose, Cadence common stock will be valued at
the average closing price during the five trading days before the second
business day before the closing date of the merger.
 
  You will have to surrender your Quickturn common stock certificates to
receive new certificates representing Cadence common stock. You do not need to
do this, however, until you receive written instructions after we have
completed the merger.
 
 Quickturn Stock Options and Warrants (page 40)
 
  In the merger, each stock option and warrant to buy Quickturn common stock
will become an option or warrant, as applicable, to buy Cadence common stock.
Each option and warrant will continue to be governed by the terms of the
Quickturn stock option plan or other agreement under which it was issued. The
number of shares of Cadence common stock subject to each new stock option or
warrant, as well as the exercise price of that stock option or warrant, will be
adjusted to reflect the exchange ratio in the merger.
 
COMPARATIVE PER SHARE MARKET PRICE INFORMATION (PAGE 63)
 
  Shares of Cadence common stock are listed on the New York Stock Exchange. On
December 8, 1998, the last trading day before we announced the merger, Cadence
common stock closed at $30 per share. Shares of Quickturn common stock are
listed on the Nasdaq National Market System. On December 8, 1998, Quickturn
common stock closed at $12.188 per share. On December 22, 1998, Cadence common
stock closed at $28 per share, and Quickturn common stock closed at $14.625 per
share.
 
THE COMPANIES (PAGES 64 AND 65)
 
CADENCE DESIGN SYSTEMS, INC.
2655 Seely Avenue
San Jose, California 95134
(408) 943-1234
 
  Cadence provides software products and comprehensive design and consulting
services for the product development requirements of the world's leading
electronics companies. Cadence is the largest supplier of software products,
consulting services, and design services used to accelerate and manage the
design of semiconductors, computer systems, networking and telecommunications
equipment, consumer electronics and a variety of other electronic-based
products.
 
  With more than 4,400 employees as of December 17, 1998 and 1997 sales of $916
million, Cadence has sales offices, design centers and research facilities
around the world. Cadence is headquartered in San Jose, California.
 
                                       3
SUMMARY
<PAGE>
 
 
QUICKTURN DESIGN SYSTEMS, INC.
55 W. Trimble Road
San Jose, California 95131
(408) 914-6000
 
  Quickturn is a leading provider of emulation systems, cycle-based simulation
software and time-to-market engineering ("TTME"(TM)) services for the
verification of complex integrated circuits ("ICS") and electronic systems.
Quickturn's principal design verification products include the System
Realizer,(TM) Mercury Design Verification System(TM) and CoBALT(TM) (Concurrent
Broadcast Array Logic Technology) emulators, and SpeedSim(TM) cycle-based
simulation software. Quickturn's products serve the needs of IC and systems
design engineers in a variety of industries, including the microprocessor,
computer, workstation, PC, telecommunications and networking, multimedia, and
graphics industries.
 
  At December 1, 1998, Quickturn had approximately 400 employees and in 1997
had sales of $110 million. Quickturn's corporate headquarters are located in
San Jose, California.
 
THE QUICKTURN STOCKHOLDERS MEETING (PAGE 28)
 
  The Quickturn stockholders meeting will be held on     , 1999 at  :00  .m.,
local time, at 55 W. Trimble Road, San Jose, California. At the Quickturn
meeting, you will be asked:
 
  1. to adopt a merger agreement that provides for the merger of a wholly-
     owned subsidiary of Cadence with and into Quickturn; and
 
  2. to vote on the postponement or adjournment of the meeting to solicit
     additional votes to approve the merger agreement, if the secretary of
     the meeting decides that there are not enough votes to approve the
     merger agreement.
 
RECORD DATE; VOTE REQUIRED (PAGE 28)
 
  You can vote at the meeting of Quickturn stockholders if you owned Quickturn
common stock at the close of business on      , 1999. You can cast one vote for
each share of Quickturn common stock you owned at that time. To adopt the
merger agreement, the holders of a majority of shares of Quickturn common stock
allowed to vote at the meeting must vote in favor of doing so.
 
  You may vote your shares in person by attending the meeting or by mailing us
your proxy if you are unable or do not wish to attend. You can revoke your
proxy at any time before we take a vote at the meeting by sending a written
notice revoking the proxy or a later-dated proxy to the secretary of Quickturn,
or by attending the meeting and voting in person.
 
OUR REASONS FOR THE MERGER (PAGE 34)
 
  Cadence and Quickturn are proposing to merge because they believe that the
combined company will be stronger than either individually and, as such, will
provide significant benefits to their respective stockholders and customers.
 
  We believe that, as the complexity of chip design increases, the complexity
of design verification increases much more. By integrating Quickturn's
hardware-based emulation approach with Cadence's design and simulation systems,
we expect that the combined company will significantly improve its ability to
meet customer demand for faster development of high-speed systems on a chip.
 
  Cadence believes that the combination of the two companies furthers its
objectives for growing its business through acquisitions of complementary
businesses that have management depth and technical talent.
 
  For its part, Quickturn believes that a merger with Cadence will increase
value for its stockholders, employees and customers, and will allow Quickturn
to continue pursuing its business strategy. Quickturn believes that the merger
will yield for its stockholders an attractive price for their shares of
Quickturn common stock while enabling them to share in Cadence's growth over
the long term. The companies believe they can leverage Cadence's strong
international sales channels to make Quickturn's technology available to a
larger customer base than is currently the case.
(TM)TtME, System Realizer, Mercury Design Verification System, CoBALT and
SpeedSim are trademarks of Quickturn Design Systems, Inc.
 
                                       4
SUMMARY
<PAGE>
 
 
  The discussion of our reasons for the merger includes forward-looking
statements about possible or assumed future results of our operations and the
performance of the combined company after the merger. For a discussion of
factors that could affect these future results, see "Forward-Looking Statements
May Prove Inaccurate" on page 8.
 
 Management after the Merger (page 62)
 
  There will be no change in the current management of Cadence as a result of
the merger.
 
  Certain members of Quickturn's current management, including Keith R. Lobo,
Quickturn's President and Chief Executive Officer (who is also a director of
Quickturn), have signed employment and non-competition agreements providing for
them to remain with Quickturn, as part of Cadence, following the merger.
 
 Quickturn Board's Recommendation to Stockholders (page 34)
 
  The Quickturn Board of Directors believes that the merger is advisable, fair
to you and in your best interests, and unanimously recommends that you vote
"FOR" the proposal to adopt the merger agreement.
 
 Opinion of Quickturn's Financial Advisor (page 36)
 
  Hambrecht & Quist LLC has delivered its written opinion to Quickturn's Board
of Directors that, as of the date of the merger agreement, the consideration to
be received by Quickturn stockholders was fair to them from a financial point
of view. We have attached this opinion as Appendix C. You should read it
completely to understand the assumptions made, matters considered and
limitations of the review undertaken by Hambrecht & Quist in providing its
opinion.
 
  Upon completion of the merger, Quickturn will pay to Hambrecht & Quist a
total fee of approximately $2.95 million and reimburse Hambrecht & Quist for
its reasonable expenses relating to this engagement.
 
 Conditions to Completion of the Merger (page 46)
 
  The completion of the merger depends on a number of conditions being met.
These include:
 
  1. approval of the merger agreement by the Quickturn stockholders;
 
  2. receipt by each of us of opinions of our legal counsel relating to
     various corporate governance and other matters, as well as their
     opinions that, for United States federal income tax purposes, Cadence,
     the merger subsidiary, Quickturn and Quickturn's stockholders will not
     recognize any gain or loss as a result of the merger, except in
     connection with the payment of cash instead of fractional shares. These
     opinions will be subject to various limitations and, in particular, we
     recommend that you read the fuller description of tax consequences
     provided in this document beginning on page  ;
 
  3. receipt by each of us of a letter from our respective independent
     accountants that the merger will qualify for "pooling-of-interests"
     accounting treatment;
 
  4. approval by the New York Stock Exchange of the listing of the shares of
     Cadence common stock to be issued in the merger;
 
  5. receipt of all governmental approvals and consents, and all important
     consents from other third parties, necessary to complete the merger and
     operate Quickturn's business after the merger the way it was operated
     before the merger;
 
  6. subject to certain exceptions, the absence of any significant and
     adverse change in Quickturn's business;
 
  7. Keith R. Lobo, Quickturn's President and Chief Executive Officer, will
     continue his employment with Quickturn after completion of the merger;
 
  8. expiration of any applicable waiting period under the Hart-Scott-Rodino
     Antitrust Improvements Act of 1976; and
 
  9. absence of any injunction or other legal restraint blocking the merger.
 
                                       5
SUMMARY
<PAGE>
 
 
  Either Cadence or Quickturn could choose to complete the merger even though a
condition to its obligation to complete the merger has not been satisfied, as
long as the law allows it to do so. We can't be certain when, or if, the
conditions to the merger will be satisfied or waived, or that the merger will
be completed.
 
 Termination of the Merger Agreement; Liquidated Damages and Expenses (page 51)
 
  We can agree at any time prior to the completion of the merger to terminate
the merger agreement. Also, either of us can decide, without the consent of the
other, to terminate the merger agreement if:
 
  1. any court or U.S. governmental entity issues a final, non-appealable
     order blocking the merger;
 
  2. the merger has not been completed by June 30, 1999, unless the failure
     to complete the merger by that time is due to a violation of the merger
     agreement by the party that wants to terminate the agreement;
 
  3. the other company breaches the merger agreement, and the breaching
     company doesn't correct the breach promptly, as long as the party
     seeking to terminate has not itself materially breached the agreement;
     or
 
  4. Quickturn's stockholders do not approve the merger.
 
  In addition, Quickturn may terminate the merger agreement if, after
Quickturn's Board of Directors has received an unsolicited proposal from
another potential acquiror, the board decides in good faith, based upon advice
from legal counsel, that it must withdraw its recommendation of the merger with
Cadence in order to comply with its fiduciary duties under Delaware law. Under
these circumstances, however, Quickturn's Board of Directors must give Cadence
a chance at least to match the potential acquiror's proposal. Cadence may
terminate the merger agreement if Quickturn's Board of Directors withdraws or
adversely modifies its recommendation that Quickturn stockholders approve the
merger with Cadence or recommends that Quickturn stockholders approve another
competing transaction.
 
  Quickturn has agreed to pay Cadence liquidated damages of $10.557 million if
the merger agreement is terminated because (1) Quickturn fails to use all
reasonable efforts to convene a meeting of its stockholders to approve the
merger, (2) Quickturn stockholders do not approve the merger at the Quickturn
special meeting of stockholders called to vote on the merger at a time when
there is a competing proposal for the acquisition of Quickturn or any material
portion of its assets, (3) Quickturn's Board of Directors recommends a
competing proposal for the acquisition of Quickturn or any material portion of
its assets, withdraws or adversely modifies its recommendation that Quickturn
stockholders approve the merger with Cadence or recommends that Quickturn
stockholders approve any competing acquisition proposal, or (4) Quickturn has
breached any of its representations, warranties and covenants in the merger
agreement in a significant enough manner, and within twelve months after
termination of the merger agreement, Quickturn enters into an agreement with a
third party for the acquisition of a majority interest in Quickturn or of a
material portion of its assets.
 
  Upon termination of the merger agreement under certain circumstances, each of
us has agreed to reimburse the other for its costs and expenses related to the
merger in the amount of $3.5 million. Otherwise, whether or not the merger is
completed, we will each pay our own fees and expenses.
 
 Waiver and Amendment (page 53)
 
  We may jointly amend the merger agreement, and each of us may waive its right
to require the other to adhere to the terms and conditions of the merger
agreement. However, we may not do so after Quickturn stockholders approve the
merger, if the amendment or waiver reduces or changes the consideration that
will be received by Quickturn stockholders, unless they approve the amendment
or waiver.
 
 Accounting Treatment (page 50)
 
  We expect the merger to qualify as a "pooling-of-interests." This means that,
for accounting and financial reporting purposes, Cadence will treat our two
companies as if they have always been one company.
 
                                       6
SUMMARY
<PAGE>
 
 
 Regulatory Approvals (page 48)
 
  The merger is subject to the requirements of the Hart-Scott-Rodino Antitrust
Improvements Act of 1976. This law provides that certain transactions may not
be completed until the parties furnish required information and material to the
U.S. Department of Justice and Federal Trade Commission, and the specified
waiting period has expired or is terminated.
 
  We have filed all of the required applications or notices with these
regulatory authorities. However, as of the date of this Proxy
Statement/Prospectus, the required waiting period has not expired or been
terminated. While we don't know of any reason that the Department of Justice or
Federal Trade Commission would seek to prevent or delay the merger, we can't be
certain that they will not.
 
 Stock Option Agreement (page 56 and Appendix B)
 
  Quickturn entered into a stock option agreement granting Cadence an option to
purchase 3,619,100 shares of the Quickturn common stock under certain
circumstances. The maximum number of shares that can be purchased if the option
is exercised is 19.9% of the outstanding shares of Quickturn common stock. The
exercise price of the option is $14 per share. Under certain circumstances,
Cadence may require Quickturn to repurchase the option. In addition, under
certain circumstances, Quickturn may require Cadence to sell to Quickturn any
shares of Quickturn common stock received by Cadence upon its exercise of the
option.
 
  Cadence may not exercise its option unless certain events occur. These events
generally are business combinations or acquisition transactions relating to
Quickturn and certain related events, other than the merger we are proposing in
this Proxy Statement/Prospectus, such as a merger or the sale of a substantial
amount of assets or stock to a company other than Cadence or one of its
subsidiaries. We don't know of any event that has occurred as of the date of
this Proxy Statement/Prospectus that would allow Cadence to exercise its
option.
 
  Cadence is limited in the total value it may receive in connection with its
exercise of the option to $14.075 million, minus any amounts it receives as
liquidated damages (other than for expense reimbursements) upon termination of
the merger agreement. The number of shares subject to purchase upon exercise of
the option is subject to reduction to comply with this limitation.
 
 Interest of Quickturn's Officers in the Merger that Differ from Your Interest
(page 54)
 
  Some of Quickturn's officers have interests in the merger that differ from,
or are in addition to, their interests as stockholders of Quickturn. These
interests exist because of employment and non-competition agreements that
certain officers of Quickturn have entered into with Quickturn and Cadence, and
rights that the officers have under some of the benefit plans maintained by
Quickturn and Cadence. These employment and non-competition agreements and
plans will provide the officers with severance benefits if their employment
with Quickturn is terminated after the merger we are proposing or any other
acquisition of Quickturn. If the employment of the current President and Chief
Executive Officer and the other four most highly compensated officers of
Quickturn were terminated after the merger, the aggregate amount payable to
them would be approximately $4 million. In addition, after the merger, Cadence
will continue the indemnification arrangements for directors and officers of
Quickturn and its subsidiaries in effect prior to the merger. Also, subject to
certain exceptions, Quickturn will maintain a policy of directors' and
officers' liability insurance for at least six years after the merger for the
benefit of those persons who were directors or officers covered by liability
insurance immediately prior to the effective time of the merger.
 
  Additional interests of some of Quickturn's directors and executive officers
are described under "Management After the Merger."
 
  The members of the Quickturn Board of Directors knew about these interests,
and considered them, when they approved the merger agreement and the merger.
 
 Dissenters' Appraisal Rights (page 73)
 
  Delaware law does not provide you with dissenters' appraisal rights in the
merger.
 
                                       7
SUMMARY
<PAGE>
 
 
 Material Federal Income Tax Consequences to Quickturn Stockholders (page 49)
 
  We expect that, for United States federal income tax purposes, your exchange
of shares of Quickturn common stock for shares of Cadence common stock
generally will not cause you to recognize any gain or loss. You will, however,
have to recognize income or gain in connection with any cash you receive
instead of fractional shares.
 
  THIS TAX TREATMENT MAY NOT APPLY TO EVERY QUICKTURN STOCKHOLDER. DETERMINING
THE ACTUAL TAX CONSEQUENCES OF THE MERGER TO YOU MAY BE COMPLICATED. THEY WILL
DEPEND ON YOUR SPECIFIC SITUATION AND ON VARIABLES NOT WITHIN OUR CONTROL. YOU
SHOULD CONSULT YOUR OWN TAX ADVISOR FOR A FULL UNDERSTANDING OF THE MERGER'S
TAX CONSEQUENCES.
 
MATERIAL DIFFERENCES IN THE RIGHTS OF STOCKHOLDERS (PAGE 69)
 
  The rights of Cadence stockholders are governed by Delaware law and Cadence's
Certificate of Incorporation and By-Laws. The rights of Quickturn stockholders
are also governed by Delaware law and Quickturn's Certificate of Incorporation
and By-Laws. Upon our completing the merger, you will become stockholders of
Cadence, and your rights will be governed by Delaware law and by Cadence's
Certificate of Incorporation and By-Laws.
 
FORWARD-LOOKING STATEMENTS MAY PROVE INACCURATE (PAGE 16)
 
  We have each made forward-looking statements in this Proxy Statement
Prospectus (and in documents to which we refer you in this document) that are
subject to risks and uncertainties. These forward-looking statements include
information about possible or assumed future results of our operations or the
performance of the new company after the merger is completed. When we use any
of the words "believes," "expects," "anticipates," "estimates" or similar
expressions, we are making forward-looking statements. Many possible events or
factors could affect the future financial results and performance of each of
our companies and the new company after the merger and could cause those
results or performance to differ materially from those expressed in our
forward-looking statements. These possible events or factors include the
following:
 
  1. our revenues after the merger are lower than we currently expect;
 
  2. competition among companies in Cadence's and Quickturn's industries
     increases;
 
  3. we have more difficulty integrating our businesses or our other acquired
     businesses than we currently expect;
 
  4. general economic conditions in the U.S. or abroad change or are worse
     than we currently expect;
 
  5. legislative or regulatory changes adversely affect our business;
 
  6. customers' financial conditions deteriorate or bankruptcies increase;
 
  7. technology-related changes, including "Year 2000" data systems
     compliance, are harder to make or more expensive than we currently
     expect;
 
  8. changes occur in the securities markets;
 
  9. a significant new competitor may emerge; and
 
  10. proprietary intellectual property rights or patents may be infringed or
      appropriated.
 
                                       8
SUMMARY
<PAGE>
 
UNAUDITED COMPARATIVE PER COMMON SHARE DATA
 
  The following table shows information about our historical income per common
share and book value per share, and similar information reflecting the
completion of our proposed merger (which we refer to as "pro forma"
information). In presenting the comparative pro forma information for certain
time periods, we assumed that we had been one company throughout those periods
(a method known as "pooling-of-interests" accounting).
 
  The information listed as "equivalent pro forma" was obtained by multiplying
the pro forma amounts by an assumed exchange ratio of 0.46 to 1.0. We present
this information to reflect the fact that Quickturn stockholders will receive a
number of shares of Cadence common stock equal to $14 for each share of
Quickturn common stock exchanged in the merger. The pro forma information,
while helpful in illustrating the financial characteristics of the new company
under one set of assumptions, does not reflect these expenses or benefits and,
accordingly, doesn't attempt to predict or suggest future results. It also
doesn't necessarily reflect what the historical results of the combined company
would have been had our companies been actually combined during the periods
presented.
 
  The information in the following table is based on, and should be read
together with, the historical financial information that we've presented in our
prior Securities and Exchange Commission filings and the "Unaudited Pro Forma
Condensed Combined Financial Information" on page 77. We have incorporated the
historical financial information into this document by reference. See "Where
You Can Find More Information" on page 74.
 
                                       9
SUMMARY
<PAGE>
 
                  UNAUDITED COMPARATIVE PER COMMON SHARE DATA
                            OF CADENCE AND QUICKTURN
 
<TABLE>
<CAPTION>
                                             FOR THE
                                           NINE MONTHS  FOR THE FISCAL YEARS
                                              ENDED      ENDED DECEMBER 31,
                                          SEPTEMBER 30, ----------------------
                                              1998       1997     1996   1995
                                          ------------- -------  ------ ------
<S>                                       <C>           <C>      <C>    <C>
HISTORICAL QUICKTURN
Net income (loss) per common share--
 basic...................................    $(0.45)    $ (0.31) $ 0.87 $ 0.81
Net income (loss) per common share--
 diluted.................................     (0.45)      (0.31)   0.79   0.74
Book value per common share(1)...........      4.70        5.22     --     --
</TABLE>
 
 
<TABLE>
<CAPTION>
                                 FOR THE
                               NINE MONTHS      FOR THE FISCAL YEARS ENDED
                                  ENDED    ------------------------------------
                               OCTOBER 3,  JANUARY 3, DECEMBER 28, DECEMBER 30,
                                  1998        1998        1996         1995
                               ----------- ---------- ------------ ------------
<S>                            <C>         <C>        <C>          <C>
HISTORICAL CADENCE(2)
Net income (loss) per common
 share--basic................    $(0.72)     $0.87       $0.19        $0.59
Net income (loss) per common
 share-- diluted.............     (0.72)      0.77        0.16         0.51
Book value per common
 share(1)....................      2.78       3.50         --           --
PRO FORMA COMBINED PER CA-
 DENCE SHARE(3)
Net income per common share--
 basic.......................      0.21       0.82        0.26         0.64
Net income per common share--
 diluted.....................      0.19       0.73        0.22         0.55
Book value per common
 share(1)....................      3.02        --          --           --
EQUIVALENT PRO FORMA COMBINED
 PER QUICKTURN SHARE(3)(4)
Net income per common share--
 basic.......................      0.10       0.38        0.12         0.29
Net income per common share--
 diluted.....................      0.09       0.34        0.10         0.25
Book value per common
 share(1)....................      1.39        --          --           --
</TABLE>
- --------
(1) The historical book value per common share is computed by dividing total
    stockholders' equity by the number of shares of common stock outstanding at
    the end of the period. The pro forma book value per common share is
    computed by dividing pro forma stockholders' equity by the pro forma number
    of shares of Cadence common stock outstanding as of October 3, 1998.
(2) Gives effect to all splits of Cadence common stock, including the two-for-
    one split effected in October 1997, and three-for-two splits effected in
    May 1996 and October 1995.
(3) Pro forma combined per share information for 1998 and 1997 also reflects
    the pro forma effects of the acquisition by Cadence of Ambit Design
    Systems, Inc. which was consummated in the quarter ended October 3, 1998.
(4) The equivalent pro forma amounts are computed by multiplying the related
    pro forma amounts for Cadence by a factor of 0.46 to reflect an assumed
    exchange ratio in the merger.
 
                                       10
SUMMARY
<PAGE>
 
SELECTED FINANCIAL DATA
 
  The following tables show summarized historical financial data for each of us
and also show similar pro forma information reflecting the completion of our
proposed merger. The pro forma information reflects the "pooling-of-interests"
method of accounting.
 
  The pro forma information, while helpful in illustrating the financial
characteristics of the combined company under one set of assumptions, doesn't
reflect these expenses or benefits and, accordingly, doesn't attempt to predict
or suggest future results. It also doesn't necessarily reflect what the
historical results of the combined company would have been had our companies
actually been combined during the periods presented.
 
  The information in the following tables is based on historical financial
information that we've presented in our prior Securities and Exchange
Commission filings. You should read all of the summary financial information we
provide in the following tables in connection with this historical financial
information and with the more detailed financial information we provide in this
document, which you can find beginning on page 77. This historical financial
information has also been incorporated into this document by reference. See
"Where You Can Find More Information" on page 74. Cadence's audited historical
financial statements were audited by Arthur Andersen LLP and Quickturn's
audited historical financial statements were audited by PricewaterhouseCoopers
LLP, each independent public accountants.
 
                                       11
SUMMARY
<PAGE>
 
    SELECTED CONSOLIDATED HISTORICAL FINANCIAL DATA OF CADENCE AND QUICKTURN
 
                          CADENCE DESIGN SYSTEMS, INC.
 
<TABLE>
<CAPTION>
                          FOR THE NINE MONTHS ENDED                         FOR THE FISCAL YEARS ENDED
                          ------------------------------  --------------------------------------------------------------
                          OCTOBER 3,      SEPTEMBER 27,   JANUARY 3, DECEMBER 28, DECEMBER 30, DECEMBER 30, DECEMBER 30,
                             1998              1997          1998        1996         1995         1994         1993
                          -------------   --------------  ---------- ------------ ------------ ------------ ------------
                                                      ($000S, EXCEPT PER SHARE AMOUNTS)
<S>                       <C>             <C>             <C>        <C>          <C>          <C>          <C>
STATEMENT OF OPERATIONS
 DATA
Revenue.................  $     870,618     $    632,881  $ 915,893    $741,459     $548,418     $429,072     $368,623
Expenses(1).............        971,219          482,608    681,886     650,200      430,558      385,025      377,038
Income (loss) before
 income taxes and
 cumulative effect of
 change in accounting
 method.................        (94,078)         172,670    259,631      90,477      135,097       48,863      (12,779)
Provision for income
 taxes..................         57,776           51,801     77,889      61,439       37,827       12,215          --
Net income (loss)(2)....       (151,854)         120,869    169,466      29,038       97,270       36,648      (12,779)
PER COMMON SHARE DATA(2)
Net income (loss):
 Basic..................          (0.72)            0.63       0.87        0.19         0.59         0.20        (0.07)
 Diluted................          (0.72)            0.56       0.77        0.16         0.51         0.19        (0.07)
BALANCE SHEET DATA
At period end:
 Total assets...........      1,183,222          934,979  1,023,850     717,001      374,035      361,048      339,301
 Long-term debt.........          1,461            1,829      1,599      20,292        1,619        2,098        4,001
 Total stockholders'
  equity................        590,432          665,480    727,097     427,548      134,081      176,063      206,122
</TABLE>
- --------
(1) Expenses include the following unusual items:
 
<TABLE>
<CAPTION>
                          FOR THE NINE MONTHS ENDED                FOR THE FISCAL YEARS ENDED
                          ----------------------------- -------------------------------------------------
                          OCTOBER 3,     SEPTEMBER 27,  JANUARY 3, DECEMBER 28, DECEMBER 30, DECEMBER 30,
                             1998             1997         1998        1996         1994         1993
                          -------------  -------------- ---------- ------------ ------------ ------------
                                                            ($000S)
<S>                       <C>            <C>            <C>        <C>          <C>          <C>
Write-off of in-process
 technology.............  $     339,500     $     4,860  $ 6,571     $ 95,700     $ 4,653      $    --
Restructuring charges...         24,790          29,254   34,417        2,119          --       13,450
Write-off of capitalized
 software development
 costs..................             --              --    3,065        2,724          --           --
Loss from operations of
 disposed division......             --              --       --           --          --        6,200
Provision for settlement
 of litigation..........             --              --       --           --      10,054           --
                          -------------     -----------  -------     --------     -------      -------
                              $ 364,290     $    34,114  $44,053     $100,543     $14,707      $19,650
                          =============     ===========  =======     ========     =======      =======
</TABLE>
 
  During the nine months ended October 3, 1998, Cadence wrote off approximately
$339.5 million of in-process technology that had not yet reached technological
feasibility and has no alternative future use in conjunction with its
acquisitions of Ambit, Bell Lab's Integrated Circuit Design Automation Group,
Symbionics Group Limited, and Excellent Design, Inc. Cadence also recorded
restructuring costs of approximately $24.8 million associated with its services
organization and the consolidation of facilities.
 
  In 1997, Cadence incurred restructuring charges of $34.4 million ($29.3
million for the nine months ended September 27, 1997) for the reduction of
personnel whose duties were made redundant, closure of duplicated and excess
facilities, fees of financial advisors, attorneys, and accountants, and other
expenses associated with its merger with Cooper and Chyan Technology, Inc.
("CCT") and its acquisition of High Level Design Systems, Inc. ("HLDS"). In
addition, Cadence wrote off approximately $6.6 million ($4.9 million for the
nine months ended September 27, 1997) of in-process technology that had not yet
reached technological feasibility and has no alternative future use in
conjunction with its acquisitions of Synthesia AB and certain assets of
Advanced Microelectronics. Cadence also wrote off capitalized software
development costs of $3.1 million for products developed by Cadence which were
replaced by CCT products or by license of replacement technology.
 
  In 1996, Cadence wrote off approximately $95.7 million of in-process
technology that had not yet reached technological feasibility and has no
alternative future use in conjunction with its acquisition of HLDS. Also
included in this write off was $2.7 million of capitalized software development
costs for products developed by Cadence which were replaced by HLDS products,
as well as $2.1 million of restructuring charges consisting of employee
termination costs and costs associated with excess facilities.
 
                                       12
SUMMARY
<PAGE>
 
 
  There were no unusual items in 1995.
 
  In 1994, Cadence entered into agreements to settle two class action lawsuits
for a combined settlement of $16.5 million, of which approximately $7.5 million
was covered by Cadence's insurance carriers. Reflected in Cadence's operating
expenses is the net settlement cost of approximately $9.0 million plus
approximately $1.0 million for related legal costs. In addition, Cadence wrote
off approximately $4.7 million of in-process technology that had not yet
reached technological feasibility and has no alternative future use in
conjunction with its acquisition of Redwood Design Automation, Inc.
 
  In 1993, Cadence sold its Automated Systems division. Cadence has classified
the respective income and loss from operations of the disposed division as
unusual items within operations. The loss of $6.0 million on disposal of the
division is included in net income (loss) in the fiscal year ended December 30,
1993.
 
(2)In addition to the unusual items discussed above, net income (loss) and net
income (loss) per common share, basic and diluted, includes a $9.2 million and
a $13.6 million after tax gain on the sale of stock of a subsidiary in the
periods ended January 3, 1998 and December 30, 1995, respectively, and $3.1
million after tax gain on the sale of an equity investment in the year ended
December 30, 1994.
 
                         QUICKTURN DESIGN SYSTEMS, INC.
 
<TABLE>
<CAPTION>
                               FOR THE
                          NINE MONTHS ENDED
                            SEPTEMBER 30,      FOR THE FISCAL YEARS ENDED DECEMBER 31,
                          ------------------  -------------------------------------------
                            1998      1997      1997      1996    1995     1994    1993
                          --------  --------  --------  -------- -------  ------- -------
                                       ($000S, EXCEPT PER SHARE AMOUNTS)
<S>                       <C>       <C>       <C>       <C>      <C>      <C>     <C>
STATEMENT OF OPERATIONS
 DATA(1)
Revenue.................  $ 73,089  $ 77,904  $110,404  $109,578 $82,442  $65,523 $54,865
Expenses................    88,949    95,926   123,870    91,605  71,357   61,469  59,258
Income (loss) before
 income taxes...........   (13,639)  (16,476)  (11,291)   19,852  11,866    5,002  (4,488)
Income tax expense
 (benefit)..............    (5,592)   (7,552)   (5,945)    5,721    (612)     401     868
Net income (loss).......    (8,047)   (8,924)   (5,346)   14,131  12,478    4,601  (5,356)
PER COMMON SHARE DATA(1)
Net income (loss):
 Basic..................     (0.45)    (0.53)    (0.31)     0.87    0.81     0.36   (0.96)
 Diluted................     (0.45)    (0.53)    (0.31)     0.79    0.74     0.32   (0.96)
BALANCE SHEET DATA
At period end:
 Total assets...........   118,070   116,577   129,192   111,977  94,240   77,349  56,199
 Long-term debt.........        --        --        --        --   3,701    3,819   3,487
 Total stockholders'
  equity................    84,856    87,508    91,898    84,045  66,337   49,895  38,296
</TABLE>
- --------
(1) The 1997 results include one-time acquisition and merger related charges of
    $19.2 million net of tax.
 
                                       13
SUMMARY
<PAGE>
 
  SELECTED UNAUDITED PRO FORMA FINANCIAL DATA OF CADENCE, AMBIT AND QUICKTURN
 
  The following table sets forth the unaudited selected pro forma combined
financial data of Cadence, Ambit Design Systems, Inc. ("AMBIT") and Quickturn.
The unaudited pro forma combined balance sheet has been prepared as if our
proposed merger, which will be accounted for as a pooling-of-interests by
Cadence, had been consummated as of October 3, 1998. The unaudited pro forma
combined statement of operations data for the nine months ended October 3,
1998, and for the fiscal year ended January 3, 1998, gives effect to both the
acquisition of Ambit and our proposed merger as if both transactions had been
completed at the beginning of the periods presented. The unaudited pro forma
combined statement of operations data for the fiscal years ended December 28,
1996 and December 30, 1995, gives effect to our proposed merger as if it had
been completed at the beginning of the periods presented. The unaudited
selected pro forma combined financial data is derived from the unaudited Pro
Forma Condensed Combined Financial Statements and notes thereto included
elsewhere in this Proxy Statement/Prospectus and should be read in conjunction
with such unaudited pro forma condensed combined financial statements and notes
thereto.
 
  The unaudited selected pro forma combined financial data is provided for
illustrative purposes only and is not necessarily indicative of the combined
financial position or combined results of operations that would have been
reported had these transactions actually occurred on the dates indicated, nor
does it represent a forecast of the combined financial position or results of
operations for any future period. No pro forma adjustments have been included
herein which reflect potential effects of (i) the efficiencies which may be
obtained by combining the operations of Cadence, Ambit and Quickturn or (ii)
the costs of restructuring, integrating or consolidating such operations.
 
  See "Where You Can Find More Information" and "Unaudited Pro Forma Condensed
Combined Financial Information."
 
<TABLE>
<CAPTION>
                                  FOR THE
                                NINE MONTHS      FOR THE FISCAL YEARS ENDED
                                   ENDED    ------------------------------------
                                OCTOBER 3,  JANUARY 3, DECEMBER 28, DECEMBER 30,
                                   1998        1998        1996         1995
                                ----------- ---------- ------------ ------------
                                       ($000S, EXCEPT PER SHARE AMOUNTS)
<S>                             <C>         <C>        <C>          <C>
STATEMENT OF OPERATIONS DATA
 Revenues.....................  $  954,523  $1,029,210   $851,037     $630,860
 Expenses(1)..................     866,761     821,362    741,805      501,915
 Income before provision for
  income taxes................      96,941     235,941    110,329      146,963
 Provision for income taxes...      50,644      69,858     67,160       37,215
 Net income(2)(3).............      46,297     166,083     43,169      109,748
PER COMMON SHARE DATA(2)(3)
Net income (loss) before
 cumulative effect of a change
 in accounting method:
 Basic........................        0.21        0.82       0.26         0.64
 Diluted......................        0.19        0.73       0.22         0.55
<CAPTION>
                                   AS OF
                                OCTOBER 3,
                                   1998
                                -----------
                                  ($000S)
<S>                             <C>         <C>        <C>          <C>
BALANCE SHEET DATA
At period end:
 Total assets.................  $1,301,292
 Long-term debt...............       1,461
 Total stockholders' equity...     665,288
</TABLE>
 
                                       14
SUMMARY
<PAGE>
 
- --------
(1) Expenses include the following unusual items:
 
<TABLE>
<CAPTION>
                          FOR THE NINE MONTHS ENDED                FOR THE FISCAL YEARS ENDED
                          ----------------------------- -------------------------------------------------
                          OCTOBER 3,     SEPTEMBER 27,  JANUARY 3, DECEMBER 28, DECEMBER 30, DECEMBER 30,
                             1998             1997         1998        1996         1994         1993
                          -------------  -------------- ---------- ------------ ------------ ------------
                                                            ($000S)
<S>                       <C>            <C>            <C>        <C>          <C>          <C>
Write-off of in-process
 technology.............  $     339,500     $     4,860  $ 6,571     $ 95,700     $ 4,653      $    --
Restructuring charges...         24,790          29,254   34,417        2,119          --       13,450
Write-off of capitalized
 software development
 costs..................             --              --    3,065        2,724          --           --
Loss from operations of
 disposed division......             --              --       --           --          --        6,200
Provision for settlement
 of litigation..........             --              --       --           --      10,054           --
                          -------------     -----------  -------     --------     -------      -------
                              $ 364,290     $    34,114  $44,053     $100,543     $14,707      $19,650
                          =============     ===========  =======     ========     =======      =======
</TABLE>
  During the nine months ended October 3, 1998, Cadence wrote off approximately
$339.5 million of in-process technology that had not yet reached technological
feasibility and has no alternative future use in conjunction with its
acquisitions of Ambit, Bell Lab's Integrated Circuit Design Automation Group,
Symbionics Group Limited, and Excellent Design, Inc. Cadence also recorded
restructuring costs of approximately $24.8 million associated with its services
organization and the consolidation of facilities.
 
  In 1997, Cadence incurred restructuring charges of $34.4 million ($29.3
million for the nine months ended September 27, 1997) for the reduction of
personnel whose duties were made redundant, closure of duplicated and excess
facilities, fees of financial advisors, attorneys, and accountants, and other
expenses associated with its merger with Cooper and Chyan Technology, Inc.
(CCT) and its acquisition of High Level Design Systems, Inc. (HLDS). In
addition, Cadence wrote off approximately $6.6 million ($4.9 million for the
nine months ended September 27, 1997) of in-process technology that had not yet
reached technological feasibility and has no alternative future use in
conjunction with its acquisitions of Synthesia AB and certain assets of
Advanced Microelectronics. Cadence also wrote off capitalized software
development costs of $3.1 million for products developed by Cadence which were
replaced by CCT products or by license of replacement technology.
 
  In 1996, Cadence wrote off approximately $95.7 million of in-process
technology that had not yet reached technological feasibility and has no
alternative future use in conjunction with its acquisition of HLDS. Also
included in this write-off was $2.7 million of capitalized software development
costs for products developed by Cadence which were replaced by HLDS products,
as well as $2.1 million of restructuring charges consisting of employee
termination costs and costs associated with excess facilities.
 
  There were no unusual items in 1995.
 
  In 1994, Cadence entered into agreements to settle two class action lawsuits
for a combined settlement of $16.5 million, of which approximately $7.5 million
was covered by Cadence's insurance carriers. Reflected in Cadence's operating
expenses is the net settlement cost of approximately $9.0 million plus
approximately $1.0 million for related legal costs. In addition, Cadence wrote
off approximately $4.7 million of in-process technology that had not yet
reached technological feasibility and has no alternative future use in
conjunction with its acquisition of Redwood Design Automation, Inc.
 
  In 1993, Cadence sold its Automated Systems division. Cadence has classified
the respective income and loss from operations of the disposed division as
unusual items within operations. The loss of $6.0 million on disposal of the
division is included in net income (loss) in the fiscal year ended December 30,
1993.
 
  (2) In addition to the unusual items discussed above, net income and net
income per common share, basic and diluted, includes a $9.2 million and a $13.6
million after tax gain on the sale of stock of a subsidiary in the periods
ended January 3, 1998 and December 30, 1995, respectively, and $3.1 million
after tax gain on the sale of an equity investment in the year ended December
30, 1994.
 
  (3) Net income and net income per common share, basic and diluted, for the
fiscal year ended January 3, 1998 excludes the cumulative effect of change in
accounting method for Cadence totalling $12.3 million net of tax.
 
                                       15
SUMMARY
<PAGE>
 
                                  RISK FACTORS
 
  Quickturn stockholders should carefully consider the following risk factors
in deciding whether to approve the merger. Quickturn stockholders should
consider these risk factors, together with the other information included and
incorporated by reference in this Proxy Statement/Prospectus.
 
RISK FACTORS RELATING TO THE MERGER
 
 Unsuccessful Integration of Business Operations
 
  Cadence and Quickturn expect that the merger will benefit both companies and
their respective stockholders. However, integrating the operations of Cadence
with those of Quickturn after the merger may be difficult and time consuming.
After the merger has been completed, Cadence must successfully integrate, among
other things, the product and service offerings, the product development, sales
and marketing, research and development, administrative and customer service
functions, and the management information systems of Quickturn with those of
Cadence. In addition, Cadence will need to retain the management, key
employees, customers, distributors, vendors and other business partners of both
companies. In this regard, Quickturn's President and Chief Executive Officer,
Keith R. Lobo, five other Quickturn officers and one other employee have signed
employment and non-competition agreements with Cadence. Their agreements will
be effective at the effective time of the merger. See "Management After the
Merger." The integration of the combined company may temporarily distract
management from the day-to-day business of Cadence and Quickturn following the
merger. Cadence and Quickturn may fail to manage this integration and to
achieve any of the anticipated benefits that both companies hope will result
from the merger.
 
 Potentially Significant Integration Costs
 
  Cadence expects to incur restructuring and integration costs in connection
with the integration of Quickturn's operations with those of Cadence. These
costs may be substantial and may include costs for employee severance,
facilities closures, relocation and disposition of excess equipment and other
merger-related costs. Cadence has not yet determined the amount of these costs.
Cadence expects to charge these costs to operations in the quarter in which the
merger is completed which will hurt Cadence's operating results in that
quarter.
 
 Reduced Returns for Quickturn Stockholders
 
  Quickturn stockholders may receive a lower return on their investment after
the merger than if the merger does not occur. Although Cadence and Quickturn
believe that the merger will result in operating and strategic benefits for the
combined company and its stockholders, these benefits may not be achieved. The
combination of Cadence's and Quickturn's businesses, even if conducted in an
efficient, effective and timely manner, may not result in combined operating
results and financial condition that are better than what each company would
have achieved independently if the merger had not occurred. In addition, the
issuance of Cadence common stock in the merger could reduce the market price of
Cadence common stock.
 
 Tax Risks Associated with the Merger
 
  Cadence and Quickturn intend the merger to constitute a tax-free
reorganization. As such, the merger will generally be tax-free to Quickturn
stockholders. However, Cadence and Quickturn have not requested or obtained a
ruling from the Internal Revenue Service. Therefore, there is a risk that the
merger may not constitute a tax free reorganization, in which case any gain
Quickturn stockholders realize as a result of the merger may be subject to tax.
See "The Merger--Material Federal Income Tax Consequences."
 
 Certain Accounting Issues
 
  Both Cadence and Quickturn have completed recent acquisitions which have been
accounted for under the purchase method of accounting. In connection with these
acquisitions, the companies recorded charges
 
                                       16
RISK FACTORS
<PAGE>
 
to earnings for acquired in-process research and development. Under the
purchase method of accounting, an acquiror must record on its balance sheet a
long-term asset called "goodwill" in an amount equal to the excess of the
purchase price paid over the fair market value of the assets of the acquired
business. Goodwill must be amortized over its estimated economic life, which
has the effect of reducing the acquiror's reported earnings during that
period. Recently, the Securities and Exchange Commission has begun to review
more critically than before and, in a number of cases, challenge the basis for
valuing in-process research and development charges. In these cases, the
Securities and Exchange Commission has claimed that acquirors are expensing
too large an amount that should otherwise be recorded as goodwill, resulting
in higher reported future earnings than would otherwise be the case. If
Cadence or Quickturn is required to restate its historical financial
statements to record as goodwill amounts that had been previously written off
as in-process research and development, the effect of such restatement would
be to reduce subsequent reported earnings (including earnings reported after
the date of this Proxy Statement/Prospectus) as this goodwill is amortized.
 
 Conflicts of Interest
 
  In considering the recommendation of the Quickturn Board of Directors to
approve the merger, Quickturn stockholders should recognize that some of
Quickturn's directors and officers have interests in the merger that differ
from, or are in addition to, their interests as Quickturn stockholders. These
interests include employment arrangements and potential severance benefits.
These and additional interests are described under the headings "The Merger--
Interests of Certain Persons in the Merger" and "Management After the Merger."
 
 Unsolicited Tender Offer for Quickturn
 
  On August 12, 1998, a wholly-owned subsidiary of Mentor Graphics Corporation
("MENTOR") initiated an unsolicited tender offer to purchase all outstanding
shares of Quickturn common stock for $12.125 per share. The tender offer is
currently scheduled to remain open to Quickturn stockholders until January 11,
1999. In addition, a special meeting of Quickturn stockholders is currently
scheduled to convene on January 8, 1999 for the purpose of voting on Mentor's
proposal to remove all members of the Quickturn Board of Directors and replace
them with new directors nominated by Mentor. Record holders of Quickturn
common stock on November 10, 1998, will be entitled to vote at this meeting.
The Quickturn Board of Directors has determined that Mentor's tender offer is
not in the best interests of Quickturn or Quickturn stockholders. See "The
Merger--Background of the Merger." The tender offer has had, and it may
continue to have, various adverse effects on Quickturn's business and results
of operations, including:
 
  . The increased risk that key employees will leave Quickturn;
 
  . Reactions among distributors, suppliers or customers to the prospect of
    Quickturn being taken over by Mentor;
 
  . The distraction of management and other key employees from the day-to-day
    business of Quickturn; and
 
  . The fees and expenses of financial, legal and other advisors in
    responding to the tender offer and related matters.
 
  On December 15, 1998, Mentor filed suit against Quickturn, the Quickturn
Board of Directors and Cadence in the Delaware Chancery Court alleging, among
other things, that the Quickturn Board of Directors violated its fiduciary
duty to Quickturn stockholders in approving the merger and that Cadence aided
and abetted this violation, and that certain terms of the merger agreement and
option agreement, including the "no shop" and liquidated damages provisions,
violate Delaware law. If Mentor prevails in its claims, there is a risk that
our merger will not be completed.
 
 
                                      17
RISK FACTORS
<PAGE>
 
 Potential Volatility of Stock Price
 
  The trading price of Cadence common stock has fluctuated significantly in
the past. The future trading price of Cadence common stock is likely to be
highly volatile and could be subject to wide price fluctuations in response to
such factors as:
 
  . Actual or anticipated fluctuations in revenues or operating results;
 
  . Failure to meet securities analysts' expectations of performance;
 
  . Announcements of technological innovations or new products by Cadence or
    its competitors;
 
  . Developments in or disputes regarding patents and other proprietary
    rights;
 
  . Proposed and completed acquisitions by Cadence or its competitors;
 
  . The mix of products and services sold;
 
  . The timing of significant orders from and shipments to customers;
 
  . Product and services pricing, discounts and margins; and
 
  . General economic conditions.
 
  Moreover, the stock market in general has experienced extreme price and
volume fluctuations that are often unrelated or disproportionate to the
operating performance of publicly-traded companies. These broad market
fluctuations, as well as general economic, political and market conditions,
may hurt the market price of Cadence common stock. We cannot predict what the
market price of Cadence common stock will be after the merger.
 
 Dependence on Key Quickturn Personnel
 
  The merger could lead to the loss of certain key Quickturn personnel.
Certain Quickturn officers and one other employee have signed employment and
non-competition agreements with Cadence, but Quickturn's contribution to the
combined company's success will depend in part on the continued service of key
groups of other Quickturn personnel. If a substantial portion of Quickturn's
research and development engineers, consulting engineers or manufacturing,
sales or customer support personnel leaves after we complete the merger,
Quickturn's business could be seriously harmed. Cadence currently has no
hardware manufacturing operations, so a loss of any of Quickturn's key
hardware manufacturing personnel in particular could seriously harm
Quickturn's business after the merger.
 
 Conditions to the Closing of the Merger
 
  The merger will not close unless several conditions are met, including:
 
  . Quickturn stockholders have approved the merger;
 
  . Quickturn has not experienced any material and adverse change in its
    business since the time Quickturn and Cadence signed the merger
    agreement;
 
  . Certain third parties have consented to the merger;
 
  . Keith R. Lobo, Quickturn's President and Chief Executive Officer, will
    continue his employment with Quickturn after completion of the merger;
 
  . Cadence and Quickturn have not materially breached any representations,
    warranties or covenants they made in the merger agreement;
 
  . Expiration of any applicable waiting period under the Hart-Scott-Rodino
    Antitrust Improvements Act of 1976;
 
  . There is no statute, order, decree or other legal restraint preventing
    consummation of the merger; and
 
  . Each of Cadence and Quickturn has received an opinion from its
    independent accountants to the effect that the merger will be accounted
    for as a "pooling-of-interests."
 
                                      18
RISK FACTORS
<PAGE>
 
 Risks of Failure to Complete Merger
 
  If the merger is not completed for any reason, Quickturn may be subject to a
number of material risks, including the following:
 
  . Quickturn may be required to pay liquidated damages of $10.557 million to
    Cadence;
 
  . The option granted to Cadence by Quickturn may become exercisable;
 
  . The price of Quickturn common stock may decline, assuming that current
    market prices for Quickturn common stock reflect a market assumption that
    the merger will be completed; and
 
  . Costs related to the merger, such as legal, accounting and financial
    advisory fees, must be paid even if the merger is not completed.
 
  Furthermore, if the merger agreement is terminated and Cadence exercises its
option to purchase Quickturn common stock, Quickturn may not be able to account
for a future transaction as a "pooling-of-interests."
 
RISK FACTORS RELATING TO CADENCE
 
 Rapid Technological Change; Dependence on New Products
 
  The industries in which Cadence competes, including the electronic design
automation ("EDA") and commercial electronic design and consulting industries,
are constantly changing. They experience rapid technological developments,
changes in industry standards, changes in customer requirements and frequent
new product introductions and improvements. To compete successfully, Cadence
must develop or acquire new products and improve its existing products and
processes on a schedule that keeps pace with the technological development in
its industries. Cadence must also be able to support a range of changing
computer software, hardware platforms and customer preferences. Cadence cannot
assure you that it will be able to successfully develop new products to address
new customer requirements and respond to technological developments, or that
the products it does develop will satisfy its customers. Cadence's inability to
respond timely and successfully to technological developments and changes could
hurt Cadence's competitive position or render its products or technologies
noncompetitive or obsolete.
 
 Fluctuations in Quarterly Results of Operations
 
  Cadence has experienced, and may continue to experience, varied quarterly
operating results. Various factors affect Cadence's quarterly operating results
and some of them are not within Cadence's control. They include, among others:
 
  . The timing and introduction of new products;
 
  . The mix of products and services sold;
 
  . The timing of significant orders from and shipments to customers;
 
  . Product and services pricing, discounts and margins;
 
  . The timing of its acquisitions of other companies and businesses; and
 
  . General economic conditions.
 
  Cadence bases its expense budgets partially on its expectations of future
revenue. However, it is difficult to predict revenue levels or growth. Revenue
levels that are below Cadence's expectations could have a significant negative
effect on Cadence's business, operating results and financial condition. If
revenue or operating results fall short of the levels expected by public market
securities analysts and investors, the trading price of Cadence common stock
could decline dramatically. Additionally, Cadence may not learn of revenue
shortfalls, earnings shortfalls or other failures to meet market expectations
until late in a fiscal quarter, which could result in even more immediate and
serious harm to the trading price of Cadence common stock.
 
 
                                       19
RISK FACTORS
<PAGE>
 
  Based on the foregoing, and because Cadence's focus on providing services is
relatively recent, Cadence believes that quarter-to-quarter comparisons of its
results of operations may not be meaningful. Therefore, Quickturn stockholders
should not view Cadence's historical results of operations as reliable
indicators of its future performance.
 
 Cadence's Industries are Highly Competitive
 
  Cadence competes in the highly competitive EDA industry and in the emerging
commercial electronic design and consulting industries. Cadence competes with a
number of companies in the EDA industry, including Avant! Corporation, Mentor,
Synopsys, Inc. and Zuken-Redac and numerous small companies. Cadence also
competes with manufacturers of electronic devices that have developed or have
the capability to develop their own EDA software. Some of these companies have
substantially greater financial, marketing and technological resources than
Cadence. To compete successfully in the EDA industry, which continuously
experiences falling prices, rapid technological change and new industry
entrants, Cadence must identify and develop innovative and cost competitive EDA
software products and market them in a timely manner. Cadence's inability to
compete successfully in the EDA industry could seriously harm its business,
operating results and financial condition.
 
  It is not difficult to enter the EDA industry and, therefore, the number of
Cadence's potential competitors is significant. The development of numerous
competitive products could result in a shift of customer preferences away from
Cadence's products and a significant decrease in sales of Cadence's products.
 
  In the electronics design and consulting services industries, Cadence
competes with numerous EDA and other consulting companies. Traditionally, most
electronics manufacturers designed their products internally. The electronics
design and consulting industries are new industries, in part, because these
manufacturers are beginning to purchase such services from outside vendors.
Consequently, Cadence's design and consulting services businesses must also
compete with the internal design capabilities of electronics manufacturers,
many of which have substantially greater financial, marketing and technological
resources than Cadence. They also may be reluctant to purchase services from
independent vendors such as Cadence because they wish to promote their own
internal design departments. To get their business, Cadence must offer better
strategic concepts, technical solutions, prices and response time, or a
combination of these factors, than those of the internal design departments of
electronic manufacturers and of its other competitors.
 
  It is not difficult to enter the electronics design and consulting
businesses. EDA and other electronics companies and management consulting firms
have entered and may continue to enter this industry. Some of Cadence's current
and potential competitors in the electronics design and consulting businesses
have substantially greater financial, marketing and technological resources
than Cadence. Cadence cannot assure you that it will be able to compete
successfully in these businesses, and any failure to do so may seriously harm
Cadence's business, operating results and financial condition.
 
 Risks Relating to Design and Consulting Services Businesses
 
  Cadence recently began to focus on offering electronics design and consulting
services. The industry for these services is relatively new and is evolving
rapidly. To be profitable and competitive in these businesses, Cadence must
continue to gain industry acceptance for its professional services and offer to
its customers better strategic concepts, technical solutions, prices and
response time than its competitors. Failure to run its services businesses
successfully may seriously harm Cadence's business, operating results and
financial condition.
 
  Cadence's electronics design and consulting services contracts generally
represent a large amount of revenue per order. Therefore, loss of individual
orders could have a significant impact on Cadence's revenue and operating
results. In addition, a substantial portion of these services contracts are
fixed price contracts, which means that no matter how much time or how many
resources Cadence must devote to perform a contract, the customer pays a fixed
price which has been agreed upon ahead of time. If Cadence's cost in
 
                                       20
RISK FACTORS
<PAGE>
 
performing the services consistently and significantly exceeds the amount the
customer has agreed to pay, it could seriously harm Cadence's business,
operating results and financial condition.
 
  The electronics design and consulting services businesses are labor
intensive. Accordingly, Cadence must hire and retain adequate personnel to
remain competitive in these businesses. Competition for qualified personnel is
intense. The failure to attract, hire and retain such personnel would impair
Cadence's success in the electronics design and consulting services businesses.
In addition, the high salaries Cadence must pay professional services personnel
to attract and retain them and the labor intensive nature of the services
business result in lower gross margins than the gross margins in Cadence's
software business. Gross margins represent the difference between the amount of
revenue from the sale of services and Cadence's cost of providing those
services. The high cost of integrating new services personnel adversely affects
gross margins in Cadence's electronics design and consulting services
businesses. In addition, not fully utilizing such personnel can significantly
lower gross margins.
 
 Risks Associated with Mergers and Acquisitions
 
  Cadence has been involved, and may in the future be involved, in a number of
merger and acquisition transactions. Cadence has participated in these
transactions for a number of reasons, including its desire to obtain new
technologies, expand and enhance its product and services lines and attract
personnel. However, growth through acquisition involves a number of risks,
including:
 
  . Difficulties related to combining previously separate businesses into a
    single unit;
 
  . The substantial diversion of management's attention from day-to-day
    business when negotiating these transactions and later integrating an
    acquired business;
 
  . The assumption of liabilities of an acquired business discovered after
    the transaction is complete;
 
  . The failure to realize anticipated benefits (such as cost savings and
    revenue enhancements);
 
  . Difficulties related to assimilating the products of an acquired business
    (for example, in distribution, engineering and customer support areas);
    and
 
  . The failure to identify or correct a material Year 2000 problem of an
    acquired business.
 
  Cadence expects to analyze carefully all potential transactions before
committing to them. However, Cadence cannot assure you that any transaction
that is completed will result in long-term benefits to Cadence or its
stockholders or that Cadence's management will be able to manage the acquired
businesses effectively. The occurrence of any of the events described above
following an acquisition by Cadence could seriously harm Cadence's business,
operating results and financial condition. See "--Unsuccessful Integration of
Business Operations."
 
 Dependence on Key Personnel
 
  Cadence is dependent upon the efforts and abilities of its senior management,
its research and development staff and a number of other key management, sales,
support, technical and services personnel. Cadence recently began to focus on
offering electronics design and consulting services to its customers, and the
growth of its services business is directly dependent on its ability to attract
and retain qualified personnel. The industry for highly skilled employees is
intensely competitive. Cadence's inability to attract, train, motivate and
retain highly skilled employees would impair the development of new products,
the ability to provide design and consulting services and the management of its
businesses. This would seriously harm Cadence's business, operating results and
financial condition.
 
 Risks Relating to International Operations
 
  Cadence's revenue from international operations as a percentage of total
revenue was approximately 50% in 1995, 47% in 1996, 51% in 1997 and 49% for the
first nine months of 1998. Cadence expects that revenues
 
                                       21
RISK FACTORS
<PAGE>
 
from its international operations will continue to account for a significant
portion of its total revenues. Cadence's international operations are subject
to a variety of risks including:
 
  . The adoption and expansion of government trade restrictions;
 
  . Volatile foreign exchange rates and currency conversion risks;
 
  . Limitations on repatriation of earnings;
 
  . Reduced protection of intellectual property rights in some countries;
 
  . Recessions in foreign economies;
 
  . Longer receivables collection periods and greater difficulty in
    collecting accounts receivable;
 
  . Difficulties in managing foreign operations;
 
  . Political and economic instability;
 
  . Unexpected changes in regulatory requirements;
 
  . Tariffs and other trade barriers;
 
  . U.S. government licensing requirements for export (licenses can be
    difficult to obtain); and
 
  . The move to a single European currency.
 
  Currency exchange fluctuations in countries in which Cadence conducts
business could also materially adversely affect Cadence's business, operating
results and financial condition. For example, Cadence derives a significant
portion of its revenues from sales in the Asia-Pacific region, including Japan.
Recent economic uncertainty and the weakening of foreign currencies in the
Asia-Pacific region has had, and may continue to have, a material adverse
effect on Cadence's revenues and operating results by creating higher effective
prices for Cadence's products compared to those products of its competitors
that are priced in local currencies.
 
  Cadence transacts business in various foreign currencies. Cadence has a
foreign currency hedging program, which means it uses foreign currency forward
exchange contracts which permit it to buy or sell specific foreign currencies
at specific prices on specific dates. Under this program, increases or
decreases in Cadence's foreign currency transactions are partially offset by
gains and losses on the forward exchange contracts. Although Cadence attempts
to reduce the impact of foreign currency fluctuations, significant exchange
rate movements may seriously harm Cadence's results of operations.
 
 Dependence on Proprietary Technology; Risks of Infringement
 
  Cadence's success is dependent, in part, upon its proprietary technology.
Cadence generally relies upon patents, copyrights, trademarks and trade secret
laws to establish and protect its proprietary rights in its technology and
products. Cadence has a program to file applications for and obtain patents in
the United States and in selected foreign countries. Cadence has a number of
patents and has patent applications currently pending. Despite these
precautions, a third party may still try to challenge, invalidate or circumvent
these patents. Cadence cannot assure you that any of the rights granted under
the patents will provide competitive advantages to Cadence. In addition,
Cadence cannot assure you that patents will be issued on its pending
applications, or that claims allowed on any of its future patents will be
sufficiently broad to protect Cadence's technology. In addition, the laws of
some foreign countries may not protect Cadence's proprietary rights to the same
extent as the laws of the United States. Furthermore, because technology in the
electronic design automation industry changes so rapidly, Cadence cannot rely
solely on patent, copyright, trademark and trade secret protection to be
successful and profitable in the industry.
 
  There are numerous patents in the EDA industry and new patents are being
issued at a rapid rate. Therefore, it is not economically practicable to
determine in advance whether a product or any of its components infringes the
patent rights of others. From time to time, Cadence receives notices from or is
sued by third parties claiming patent or other intellectual property
infringement or is called upon to defend a customer against such third party
claims. Responding to these kinds of claims, regardless of merit, could
 
                                       22
RISK FACTORS
<PAGE>
 
consume valuable time, result in costly litigation or cause product shipment
delays, all of which could seriously harm Cadence's business, operating results
and financial condition. Responding to these claims could also require Cadence
to enter into royalty or licensing agreements with the third parties claiming
infringement. Such royalty or licensing agreements, if available, may not be
available on terms acceptable to Cadence. Being forced to enter into a license
agreement with unfavorable terms could seriously harm Cadence's business,
operating results and financial condition.
 
  Many of Cadence's products include software or other intellectual property
licensed from third parties, and Cadence may have to seek new or renew existing
licenses in the future. The inability to obtain certain licenses or other
rights on favorable terms, or the need to engage in litigation over such
licenses or rights, could seriously harm Cadence's business, operating results
and financial condition.
 
 Risk of Failure to Obtain Export Licenses
 
  Cadence must comply with United States Department of Commerce regulations in
shipping its software products and other technologies outside the United States
to certain countries and certain customers. Although Cadence has not had any
material difficulty complying with these regulations so far, any significant
future difficulty in complying could harm Cadence's business, operating results
and financial condition.
 
 Year 2000 Compliance Risk
 
  Cadence's failure to correct a material Year 2000 problem (the inability of
certain computer programs and embedded microprocessors to process date
information correctly after December 31, 1998) could result in an interruption
in, or a failure of, normal business activities or operations and seriously
harm Cadence's business, operating results and financial condition. Cadence has
not fully assessed the risks the Year 2000 problem poses to its business. For
example, Cadence is uncertain about the Year 2000 readiness of its third-party
suppliers and customers. Additionally, Cadence has not yet assessed
approximately 30% of its internal business systems for Year 2000 compliance.
Further, while Cadence believes that its own internally developed software
products are generally Year 2000 compliant, we cannot assure you that Cadence
products acquired through acquisitions are Year 2000 compliant. Due to these
uncertainties, Cadence is currently unable to determine whether Year 2000
problems will harm its business, operating results or financial condition.
However, in July 1998, Cadence established a Year 2000 project team to identify
and resolve all remaining Year 2000 issues. Cadence is also continuing its
efforts to assess the Year 2000 readiness of its products. Cadence expects its
Year 2000 project to significantly reduce its level of uncertainty regarding
potential Year 2000 problems and, in particular, about the Year 2000 readiness
of all of its internal business systems and third-party suppliers and
customers. Cadence's project, however, may not be successful and its failure to
be Year 2000 compliant could seriously harm Cadence's operations.
 
 Stock Repurchase Program Risks
 
  Cadence has stock repurchase programs. Cadence repurchases Cadence common
stock under these programs to make sure it has enough shares for issuance under
its Employee Stock Purchase Plan, its 1997 Stock Option Plan and for other
corporate purposes. As part of these programs, Cadence has purchased call
options, which means that Cadence is entitled to buy one share of Cadence
common stock on a specified day at a specified price. Also as part of these
programs, Cadence has sold put warrants, which means that the put warrant
holder is entitled to sell one share of Cadence common stock to Cadence on a
specified day at a specified price. Cadence has the right to settle the put
warrants with stock valued at the difference between the exercise price and the
fair value of the stock at the date of exercise. Settlement of the put warrants
with stock could cause Cadence to issue a substantial number of shares,
depending on the exercise price of the put warrant and the value of Cadence
common stock at the time of exercise. This could impact the market price of
Cadence common stock. In addition, put warrant holders could accumulate a
substantial number of shares of Cadence common stock in anticipation of
exercising their put warrants or Cadence exercising its call options. These
holders might dispose of those shares when they exercise their put warrants, in
addition to the shares Cadence
 
                                       23
RISK FACTORS
<PAGE>
 
issues for exercise of their put warrants, which could also cause the market
price of Cadence common stock to fall.
 
 Risks Relating to Anti-Takeover Defenses
 
  Delaware law and Cadence's charter could make it difficult for another
company to acquire Cadence. Certain provisions of the Delaware General
Corporation Law (the "DELAWARE LAW") which apply to Cadence could delay or make
more difficult a merger, tender offer or proxy contest involving Cadence.
Section 203 of the Delaware Law prohibits a Delaware corporation from engaging
in any business combination with any interested stockholder for a period of
three years from the date the person became an interested stockholder unless
certain conditions are met. In addition, the Cadence Board of Directors may
issue shares of preferred stock without stockholder approval on terms it may
determine. No shares of Cadence preferred stock are currently outstanding.
However, the rights of holders of any Cadence preferred stock that may be
issued in the future may adversely affect the rights of holders of Cadence
common stock. In addition, Cadence has a rights plan which would make it
difficult for a company or investor to buy Cadence without the approval of
Cadence's Board of Directors. Cadence's rights plan is described in more detail
in "Cadence Capital Stock and Comparison of Stockholder Rights--Description of
Cadence Capital Stock--Cadence Rights Plan." All of the foregoing could delay
or prevent a change in control of Cadence and could limit the price that
certain investors might be willing to pay in the future for shares of Cadence
common stock.
 
RISK FACTORS RELATING TO QUICKTURN
 
 Fluctuations In Quarterly Results of Operations
 
  Many of Quickturn's customers only order products when needed. This means
they do not order regularly, but often wait until they know when their
development projects will begin. Moreover, a significant portion of Quickturn's
revenue in each quarter generally results from shipments in the last few weeks
of the quarter. Therefore, a delay in the shipment of a few orders can have a
significant adverse impact upon Quickturn's total revenue and results of
operations in a given quarter. If revenue or operating results fall short of
the levels expected by public market analysts and investors, the trading price
of Quickturn common stock could decline dramatically. Additionally, Quickturn
may not learn of revenue shortfalls, earnings shortfalls or other failures to
meet market expectations until late in a fiscal quarter, which could result in
even more immediate harm to the trading price of Quickturn common stock.
 
 Customer Concentration
 
  Quickturn relies on a limited number of customers for a substantial portion
of its total revenue. Quickturn's top ten customers represented, as a
percentage of total revenue, 52% in 1996, 43% in 1997 and 53% in the first nine
months of 1998. Quickturn expects that sales to a limited number of customers
will continue to represent a high percentage of its total revenue. The loss of
a major customer or fewer or smaller orders by such a customer could adversely
affect Quickturn's financial condition or results of operations. In addition,
any significant delays in or cancellations of a major customer's development
projects, new product announcements and releases by Quickturn, and economic
conditions generally, and in the electronics industry in particular, could
result in delayed, smaller or cancelled orders for Quickturn's products and
seriously harm Quickturn's financial condition or results of operations.
 
 New Product Transition
 
  In June 1998, Quickturn announced its new Mercury Design Verification
System,(TM) which is designed to replace certain of Quickturn's existing
emulation products. Electronics design engineers use emulation products to
generate "virtual silicon"(TM) prototypes of their electronic circuit designs.
These prototypes, which are far less expensive to make than the actual
electronic circuit designs, help the engineers to test and improve their
electronic circuit designs. This announcement could cause customers to defer
purchasing existing emulation
(TM)Mercury Design Verification System and virtual silicon are trademarks of
Quickturn Design Systems, Inc.
 
                                       24
RISK FACTORS
<PAGE>
 
products, and the transition to the new Mercury system may be disrupted by slow
industry acceptance or interruptions in manufacturing or component
availability, all of which could seriously harm Quickturn's financial condition
or results of operations.
 
 International Sales
 
  Quickturn derives a significant portion of its total revenue and net income
from its international operations. Fluctuations of the U.S. dollar against
foreign currencies and the seasonality of the Asia-Pacific region, European and
other international markets could harm Quickturn's results of operations and
financial condition.
 
  Revenue from most international customers is in U.S. dollars, but Quickturn
does transact business in foreign currencies with certain customers. Quickturn
has a foreign currency hedging program, which means it uses foreign currency
forward exchange contracts which permit it to buy or sell specific foreign
currencies at specific prices on specific dates. Quickturn has not experienced
any material gains or losses in connection with its hedging program. However,
future fluctuations in currency exchange rates could seriously harm the value
of receivables generated by sales denominated in foreign currencies, which in
turn could seriously harm Quickturn's operating results and financial
condition.
 
  Quickturn plans to continue expanding its international sales and
distribution channels. However, Quickturn's products may not achieve widespread
commercial acceptance in international markets in the future. Quickturn is
uncertain whether the recent weakness experienced in Asia-Pacific markets will
continue. Because of this downturn, sales of Quickturn's design verification
products in Japan have decreased in the first three quarters of 1998. The
downturn could also cause major Japanese electronics firms to continue lowering
their electronic design automation spending budgets. Consequently, sales of
Quickturn's design verification products in Japan may continue to decrease.
Quickturn's future international sales may be subject to additional risks
associated with international operations, including:
 
  . The adoption and expansion of government trade restrictions;
 
  . Currency conversion risks;
 
  . Limitations on repatriation of earnings;
 
  . Reduced protection of intellectual property rights in some countries;
 
  . Recessions in foreign economies;
 
  . Longer receivables collection periods and greater difficulty in
    collecting accounts receivable;
 
  . Difficulties in managing foreign operations;
 
  . Political and economic instability;
 
  . Unexpected changes in regulatory requirements;
 
  . Tariffs and other trade barriers;
 
  . U.S. government licensing requirements for export (licenses can be
    difficult to obtain); and
 
  . The move to a single European currency.
 
 Dependence Upon Certain Suppliers
 
  Quickturn depends on several suppliers for certain key components and board
assemblies used in its emulation products. Quickturn's inability to develop
alternative sources or to obtain sufficient quantities of these components or
board assemblies could result in delays or reductions in product shipments
which could adversely affect Quickturn's financial condition or results of
operations. In particular, Quickturn currently relies on Xilinx, Inc. for its
supply of field programmable gate arrays ("FPGAS") and on General Dynamics for
its computer board assemblies. General Dynamics has recently informed Quickturn
that it will terminate its board assembly services to Quickturn some time in
early 1999. Quickturn is currently in the final stages of
 
                                       25
RISK FACTORS
<PAGE>
 
negotiations with IBM Corporation ("IBM") to replace the services currently
provided by General Dynamics Corporation. We cannot assure you that these
negotiations will be successfully completed or that other disruptions will not
occur during the transition from General Dynamics to IBM. If for this or any
other reason there were to be a reduction or interruption of FPGA supply or
board assemblies to Quickturn, Quickturn's results of operations would be
seriously harmed. Although Quickturn believes that it can eventually obtain
FPGAs and board assemblies from alternative sources in the event of a reduction
or interruption of FPGA supply or board assemblies from Xilinx, IBM or General
Dynamics, a significant amount of time and resources would be required to
redesign Quickturn's emulation systems and software to accommodate an
alternative FPGA supplier or board assembler. In such event, Quickturn's
results of operations could be seriously harmed. Quickturn currently mitigates
this risk by maintaining inventory of these components in excess of its near-
term forecasted requirements. However, we cannot assure you that these measures
will be adequate to alleviate any future supply problems.
 
 Gross Margins
 
  Quickturn has traditionally had high gross margins, which represent the
difference between the amount of revenue from the sale of product (less returns
and allowances) and the cost of making such product. Quickturn has experienced,
and expects to continue to experience, competitive pressures in its industry
from existing companies and new entrants. These pressures could cause Quickturn
to decrease its average price per logic gate emulated. Accordingly, we cannot
assure you that Quickturn will be able to sustain its gross margins.
Furthermore, to the extent that Quickturn's cost reduction goals are achieved,
any resulting cost savings that are passed on to Quickturn's customers may also
hurt gross margins.
 
 Quickturn's Industry is Highly Competitive
 
  The EDA industry is highly competitive and rapidly changing. Quickturn faces
significant competition for emulation-based system-level verification and
cycle-based simulation, in addition to competition from traditional design
verification methodologies which rely on the approach of building and then
testing complete system prototypes and new technologies, such as formal
verification, employing other methodologies. Because of the growing demand for
a design verification methodology which reduces the number of costly design
iterations and improves product quality, Quickturn expects competition in the
industry for system-level verification and cycle-based simulation to increase
as other companies attempt to introduce emulation and cycle-based simulation
products and product enhancements, and as major new EDA technologies may
emerge. Moreover, Quickturn competes with companies that have significantly
greater financial, technical and marketing resources and greater name
recognition than Quickturn. In addition, many of these competitors have
established relationships with current and potential customers of Quickturn.
Increased competition could result in price reductions, reduced profits and
loss of market share, which could seriously harm Quickturn's business,
operating results and financial condition. Quickturn believes that, to compete
successfully in the EDA industry, it must focus on quality of results, the
mission-critical nature of the technology, technical support, product
performance, reputation, price and support of industry standards.
 
  Certain competitors may sue Quickturn in order to obtain a competitive edge.
Litigation can result in substantial costs to Quickturn and significant
diversions of management time from Quickturn's day-to-day operations. In 1995,
Quickturn's competitor, Mentor, sued Quickturn. Mentor asked the court for a
declaratory judgment of noninfringement, invalidity and unenforceability with
respect to several of Quickturn's patents. Quickturn has filed counterclaims
against Mentor and Mentor's French subsidiary, Meta Systems, for infringement
and threatened infringement of six Quickturn patents. Quickturn is also
involved in litigation with Mentor's subsidiary in Germany, with Meta Systems
in France and with Aptix Corporation and Meta Systems in California. Although
patent and intellectual property disputes in the EDA industry are often
settled, costs associated with such litigation can be substantial. The costs
and the outcome of Quickturn's current litigation could seriously harm its
business, operating results and financial condition.
 
 
                                       26
RISK FACTORS
<PAGE>
 
 Year 2000 Compliance Risk
 
  Quickturn's failure to correct a material Year 2000 problem (the inability
of certain computer programs and embedded microprocessors to process date
information correctly on or after December 31, 1998) could result in an
interruption in, or a failure of, certain normal business activities or
operations. Such failures could seriously harm Quickturn's business, operating
results and financial condition.
 
  Quickturn initiated a Year 2000 compliance project in the fall of 1997. The
project involves assessing key areas of Quickturn's business in several phases
to determine the risks the Year 2000 problem poses to its business. So far,
Quickturn has:
 
  . Identified all major areas where a material disruption of Quickturn's
    activities might occur in case of a Year 2000 failure;
 
  . Implemented a plan to fix problem areas;
 
  . Identified computer and other systems, including Quickturn verification
    products and third party systems used in Quickturn products and business
    operations, that are vulnerable to Year 2000 failure; and
 
  . Substantially completed formal communications with its significant
    suppliers to determine how Quickturn might be affected by their failure
    to remedy their own Year 2000 problems.
 
  Quickturn's suppliers generally have indicated that they are substantially
Year 2000 compliant. However, Quickturn's operations could be seriously harmed
if third parties which deal with these suppliers, such as utilities and
government entities, are not Year 2000 compliant.
 
  Quickturn has determined that it must modify or replace portions of its
software so that its computer systems and design verification products will
recognize dates beyond December 31, 1998. Quickturn presently believes that
modifications to existing software or conversion to new software will mitigate
potential Year 2000 problems. However, if such modifications and conversions
are not made, the Year 2000 problem could seriously harm Quickturn's
operations. In addition, other systems on which Quickturn's systems rely may
not be converted in a timely fashion or in a way that is compatible with
Quickturn's systems, all of which would harm Quickturn. Quickturn is currently
developing contingency plans in the event of such a failure. These contingency
plans may include the stockpiling of raw materials, seeking alternate
suppliers or using alternate operating sites or backup systems.
 
  Quickturn has identified and fixed Year 2000 problems on a majority of its
critical business and development computer systems. Quickturn is currently
testing these computer systems to make sure they do not have Year 2000
failures. Quickturn expects testing to be completed by March 1999. In
addition, Quickturn has begun verification product remediation. Quickturn
expects this effort to be complete by mid-1999 for all current products as
well as products that may be introduced between now and then. Quickturn does
not expect Year 2000 remediation efforts to materially impact or delay its
other information technology projects or new product introductions. In
addition, Quickturn intends to monitor closely remediation efforts of third
party service providers, customers and partners. However, their efforts may
not be successful and their failure to be Year 2000 compliant could seriously
harm Quickturn's business, operating results and financial condition.
 
                                      27
RISK FACTORS
<PAGE>
 
                           QUICKTURN SPECIAL MEETING
 
GENERAL
 
  This Proxy Statement/Prospectus is first being mailed to the holders
("QUICKTURN STOCKHOLDERS") of common stock, $.001 par value per share (the
"QUICKTURN COMMON STOCK"), of Quickturn Design Systems, Inc. ("QUICKTURN") on
or about      , 1999, and is accompanied by the notice of the Special Meeting
of Quickturn Stockholders and a form of proxy that is solicited by the Board of
Directors of Quickturn (the "QUICKTURN BOARD") for use at the special meeting
of Quickturn Stockholders (the "QUICKTURN SPECIAL MEETING"), to be held on
     ,        , 1999, at  .m., local time, at 55 W. Trimble Road, San Jose,
California, and at any adjournments or postponements thereof.
 
MATTERS TO BE CONSIDERED
 
  The purpose of the Quickturn Special Meeting is to take action with respect
to the adoption of the Agreement and Plan of Merger, dated as of December 8,
1998, by and among Cadence Design Systems, Inc. ("CADENCE"), CDSI Acquisition,
Inc., a wholly-owned subsidiary of Cadence ("MERGER SUB"), and Quickturn, as
amended on December 16, 1998 (the "MERGER AGREEMENT"). Pursuant to the Merger
Agreement, Merger Sub will merge with and into Quickturn (the "MERGER").
Quickturn Stockholders may also be asked to vote upon a proposal to adjourn or
postpone the Quickturn Special Meeting to allow additional time for the
solicitation of additional votes to approve the Merger Agreement if the
secretary of the Quickturn Special Meeting determines that there are not
sufficient votes to approve the Merger Agreement.
 
PROXIES
 
  The accompanying form of proxy is for use at the Quickturn Special Meeting if
a Quickturn Stockholder will be unable to attend in person. The proxy may be
revoked by the Quickturn Stockholder at any time before it is exercised by
submitting to the secretary of Quickturn written notice of revocation, a
properly executed proxy of a later date or by attending the Quickturn Special
Meeting and electing to vote in person. Written notices of revocation and other
communications with respect to the revocation of Quickturn proxies should be
addressed to Quickturn Design Systems, Inc., 55 W. Trimble Road, San Jose,
California 95131, Attention: secretary. All shares represented by valid proxies
received pursuant to this solicitation, and not revoked before they are
exercised, will be voted in the manner specified therein. If no specification
is made, the proxies will be voted in favor of adoption of the Merger
Agreement. No proxy that is voted against adoption of the Merger Agreement will
be voted in favor of any adjournment or postponement of the Quickturn Special
Meeting for the purpose of soliciting additional proxies.
 
SOLICITATION OF PROXIES
 
  The entire cost of soliciting the proxies from the Quickturn Stockholders
will be borne by Quickturn. In addition to the solicitation of the proxies by
mail, Quickturn will request banks, brokers and other record holders to send
proxies and proxy material to the beneficial owners of the stock and secure
their voting instructions, if necessary. Quickturn will reimburse such record
holders for their reasonable expenses in so doing. Quickturn has also made
arrangements with       to assist it in soliciting proxies from banks, brokers
and nominees and has agreed to pay approximately $    plus expenses for such
services. If necessary, Quickturn may also use several of its regular
employees, who will not be specially compensated, to solicit proxies from
Quickturn Stockholders, either personally or by telephone, telegram, facsimile,
letter or special delivery letter.
 
RECORD DATE AND VOTING RIGHTS
 
  In accordance with the provisions of the DELAWARE LAW, the By-Laws of
Quickturn (the "QUICKTURN BY-LAWS") and the rules of the National Association
of Securities Dealers (the "NASD"),      , 1999 has been fixed as the record
date for determination of Quickturn Stockholders entitled to notice of and to
vote at
 
                                       28
QUICKTURN SPECIAL MEETING
<PAGE>
 
the Quickturn Special Meeting (the "QUICKTURN RECORD DATE"). Accordingly, only
Quickturn Stockholders of record at the close of business on the Quickturn
Record Date will be entitled to notice of and to vote at the Quickturn Special
Meeting. At the close of business on the Quickturn Record Date, there were
shares of Quickturn Common Stock outstanding held by approximately     holders
of record. The presence, in person or by proxy, of shares of Quickturn Common
Stock representing a majority of such shares outstanding and entitled to vote
on the Quickturn Record Date is necessary to constitute a quorum at the
Quickturn Special Meeting. Each share of Quickturn Common Stock outstanding on
the Quickturn Record Date entitles its holder to one vote.
 
  Shares of Quickturn Common Stock present in person at the Quickturn Special
Meeting but not voting, and shares of Quickturn Common Stock for which
Quickturn has received proxies but with respect to which holders of such shares
have abstained, will be counted as present at the Quickturn Special Meeting for
purposes of determining the presence or absence of a quorum for the transaction
of business. Brokers who hold shares of Quickturn Common Stock in nominee or
"street" name for customers who are the beneficial owners of such shares are
prohibited from giving a proxy to vote shares held for such customers with
respect to the matters to be considered and voted upon the Quickturn Special
Meeting without specific instructions from such customers. However, broker non-
votes will be counted for purposes of determining whether a quorum exists.
 
  Under the Delaware Law and the Quickturn Certificate of Incorporation, as
amended (the "QUICKTURN CERTIFICATE"), adoption of the Merger Agreement
requires the affirmative vote of the holders of a majority of the outstanding
shares of Quickturn Common Stock entitled to vote at the Quickturn Special
Meeting.
 
  BECAUSE ADOPTION OF THE MERGER AGREEMENT REQUIRES THE AFFIRMATIVE VOTE OF THE
HOLDERS OF A MAJORITY OF THE OUTSTANDING SHARES OF QUICKTURN COMMON STOCK
ENTITLED TO VOTE AT THE QUICKTURN SPECIAL MEETING, ABSTENTIONS AND BROKER NON-
VOTES WILL HAVE THE SAME EFFECT AS VOTES AGAINST SUCH ADOPTION. ACCORDINGLY,
THE QUICKTURN BOARD URGES QUICKTURN STOCKHOLDERS TO COMPLETE, DATE AND SIGN THE
ACCOMPANYING PROXY AND RETURN IT PROMPTLY IN THE ENCLOSED, POSTAGE-PAID
ENVELOPE.
 
  As of the Quickturn Record Date, directors and executive officers of
Quickturn beneficially owned approximately    shares of Quickturn Common Stock,
entitling them to exercise approximately  % of the voting power of the
Quickturn Common Stock entitled to vote at the Quickturn Special Meeting. It is
currently expected that each such director and/or executive officer of
Quickturn will vote the shares of Quickturn Common Stock beneficially owned by
him or her for approval of the Merger Agreement and the transactions
contemplated thereby.
 
  Additional information with respect to beneficial ownership of Quickturn
Common Stock by persons and entities owning more than 5% of such stock, and
more detailed information with respect to beneficial ownership of Quickturn
Common Stock by directors and executive officers of Quickturn, is incorporated
by reference to Quickturn's Annual Report on Form 10-K for the year ended
December 31, 1997. See "Where You Can Find More Information."
 
RECOMMENDATION OF QUICKTURN BOARD
 
  The Quickturn Board has unanimously approved the Merger Agreement and the
transactions contemplated thereby. The Quickturn Board believes that the Merger
Agreement is in the best interests of Quickturn and Quickturn Stockholders and
recommends that the Quickturn Stockholders vote "FOR" the adoption of the
Merger Agreement. See "The Merger--Recommendation of the Quickturn Board and
Quickturn's Reasons for the Merger."
 
                                       29
QUICKTURN SPECIAL MEETING
<PAGE>
 
                                   THE MERGER
 
  The following summary of the material terms and provisions of the Merger
Agreement and the Option Agreement (each as defined herein) is qualified in its
entirety by reference to the Merger Agreement and the Option Agreement. The
Merger Agreement is attached as Appendix A and the Option Agreement is attached
as Appendix B to this Proxy Statement/Prospectus, each of which is incorporated
herein by reference.
 
GENERAL
 
  The Board of Directors of Cadence (the "CADENCE BOARD") and the Quickturn
Board have each unanimously approved the Merger Agreement, which provides for
combining Cadence and Quickturn through the merger of Merger Sub with and into
Quickturn at the effective time of the Merger (the "EFFECTIVE TIME"), with
Quickturn as the surviving corporation in the Merger (the "SURVIVING
CORPORATION"). Each share of common stock, par value $.01 per share, of Merger
Sub (the "MERGER SUB COMMON STOCK") issued and outstanding at the Effective
Time will remain issued and outstanding as one share of common stock of the
Surviving Corporation, and, with certain limited exceptions described below,
each share of Quickturn Common Stock issued and outstanding at the Effective
Time will be converted into the right to receive (A) a number of shares of
Cadence Common Stock equal to (i) $14.00 divided by (ii) the average closing
price of one share of common stock, par value $.01 per share, of Cadence
("CADENCE COMMON STOCK") (as reported on the NYSE Composite Transactions
reporting system) for the five trading days immediately preceding the business
day that is two business days before the Closing Date (the "EXCHANGE RATIO"),
together with (B) associated Series A Junior Participating Preferred Share
Purchase Rights (the "CADENCE STOCKHOLDER RIGHTS") issued to the Cadence
Stockholders pursuant to the Rights Agreement, dated as of February 9, 1996
(the "CADENCE RIGHTS AGREEMENT"), between Cadence and Harris Trust and Savings
Bank, as Rights Agent (the "CADENCE RIGHTS AGENT"). This section of the Proxy
Statement/Prospectus describes the material aspects of the Merger, including
the principal provisions of the Merger Agreement and the Stock Option
Agreement, dated as of December 8, 1998, between Quickturn and Cadence (the
"OPTION AGREEMENT"). Certain capitalized terms used herein without definition
have the meanings given to them in the Merger Agreement or the Option
Agreement, as applicable.
 
BACKGROUND OF THE MERGER
 
  The Mentor Tender Offer. On August 12, 1998, MGZ Corporation, a Delaware
corporation ("MGZ") and wholly-owned subsidiary of Mentor, commenced an offer
to purchase all outstanding shares of Quickturn Common Stock (together with the
associated Quickturn Rights) at a price of $12.125 per share, net to the seller
in cash, without interest thereon, upon the terms and subject to the conditions
set forth in MGZ's Offer to Purchase and related Letter of Transmittal (which
together constitute the "MENTOR OFFER"). You can find more information about
the Mentor Offer by reviewing the Tender Offer Statement on Schedule 14D-1,
dated August 12, 1998, as amended, filed with the Commission by MGZ.
 
  On August 21, 1998, the Quickturn Board held a meeting, at which the
Quickturn Board reviewed and considered the Mentor Offer and related matters in
consultation with its financial and legal advisors. Presentations were made by
Quickturn's senior management concerning Quickturn's business plan, and by
Hambrecht & Quist LLC ("HAMBRECHT & QUIST") concerning analyses of the Mentor
Offer. At the conclusion of its presentations, Hambrecht & Quist provided the
Quickturn Board its opinion that the Mentor Offer was inadequate from a
financial point of view. After further review by the Quickturn Board and
consideration of the interests of Quickturn Stockholders, the Quickturn Board
determined that the Mentor Offer was inadequate and not in the best interests
of Quickturn Stockholders, that the Mentor Offer did not fully reflect the
long-term value of Quickturn and that stockholder interests would be better
served by Quickturn continuing to pursue its business plan. In particular, the
Quickturn Board determined that Quickturn's business plan offered the potential
for obtaining higher long-term benefits for Quickturn Stockholders than the
Mentor Offer. This determination was based on, among other things, the
opportunities for business expansion and revenue and earnings growth resulting
from recently introduced products and from products under development
 
                                       30
THE MERGER
<PAGE>
 
for use in the electronic design automation industry and in other related parts
of the industry. You can obtain more information about the Quickturn Board's
response to the Mentor Offer from the Solicitation/Recommendation Statement on
Schedule 14D-9 filed by Quickturn with the Commission on August 24, 1998 (as
amended to the date of this Proxy Statement/Prospectus, the "QUICKTURN 14D-9").
The Quickturn 14D-9 contains a complete discussion of the Mentor Offer and the
Quickturn Board's position with respect to such offer. We urge you to read the
Quickturn 14D-9 in its entirety. You may obtain a copy of the Quickturn 14D-9
from the Commission. See "Where You Can Find More Information."
 
  On August 12, 1998, Mentor and MGZ filed a complaint (the "MENTOR DELAWARE
COMPLAINT") against Quickturn and the Quickturn Board in the Court of Chancery
of the State of Delaware (the "CHANCERY COURT") seeking, among other things, an
order (i) declaring that Quickturn's failure to redeem the Quickturn
Stockholder Rights (as defined below) or to render the Quickturn Stockholder
Rights inapplicable to the Mentor Offer or failure to approve the Mentor Offer
would constitute a breach of the Quickturn Board's fiduciary duties under
Delaware law, (ii) invalidating the Quickturn Stockholder Rights or compelling
the Quickturn Board to redeem the Quickturn Stockholder Rights or render the
Quickturn Stockholder Rights inapplicable to the Mentor Offer, (iii) declaring
that failure to approve the Mentor Offer for purposes of Section 203 of the
Delaware Law would constitute a breach of the Quickturn Board's fiduciary
duties under Delaware Law, (iv) compelling the Quickturn Board to approve the
Mentor Offer for purposes of Section 203 of the Delaware Law, (v) enjoining the
Quickturn Board from taking any actions designed to impede or which have the
effect of impeding the Mentor Offer or the solicitation by Mentor of agent
designations (the "SOLICITATION") and declaring that any such actions would
constitute a breach of the Quickturn Board's fiduciary duties under Delaware
Law, (vi) enjoining the Quickturn Board from taking any actions to impede, or
refuse to recognize the validity of, Mentor's call for a special meeting of
Quickturn Stockholders, provided that Mentor has obtained agent designations
from Quickturn Stockholders holding not less than 10% of the outstanding shares
of Quickturn Common Stock, and (vii) enjoining the Quickturn Board from taking
any action to cause Quickturn to become subject to Section 2115 of the
California General Corporation Law. The Mentor Delaware Complaint is attached
as Exhibit 7 to the Quickturn 14D-9.
 
  On December 3, 1998, the Chancery Court rendered its decision (revised
December 7, 1998) on the Mentor Delaware Complaint (the "CHANCERY COURT
DECISION"). The Chancery Court upheld the right of the Quickturn Board to set
the meeting date and the record date of the special stockholder meeting called
by Mentor, in accordance with the Quickturn By-Laws. The special meeting has
been set for January 8, 1999. Quickturn Stockholders of record as of November
10, 1998 will be entitled to vote at the special meeting. The Chancery Court
also ruled that certain provisions of an amendment to the Quickturn Rights
Agreement (as defined below) were invalid. The provisions ruled invalid relate
to a 180 day delay in the ability of a Board of Directors elected by
stockholder action in certain cases to redeem or exchange the Quickturn
Stockholder Rights or to amend the Quickturn Rights Agreement. The Chancery
Court Decision is attached as Exhibit 53 to the Quickturn 14D-9.
 
  On December 14, 1998, Quickturn filed an appeal of the Chancery Court
Decision with the Supreme Court of the State of Delaware (the "DELAWARE SUPREME
COURT"). The Delaware Supreme Court is currently scheduled to hear Quickturn's
appeal on December 29, 1998.
 
  Also on August 12, 1998, Mentor and MGZ filed a complaint (the "MENTOR
FEDERAL COMPLAINT") against Quickturn in the United States District Court for
the District of Delaware (the "DELAWARE DISTRICT COURT") seeking, among other
things, a declaratory judgment that Mentor and MGZ have disclosed all
information required by, and are otherwise in full compliance with, the
Exchange Act and any other federal securities laws, rules and regulations
deemed applicable to the Mentor Offer and the Solicitation. The Mentor Federal
Complaint is attached as Exhibit 8 to the Quickturn 14D-9.
 
  As of the date of this Proxy Statement/Prospectus, the Delaware District
Court has not rendered a decision on the Mentor Federal Complaint.
 
                                       31
THE MERGER
<PAGE>
 
  On August 13, 1998, Howard Shapiro filed a purported class action suit on
behalf of individual plaintiffs (the "SHAPIRO I COMPLAINT") against Quickturn
and the Quickturn Board in the Chancery Court. The complaint alleges, among
other things, that the defendants breached their fiduciary duties to Quickturn
Stockholders by failing to maximize stockholder value. The complaint seeks,
among other things, to compel the defendants to carry out their fiduciary
duties and to cooperate with any person or entity having a bona fide interest
in proposing any transaction which would maximize stockholder value. A copy of
the Shapiro I Complaint is attached as Exhibit 9 to the Quickturn 14D-9.
 
  The Proposed Transaction with Cadence. On September 1, 1998, Glen M. Antle,
Chairman of the Quickturn Board, met with John R. Harding, President and Chief
Executive Officer of Cadence, to inquire about Cadence's interest in pursuing a
possible combination with Quickturn. Mr. Harding replied that Cadence would not
be interested in having discussions about such a combination.
 
  During the week of November 16, 1998, Mr. Antle again contacted Mr. Harding
and requested that they and certain other representatives from each of their
companies meet to provide Quickturn the opportunity to explain its business and
product strategy. Mr. Harding agreed to such a meeting.
 
  On December 1, 1998, Mr. Harding, Shane V. Robinson, Executive Vice
President, Research and Development of Cadence and Michael J. Casey, Associate
General Counsel of Cadence, met with Mr. Antle, Keith R. Lobo, President and
Chief Executive Officer of Quickturn, Raymond K. Ostby, Chief Financial Officer
of Quickturn, Christopher J. Tice, Vice President, Worldwide Support Services
of Quickturn, and Naeem Zafar, Vice President, Marketing of Quickturn, at
Quickturn's headquarters in San Jose, California, at which meeting the
Quickturn representatives made a presentation regarding Quickturn's business
and product strategy.
 
  On December 3, 1998, Messrs. Lobo and Harding met at Cadence's headquarters
in San Jose, California and discussed the broad outlines of a possible
combination of Quickturn and Cadence. At the conclusion of this meeting, they
agreed to meet again the following day with their respective legal, accounting
and financial advisors to commence due diligence and discuss documentation for
a possible combination of Cadence and Quickturn. Later that day, the Quickturn
Board held a telephonic meeting to discuss, among other things, the meetings
with Cadence.
 
  On December 4, 1998, Messrs. Harding and Casey, H. Raymond Bingham, Executive
Vice President and Chief Financial Officer of Cadence, Margaret McCarthy, Vice
President, Business Development of Cadence, R.L. Smith McKeithen, Senior Vice
President, General Counsel and Secretary of Cadence, and Dr. Alberto
Sangiovanni-Vincentelli, a member of the Cadence Board, together with certain
other Cadence employees and its attorneys from Gibson, Dunn & Crutcher LLP
("GDC") and Drinker, Biddle & Reath LLP ("DBR") and accounting advisors from
PricewaterhouseCoopers LLP ("PRICEWATERHOUSECOOPERS"), which performs due
diligence for Cadence on its acquisitions, met with Messrs. Antle, Lobo and
Ostby and Quickturn's intellectual property attorneys and financial advisors,
Lyon & Lyon and Hambrecht & Quist, respectively, at the offices of Lyon & Lyon
in San Jose. At this meeting, Quickturn and its representatives discussed
Quickturn's patent infringement litigation with Mentor, Meta Systems (a French
subsidiary of Mentor) and Aptix Corporation, as well as the litigation between
Quickturn and Mentor in the Delaware state and federal courts relating to the
Mentor Offer, and the Shapiro Complaint. The parties also discussed logistics
for the two companies' due diligence of each other and a schedule for
negotiating a transaction between them over the next few days. Cadence and
Quickturn agreed on the basic terms of a confidentiality agreement. Cadence and
Quickturn entered into a confidentiality and standstill agreement dated
December 4, 1998.
 
  On December 5, 1998, representatives of Quickturn and Hambrecht & Quist met
with representatives of Cadence and its attorneys, accounting advisors and
financial advisors, Goldman, Sachs & Co. ("GOLDMAN SACHS"), at the Palo Alto
offices of GDC. At this meeting, Messrs. Lobo, Ostby and Zafar made a
presentation about Quickturn and its business operations, strategy and
financial results. Other due diligence was also conducted. That morning, GDC
delivered to attorneys from Wilson Sonsini Goodrich & Rosati ("WSGR"),
Quickturn's corporate legal counsel, draft forms of a merger agreement and
stock option agreement, although such forms did not contain an exchange ratio
or other material terms of any proposal for a combination
 
                                       32
THE MERGER
<PAGE>
 
between Cadence and Quickturn. On the same day, representatives of Cadence,
GDC, PricewaterhouseCoopers and Goldman Sachs conducted due diligence of
Quickturn at Quickturn's headquarters office in San Jose and at the Palo Alto
offices of GDC.
 
  On December 6, 1998, the Quickturn Board held a meeting at the offices of
WSGR to consider the discussions with Cadence.
 
  Later on December 6, 1998, Messrs. Harding, Bingham and McKeithen and Ms.
McCarthy and representatives of Goldman Sachs made a presentation about Cadence
to Messrs. Antle, Lobo, Ostby, the entire Quickturn Board, and representatives
of Hambrecht & Quist and WSGR, at the Palo Alto offices of GDC. At the
conclusion of this presentation, Messrs. Antle, Lobo and Ostby and the members
of the Quickturn Board departed, but representatives of Hambrecht & Quist and
WSGR remained to continue discussions with the Cadence representatives. Also on
that day, Cadence's employees, attorneys, accounting advisors and financial
advisors continued their due diligence of Quickturn, and representatives of GDC
and WSGR met to discuss the draft forms of merger agreement and stock option
agreement, although such forms still did not contain an exchange ratio or
certain other material terms.
 
  On December 7, 1998, representatives of Cadence and Quickturn, and their
respective attorneys, accounting advisors and financial advisors, continued
their due diligence of each other. That evening, Messrs. Harding, Bingham,
McKeithen and Casey and Ms. McCarthy met with representatives of GDC,
PricewaterhouseCoopers and Goldman Sachs at Cadence's offices in San Jose to
discuss and formulate a proposed Exchange Ratio and certain other terms
material to a combination of Quickturn and Cadence.
 
  On December 8, 1998, representatives of Cadence and Quickturn, and their
respective attorneys, accounting advisors and financial advisors, continued
their due diligence of each other. That morning, the Cadence Board held a
special meeting to consider and approve the terms of a proposal to acquire all
the outstanding shares of Quickturn Common Stock. The Cadence Board unanimously
approved the proposal and authorized Cadence's officers to convey the proposal
to Quickturn's management and conclude an agreement substantially on the terms
of such proposal. Early in the evening of December 8, 1998, Messrs. Harding,
Bingham, McKeithen and Casey and Ms. McCarthy conveyed to Messrs. Antle, Lobo
and Ostby and Quickturn's legal and financial advisors Cadence's proposal for a
combination with Quickturn.
 
  In the evening of December 8, 1998, the Quickturn Board held a special
meeting at which senior management of Quickturn, together with Quickturn's
legal and financial advisors, reviewed the terms of Cadence's proposal, the
status of the discussions with Cadence, the results of Quickturn's due
diligence of Cadence, the consistency of a merger with Quickturn's business
strategy and the Quickturn Board's fiduciary duties in connection with its
consideration of the proposal. After extensive discussion among the members of
the Quickturn Board, and consideration of the factors described under "--
Recommendation of the Quickturn Board and Quickturn's Reasons for the Merger,"
the Quickturn Board concluded that a business combination with Cadence would be
advisable and in the best interests of Quickturn and its stockholders. The
Quickturn Board voted unanimously to approve the Merger Agreement and the
Option Agreement and the transactions contemplated thereby.
 
  The Merger Agreement and the Option Agreement were entered into by Cadence,
its wholly-owned subsidiary, CDSI Acquisition, Inc., and Quickturn as of
December 8, 1998. Mr. Lobo, five other Quickturn officers and one other
Quickturn employee also entered into employment and non-competition agreements,
confidentiality agreements and non-disclosure agreements with Quickturn and
Cadence substantially concurrently with the execution and delivery of the
Merger Agreement and Option Agreement (collectively, the "EMPLOYMENT
AGREEMENTS").
 
  On December 15, 1998, Mentor and MGZ filed suit against Quickturn, the
Quickturn Board and Cadence in the Delaware Chancery Court alleging, among
other things, that the Quickturn Board violated its fiduciary duty to Quickturn
Stockholders in approving the Merger and that Cadence aided and abetted this
violation, and that certain terms of the Merger Agreement and Option Agreement,
including the "no shop" and liquidated damages provisions, violate Delaware
law. If Mentor prevails in its claims, there is a risk that the Merger will not
be completed. The complaint filed by Mentor and MGZ is attached as Exhibit 59
to the Quickturn 14D-9.
 
                                       33
THE MERGER
<PAGE>
 
  On December 16, 1998, Howard Shapiro filed a purported class action suit on
behalf of individual plaintiffs (the "SHAPIRO II COMPLAINT") against Quickturn,
the Quickturn Board and Cadence in the Chancery Court alleging among other
things, that the Quickturn Board violated its fiduciary duties by entering into
a merger agreement with preclusive lock-up and no-shop clauses designed to
entrench management to the detriment of Quickturn Stockholders, and that
Cadence aided and abetted this violation. If Mr. Shapiro prevails in his claim,
there is a risk that the Merger will not be completed or will be delayed. A
copy of the Shapiro II Complaint is attached as Exhibit 60 to the Quickturn
14D-9.
 
RECOMMENDATION OF THE QUICKTURN BOARD AND QUICKTURN'S REASONS FOR THE MERGER
 
  THE QUICKTURN BOARD BELIEVES THAT THE MERGER IS ADVISABLE, FAIR TO AND IN THE
BEST INTERESTS OF, QUICKTURN AND QUICKTURN STOCKHOLDERS. ACCORDINGLY, THE
QUICKTURN BOARD HAS UNANIMOUSLY APPROVED THE MERGER AGREEMENT AND UNANIMOUSLY
RECOMMENDS THAT QUICKTURN STOCKHOLDERS VOTE FOR THE ADOPTION OF THE MERGER
AGREEMENT AND THE TRANSACTIONS CONTEMPLATED THEREBY, INCLUDING THE MERGER.
 
  The Quickturn Board has approved the Merger because it believes that the
greater strength of the combined company, as compared to that of Quickturn on
its own, will provide significant benefits to Quickturn Stockholders. The
Quickturn Board believes that the consummation of the Merger presents a unique
opportunity to combine two of the nation's strongest electronics simulation and
verification businesses with sufficient capital to accelerate new product
development and a powerful worldwide distribution network for Quickturn's
products. As the complexity of integrated circuit design increases, the
Quickturn Board believes that the complexity of design verification will
increase at an even greater rate. As a result of the integration of Quickturn's
hardware-based emulation approach with Cadence's design and simulation systems,
the Quickturn Board expects that the combined company should significantly
improve its ability to meet customer demand for faster development of high-
speed integrated circuits and "systems on a chip."
 
  The Quickturn Board also believes that the Merger will increase value for
Quickturn Stockholders, as well as Quickturn's employees and customers, and
should allow Quickturn to continue to pursue its business strategy. In
particular, the Quickturn Board believes that Quickturn should be able to
leverage Cadence's strong international sales channels to make Quickturn's
technology available to a larger customer base than is currently the case. As a
result, the Quickturn Board believes that the Merger will yield for Quickturn
Stockholders an attractive price for their shares of Quickturn Common Stock,
while enabling them to share in Cadence's growth over the long term.
 
  The foregoing discussion of reasons for the Merger includes forward-looking
statements about possible or assumed future results of operations of the
combined company and the performance of the combined company after the Merger.
Future results and performance are subject to risks and uncertainties, which
could cause such results and performance to differ materially from those
expressed in these statements. For a discussion of these risks and
uncertainties, and other factors that could affect future results and
performance, see "Risk Factors."
 
  In reaching its decision to approve the Merger Agreement and the Option
Agreement, the Quickturn Board consulted with Quickturn management, as well as
with its financial and legal advisors, and considered a number of factors,
including the following:
 
    (i) historical information concerning Quickturn's and Cadence's
  respective businesses, financial performance and condition, operations,
  technology, management and competitive position, including public reports
  concerning results of operations during the most recent fiscal year and
  fiscal quarter for each company as filed with the Commission;
 
    (ii) the financial condition, results of operations, businesses and
  prospects of Quickturn and Cadence before and after giving effect to the
  Merger;
 
    (iii) current financial market conditions and historical market prices,
  volatility and trading information with respect to the Quickturn Common
  Stock and Cadence Common Stock;
 
 
                                       34
THE MERGER
<PAGE>
 
    (iv) the complementary nature of the businesses of Quickturn and Cadence;
 
    (v) the anticipated financial impact of the proposed transaction on the
  combined company's future financial performance;
 
    (vi) the expectation that the Merger will result in certain synergies for
  the combined company's operations;
 
    (vii) the consideration to be received by Quickturn Stockholders in the
  Merger and the relationship between the market value of Cadence Common
  Stock to be issued in exchange for each share of Quickturn Common Stock and
  a comparison of comparable merger transactions;
 
    (viii) the belief that the terms of the Merger Agreement and the Option
  Agreement, including the parties' representations, warranties and
  covenants, and the conditions to their respective obligations, are
  reasonable;
 
    (ix) the prospects for Quickturn as an independent company;
 
    (x) the potential for other third parties to enter into strategic
  relationships with or to acquire Quickturn;
 
    (xi) detailed financial analyses and pro forma and other information with
  respect to the companies presented by Hambrecht & Quist, including
  Hambrecht & Quist's opinion that the consideration to be received by
  Quickturn Stockholders in the Merger is fair to such stockholders from a
  financial point of view;
 
    (xii) the impact of the Merger on Quickturn's customers and employees;
  and
 
    (xiii) reports from Quickturn's management and its financial advisors as
  to the results of their due diligence investigation of Cadence.
 
  The Quickturn Board also considered the terms of the proposed Merger
Agreement regarding Quickturn's rights to consider and negotiate other
acquisition proposals in certain circumstances, as well as the possible effects
of the Option Agreement and the provisions regarding liquidated damages. In
addition, the Quickturn Board noted that the Merger is expected to be accounted
for as a pooling-of-interests and that no goodwill is expected to be created on
the books of the combined company as a result thereof.
 
  The Quickturn Board also identified and considered a variety of potentially
negative factors in its deliberations concerning the Merger, including, but not
limited to: (1) the risk that the potential benefits sought in the Merger might
not be fully realized; (2) the possibility that the Merger might not be
consummated and the effect of public announcement of the Merger on (a)
Quickturn's sales, operating results and stock price, (b) Quickturn's ability
to attract and retain key management, sales and marketing and technical
personnel and (c) the progress of certain development projects; (3) the
possibility of substantial charges to be incurred in connection with the
Merger, including costs of integrating the businesses and transaction expenses
arising from the Merger; (4) the risk that despite the efforts of the combined
company, key technical and management personnel might not remain employed by
the combined company; (5) risks associated with fluctuations in Cadence's stock
price prior to closing of the Merger; and (6) various other risks.
 
  The foregoing discussion of the information and factors considered by the
Quickturn Board is not intended to be exhaustive but includes all material
factors considered by the Quickturn Board. In reaching its determination to
approve and recommend the Merger, the Quickturn Board did not assign any
relative or specific weights to the foregoing factors, and individual directors
may have given differing weights to different factors. The Quickturn Board is
unanimous in its recommendation that Quickturn Stockholders vote for approval
and adoption of the Merger Agreement. For a discussion of the interests of the
executive officers and directors of Quickturn in the Merger, see "--Interests
of Certain Persons in the Merger."
 
 
                                       35
THE MERGER
<PAGE>
 
OPINION OF QUICKTURN'S FINANCIAL ADVISOR
 
  Quickturn engaged Hambrecht & Quist to act as its exclusive financial advisor
in connection with the Mentor Offer and the evaluation of strategic
alternatives, including the Merger and to render an opinion as to the fairness
from a financial point of view to the holders of the outstanding shares of
Quickturn Common Stock of the consideration to be received by said holders of
Quickturn Common Stock. Hambrecht & Quist was selected by the Quickturn Board
based on Hambrecht & Quist's qualifications, expertise and reputation, as well
as Hambrecht & Quist's prior investment banking relationship and familiarity
with Quickturn and the EDA industry. Hambrecht & Quist rendered its oral
opinion (subsequently confirmed in writing) on December 8, 1998 to the
Quickturn Board that, as of such date, the consideration to be received by the
holders of Common Stock of Quickturn is fair from a financial point of view.
 
  THE FULL TEXT OF THE OPINION DELIVERED BY HAMBRECHT & QUIST TO THE QUICKTURN
BOARD DATED DECEMBER 8, 1998, WHICH SETS FORTH THE ASSUMPTIONS MADE, GENERAL
PROCEDURES FOLLOWED, MATTERS CONSIDERED, AND LIMITATIONS ON THE SCOPE OF REVIEW
UNDERTAKEN BY HAMBRECHT & QUIST IN RENDERING ITS OPINION, IS ATTACHED AS
APPENDIX C TO THIS PROXY STATEMENT/PROSPECTUS AND IS INCORPORATED HEREIN BY
REFERENCE. HAMBRECHT & QUIST'S OPINION IS DIRECTED ONLY TO THE FAIRNESS, FROM A
FINANCIAL POINT OF VIEW, OF THE CONSIDERATION TO BE RECEIVED BY THE HOLDERS OF
QUICKTURN COMMON STOCK AND DOES NOT CONSTITUTE A RECOMMENDATION TO ANY
QUICKTURN STOCKHOLDER AS TO HOW SUCH STOCKHOLDER SHOULD VOTE WITH RESPECT TO
THE MERGER AGREEMENT. THE SUMMARY OF HAMBRECHT & QUIST'S FAIRNESS OPINION SET
FORTH BELOW IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO THE FULL TEXT OF SUCH
FAIRNESS OPINION ATTACHED HERETO AS APPENDIX C. QUICKTURN STOCKHOLDERS ARE
URGED TO READ THE OPINION CAREFULLY IN ITS ENTIRETY.
 
  In its review of the Merger, and in arriving at its opinion, Hambrecht &
Quist, among other things:
 
  (i) Reviewed the publicly available consolidated financial statements of
Cadence for recent years and interim periods to date and certain other relevant
financial and operating data of Cadence (including its capital structure) made
available to it from published sources;
 
  (ii) Discussed the business, financial condition and prospects of Cadence
with certain members of senior management of Cadence;
 
  (iii) Reviewed the publicly available consolidated financial statements of
Quickturn for recent years and interim periods to date and certain other
relevant financial and operating data of Quickturn made available to it from
published sources and from the internal records of Quickturn;
 
  (iv) Reviewed certain internal financial and operating information relating
to Quickturn prepared by the senior management of Quickturn;
 
  (v) Discussed the business, financial condition and prospects of Quickturn
with certain members of senior management of Quickturn;
 
  (vi) Reviewed the recent reported prices and trading activity for Cadence
Common Stock and Quickturn Common Stock and compared such information and
certain financial information for Cadence and Quickturn with similar
information for certain other companies engaged in businesses it considers
comparable;
 
  (vii) Reviewed the financial terms, to the extent publicly available, of
certain comparable merger and acquisition transactions;
 
  (viii) Reviewed a draft of the Merger Agreement dated December 7, 1998; and
 
  (ix) Performed such other analyses and examinations and considered such other
information, financial studies, analyses and investigations and financial,
economic and market data as Hambrecht & Quist deemed relevant.
 
  Hambrecht & Quist did not independently verify any of the information
concerning Quickturn or Cadence considered in connection with its review of the
Merger and, for purposes of its opinion, Hambrecht & Quist assumed and relied
upon the accuracy and completeness of all such information. In connection with
its opinion,
 
                                       36
THE MERGER
<PAGE>
 
Hambrecht & Quist did not prepare or obtain any independent valuation or
appraisal of any of the assets or liabilities of Quickturn or Cadence, nor did
it conduct a physical inspection of the properties and facilities of Quickturn
or Cadence. With respect to the financial forecasts and projections published
by securities research analysts or provided to it by Quickturn and used in its
analysis, Hambrecht & Quist assumed that such forecasts and projections
reflected the best currently available estimates and judgments of the expected
future financial performance of Cadence and Quickturn. For the purposes of its
opinion, Hambrecht & Quist also assumed that neither Quickturn nor Cadence was
a party to any pending transactions, including external financings (other than
those contemplated that have been disclosed to Hambrecht & Quist),
recapitalizations or merger discussions, other than the Merger and those
activities undertaken in the ordinary course of conducting their respective
businesses. For purposes of its opinion, Hambrecht & Quist assumed that the
Merger will qualify as a tax-free reorganization under the Code for the
Quickturn Stockholders and that the Merger will be accounted for as a pooling-
of-interests. Hambrecht & Quist's opinion is necessarily based upon market,
economic, financial and other conditions as they existed and could be evaluated
as of the date of the opinion and any subsequent change in such conditions
would require a reevaluation of such opinion.
 
  The preparation of a fairness opinion is a complex process and is not
necessarily susceptible to partial analysis or summary description. The summary
of the Hambrecht & Quist analyses set forth below does not purport to be a
complete description of the presentation by Hambrecht & Quist to the Quickturn
Board. In arriving at its opinion, Hambrecht & Quist did not attribute any
particular weight to any analyses or factors considered by it, but rather made
qualitative judgments as to the significance and relevance of each analysis and
factor. Accordingly, Hambrecht & Quist believes that its analyses and the
summary set forth below must be considered as a whole and that selection of
portions of its analyses, without considering all analyses, or of the following
summary, without considering all factors and analyses, could create an
incomplete view of the processes underlying the analyses set forth in the
Hambrecht & Quist presentation to the Quickturn Board and its opinion. In
performing its analyses, Hambrecht & Quist made numerous assumptions with
respect to industry performance, general business and economic conditions and
other matters, many of which are beyond the control of Quickturn and Cadence.
The analyses performed by Hambrecht & Quist (and summarized below) are not
necessarily indicative of actual values or actual future results, which may be
significantly more or less favorable than suggested by such analyses.
Additionally, analyses relating to the values of businesses do not purport to
be appraisals or to reflect the prices at which businesses actually may be
acquired.
 
  In performing its analyses, Hambrecht & Quist used published Wall Street
research estimates and selected financial and operating data made available to
it from the internal records of Quickturn for projections of Quickturn's
calendar years 1999 and 2000 financial performance, as well as unpublished
Hambrecht & Quist research estimates, for calendar year 2000. Hambrecht & Quist
used published Wall Street research estimates for projections of Cadences
calendar year 1999, as well as unpublished Hambrecht & Quist research estimates
for Cadence, for calendar year 2000.
 
  The following is a brief summary of certain financial analyses performed by
Hambrecht & Quist in connection with providing its written opinion to the
Quickturn Board on December 8, 1998:
 
  Contribution Analysis. Hambrecht & Quist analyzed the contribution of each of
Quickturn and Cadence to certain calendar year 1999 and 2000 financial
statement categories of the pro forma combined company. The financial statement
categories included revenue, gross profit, earnings before interest and taxes
("EBIT") and net income. This contribution analysis was then compared to the
pro forma ownership percentage of Quickturn and Cadence Stockholders in the pro
forma post-merger combined company. Hambrecht & Quist observed that, calculated
on a treasury share basis, and based upon an implied exchange ratio of 0.464
shares of Cadence Common Stock for each share of Quickturn Common Stock,
Quickturn Stockholders are expected to own approximately 3.6% of the combined
company's equity at the close of the Merger and Cadence Stockholders are
expected to own approximately 96.4% of the combined company's equity at the
close of the Merger. It was estimated that Quickturn and Cadence would
contribute approximately 8.2% and 91.8%, respectively, of the combined
company's revenue, approximately 7.7% and 92.3%, respectively, of the combined
company's gross profit, approximately 3.3% and 96.7%, respectively, of the
combined company's EBIT, and approximately
 
                                       37
THE MERGER
<PAGE>
 
3.6% and 96.4%, respectively, of the combined company's net income in calendar
year 1999. It was estimated that Quickturn and Cadence would contribute
approximately 8.1% and 91.9%, respectively, of the combined company's revenue,
approximately 8.0% and 92.0%, respectively, of the combined company's gross
profit, approximately 5.0% and 95.0%, respectively, of the combined company's
EBIT, and approximately 5.2% and 94.8%, respectively, of the combined company's
net income in calendar year 2000.
 
  Pro Forma Merger Analysis. Hambrecht & Quist analyzed the pro forma impact of
the Merger on the combined company's calendar year 1999 and 2000 earnings per
share ("EPS") using financial and operating data made available to it from the
internal records of Quickturn for projections of Quickturn's calendar year 1999
and 2000 financial performance and published Wall Street research estimates for
projections of Cadences calendar year 1999 financial performance, as well as
unpublished Hambrecht & Quist research estimates for Cadence for calendar year
2000 financial performance. Hambrecht & Quist observed that this resulted in
lower EPS in calendar year 1999 for the combined company than for Cadence on a
stand-alone basis and higher EPS in calendar year 2000 than for Cadence on a
stand-alone basis. The foregoing analysis did not assume any adjustments in
revenues or costs resulting from the operating synergies potentially realized
from the Merger. The actual results and savings achieved by the combined
company after the Merger may vary from the projected results and such
variations may be material.
 
  Analysis of Publicly Traded Comparable Companies. Hambrecht & Quist compared
selected historical and projected financial information of Quickturn to
publicly traded EDA companies that Hambrecht & Quist deemed to be comparable to
Quickturn. EDA companies deemed comparable were Ansoft Corp., Avant! Corp.,
Cadence, Mentor, Summit Design Inc., and Synopsys, Inc. Such information
included the ratio of market value to projected net income as well as the ratio
of the enterprise value (market value plus debt less cash) to historical and
projected revenue. The foregoing multiples were applied to historical financial
results of Quickturn for the latest twelve-month ("LTM") period ended June 30,
1998 and projected revenue and net income for calendar year 1998 and 1999 based
on Wall Street consensus estimates and selected financial and operating data
made available to Hambrecht & Quist from the internal records of Quickturn.
 
  Hambrecht & Quist determined median values for the EDA companies of 2.2 times
LTM revenue, 2.0 times projected calendar year 1998 revenue, 1.5 times
projected calendar year 1999 revenue, and 17.2 times projected calendar year
1999 net earnings. Based on the analysis of comparable EDA companies,
Quickturn's implied equity value per share ranged from $6.38 to $15.27. This
implied equity value range compared to an offer in the proposed Merger of
$14.00 per share.
 
  Analysis of Selected Merger and Acquisition Transactions. Hambrecht & Quist
compared the proposed Merger with selected merger and acquisition transactions.
This analysis included 23 transactions involving companies in the EDA industry
("COMPARABLE M&A TRANSACTIONS"). In examining these transactions, Hambrecht &
Quist analyzed certain income statement parameters of the acquired company
relative to the consideration offered. The foregoing multiples were applied to
the LTM revenue of Quickturn for the twelve-month period ended September 30,
1998. The median multiple offered in the selected Comparable M&A Transactions
was 6.4 times LTM revenues. Based on the analysis of selected Comparable M&A
Transactions, Quickturn's implied equity value from applying multiples to
historical results was $38.74 per share. This implied equity value range
compared to an offer in the proposed Merger of $14.00 per share.
 
  No company or transaction used in the "Analysis of Publicly Traded Comparable
Companies" and "Analysis of Selected Merger and Acquisition Transactions" is
identical to Quickturn or the Merger. Accordingly, an analysis of the results
of the foregoing is not mathematical; rather, it involves complex
considerations and judgments concerning differences in financial and operating
characteristics of the companies and other factors that could affect the public
trading values of the companies or company to which they are compared.
 
  Premium Analysis. Hambrecht & Quist compared the implied premium of the offer
as of December 8, 1998 to similar premiums for relevant Comparable M&A
Transactions. Hambrecht & Quist observed that the
 
                                       38
THE MERGER
<PAGE>
 
mean one-day and twenty-day premiums paid in the selected Comparable M&A
Transactions was 19.3% and 31.8%, respectively. Additionally, Hambrecht & Quist
compared the implied premium of the offer in the proposed Merger as of December
8, 1998 to a broader range of 95 acquisitions of public technology companies.
Hambrecht & Quist noted that the median one-day and twenty-day premiums paid in
these acquisitions were 25.9% and 41.5%, respectively. This compared with the
proposed Merger which, as of December 8, 1998, represented a premium over the
closing price for Quickturn Common Stock on August 11, 1998 (the last trading
day prior to the announcement of the Mentor Offer) of 75.0%. Hambrecht & Quist
also analyzed the implied premiums to mean historical closing prices for the
one week, one month and three months ended August 11, 1998 using the Merger
offer price of $14.00 and found that the implied premiums were 89.8%, 85.1% and
41.8%, respectively.
 
  Potential Future Market Valuation. Hambrecht & Quist compared the offer in
the proposed Merger to a range of potential future market values based on
projected earnings and revenue and ranges of corresponding forward multiples.
Hambrecht & Quist applied multiples of earnings of 15.0, 17.5, and 20.0 times
forward earnings and multiples of revenue of 1.5, 2.0, and 2.5 times trailing
revenue to projected results for Quickturn based on Wall Street consensus
estimates and selected financial and operating data made available to it from
the internal records of Quickturn. By applying discount rates based on
Quickturn's expected cost of capital to the implied future market value,
Hambrecht & Quist was able to determine a present value of the implied future
market values. Hambrecht & Quist used a range of discount rates from 14% to 22%
for purposes of discounting Quickturn's projected market value. Based on this
analysis, Hambrecht & Quist estimated that the range of potential future market
value for Quickturn was between $5.70 and $19.13 based on projected EPS and
between $8.36 and $17.06 based on projected revenue. This implied equity value
range compared to an offer in the proposed Merger of $14.00 per share.
 
  The foregoing description of Hambrecht & Quist's opinion is qualified in its
entirety by reference to the full text of such opinion which is attached as
Appendix C to this Proxy Statement/Prospectus.
 
  Hambrecht & Quist, as part of its investment banking services, is regularly
engaged in the valuation of businesses and their securities in connection with
mergers and acquisitions, strategic transactions, corporate restructurings,
negotiated underwritings, secondary distributions of listed and unlisted
securities, private placements and valuations for corporate and other purposes.
Hambrecht & Quist has acted as a financial advisor to the Quickturn Board in
connection with the Merger, and it will receive a fee for its services, which
include the rendering of the fairness opinion.
 
  In the past, Hambrecht & Quist has provided investment banking and other
financial advisory services to Quickturn and has received fees for rendering
these services. Hambrecht & Quist served as co-manager in Quickturn's December
1993 initial public offering, advised Quickturn in the January 1996 adoption of
its Shareholder Rights Plan, advised Quickturn in its February 1997 acquisition
of SpeedSim, Inc., and advised Quickturn in its June 1997 acquisition of the
assets of Arkos Design, Inc. from Synopsys, Inc. In the ordinary course of
business, Hambrecht & Quist acts as a market maker and broker in the publicly
traded securities of Quickturn and receives customary compensation in
connection therewith, and also provides research coverage for Cadence and
Quickturn. In the ordinary course of business, Hambrecht & Quist actively
trades in the equity and derivative securities of Cadence and Quickturn for its
own account and for the accounts of its customers and, accordingly, may at any
time hold a long or short position in such securities. Moreover, Hambrecht &
Quist and its affiliates own 40,000 shares of Quickturn Common Stock. Hambrecht
& Quist may in the future provide investment banking or other financial
advisory services to Cadence or Quickturn.
 
  Pursuant to an engagement letter dated August 14, 1998, Quickturn has agreed
to pay Hambrecht & Quist a fee of $250,000 in connection with the delivery of
the fairness opinion rendered on December 8, 1998. Quickturn has agreed to pay
Hambrecht & Quist upon consummation of the Merger, a fee of 1.0% of the
aggregate consideration paid in the transaction, less any fees previously paid.
This fee is expected to total approximately $2.95 million. Quickturn also has
agreed to reimburse Hambrecht & Quist for its reasonable out-
 
                                       39
THE MERGER
<PAGE>
 
of-pocket expenses and to indemnify Hambrecht & Quist against certain
liabilities, including liabilities under the federal securities laws or
relating to or arising out of Hambrecht & Quist's engagement as financial
advisor.
 
THE MERGER
 
  Subject to the terms and conditions of the Merger Agreement and in
accordance with the Delaware Law, at the Effective Time, Merger Sub will merge
with and into Quickturn. Quickturn will be the surviving corporation and will
continue its corporate existence under the laws of the State of Delaware as a
wholly-owned subsidiary of Cadence. At the Effective Time, the separate
corporate existence of Merger Sub will terminate. The Certificate of
Incorporation of Merger Sub will be the Certificate of Incorporation of the
Surviving Corporation, and the By-Laws of Merger Sub will be the By-Laws of
the Surviving Corporation.
 
  Cadence and Quickturn may at any time provide for a Merger of Quickturn with
and into Merger Sub in which Merger Sub is the Surviving Corporation.
 
CONVERSION OF QUICKTURN STOCK; TREATMENT OF QUICKTURN STOCK OPTIONS AND
WARRANTS
 
  At the Effective Time, each share of Quickturn Common Stock outstanding,
other than shares held by Cadence, Merger Sub or Quickturn or any subsidiary
thereof, will be converted into the right to receive a number of shares of
Cadence Common Stock equal to the Exchange Ratio. Because the Exchange Ratio
will be fixed two business days prior to the Closing Date and because the
market price of Cadence Common Stock during that two day period is subject to
fluctuation, the value of the shares of Cadence Common Stock that Quickturn
Stockholders will receive in the Merger may increase or decrease, both before
and after the Merger.
 
  Each outstanding share of Quickturn Common Stock owned by Cadence, Merger
Sub or their subsidiaries or by Quickturn or its subsidiaries will be canceled
at the Effective Time and will cease to exist, and no Cadence Common Stock or
other consideration will be delivered in exchange therefor.
 
  Each share of Merger Sub Common Stock issued and outstanding immediately
prior to the Effective Time will remain issued and outstanding as one share of
common stock of the Surviving Corporation immediately after consummation of
the Merger.
 
  Each stock option to acquire Quickturn Common Stock granted under
Quickturn's stock option and incentive plans (collectively, the "QUICKTURN
STOCK PLANS"), and each warrant to acquire Quickturn Common Stock, outstanding
and unexercised immediately prior to the Effective Time will be converted
automatically at the Effective Time into, and will become, a stock option and
warrant, respectively, to purchase Cadence Common Stock, and will continue to
be governed by the terms of the Quickturn Stock Plans and the terms of such
warrants, respectively. The Quickturn Stock Plans will be assumed by the
Surviving Corporation. In each case, the number of shares of Cadence Common
Stock subject to the new Cadence options and warrants will be equal to the
number of shares of Cadence Common Stock that the holder of such option or
warrant would have been entitled to receive in the Merger had such holder
exercised such option or warrant in full immediately prior to the Effective
Time at a price per share equal to (x) the aggregate exercise price for the
shares of Quickturn Common Stock otherwise purchasable pursuant to such option
or warrant divided by (y) the product of (i) the number of shares of Quickturn
Common Stock otherwise purchasable pursuant to such option or warrant, and
(ii) the Exchange Ratio. The duration and other terms of each such new Cadence
option and warrant will be substantially the same as the prior corresponding
Quickturn option and warrant. In any event, options that are incentive stock
options under the Code shall be adjusted in the manner prescribed thereby.
 
  As soon as practicable after the Effective Time, Cadence will deliver to the
holders of Quickturn options and warrants appropriate notices setting forth
such holders' rights pursuant to the Quickturn Stock Plan and warrants,
respectively, and that the agreements evidencing the grants of such options or
warrants, as applicable, shall continue in effect on the same terms and
conditions (subject to the adjustments described above after giving effect to
the Merger). Cadence has agreed to comply with the terms of the Quickturn
Stock Plans and
 
                                      40
THE MERGER
<PAGE>
 
ensure, to the extent required by and subject to the provisions of such plans,
that Quickturn stock options that qualified as incentive stock options prior to
the Effective Time continue to qualify as incentive stock options of Cadence
after the Effective Time.
 
EXCHANGE OF CERTIFICATES; FRACTIONAL SHARES
 
  At or prior to the Effective Time, Cadence will deliver to its transfer
agent, or a depository or trust institution of recognized standing selected by
it (the "EXCHANGE AGENT"), for the benefit of the holders of shares of
Quickturn Common Stock, certificates representing the shares of Cadence Common
Stock and cash in lieu of any fractional shares (such certificates and cash,
together with any dividends or distributions with respect thereto, being
referred to herein as the "EXCHANGE FUND") to be issued pursuant to the Merger
Agreement in exchange for outstanding shares of Quickturn Common Stock.
 
  As soon as is practicable after the Effective Time, a form of transmittal
letter will be mailed by the Exchange Agent to Quickturn Stockholders. The form
of transmittal letter will contain instructions with respect to the surrender
of certificates representing Quickturn Common Stock.
 
  QUICKTURN COMMON STOCK CERTIFICATES SHOULD NOT BE RETURNED WITH THE ENCLOSED
PROXY AND SHOULD NOT BE FORWARDED TO THE EXCHANGE AGENT UNLESS AND UNTIL YOU
RECEIVE A LETTER OF TRANSMITTAL FOLLOWING THE EFFECTIVE TIME.
 
  Until the certificates representing Quickturn Common Stock are surrendered
for exchange after the Effective Time, holders of such certificates will not be
paid any cash instead of any fractional shares of Cadence Common Stock and will
accrue but will not be paid dividends or other distributions declared after the
Effective Time with respect to Cadence Common Stock into which their shares
have been converted. When such certificates or receipts are surrendered, any
unpaid dividends or other distributions will be paid, without interest. After
the Effective Time, there will be no transfers on the stock transfer books of
Quickturn of shares of Quickturn Common Stock issued and outstanding
immediately prior to the Effective Time. If certificates representing shares of
Quickturn Common Stock are presented after the Effective Time, they will be
canceled and exchanged for the relevant certificate representing the applicable
number of shares of Cadence Common Stock.
 
  No fractional shares of Cadence Common Stock will be issued to any Quickturn
Stockholder upon consummation of the Merger. For each fractional share that
would otherwise be issued, Cadence will pay cash in an amount equal to such
fraction multiplied by the average of the closing prices of Cadence Common
Stock as reported on the NYSE Composite Transactions reporting system for the
five trading days immediately preceding the Closing Date. No interest will be
paid or accrued on the cash in lieu of fractional shares payable to any
Quickturn Stockholder.
 
  Neither Cadence nor Quickturn will be liable to any former Quickturn
Stockholder for any shares or cash from the Exchange Fund properly delivered to
a public official pursuant to applicable abandoned property, escheat or similar
laws.
 
  If a certificate for Quickturn Common Stock has been lost, stolen or
destroyed, the Exchange Agent will issue the consideration properly payable
under the Merger Agreement upon receipt of an affidavit as to such loss, theft
or destruction and as to the ownership of such certificate by the claimant.
Cadence or the Exchange Agent may, in its discretion, require the claimant to
post bond in such amount as Cadence or the Exchange Agent may determine is
necessary as indemnity against any claim that may be made against Cadence with
respect to such certificate.
 
  For a description of the Cadence Common Stock and a description of the
differences between the rights of Quickturn Stockholders, on the one hand, and
Cadence Stockholders, on the other, see "Cadence Capital Stock and Comparison
of Stockholder Rights."
 
                                       41
THE MERGER
<PAGE>
 
EFFECTIVE TIME
 
  The Effective Time will be as set forth in the certificate of Merger that
will be filed with the Secretary of State of the State of Delaware on the
closing date of the Merger (the "CLOSING DATE"). The Closing Date will occur on
a date to be specified by the parties, which date will be no later than two
business days after the satisfaction or waiver (subject to applicable law) of
the latest to occur of the conditions precedent to the Merger set forth in the
Merger Agreement. Cadence and Quickturn anticipate that the Merger will be
consummated no later than March 2, 1999. However, the consummation of the
Merger could be delayed if there is a delay in obtaining any required
governmental approval. There can be no assurances as to if or when such
approvals will be obtained or that the Merger will be consummated. If the
Merger is not consummated on or before June 30, 1999, the Merger Agreement may
be terminated by either Cadence or Quickturn, unless the failure to consummate
the Merger by such date is due to the failure of the party seeking to terminate
the Merger Agreement to perform or observe the covenants and agreements of such
party set forth therein. See "--Conditions to Consummation of the Merger" and
"--Regulatory Approvals Required for the Merger."
 
REPRESENTATIONS AND WARRANTIES
 
  The Merger Agreement contains representations and warranties of Cadence and
Merger Sub, on the one hand, and Quickturn, on the other, as to, among other
things: (i) the corporate organization, existence, good standing and
qualification to do business of each party and, in the case of Quickturn, its
subsidiaries; (ii) the capitalization of each party and, in the case of
Quickturn, its subsidiaries; (iii) the corporate power and authority of each
party to enter into the Merger Agreement and perform its obligations
thereunder; (iv) the compliance of the Merger Agreement with (a) the
certificate of incorporation and by-laws of each party, (b) applicable law and
(c) certain material agreements of each party; (v) governmental and third-party
approvals; (vi) the timely filing of required regulatory reports; (vii) each
party's financial statements and filings with the Commission, and the
availability and accuracy thereof; (viii) each party's broker's fees; (ix) the
absence of certain changes in each party's business since September 30, 1998;
(x) the absence of material legal proceedings and injunctions; (xi) the
accuracy of the information about each party included in this Proxy
Statement/Prospectus; (xii) each party's (and, in the case of Quickturn, its
subsidiaries') compliance with applicable law; (xiii) the absence of
undisclosed liabilities; (xiv) the absence of material environmental
liabilities and (xv) the qualification of the Merger as a reorganization under
368(a) of the Code and for "pooling-of-interests" accounting treatment.
 
  The Merger Agreement contains certain additional representations and
warranties of Quickturn as to, among other things: (i) the filing and accuracy
of its tax returns; (ii) its employee benefit plans and related matters; (iii)
its insurance; (iv) certain of its business practices; (v) its intellectual
property; (vi) its product warranties and guaranties; (vii) its customers and
suppliers; (viii) the Quickturn Stockholder Rights not becoming separated from
the shares of Quickturn Common Stock or not becoming triggered or exercisable
as a result of the transactions contemplated by the Merger Agreement or the
Option Agreement; and (ix) its "Year 2000" compliance.
 
CONDUCT OF BUSINESS PENDING THE MERGER AND OTHER AGREEMENTS
 
  Pursuant to the Merger Agreement, prior to the Effective Time, each of
Cadence and Quickturn has agreed to, and to cause its subsidiaries to, (i)
conduct its business in the ordinary course and (ii) seek to preserve intact
its business organization and advantageous business relationships and retain
the services of its current officers and employees.
 
  Cadence and Quickturn have also agreed to cooperate with each other and to
use all reasonable efforts to promptly prepare and file all necessary
documentation to effect all applications, notices, petitions and filings, and
to obtain and to cooperate in obtaining permits, consents, approvals and
authorizations of all third parties and governmental entities necessary or
advisable to consummate the transactions contemplated by the Merger Agreement
and to comply with the terms and conditions of all such permits, consents,
approvals and authorizations. Cadence and Quickturn have each agreed, upon
request, to furnish to the other party all
 
                                       42
THE MERGER
<PAGE>
 
information concerning themselves and their subsidiaries and such other matters
as may be reasonably requested by the other party in connection with the
Merger. Cadence and Quickturn have further agreed, subject to the terms and
conditions of the Merger Agreement, to use all reasonable efforts to take, or
cause to be taken, all actions necessary, proper or advisable to comply
promptly with all legal requirements which may be imposed on such party or its
subsidiaries and to consummate the Merger. Cadence also agreed to use all
reasonable efforts to cause the shares of Cadence Common Stock to be issued in
the Merger and shares of Cadence Common Stock to be reserved for issuance upon
the exercise of Quickturn options and warrants to be approved for listing on
the NYSE, subject to official notice of issuance, prior to the Effective Time.
Subject to the terms and conditions of the Merger Agreement, Cadence and Merger
Sub have agreed to use all reasonable efforts to cause the Effective Time to
occur as soon as practicable after Quickturn Stockholders vote to approve the
Merger. Cadence and Quickturn also reached certain agreements with respect to
directors' and officers' indemnification and insurance. See "--Interests of
Certain Persons in the Merger."
 
  Quickturn has further agreed to give Cadence access to all of its employees,
properties, books, facilities and records, and to furnish information
concerning its businesses and properties, as Cadence may from time to time
reasonably request. Cadence has agreed to make a Cadence officer available to
Quickturn to answer questions and provide information regarding Cadence and its
subsidiaries, reasonably requested by Quickturn, taking into account the nature
of the transactions contemplated by the Merger Agreement.
 
  Quickturn has agreed not to redeem any of Quickturn Rights issued pursuant to
the Quickturn Rights Agreement. Quickturn has also agreed not to take any
action to amend the Quickturn Rights Agreement to facilitate the acquisition of
shares of Quickturn Common Stock by any person other than Cadence or Merger
Sub, unless the Merger Agreement is first terminated in accordance with its
terms.
 
  In addition, except as expressly contemplated by the Merger Agreement or
specified in a schedule thereto, Quickturn has agreed that, prior to the
Effective Time, without the prior written consent of Cadence, neither Quickturn
nor any of its subsidiaries will, among other things:
 
    (i) amend its certificate or articles of incorporation or bylaws (or
  other similar governing instrument);
 
    (ii) authorize for issuance, issue, sell, deliver or agree or commit to
  issue, sell or deliver (whether through the issuance or granting of
  options, warrants, commitments, subscriptions, rights to purchase or
  otherwise) any stock of any class or any other securities (except bank
  loans) or equity equivalents (including any stock options or stock
  appreciation rights), except for the issuance and sale of shares of
  Quickturn Common Stock pursuant to options granted under the Quickturn
  Stock Plans prior to the date of the Merger Agreement;
 
    (iii) split, combine or reclassify any shares of its capital stock,
  declare, set aside or pay any dividend or other distribution (whether in
  cash, stock or property or any combination thereof) in respect of its
  capital stock, make any other actual, constructive or deemed distribution
  in respect of its capital stock or otherwise make any payments to
  stockholders in their capacity as such, or redeem or otherwise acquire any
  of its securities or any securities of any of its subsidiaries;
 
    (iv) adopt a plan of complete or partial liquidation, dissolution,
  merger, consolidation, restructuring, recapitalization or other
  reorganization (other than the Merger);
 
    (v) alter through merger, liquidation, reorganization, restructuring or
  any other fashion the corporate structure of ownership of any subsidiary;
 
    (vi) (a) incur or assume any long-term or short-term debt or issue any
  debt securities, except for borrowings under existing lines of credit in
  the ordinary course of business; (b) assume, guarantee, endorse or
  otherwise become liable or responsible (whether directly, contingently or
  otherwise) for the obligations of any other person except for obligations
  of subsidiaries of Quickturn incurred in the ordinary course of business;
  (c) make any loans, advances or capital contributions to or investments in
  any other person (other than to subsidiaries of Quickturn or customary
  loans or advances to employees, in each case
 
                                       43
THE MERGER
<PAGE>
 
  in the ordinary course of business consistent with past practice); (d)
  pledge or otherwise encumber its shares of capital stock; or (e) mortgage
  or pledge any of its material assets, tangible or intangible, or create or
  suffer to exist any material lien thereupon;
 
    (vii) except as may be required by law, enter into, adopt or amend or
  terminate any bonus, profit sharing, compensation, severance, termination,
  stock option, stock appreciation right, restricted stock, performance unit,
  stock equivalent, stock purchase agreement, pension, retirement, deferred
  compensation, employment, health, life, or disability insurance, dependent
  care, severance or other employee benefit plan, agreement, trust, fund or
  other arrangement for the benefit or welfare of any director, officer or
  employee in any manner or increase in any manner the compensation or fringe
  benefits of any director, officer or employee or pay any benefit not
  required by any plan and arrangement as in effect as of the date hereof
  (including the granting of stock appreciation rights or performance units);
  however, it may increase annual compensation and/or provide for or amend
  bonus arrangements for employees for fiscal 1998 in the ordinary course of
  year-end compensation reviews consistent with past practice (to the extent
  that such compensation increases and new or amended bonus arrangements do
  not result in a material increase in benefits or compensation expense to
  Quickturn or any such subsidiary);
 
    (viii) acquire, sell, lease or dispose of any assets in any single
  transaction or series of related transactions having a fair market value in
  excess of $100,000 in the aggregate, other than sales of its products in
  the ordinary course of business consistent with past practices;
 
    (ix) except as may be required as a result of a change in law or in
  generally accepted accounting principles, change any of the accounting
  principles, practices or methods used by it;
 
    (x) revalue in any material respect any of its assets, including writing
  down the value of inventory or writing-off notes or accounts receivable,
  other than in the ordinary course of business;
 
    (xi) (a) acquire (by merger, consolidation or acquisition of stock or
  assets) any corporation, partnership or other business organization or
  division thereof or any equity interest therein; (b) enter into any
  contract or agreement other than in the ordinary course of business
  consistent with past practice that would be material to Quickturn and its
  subsidiaries, taken as a whole; (c) amend, modify or waive any right under
  any of its material contracts; (d) modify its standard warranty terms for
  its products or amend or modify any product warranties in effect as of the
  date hereof in any material manner that is adverse to it; or (e) authorize
  any new capital expenditure or expenditures that individually is in excess
  of $100,000 or in the aggregate are in excess of $300,000 (for Quickturn
  and its subsidiaries combined), except that Quickturn and its subsidiaries
  may make any capital expenditure required pursuant to existing customer
  contracts;
 
    (xii) make any tax election or settle or compromise any income tax
  liability material to Quickturn and its subsidiaries taken as a whole;
 
    (xiii) settle or compromise any pending or threatened suit, action or
  claim that (a) relates to the transactions contemplated by the Merger
  Agreement or (b) the settlement or compromise of which would have a
  material adverse effect on Quickturn;
 
    (xiv) commence any material software development project or terminate any
  material software development project that is currently ongoing, in either
  case except pursuant to the terms of existing contracts with customers or
  except as contemplated by Quickturn's project development budget; or
 
    (xv) take or agree in writing or otherwise to take any of the actions
  described above (and it shall use all reasonable efforts not to take any
  action that would make any of the representations or warranties of
  Quickturn contained in the Merger Agreement untrue or incorrect).
 
  Cadence has agreed that neither Cadence nor any of its subsidiaries will,
without the prior written consent of Quickturn:
 
    (i) knowingly take any action that would result in a failure to maintain
  the trading of the Cadence Common Stock on the New York Stock Exchange (the
  "NYSE");
 
 
                                       44
THE MERGER
<PAGE>
 
    (ii) acquire or agree to acquire by merging or consolidating with, by
  purchasing an equity interest in or the assets of, or by any other manner,
  any business or any corporation, partnership or other business organization
  or division thereof or otherwise acquire or agree to acquire any assets of
  any other entity (other than the purchase of assets from suppliers, clients
  or vendors in the ordinary course of business and consistent with past
  practice), if such transaction would prevent or materially delay the
  consummation of the transactions contemplated by the Merger Agreement;
 
    (iii) adopt or propose to adopt any amendments to its charter documents
  that would have an adverse impact on the consummation of the transactions
  contemplated by the Merger Agreement; or
 
    (iv) take or agree in writing or otherwise to take any of the actions
  described above or any action that would make any of the representations or
  warranties of Cadence contained in the Merger Agreement untrue or
  incorrect.
 
  The Merger Agreement contains certain provisions restricting the ability of
Quickturn and its representatives to discuss or negotiate proposals for certain
material transactions with persons other than Cadence. Under these provisions,
Quickturn, its affiliates (as reasonably determined by Quickturn) and their
respective officers and other employees with managerial responsibilities,
directors, representatives and agents are required to immediately cease any
discussions or negotiations with any parties with respect to any Third Party
Acquisition (as defined below). Quickturn has also agreed that neither
Quickturn nor any of its affiliates (as reasonably determined by Quickturn)
will, nor will Quickturn authorize or permit any of its or their respective
officers, directors, employees, representatives or agents to, directly or
indirectly, encourage, solicit, participate in or initiate discussions or
negotiations with or provide any non-public information to any person or group
(other than Cadence and Merger Sub or their representatives) concerning any
Third Party Acquisition; provided, however, that nothing in the Merger
Agreement will prevent the Quickturn Board from taking and disclosing to
Quickturn Stockholders a position contemplated by Rules 14d-9 and 14e-2
promulgated under the Exchange Act with regard to any tender or exchange offer.
Quickturn has agreed to promptly notify Cadence in the event it receives any
proposal or inquiry concerning a Third Party Acquisition, including the terms
and conditions thereof and the identity of the party submitting such proposal,
and to advise Cadence from time to time of the status and any material
developments concerning such proposal or inquiry.
 
  Except as described above, the Quickturn Board may not withdraw its
recommendation of the Merger or approve or recommend, or cause Quickturn to
enter into any agreement with respect to, any Third Party Acquisition. However,
if the Quickturn Board by a majority vote determines in its good faith
judgment, after consultation with and based upon the advice of legal counsel,
that it is required to do so in order to comply with its fiduciary duties, the
Quickturn Board may withdraw its recommendation of the Merger or approve or
recommend a Superior Proposal (as defined below), but in each case only (a)
after providing written notice to Cadence (a "NOTICE OF SUPERIOR PROPOSAL")
advising Cadence that the Quickturn Board has received a Superior Proposal,
specifying the material terms and conditions of such Superior Proposal and
identifying the person making such Superior Proposal and (b) if Cadence does
not, within five (5) business days of Cadence's receipt of the Notice of
Superior Proposal, make an offer that the Quickturn Board by a majority vote
determines in its good faith judgment (based on the written advice of a
financial advisor of nationally recognized reputation) to be at least as
favorable to Quickturn Stockholders as such Superior Proposal; provided,
however, that Quickturn may not enter into any agreement with respect to a
Superior Proposal unless and until the Merger Agreement is terminated in
accordance with its terms and Quickturn has paid all amounts due to Cadence
pursuant to Section 6.3 of the Merger Agreement (as described below under "--
Termination of the Merger Agreement--Effect of Termination"). Any disclosure
that the Quickturn Board may be compelled to make with respect to the receipt
of a proposal for a Third Party Acquisition or otherwise in order to comply
with its fiduciary duties or Rule 14d-9 or 14e-2 under the Exchange Act will
not constitute a violation of the Merger Agreement, provided that such
disclosure states that no action will be taken by the Quickturn Board in
violation of the above-described provisions.
 
  As used above, "THIRD PARTY ACQUISITION" means the occurrence of any of the
following events: (i) the acquisition of Quickturn by merger or otherwise by
any person (which includes a "person" as such term is
 
                                       45
THE MERGER
<PAGE>
 
defined in Section 13(d)(3) of the Exchange Act) other than Cadence, Merger Sub
or any of their affiliates (a "THIRD PARTY"); (ii) the acquisition by a Third
Party of any material portion of the assets of Quickturn and its subsidiaries
taken as a whole, other than the sale of its products in the ordinary course of
business consistent with past practices; (iii) the acquisition by a Third Party
of 15% or more of the outstanding shares of Quickturn Common Stock; (iv) the
adoption by Quickturn of a plan of liquidation or the declaration or payment of
an extraordinary dividend; (v) the repurchase by Quickturn or any of its
subsidiaries of more than 10% of the outstanding shares of Quickturn Common
Stock; or (vi) the acquisition by Quickturn or any of its subsidiaries by
merger, purchase of stock or assets, joint venture or otherwise of a direct or
indirect ownership interest or investment in any business whose annual
revenues, net income or assets is equal to or greater than 10% of the annual
revenues, net income or assets of Quickturn. As used above, a "SUPERIOR
PROPOSAL" means any bona fide proposal to acquire directly or indirectly for
consideration consisting of cash and/or securities more than 50% of the shares
of Quickturn Common Stock then outstanding or all or substantially all the
assets of Quickturn and otherwise on terms that the Quickturn Board by a
majority vote determines in its good faith judgment (based on the written
advice of Hambrecht & Quist or another financial advisor of nationally
recognized reputation) to be more favorable to Quickturn Stockholders than the
Merger.
 
CONDITIONS TO CONSUMMATION OF THE MERGER
 
  Each party's obligation to consummate the Merger is subject to the
satisfaction or waiver, where permissible, of the following conditions at or
prior to the Effective Time:
 
    (i) the Merger Agreement has been approved and adopted by the requisite
  vote of the Quickturn Stockholders;
 
    (ii) no statute, rule, regulation, executive order, decree, ruling or
  injunction has been enacted, entered, promulgated or enforced by any United
  States federal or state court or United States federal or state
  governmental entity that prohibits, restrains, enjoins or restricts the
  consummation of the Merger;
 
    (iii) any waiting period applicable to the Merger under the HSR Act has
  terminated or expired;
 
    (iv) any governmental or regulatory notices, approvals or other
  requirements necessary to consummate the transactions contemplated and to
  operate Quickturn's business after the Effective Time in all material
  respects as it was operated prior thereto (other than under the HSR Act)
  (the "REQUISITE REGULATORY APPROVALS") have been given, obtained or
  complied with, as applicable;
 
    (v) the registration statement of which this Proxy Statement/Prospectus
  is a part has become effective under the Securities Act of 1933, as amended
  (the "SECURITIES ACT"), and shall not be the subject of any stop order or
  proceedings seeking a stop order and Cadence shall have received all state
  securities laws or "blue sky" permits and authorizations necessary to issue
  shares of Cadence Common Stock in exchange for shares of Quickturn Common
  Stock in the Merger; and
 
    (vi) Quickturn has received from PricewaterhouseCoopers and Cadence has
  received from Arthur Andersen LLP ("ARTHUR ANDERSEN"), their respective
  independent accountants, a copy of a letter addressed to them and dated the
  Closing Date, in substance reasonably satisfactory to Cadence and Quickturn
  (and which may contain customary qualifications and assumptions),
  respectively, to the effect that such independent accountants concur with
  Quickturn's and Cadence's managements' conclusions that no conditions exist
  related to Quickturn and Cadence, respectively, that would preclude Cadence
  from accounting for the Merger as a "pooling-of-interests."
 
  The obligation of Quickturn to consummate the Merger is subject to the
satisfaction at or prior to the Effective Time of the following conditions:
 
    (i) the representations and warranties of Cadence and Merger Sub
  contained in the Merger Agreement and in the Option Agreement are true and
  correct (except to the extent that the aggregate of all breaches would not
  have a material adverse effect on Cadence) at and as of the Effective Time
  with the same effect as if made at and as of the Effective Time (except to
  the extent such representations specifically related to an earlier date, in
  which case such representations are true and correct as of such
 
                                       46
THE MERGER
<PAGE>
 
  earlier date, and in any event, subject to the foregoing material adverse
  effect qualification) and, at the Closing, Cadence and Merger Sub have
  delivered to Quickturn a certificate to that effect, executed by two
  executive officers of Cadence and Merger Sub;
 
    (ii) each of the covenants and obligations of Cadence and Merger Sub to
  be performed at or before the Effective Time pursuant to the terms of the
  Merger Agreement have been duly performed in all material respects at or
  before the Effective Time and, at the Closing, Cadence and Merger Sub have
  delivered to Quickturn a certificate to that effect, executed by two
  executive officers of Cadence and Merger Sub;
 
    (iii) the shares of Cadence Common Stock issuable to Quickturn
  Stockholders pursuant to the Merger Agreement and such other shares
  required to be reserved for issuance in connection with the Merger have
  been authorized for listing on the NYSE, upon official notice of issuance;
 
    (iv) Quickturn has received the opinion of its tax counsel to the effect
  that (x) the Merger will be treated for federal income tax purposes as a
  reorganization within the meaning of Section 368(a) of the Internal Revenue
  Code of 1986, as amended (the "CODE") and (y) each of Cadence, Merger Sub
  and Quickturn will be a party to the reorganization within the meaning of
  Section 368(b) of the Code, which opinion may rely on certain
  representations, and such opinion has not been withdrawn or modified in any
  material respect;
 
    (v) Quickturn has received the opinion of legal counsel to Cadence
  relating to certain legal matters;
 
    (vi) Cadence has obtained the consent or approval of each person whose
  consent or approval is required in connection with the transactions
  contemplated by the Merger Agreement under any loan or credit agreement,
  note, mortgage, indenture, lease, or other agreement or instrument, except
  those for which the failure to obtain would not, in the reasonable opinion
  of Quickturn, individually or in the aggregate, have a material adverse
  effect on Cadence; and
 
    (vii) there have been no events, changes or effects with respect to
  Cadence or its subsidiaries having or that would reasonably be expected to
  have a material adverse effect on Cadence.
 
  The respective obligations of Cadence and Merger Sub to consummate the Merger
are subject to the satisfaction at or prior to the Effective Time of the
following conditions:
 
    (i) the representations and warranties of Quickturn contained in the
  Merger Agreement (other than those relating to the status of the Quickturn
  Rights Agreement and effect of the transactions contemplated by the Merger
  Agreement and Option Agreement thereon) and in the Option Agreement are
  true and correct (except to the extent that the aggregate of all breaches
  would not have a material adverse effect on Quickturn) at and as of the
  Effective Time with the same effect as if made at and as of the Effective
  Time (except to the extent such representations specifically related to an
  earlier date, in which case such representations are true and correct as of
  such earlier date, and in any event, subject to the foregoing material
  adverse effect qualification) and the representations and warranties of
  Quickturn relating to the status of the Quickturn Rights Agreement and
  effect of the transactions contemplated by the Merger Agreement and Option
  Agreement thereon are true and correct in all respects at and as of the
  Effective Time, and, at the Closing, Quickturn has delivered to Cadence and
  Merger Sub a certificate to that effect, executed by two executive officers
  of Quickturn;
 
    (ii) each of the covenants and obligations of Quickturn to be performed
  at or before the Effective Time pursuant to the terms of this Agreement has
  been duly performed in all material respects at or before the Effective
  Time and, at the Closing, Quickturn has delivered to Cadence and Merger Sub
  a certificate to that effect, executed by two executive officers of
  Quickturn;
 
    (iii) Cadence has received from each affiliate of Quickturn an executed
  copy of a letter restricting such affiliate's ability to sell, transfer,
  pledge or otherwise dispose of, or otherwise reduce his risk with respect
  to, his shares of Quickturn Common Stock and shares of Cadence Common Stock
  issued in exchange therefor in the Merger;
 
 
                                       47
THE MERGER
<PAGE>
 
    (iv) there have been no events, changes or effects with respect to
  Quickturn or its subsidiaries having or that, individually or in the
  aggregate, would reasonably be expected to have, a material adverse effect
  on Quickturn;
 
    (v) Cadence shall have received the opinion of its tax counsel to the
  effect that (x) the Merger will be treated for federal income tax purposes
  as a reorganization within the meaning of Section 368(a) of the Code and
  (y) each of Cadence, Merger Sub and Quickturn will be a party to the
  reorganization within the meaning of Section 368(b) of the Code, which
  opinion may rely on the representations, and such opinion has not been
  withdrawn or modified in any material respect;
 
    (vi) Cadence has received the opinion of legal counsel to Quickturn
  relating to certain legal matters;
 
    (vii) Quickturn has obtained the consent or approval of each person whose
  consent or approval is required in order to permit the succession by the
  Surviving Corporation pursuant to the Merger to any obligation, right or
  interest of Quickturn or any subsidiary of Quickturn under the agreements
  and instruments set forth on Quickturn's disclosure schedule to the Merger
  Agreement; and
 
    (viii) Keith R. Lobo has not questioned the validity or enforceability of
  his Employment Agreement or otherwise expressed his intent not to continue
  his employment with the Surviving Corporation.
 
  No assurance can be provided as to whether all of the conditions precedent to
the Merger will be satisfied or waived by the party permitted to do so. If the
Merger is not consummated on or before June 30, 1999, the Merger Agreement may
be terminated by either Cadence or Quickturn, unless the failure to consummate
the Merger by such date is due to the failure of the party seeking to terminate
the Merger Agreement to perform or observe covenants and agreements of such
party set forth therein.
 
REGULATORY APPROVALS REQUIRED FOR THE MERGER
 
  Each of Cadence and Quickturn has agreed to use all reasonable efforts to
take or cause to be taken all action and to do or cause to be done all things
reasonably necessary, proper or advisable under applicable laws and regulations
to consummate and make effective the transactions contemplated by the Merger
Agreement, including using all reasonable efforts to do the following: (i)
cooperate in the preparation and filing of the registration statement of which
this Proxy Statement/Prospectus forms a part, and any amendments thereto, with
the Commission, any filings that may be required under the Hart-Scott-Rodino
Antitrust Improvements Act of 1976, as amended (the "HSR ACT"), and any filings
under similar merger notification laws or regulations of foreign governmental
entities; (ii) obtain consents of all third parties and governmental entities
necessary, proper or advisable for the consummation of the transactions
contemplated by the Merger Agreement; and (iii) contest any legal proceeding
relating to the Merger.
 
  Antitrust. Under the HSR Act, and the rules promulgated thereunder by the
U.S. Federal Trade Commission (the "FTC"), the Merger may not be consummated
until notifications have been given and certain information has been furnished
to the FTC or the Antitrust Division of the U.S. Department of Justice (the
"DOJ") and the specified waiting period has been satisfied. Consummation of the
Merger is subject to compliance with the HSR Act. On December 11, 1998, Cadence
and Quickturn filed the notifications required under the HSR Act, as well as
certain information required to be furnished to the FTC and the DOJ. At any
time before or after consummation of the Merger, and notwithstanding that the
HSR Act waiting period has expired, the DOJ, the FTC or any state or foreign
governmental entity could take such action under the antitrust laws as it deems
necessary or desirable in the public interest. Such action could include
seeking to enjoin the consummation of the Merger or seeking divestiture of
Quickturn or businesses of Cadence or Quickturn by Cadence. Private parties may
also seek to take legal action under the antitrust laws under certain
circumstances.
 
  Based on information available to them, Cadence and Quickturn believe that
the Merger will be effected in compliance with all material federal, state and
foreign antitrust laws. However, there can be no assurance that a challenge to
the consummation of the Merger on antitrust grounds will not be made or that,
if such a challenge were made, Cadence and Quickturn would prevail.
 
 
                                       48
THE MERGER
<PAGE>
 
  Filings with the Secretary of State of the State of Delaware. A Certificate
of Merger must be filed with the Secretary of State of the State of Delaware to
consummate the Merger.
 
  Cadence and Quickturn are not aware of any other Required Regulatory
Approvals or actions that are required prior to the parties' consummation of
the Merger. Cadence and Quickturn presently contemplate that if any such
additional governmental approvals or actions are required that they will try to
get them. There can be no assurance, however, that any such additional
approvals or actions will be obtained.
 
MATERIAL FEDERAL INCOME TAX CONSEQUENCES
 
  The following discussion addresses the material federal income tax
considerations of the Merger that are generally applicable to holders of
Quickturn Common Stock exchanging their Quickturn Common Stock for Cadence
Common Stock. Quickturn Stockholders should be aware that the following
discussion does not deal with all federal income tax considerations that may be
relevant to particular Quickturn Stockholders in light of their particular
circumstances, such as stockholders who are dealers in securities, who are
banks, insurance companies or tax-exempt organizations, who are subject to the
alternative minimum tax provisions of the Code, who hold their shares as part
of a hedge, straddle or other risk reduction transaction, who are foreign
persons or who acquired their Quickturn Common Stock through stock option or
stock purchase programs or in other compensatory transactions. In addition, the
following discussion does not address the tax consequences of the Merger under
foreign, state or local tax laws or tax consequences of transactions
effectuated prior to or after the Merger (whether or not such transactions are
in connection with the Merger) including, without limitation, the exercise of
options or rights to purchase Quickturn Common Stock in anticipation of the
Merger.
 
  QUICKTURN STOCKHOLDERS ARE URGED TO CONSULT THEIR OWN TAX ADVISORS AS TO THE
SPECIFIC TAX CONSEQUENCES TO THEM OF THE MERGER, INCLUDING THE APPLICABLE
FEDERAL, STATE, LOCAL AND FOREIGN TAX CONSEQUENCES TO THEM OF THE MERGER.
 
  The following discussion is based on the Code, applicable Treasury
Regulations, judicial authority and administrative rulings and practice, all as
of the date hereof. There can be no assurance that future legislative, judicial
or administrative changes or interpretations will not adversely affect the
accuracy of the statements and conclusions set forth herein. Any such changes
or interpretations could be applied retroactively and could affect the tax
consequences of the Merger to Cadence, Merger Sub, Quickturn and/or their
respective stockholders.
 
  Neither Cadence nor Quickturn has requested or will request a ruling from the
Internal Revenue Service ("IRS") with regard to any of the U.S. federal income
tax consequences of the Merger. GDC, counsel to Cadence, has rendered its
opinion to Cadence and WSGR, counsel to Quickturn, has rendered an opinion to
Quickturn (collectively, the "TAX OPINIONS") that, if the Merger is consummated
in accordance with the Merger Agreement (and without any waiver, breach or
amendment of any of the provisions thereof), the Merger will constitute a
reorganization under Section 368(a) of the Code (a "REORGANIZATION") and each
of Cadence, Quickturn and Merger Sub will be a party to the reorganization
within the meaning of Section 368(b) of the Code. Moreover, as a condition to
the consummation of the Merger, such counsel must also render tax opinions at
the closing of the Merger that the Merger will constitute a Reorganization and
that each of Cadence, Quickturn and Merger Sub will be a party to the
reorganization within the meaning of Section 368(b) of the Code (the "CLOSING
OPINIONS"). The Tax Opinions assume and are conditioned upon, and the Closing
Opinions will assume and be conditioned upon, (i) the truth and accuracy of the
statements, covenants, representations and warranties contained in the Merger
Agreement, in the representations received from Cadence, Merger Sub and
Quickturn to support the Tax Opinions and the Closing Opinions, including those
attached as exhibits to the Merger Agreement (the "TAX REPRESENTATIONS") and in
all other instruments and documents related to the formation, organization and
operation of Cadence, Merger Sub and Quickturn examined by and relied upon by
GDC and WSGR, in connection with those opinions, (ii) the authenticity of
original documents submitted to such counsel, the conformity to the originals
of documents submitted to such counsel as copies, and the due and valid
execution and delivery of all such documents where due execution and delivery
are a prerequisite to the effectiveness thereof; (iii) the performance of all
covenants contained in the
 
                                       49
THE MERGER
<PAGE>
 
Merger Agreement and the Tax Representations without waiver or breach of any
material provision thereof; (iv) the accuracy of any representation or
statement made "to the best of knowledge" or similarly qualified without such
qualification; and (v) the reporting of the Merger as a Reorganization by
Cadence and Quickturn in their respective federal income tax returns. Subject
to the limitations and qualifications referred to herein and in the Tax
Opinions and Closing Opinions, and assuming that the Merger is treated as a
Reorganization, the following U.S. federal income tax consequences will result:
 
    (a) No gain or loss will be recognized by the holders of Quickturn Common
  Stock upon the receipt of Cadence Common Stock solely in exchange for such
  Quickturn Common Stock in the Merger (except to the extent of cash received
  in lieu of fractional shares);
 
    (b) The aggregate tax basis of the Cadence Common Stock so received by
  Quickturn Stockholders in the Merger (including any fractional share of
  Cadence Common Stock not actually received) will be the same as the
  aggregate tax basis of the Quickturn Common Stock surrendered in exchange
  therefor;
 
    (c) The holding period of the Cadence Common Stock so received by each
  Quickturn Stockholder in the Merger will include the period for which the
  Quickturn Common Stock surrendered in exchange therefor was considered to
  be held, provided that the Quickturn Common Stock so surrendered is held as
  a capital asset at the Effective Time;
 
    (d) Cash payments received by holders of Quickturn Common Stock in lieu
  of receipt of a fractional share of Cadence Common Stock will be treated as
  if such fractional share of Cadence Common Stock had been issued in the
  Merger and then redeemed by Cadence, and a stockholder of Quickturn
  receiving such cash will generally recognize gain or loss upon such
  payment, measured by the difference (if any) between the amount of cash
  received and the basis in such fractional share; and
 
    (e) None of Cadence, Merger Sub and Quickturn will recognize gain or loss
  solely as a result of the Merger.
 
  None of the Tax Opinions and the Closing Opinions is binding on the IRS or
the courts. A successful IRS challenge to the Reorganization status of the
Merger would result in a Quickturn Stockholder recognizing gain or loss with
respect to each share of Quickturn Common Stock surrendered equal to the
difference between the stockholder's basis in such share and the fair market
value, as of the Effective Time, of the Cadence Common Stock received in
exchange therefor. In such event, a Quickturn Stockholder's aggregate basis in
the Cadence Common Stock so received would equal its fair market value, and the
stockholder's holding period for such stock would begin the day after the
Merger. Even if the Merger qualifies as a Reorganization, a recipient of shares
of Cadence Common Stock would recognize gain to the extent that such shares
were considered to be received in exchange for services or property (other than
solely Quickturn Common Stock). All or a portion of such gain may be taxable as
ordinary income. Gain would also have to be recognized to the extent that a
Quickturn Stockholder was treated as receiving (directly or indirectly)
consideration other than Cadence Common Stock in exchange for the Quickturn
Common Stock.
 
  Payments in respect of Quickturn Common Stock or Cadence Common Stock may be
subject to information reporting to the IRS and to a 31% backup withholding
tax. Backup withholding will not apply, however, to a payment to a holder of
such stock if such holder completes and signs the substitute Form W-9 that will
be included as part of the transmittal letter, or otherwise proves to Cadence
and the Exchange Agent that it is exempt from backup withholding.
 
ACCOUNTING TREATMENT
 
  It is anticipated that the Merger will be accounted for as a "pooling-of-
interests" transaction under generally accepted accounting principles. Under
this method of accounting, Quickturn Stockholders and Cadence Stockholders will
be deemed to have combined their existing voting common stock interests by
virtue of the exchange of shares of Quickturn Common Stock for shares of
Cadence Common Stock. Accordingly, the book value of the assets, liabilities
and stockholders' equity of each of Cadence and Quickturn, as reported on its
consolidated balance sheet, will be carried over to the consolidated balance
sheet of the combined company,
 
                                       50
THE MERGER
<PAGE>
 
and no goodwill will be created. The combined company will be able to include
in its consolidated income the consolidated income of both companies for the
entire fiscal year in which the Merger occurs.
 
  It is a condition to consummation of the Merger that each of Cadence and
Quickturn receive an opinion from Arthur Andersen and PricewaterhouseCoopers,
their respective independent accountants, to the effect that the Merger will be
accounted for as a "pooling-of-interests." See "--Conditions to Consummation of
the Merger."
 
  The unaudited pro forma financial information contained in this Proxy
Statement/Prospectus has been prepared using the "pooling-of-interests"
accounting method to account for the Merger. See "Summary--Unaudited
Comparative Per Common Share Data of Cadence and Quickturn" and "--Selected
Unaudited Pro Forma Financial Data of Cadence and Quickturn."
 
TERMINATION OF THE MERGER AGREEMENT
 
  Termination. The Merger Agreement may be terminated at any time prior to the
Effective Time, whether before or after approval by the Quickturn Stockholders:
 
    (i) by mutual consent of Cadence, Merger Sub and Quickturn;
 
    (ii) by Cadence and Merger Sub or Quickturn if (a) any court of competent
  jurisdiction in the United States or other United States federal or state
  governmental entity has issued a final order, decree or ruling, or taken
  any other final action, restraining, enjoining or otherwise prohibiting the
  Merger and such order, decree, ruling or other action is nonappealable or
  (b) the Merger is not consummated on or before June 30, 1999 (the "FINAL
  DATE"), unless the failure to close by the Final Date is due to the failure
  of the party seeking to terminate the Merger Agreement to perform or
  observe its covenants and agreements in the Merger Agreement;
 
    (iii) by Quickturn if (a) there has been a breach of any of Cadence's or
  Merger Sub's representations or warranties in the Merger Agreement or if
  any of such representations or warranties has become untrue such that the
  conditions to Cadence's and Merger Sub's obligations to complete the Merger
  could not be satisfied by the Final Date, provided that Quickturn has not
  breached any of its obligations under the Merger Agreement in any material
  respect; (b) there has been a breach by Cadence or Merger Sub of any of
  their respective covenants or agreements in the Merger Agreement which has
  a material adverse effect on Cadence or materially adversely affects (or
  materially delays) the consummation of the Merger, and Cadence or Merger
  Sub, as the case may be, has not cured the breach within 20 business days
  after Quickturn has given it notice of the breach, provided that Quickturn
  has not breached any of its obligations in the Merger Agreement in any
  material respect; (c) Quickturn convened a meeting of the Quickturn
  Stockholders to vote upon the Merger failed to obtain the requisite vote of
  the Quickturn Stockholders at the meeting (including any adjournments
  thereof); or (d) the Quickturn Board has received a Superior Proposal, and
  has complied with the provisions of the Merger Agreement relating thereto;
  or
 
    (iv) by Cadence and Merger Sub if (a) there has been a breach of any of
  Quickturn's representations or warranties in the Merger Agreement or if any
  of Quickturn's representations or warranties has become untrue such that
  the conditions to Quickturn's obligation to complete the Merger could not
  be satisfied by the Final Date, provided that neither Cadence nor Merger
  Sub has breached any of its obligations in the Merger Agreement in any
  material respect; (b) Quickturn has breached any of its covenants or
  agreements in the Merger Agreement and the breach has a material adverse
  effect on Quickturn or materially adversely affects (or materially delays)
  the consummation of the Merger, and Quickturn has not cured such breach
  within 20 business days after Cadence or Merger Sub has given it notice of
  the breach, provided that neither Cadence nor Merger Sub has breached any
  of its obligations in the Merger Agreement in any material respect; (c) the
  Quickturn Board has recommended to the Quickturn Stockholders a Superior
  Proposal; (d) the Quickturn Board has withdrawn or adversely modified its
  approval or recommendation of the Merger Agreement or the Merger; (e)
  Quickturn has ceased using all
 
                                       51
THE MERGER
<PAGE>
 
  reasonable efforts to call, give notice of, or convene or hold a
  stockholders' meeting to vote on the Merger as promptly as practicable
  after the date of the Merger Agreement or has adopted a resolution not to
  effect any of the foregoing; or (f) Quickturn convened a meeting of the
  Quickturn Stockholders to vote upon the Merger but failed to obtain the
  requisite vote of its stockholders at such meeting (including any
  adjournments thereof).
 
  Effect of Termination. If the Merger Agreement is terminated as described
above, the Merger Agreement shall immediately become void and have no effect
without any liability on the part of any party thereto or its affiliates,
directors, officers or stockholders other than the confidentiality provisions
of the Merger Agreement and the fees and expenses provisions described below.
No such termination, however, will relieve any party from liability for any
breach of the Merger Agreement prior to such termination.
 
  Fees and Expenses. (a) If the Merger Agreement is terminated:
 
    (i) by Quickturn because the Quickturn Board has received a Superior
  Proposal and has complied with the provisions of the Merger Agreement
  relating thereto;
 
    (ii) by Cadence and Merger Sub because:
 
      (A) the Quickturn Board has recommended a Superior Proposal to the
    Quickturn Stockholders,
 
      (B) the Quickturn Board withdrew or adversely modified its approval
    or recommendation of the Merger Agreement or the Merger, or
 
      (C) Quickturn has ceased using all reasonable efforts to hold a
    stockholders' meeting to vote on the Merger or;
 
    (iii) by Cadence and Merger Sub because:
 
      (A) Quickturn has breached any of its representations or warranties
    in the Merger Agreement or any of its representations or warranties
    have become untrue such that the conditions to Cadence's and Merger
    Sub's obligations to complete the Merger could not be satisfied by the
    Final Date, or
 
      (B) Quickturn has breached and not cured any of its covenants or
    agreements in the Merger Agreement and the breach has a material
    adverse effect on Quickturn or materially adversely affects or
    materially delays the consummation of the Merger,
 
  and, in the case of either clause (A) or (B), within 12 months thereafter,
  Quickturn enters into an agreement with respect to a Company Acquisition
  (as defined below) or a Company Acquisition occurs involving any party (or
  any affiliate thereof) (x) with whom Quickturn (or its agents) had
  negotiations with a view to a Company Acquisition, (y) to whom Quickturn
  (or its agents) furnished information with a view to a Company Acquisition
  or (z) who had submitted a proposal or expressed an interest in a Company
  Acquisition, in the case of each of clauses (x), (y) and (z), prior to such
  termination; or
 
    (iv) either by Quickturn or by Cadence and Merger Sub because Quickturn
  convened a meeting of the Quickturn Stockholders to vote on the Merger but
  failed to obtain the requisite vote and, at the time of such meeting, there
  was outstanding an offer by a Third Party to consummate, or a third party
  publicly announced (and did not withdraw) a plan or proposal with respect
  to, a Company Acquisition,
 
then Quickturn has agreed that Cadence and Merger Sub would suffer direct and
substantial damages, which damages are not determinable with reasonable
certainty. To compensate Cadence and Merger Sub for such damages, Quickturn has
agreed to pay to Cadence the amount of $10,557,000 as liquidated damages
immediately upon the occurrence of any the events described above giving rise
to such damages. Quickturn has waived any right to set-off or counterclaim
against such amount.
 
  (b) In addition, if the Merger Agreement is terminated:
 
    (i) by Quickturn because (A) Quickturn convened a meeting of the
  Quickturn Stockholders to vote on the Merger but failed to obtain the
  requisite vote or (B) the Quickturn Board received a Superior Proposal; or
 
                                       52
THE MERGER
<PAGE>
 
    (ii) by Cadence and Merger Sub because:
 
      (A) Quickturn has breached any of its representations or warranties
    in the Merger Agreement or any of its representations or warranties
    have become untrue such that the conditions to Cadence's and Merger
    Sub's obligations to complete the Merger could not be satisfied by the
    Final Date,
 
      (B) Quickturn has breached and not cured any of its covenants or
    agreements in the Merger Agreement and the breach has a material
    adverse effect on Quickturn or materially adversely affects or
    materially delays the consummation of the Merger,
 
      (C) the Quickturn Board withdrew or adversely modified its approval
    or recommendation of the Merger Agreement or the Merger,
 
      (D) Quickturn has ceased using all reasonable efforts to hold a
    stockholders' meeting to vote on the Merger, or
 
      (E) Quickturn convened a meeting of the Quickturn Stockholders to
    vote on the Merger but failed to obtain the requisite vote,
 
  then, in addition to any other remedies that Cadence, Merger Sub or their
  affiliates may have as a result of such termination, Quickturn has agreed
  to pay to Cadence the amount of $3,500,000 as reimbursement for the costs,
  fees and expenses incurred by any of them or on their behalf in connection
  with the Merger Agreement, the Merger and the consummation of all
  transactions contemplated by the Merger Agreement (including fees payable
  to investment bankers, counsel to any of the foregoing and accountants).
 
  (c) Further, if the Merger Agreement is terminated by Quickturn because:
 
    (i) Cadence or Merger Sub has breached any of its representations or
  warranties in the Merger Agreement or any of their representations or
  warranties have become untrue such that the conditions to Quickturn's
  obligation to complete the Merger could not be satisfied by the Final Date;
  or
 
    (ii) Cadence or Merger Sub has breached and not cured any of its
  covenants or agreements in the Merger Agreement and the breach has a
  material adverse effect on Cadence or materially adversely affects or
  materially delays the consummation of the Merger,
 
  then, in addition to any other remedies that Quickturn or its affiliates
  may have as a result of such termination, Cadence has agreed to pay to
  Quickturn the amount of $3,500,000 as reimbursement for the costs, fees and
  expenses incurred by any of them or on their behalf in connection with the
  Merger Agreement, the Merger and the consummation of all transactions
  contemplated by the Merger Agreement (including fees payable to investment
  bankers, counsel to any of the foregoing and accountants).
 
  The term "Company Acquisition" means the occurrence of any of the following
events: (i) the acquisition of Quickturn by merger or otherwise by any Third
Party; (ii) the acquisition by a Third Party of any material portion of the
assets of Quickturn and its subsidiaries taken as a whole; or (iii) the
acquisition by a Third Party of 30% or more of the outstanding shares of
Quickturn Common Stock or any securities convertible into or exchangeable for
such number of shares.
 
  Except as described above, whether or not the Merger is consummated, all fees
and expenses incurred in connection with the Merger Agreement and the
transactions contemplated thereby will be paid by the party incurring such fees
and expenses.
 
EXTENSION, WAIVER AND AMENDMENT OF THE MERGER AGREEMENT
 
  Extension and Waiver. At any time prior to the Effective Time, each of
Cadence and Merger Sub, on the one hand, and Quickturn, on the other hand, may
(i) extend the time for the performance of any of the obligations or other acts
of the other party, (ii) waive any inaccuracies in the representations and
warranties of the other party contained in the Merger Agreement or in any
document delivered pursuant to the Merger Agreement and (iii) waive compliance
by the other party with any of the agreements or conditions contained in the
Merger Agreement.
 
                                       53
THE MERGER
<PAGE>
 
  Amendment. The Merger Agreement may be amended in writing by Cadence, Merger
Sub and Quickturn at any time before or after approval of the Merger by the
Quickturn Stockholders, except that after any such approval there may not be
made, without further approval of such stockholders, any amendment which
requires the approval of the Quickturn Stockholders under applicable law.
 
EMPLOYEE BENEFITS AND PLANS
 
  From and after the Effective Time, the employee or director benefit plans,
arrangements or agreements maintained, or contributed to, as of the date of the
Merger Agreement, by Quickturn and certain affiliates and disclosed to Cadence
in connection with the execution and delivery of the Merger Agreement (the
"QUICKTURN BENEFIT PLANS"), will remain in effect with respect to employees of
Quickturn (or its subsidiaries) covered by such plans at the Effective Time
until such time as Cadence, subject to applicable law, determines to modify or
terminate any of such Quickturn Benefit Plans.
 
STOCK EXCHANGE LISTING
 
  Cadence has agreed to use all reasonable efforts to cause the shares of
Cadence Common Stock to be issued in the Merger and the shares of Cadence
Common Stock to be reserved for issuance upon exercise of Quickturn stock
options and warrants outstanding at the Effective Time to be approved for
listing on the NYSE. It is a condition to the consummation of the Merger that
such shares of Cadence Common Stock be authorized for listing on the NYSE,
subject to official notice of issuance.
 
INTERESTS OF CERTAIN PERSONS IN THE MERGER
 
  Certain members of Quickturn's management have interests in the Merger that
are in addition to their interests as Quickturn Stockholders generally. The
Quickturn Board was aware of these interests and considered them, among other
matters, in approving the Merger Agreement and the transactions contemplated
thereby.
 
  The directors, officers and principal stockholders of Quickturn and their
associates may have had in the past, and may have in the future, transactions
in the ordinary course of business with Cadence and its subsidiaries and
affiliates. Any such transactions were, and are expected to be, on
substantially the same terms as those prevailing at the time for comparable
transactions with others.
 
  Employment Agreements. In connection with the execution of the Merger
Agreement, Cadence entered into the Employment Agreements with each of Keith
Lobo, K.C. Chu, Stephen Sample, Christopher Tice, Tung-Sun Tung, Kevin Ladd and
Mikhail Bershteyn (the "EMPLOYEES"). Each Employment Agreement commences at the
Effective Time for a term of eighteen months (the "EMPLOYMENT PERIOD"). During
the Employment Period, Mr. Lobo and each of the other Employees will serve the
Surviving Corporation in a capacity functionally equivalent to his current
position with Quickturn and will be entitled to a specified annual base salary
and bonus (based on a percentage of base salary). In addition to his cash
compensation, each Employee will be entitled to receive options to purchase
shares of Cadence Common Stock pursuant to his Employment Agreement.
 
  The Employment Agreements further provide that, upon termination of the
Employee's employment with the Surviving Corporation at any time before the one
year anniversary of the Effective Time, the Employee's compensation will be
determined solely in accordance with the applicable Quickturn Retention Plan,
as described below. Between such one year anniversary and the date which is 18
months following the Effective Time, termination of any Employee without cause
(as defined in the Employment Agreements), or voluntarily termination as a
result of a reduction in base pay, reduction in title or a material change in
such Employee's job responsibilities, or because of his relocation to more than
35 miles from his work location immediately prior to the Effective Time,
entitles such Employee to a cash payment equal to the Employee's base salary
for the remainder of the Employment Period. Upon termination at any time during
the Employment Period, the
 
                                       54
THE MERGER
<PAGE>
 
Cadence stock options granted to the terminated Employee during the Employment
Period will cease to vest and all other employee medical, dental and other
benefits will terminate, except as otherwise required under the applicable
Quickturn Management Retention Plan, as discussed below.
 
  Each Employee has also agreed not to compete with the Surviving Corporation
before the later of (i) the eighteen month anniversary of the Effective Time
and (ii) such Employee's termination of employment with the Surviving
Corporation. In addition, until one year after termination of his employment,
the Employee may solicit neither Cadence's or the Surviving Corporation's
employees nor their clients or customers; nor may such Employee: (x) use any
Cadence or Quickturn trade secret or proprietary information, (y) interfere or
attempt to interfere with the Surviving Corporation's or Cadence's relationship
with its customers or clients, or (z) solicit the business of any client or
customer of Cadence or the Surviving Corporation.
 
  Management Retention Plan. The Quickturn Management Retention Plan provides
severance benefits to management employees where their employment is
constructively terminated within the twelve-month period following a "change of
control." Consummation of the Merger will be a change of control for purposes
of the Quickturn Management Retention Plan. Constructive termination includes:
(i) a significant reduction of the employee's (a) duties or responsibilities,
(b) annual base salary, (c) the maximum amount of the participant's potential
annual cash bonus and (d) kind or level of the participant's employee benefits;
(ii) his relocation to a location more than 35 miles from his location prior to
the Merger; (iii) failure of the Surviving Corporation to assume the Quickturn
Management Retention Plan; or (iv) any act which would constitute constructive
termination under applicable law.
 
  Upon constructive termination, each of the Employees would be entitled to
receive a payment equal to between 150% and 250% (depending on the Employee) of
his (x) then base salary plus (y) average bonus over the prior three years,
and, if not previously paid, an additional pro-rated bonus for the year in
which the Employee is terminated. Mr. Lobo would receive an amount representing
250% of his base salary plus average annual bonus for the prior three years.
Messrs. Tice and Tung would be entitled to receive 200% of their respective
base salaries plus average annual bonus. Messrs. Chu, Sample and Ladd would be
entitled to receive 150% of their respective base salaries plus average annual
bonus. In addition to these severance payments, Mr. Lobo would continue to
receive benefits for two and one-half years after his termination date, Messrs.
Tice and Tung would continue to receive benefits for two years after their
respective termination dates, and Messrs. Chu, Sample and Ladd would continue
to receive benefits for one and a half years after their respective termination
dates.
 
  Under the Quickturn Management Retention Plan, benefits and payments under
the plan are only reduced to avoid triggering the golden parachute excise tax
and non-deductibility provisions of the Code if doing so would maximize the
after-tax economic benefit to such officers, as determined by Quickturn's
independent accountants.
 
  Employee Retention Plan. The Quickturn Employee Retention Plan provides
severance benefits for employees who are not participants in the Quickturn
Management Retention Plan, including Mr. Bershteyn. If the participant is
involuntarily terminated without cause within 12 months following a "change of
control," the Quickturn Employee Retention Plan entitles the employee to a
severance payment equaling two weeks' base salary for each full year of
employment with Quickturn up to and including the date of the change of
control, with a minimum payment of three months (or six months for director-
level employees and employees designated as key contributors by the chief
executive officer, including Mr. Bershteyn). Consummation of the Merger will be
a change of control for purposes of the Quickturn Employee Retention Plan.
 
  In the event the golden parachute excise tax and non-deductibility provisions
of the Code would be triggered as a result of the payments and benefits under
the Quickturn Employee Retention Plan, a participant's payments and benefits
may be reduced to the largest amount that would not trigger the golden
parachute excise tax and non-deductibility provisions.
 
 
                                       55
THE MERGER
<PAGE>
 
  Stock-Based Rights. The Merger Agreement provides that, at the Effective
Time, each outstanding and unexercised stock option and warrant to acquire
shares of Quickturn Common Stock granted under the Quickturn Stock Plans or
otherwise will cease to represent the right to acquire shares of Quickturn
Common Stock and will be converted into and become a stock option or warrant,
as applicable, with respect to Cadence Common Stock, and that Cadence will
comply with the terms of the Quickturn Stock Plans.
 
  Indemnification; Directors' and Officers' Insurance. The Merger Agreement
provides that, after the Effective Time, in the event of any threatened or
actual claim or proceeding in which any person who is or has been a director,
officer or employee of Quickturn or any of its subsidiaries is, or is
threatened to be, made a party based in whole or in part on, or pertaining to,
(i) the fact that such person was a director, officer or employee of Quickturn
or any of its subsidiaries or (ii) the Merger Agreement, or the transactions
contemplated thereby, Cadence will, subject to the conditions set forth in the
Merger Agreement, indemnify such person to the fullest extent required of
permitted by applicable law against any liability or expense incurred in
connection with any such claim or proceeding. The Merger Agreement further
provides that Cadence will, subject to the conditions set forth in the Merger
Agreement, cause the persons serving as officers and directors of Quickturn or
its subsidiaries immediately prior to the Effective Time to be covered for a
period of at least six years following the Effective Time by Quickturn's
directors' and officers' liability insurance policy (or any equivalent
substitute therefor) with respect to acts or omissions occurring prior to the
Effective Time which were committed by such officers and directors in their
capacities as such. In addition, Cadence has agreed to honor in all respects
all of Quickturn's agreements to indemnify its officers and directors in effect
on December 8, 1998 (or indemnity agreements with directors joining the
Quickturn Board before the Effective Time if in Quickturn's customary form),
and any indemnification provisions under the Quickturn Certificate and
Quickturn Bylaws in effect on December 8, 1998.
 
OPTION AGREEMENT
 
  Immediately after the execution of the Merger Agreement, Cadence and
Quickturn executed and delivered the Option Agreement, pursuant to which
Quickturn granted Cadence an option to purchase Quickturn Common Stock from
Quickturn under the conditions described below (the "OPTION"). Quickturn
approved and entered into the Option Agreement to induce Cadence to enter into
the Merger Agreement.
 
  The Option Agreement provides for the purchase by Cadence of up to 3,619,100
shares (the "OPTION SHARES") of Quickturn Common Stock at an exercise price of
$14 per share, payable in cash (the "OPTION PRICE"). The Option Shares, if
issued pursuant to the Option Agreement, will in no event exceed 19.9% of the
number of shares of Quickturn Common Stock issued and outstanding without
giving effect to the issuance of any shares of Quickturn Common Stock subject
to the Option.
 
  The number of shares of Quickturn Common Stock subject to the Option will be
increased or decreased, as appropriate, to the extent that additional shares of
Quickturn Common Stock are either (i) issued or otherwise become outstanding
(other than pursuant to an exercise of the Option) or (ii) redeemed,
repurchased, retired or otherwise cease to be outstanding after December 8,
1998, such that, after such event, the number of Option Shares will continue to
equal 19.9% of the Quickturn Common Stock then issued and outstanding without
giving effect to the issuance of any Quickturn Common Stock subject to the
Option. In the event of any change in the number of outstanding shares of
Quickturn Common Stock by reason of a stock dividend, stock split, merger,
recapitalization, rights offering, share exchange or other similar change,
Cadence will receive, upon exercise of the Option, the stock or other
securities, cash or property to which Cadence would have been entitled if
Cadence had exercised the Option and had held shares of Quickturn Common Stock
on the record date fixed for determination of holders of shares of Quickturn
Common Stock entitled to receive such stock or other securities, cash or
property at the same aggregate price as the aggregate Option Price of the
Option Shares.
 
  The Option Agreement provides that Cadence or any other permitted holder or
holders of the Option (as used in this section, collectively, the "HOLDER") may
exercise the Option, in whole or in part, if a Triggering
 
                                       56
THE MERGER
<PAGE>
 
Event (as defined below) has occurred prior to the Expiration Date (as defined
below). If Cadence wishes to exercise the Option, it must deliver written
notice (the "EXERCISE NOTICE") to Quickturn specifying its intention to
exercise the Option, the total number of Option Shares it wishes to purchase
and a date and time for the closing of such purchase that is not less than one
nor more than 30 business days after the later of (i) the date such Exercise
Notice is given and (ii) the expiration or termination of any applicable
waiting period under the HSR Act. However, the Option will not be exercisable
if Cadence has willfully and materially breached the Merger Agreement. Any
exercise of the Option will be deemed to occur on the date such notice is sent.
 
  For purposes of the Option Agreement:
 
    (i) The term "TRIGGERING EVENT" means the occurrence after December 8,
  1998 of any of the events or transactions described in paragraphs (a)(i),
  (ii), (iii) and (iv) under "--Termination of the Merger Agreement--Fees and
  Expenses" above, all of which involve termination of the Merger Agreement.
 
    (ii) The term "COMPANY ACQUISITION" means the occurrence of any of the
  following events: (a) the acquisition of Quickturn by merger or otherwise
  by any Third Party; (b) the acquisition by a Third Party of any material
  portion of the assets of Quickturn and its subsidiaries taken as a whole;
  and (c) the acquisition by a Third Party of 30% or more of the outstanding
  shares of Quickturn Common Stock or any securities convertible into or
  exchangeable for such number of shares.
 
    (iii) The term "EXPIRATION DATE" means the earlier of (a) the Effective
  Time and (b) 5:00 p.m., California time, on the day that is the 12 month
  anniversary of the date on which the Merger Agreement has been terminated
  in accordance with its terms.
 
  If prior to the Expiration Date any person or group (other than Cadence and
its affiliates) has acquired 30% or more of the then outstanding shares of
Quickturn Common Stock (a "SHARE ACQUISITION"), or Quickturn has entered into a
written definitive agreement with any person or group (other than Cadence and
its affiliates) providing for a Company Acquisition, then Cadence, in lieu of
exercising the Option, will have the right at any time thereafter (as long as
the Option is exercisable under its terms) to request that Quickturn pay, and
promptly (but in any event not more than five business days) after the giving
by Cadence of such request Quickturn will pay to Cadence, in cancellation of
the Option, an amount in cash (the "CANCELLATION AMOUNT") equal to:
 
    (i) the lesser of (x) the excess over the Option Price of the greater of
  (A) the last sale price of a share of Quickturn Common Stock as reported on
  Nasdaq on the last trading day prior to the date of the Exercise Notice,
  and (B) (1) the highest price per share of Quickturn Common Stock offered
  to be paid or paid by any such person or group pursuant to or in connection
  with such Share Acquisition or Company Acquisition or (2) if such Company
  Acquisition consists of a purchase and sale of assets, the aggregate
  consideration offered to be paid or paid in any transaction or proposed
  transaction in connection with a Company Acquisition, divided by the number
  of shares of Quickturn Common Stock then outstanding, and (y) $3.8890884474
 
  multiplied by
 
    (ii) the number of Option Shares then covered by the Option.
 
If all or a portion of the price per share of Quickturn Common Stock offered,
paid or payable or the aggregate consideration offered, paid or payable for the
stock or assets of Quickturn, each as contemplated by the preceding sentence,
consists of noncash consideration, such price or aggregate consideration will
be the cash consideration, if any, plus the fair market value of the non-cash
consideration as determined by the investment bankers of Quickturn and the
investment bankers of Cadence.
 
  Notwithstanding anything to the contrary contained in the Option Agreement,
the economic benefit, if any, which Cadence may derive thereunder is limited as
follows:
 
 
                                       57
THE MERGER
<PAGE>
 
    (1) in no event may Cadence's Total Payment (as defined below) exceed
  $14,075,000, and Cadence must pay any excess over such amount to Quickturn;
  and
 
    (2) the Option may not be exercised for a number of Option Shares as
  would, as of the date of exercise, result in a Notional Total Payment (as
  defined below), together with the actual Total Payment immediately
  preceding such exercise, exceeding $14,075,000.
 
  For purposes of the Option Agreement:
 
    (1) "TOTAL PAYMENT" means the sum (before taxes) of the following: (i)
  any Cancellation Amount received by Cadence, (ii)(x) the net cash amounts
  received by Cadence pursuant to the sale of Option Shares (or any other
  securities into which such Option Shares have been converted or exchanged)
  pursuant to the Quickturn Call (as defined below) or otherwise to any
  unaffiliated party, less (y) the aggregate Option Price for such shares,
  (iii) any amounts Cadence receives upon transfer of the Option (or any
  portion thereof) to any unaffiliated party, and (iv) the amount Cadence
  actually receives pursuant to the Merger Agreement and described in
  paragraph (a)(i), (ii), (iii) or (iv) under "--Termination of the Merger
  Agreement--Fees and Expenses" above; and
 
    (2) "NOTIONAL TOTAL PAYMENT" with respect to any number of Option Shares
  as to which Cadence may propose to exercise the Option means the Total
  Payment determined as of the date of such proposed exercise assuming that
  the Option were exercised on such date for such number of shares and,
  assuming further, that such shares, together with all other Option Shares
  held by Cadence as of such date, were sold for cash at the closing market
  price for the Quickturn Common Stock as of the close of business on the
  preceding trading day (less customary brokerage commissions).
 
  For purposes of the above description, references to Cadence include
references to any affiliate of Cadence.
 
  As of the date of this Proxy Statement/Prospectus, to the knowledge of
Cadence and Quickturn, no Triggering Event has occurred.
 
  Quickturn's obligation to issue Option Shares upon exercise of the Option is
subject to the satisfaction or waiver of the following conditions:
 
    (i) any waiting periods applicable to Cadence's acquisition of the Option
  Shares under the HSR Act and any material foreign competition laws have
  expired or been terminated;
 
    (ii) Cadence's representations and warranties in the Option Agreement are
  true and correct in all material respects as of the date of the issuance of
  such Option Shares; and
 
    (iii) no statute, rule or regulation is in effect, and no order, decree
  or injunction entered by any court of competent jurisdiction or
  governmental, regulatory or administrative agency or commission in the
  United States is in effect, which prohibits the exercise of the Option or
  acquisition or issuance of Option Shares.
 
  If Cadence has acquired Option Shares upon exercise of the Option (the date
of any closing relating to any such exercise herein referred to as an "EXERCISE
DATE"), then, at any time after the date that is 13 months following such
Exercise Date (the "PURCHASE PERIOD"), Quickturn may require Cadence, upon
delivery to Cadence of written notice, to sell to Quickturn any Option Shares
held by Cadence as of the date that is 10 business days after the date of such
notice, up to a number of shares equal to the number of Option Shares acquired
by Cadence pursuant to exercise of the Option in connection with such Exercise
Date (the "QUICKTURN CALL"). The per share purchase price for such sale (the
"QUICKTURN CALL PRICE") is equal to the higher of (i) the Option Price, less
any dividends paid on the Option Shares to be purchased by Quickturn pursuant
to the Quickturn Call, plus an amount equal to a return at an annual rate of
15% of the Option Price from the Exercise Date and (b) an amount equal to the
average of the high and low trading prices per share of Quickturn Common Stock
for the 30 trading day period ending one day prior to the delivery of
Quickturn's notice exercising the Quickturn Call.
 
                                       58
THE MERGER
<PAGE>
 
  Subject to any limitations imposed on Quickturn pursuant to any other
registration rights in effect, Quickturn will, if requested by Cadence at any
time or from time to time within two years following a Triggering Event (the
"REGISTRATION PERIOD"), to permit the sale or other disposition of Option
Shares that have been acquired by or are issuable to Cadence upon exercise of
the Option ("REGISTRABLE SECURITIES"), register under the Securities Act, the
offering, sale and delivery, or other disposition, of the Registrable
Securities. In connection with any such sale or other disposition, Cadence will
use all reasonable efforts to prevent any person or group from purchasing
through such offering shares of Quickturn Common Stock representing more than
5% of the outstanding shares of Quickturn Common Stock on a fully diluted basis
at the time of such request. Any such request for registration must relate to a
number of Registrable Securities equal to at least 20% of the Option Shares,
unless the remaining number of Registrable Securities is less than such amount,
in which case Cadence will be entitled to exercise its registration rights only
for all of the remaining Registrable Securities (a "PERMITTED OFFERING").
Cadence's rights described in this paragraph will terminate when Cadence
becomes entitled to sell all of the remaining Registrable Securities pursuant
to Rule 144(k) under the Securities Act. Quickturn will use all reasonable
efforts to qualify any Registrable Securities Cadence desires to sell or
otherwise dispose of under applicable state securities or "blue sky" laws;
provided, however, that Quickturn will not be required to qualify to do
business, or consent to general service of process, in any jurisdiction by
reason of this provision. Without Cadence's prior written consent, Quickturn
may not include any other securities in any such registration. Quickturn will
use all reasonable efforts to cause each such registration statement to become
effective, to obtain all consents or waivers of other parties that are required
therefor and to keep such registration statement effective for a period of 90
days from the day such registration statement first becomes effective.
Quickturn's obligations to file a registration statement and to maintain its
effectiveness may be suspended for one or more periods not exceeding 90 days in
the aggregate if the Quickturn Board determines in good faith that the filing
of such registration statement or the maintenance of its effectiveness would
require disclosure of nonpublic information that would materially and adversely
affect Quickturn, or Quickturn is required under the Securities Act to include
audited financial statements for any period in such registration statement and
such financial statements are not yet available for inclusion in such
registration statement. Cadence may make up to two registration requests
(counting only requests relating to a registration statement that has become
effective under the Securities Act). If, during the Registration Period,
Quickturn proposes to register under the Securities Act the offering, sale and
delivery of Quickturn Common Stock for cash for its own account or for any
other Quickturn Stockholder pursuant to a firm underwriting, it will (subject
to certain limitations), in addition to Quickturn's other registration
obligations, allow Cadence to participate in such registration provided that
Cadence participates in such underwriting.
 
  The expenses of preparing and filing any registration statement for
Registrable Securities and any sale covered thereby (including any fees related
to blue sky qualifications and filing fees of the Commission or the NASD)
("REGISTRATION EXPENSES") will, subject to certain exceptions, be paid by
Quickturn, except for underwriting discounts or commissions or brokers' fees in
respect of shares of Quickturn Common Stock to be sold by Cadence and the fees
and disbursements of Cadence's counsel.
 
  In connection with each registration of Registrable Securities, Quickturn has
agreed to indemnify and hold each Holder participating in such offering, its
underwriters and each of their respective affiliates harmless against any and
all losses, claims, damage, liabilities and expenses (including, without
limitation, investigation expenses and fees and disbursements of counsel and
accountants), joint or several, to which such Holder, its underwriters and each
of their respective affiliates may become subject, under the Securities Act or
otherwise, insofar as such losses, claims, damages, liabilities or expenses (or
actions in respect thereof) arise out of or are based upon an untrue statement
or alleged untrue statement of a material fact contained in any registration
statement (including any prospectus therein), or any amendment or supplement
thereto, or arise out of or are based upon the omission or alleged omission to
state therein a material fact required to be stated therein or necessary to
make the statements therein not misleading, other than such losses, claims,
damages, liabilities or expenses (or actions in respect thereof) which arise
out of or are based upon an untrue statement or alleged untrue statement of a
material fact contained in written information furnished by a Holder to
Quickturn expressly for use in such registration statement. In addition,
Cadence and each Holder have agreed to
 
                                       59
THE MERGER
<PAGE>
 
indemnify and hold Quickturn, its underwriters and each of their respective
affiliates harmless against any and all losses, claims, damages, liabilities
and expenses (including, without limitation, investigation expenses and fees
and disbursement of counsel and accountants), joint or several, to which
Quickturn, its underwriters and each of their respective affiliates may become
subject under the Securities Act or otherwise, insofar as such losses, claims,
damages, liabilities or expenses (or actions in respect thereof) arise out of
or are based upon an untrue statement or alleged untrue statement of a material
fact contained in written information furnished by any Holder to Quickturn
expressly for use in such registration statement; provided, however, that in no
event shall any indemnification amount contributed by a Holder exceed the
proceeds of the offering received by such Holder.
 
  Upon the issuance of Option Shares, Quickturn will promptly list such Option
Shares on Nasdaq or on such national or other exchange on which the shares of
Quickturn Common Stock are at the time listed.
 
  Neither Quickturn nor Cadence may assign any of its rights or obligations
under the Option Agreement to any other person without the express written
consent of the other party, except that Cadence may assign its rights and
obligations thereunder to any of its wholly-owned subsidiaries, so long as such
subsidiary agrees in writing to be bound by the terms and provisions of the
Option Agreement.
 
  Certain rights and obligations of Cadence and the Quickturn under the Option
Agreement are subject to compliance with the HSR Act. Accordingly, Cadence has
included in its merger notifications filed with the DOJ and FTC a description
of its rights under the Option Agreement, including its right to purchase more
than 15% of the outstanding shares of Quickturn Common Stock. See "--Regulatory
Approvals Required for the Merger."
 
RESTRICTIONS ON RESALES BY AFFILIATES
 
  The issuance of shares of Cadence Common Stock to Quickturn Stockholders in
the Merger and upon exercise of outstanding Quickturn stock options or warrants
after the Merger has been registered under the Securities Act. The shares of
Cadence Common Stock exchanged in the Merger may be traded freely and without
restriction by those Quickturn Stockholders and holders of Quickturn stock
options or warrants not deemed to be "affiliates" of Quickturn as that term is
defined under the Securities Act. An affiliate of Quickturn, as defined by the
rules promulgated under the Securities Act, is a person who directly, or
indirectly through one or more intermediaries, controls, is controlled by, or
is under common control with, Quickturn. Any subsequent transfer of such shares
by any person who is an affiliate of Quickturn at the time the Merger is
submitted for a vote of Quickturn Stockholders will, under existing law require
either (i) the further registration under the Securities Act of the shares of
Cadence Common Stock to be transferred, (ii) compliance with Rule 145
promulgated under the Securities Act (permitting limited sales under certain
circumstances) or (iii) the availability of another exemption from
registration. The foregoing restrictions are expected to apply to the directors
and executive officers of Quickturn and the holders of 10% or more of the
outstanding shares of Quickturn Common Stock (and to certain relatives or the
spouse of any such person and any trusts, estates, corporations or other
entities in which any such person has a 10% or greater beneficial or equity
interest). Cadence will give stop transfer instructions to the transfer agent
with respect to the Cadence Common Stock to be received by persons subject to
the restrictions described above, and the certificates for such stock will be
appropriately legended.
 
  Commission guidelines regarding qualifying for the "pooling-of-interests"
method of accounting also limit sales of shares of the acquiring and acquired
company by affiliates of either company in a business combination. Commission
guidelines indicate further that the "pooling-of-interests" method of
accounting will generally not be challenged on the basis of sales by affiliates
of the acquiring or acquired company if such affiliates do not dispose of any
of the shares of the corporation they own or shares of a corporation they
receive in connection with a merger during the period beginning 30 days before
the merger and ending when financial results covering at least 30 days of post-
merger operations of the combined entity have been published.
 
 
                                       60
THE MERGER
<PAGE>
 
  Each of Quickturn and Cadence has agreed in the Merger Agreement to use all
reasonable efforts to cause each person who is an affiliate (for purposes of
Rule 145 and for purposes of qualifying the Merger for "pooling-of-interests"
accounting treatment) of such party to deliver to the other party a written
agreement intended to ensure compliance with the Securities Act and preserve
the companies' ability to treat the Merger as a "pooling-of-interests."
 
                                       61
THE MERGER
<PAGE>
 
                          MANAGEMENT AFTER THE MERGER
 
BOARDS OF DIRECTORS
 
  The composition of the Cadence Board will not change as a result of the
Merger. However, immediately after the Effective Time, the Board of Directors
of the Surviving Corporation will consist of three directors, all of whom will
be selected by Cadence.
 
MANAGEMENT
 
  The composition of Cadence's management will not change as a result of the
Merger. It is expected that, at the Effective Time, Mr. Lobo and each of
Messrs. Chu, Sample, Tice, Tung and Ladd will remain with the Surviving
Corporation with responsibilities comparable to those of their current
positions pursuant to their Employment Agreements.
 
  Except for the foregoing, key staff positions within the Surviving
Corporation have not yet been finally determined. From time to time prior to
consummation of the Merger, decisions may be made with respect to the
management and operations of the Surviving Corporation, including its other
officers and managers.
 
  Information about the current Cadence directors and executive officers can be
found in Cadence's proxy statement, which is incorporated by reference into
Cadence's Annual Report on Form 10-K for the year ended January 3, 1998.
Information about the current Quickturn directors and executive officers can be
found in Quickturn's proxy statement, which is incorporated by reference into
Quickturn's Annual Report on Form 10-K for the year ended December 31, 1997.
Cadence's and Quickturn's Annual Reports on Form 10-K are incorporated by
reference into this Proxy Statement/Prospectus. See "Where You Can Find More
Information."
 
                                       62
MANAGEMENT AFTER THE MERGER
<PAGE>
 
                          PRICE RANGE OF COMMON STOCK
 
  CADENCE. Cadence Common Stock is listed on the NYSE and traded under the
symbol "CDN." The following table sets forth, for the periods indicated, the
high and low reported closing sale prices per share of Cadence Common Stock on
the NYSE Composite Transactions reporting system. Cadence has never declared or
paid any cash dividends on the Cadence Common Stock, and does not plan on
declaring any such dividends in the near future.
<TABLE>
<CAPTION>
                                                                PRICE RANGE OF
                                                                 COMMON STOCK
                                                                ---------------
                                                                 HIGH     LOW
                                                                ------- -------
   <S>                                                          <C>     <C>
   1996
     First Quarter............................................. $ 15.17 $ 11.50
     Second Quarter............................................   21.88   14.84
     Third Quarter.............................................   18.94   11.50
     Fourth Quarter............................................   20.69   16.32
   1997
     First Quarter.............................................   21.94   15.69
     Second Quarter............................................   19.00   13.38
     Third Quarter.............................................   27.50   16.75
     Fourth Quarter............................................   28.75   22.31
   1998
     First Quarter.............................................   37.44   22.75
     Second Quarter............................................   38.00   27.63
     Third Quarter.............................................   31.13   20.69
     Fourth Quarter (through December 22, 1998)................   30.63   19.19
</TABLE>
 
  QUICKTURN. Quickturn Common Stock is listed on the Nasdaq National Market
System ("NASDAQ") and traded under the symbol "QKTN." The following table sets
forth the high and low closing sales prices for Quickturn Common Stock for the
periods indicated, as listed on Nasdaq. Quickturn has never declared or paid
any cash dividends on the Quickturn Common Stock, and does not plan on
declaring any such dividends in the near future.
<TABLE>
<CAPTION>
                                                                PRICE RANGE OF
                                                                 COMMON STOCK
                                                                ---------------
                                                                 HIGH     LOW
                                                                ------- -------
   <S>                                                          <C>     <C>
   1996
     First Quarter............................................. $ 11.50 $  9.00
     Second Quarter............................................   16.50   11.13
     Third Quarter.............................................   15.13   11.88
     Fourth Quarter............................................   21.63   11.75
   1997
     First Quarter.............................................   21.00   15.00
     Second Quarter............................................   15.88    6.69
     Third Quarter.............................................   16.63   12.13
     Fourth Quarter............................................   16.31   10.69
   1998
     First Quarter.............................................   15.50    9.94
     Second Quarter............................................   10.63    6.50
     Third Quarter.............................................   11.38    7.38
     Fourth Quarter (through December 22, 1998)................   14.63    9.50
</TABLE>
 
  The Merger Agreement prohibits Quickturn from paying cash dividends on
Quickturn Common Stock pending consummation of the Merger. See "The Merger--
Conduct of Business Pending the Merger and Other Agreements."
 
                                       63
PRICE RANGE OF COMMON STOCK
<PAGE>
 
                           INFORMATION ABOUT CADENCE
 
GENERAL
 
  Cadence provides software technology and comprehensive design and consulting
services and technology for the product development requirements of the world's
leading electronics companies. Cadence licenses its leading-edge EDA software
technology and provides a range of professional services to companies
throughout the world to help optimize their product development processes.
Recently, Cadence has expanded the role it plays with companies that produce
electronic products and with an emerging class of companies that require
electronic content in their products, but who desire to purchase from external
sources. Cadence is now a supplier of "design realization" solutions, which are
used by companies to design and develop ICs and systems including
semiconductors, computer systems and peripherals, telecommunications and
networking equipment, mobile and wireless devices, automotive electronics,
consumer products, and other advanced electronics.
 
  Cadence serves the worldwide electronics industry, which is quickly evolving
from a business-to-business mode to more of a consumer electronics industry.
The shift of the electronics industry to the consumer electronics industry is
evidenced by the incorporation of electronic content in consumer items such as
home appliances, automotive products, entertainment products and games, and
personal communication and organization devices. The electronics industry
presents challenges for developers of electronic products, where time-to-
market, cost, and the need for product diversity become the focus in a fast-
paced and volatile industry.
 
  Cadence's product offerings include a variety of EDA tools. These EDA tools
include system level design, custom IC design, deep submicron design, logic
design and verification, and printed circuit board design, which enable
electronic product designers to improve the quality of their products as well
as their productivity. These products apply to one or more steps in the
electronics system design process.
 
  Cadence offers developers of electronic products a portfolio of services
within the broad categories of consulting services, design services, and
industry services. Cadence provides a variety of services that help improve
design environments, from training classes and custom software coding to flow
and methodology deployment to complete design process re-engineering. Cadence's
Educational Services offer more than 50 training courses within all areas of
Cadence technology. Cadence's Applications Services help developers of
electronic products to maximize their productivity with Cadence software
applications by transferring knowledge from Cadence applications engineers to
customer design teams in new methodologies and technologies. In addition,
Cadence offers Design Process Service solutions including optimizing existing
product development processes, creating new design methodologies, migrating to
new methodologies based on significant upgrades of EDA technology, constructing
high re-use product development systems, and transferring technological
competency. In addition, Cadence offers services to perform design projects for
electronic system components such as integrated circuits or software.
 
  As of December 17, 1998, Cadence employed 4,432 persons, including 2,465 in
services, sales, marketing and support activities, 1,287 in product
development, and 680 in management, administration, and finance.
 
  Cadence was formed as a result of the merger of SDA Systems, Inc. into ECAD,
Inc. in May 1988. Cadence's executive offices are located at 2655 Seely Avenue,
Building 5, San Jose, California 95134, and its telephone number at that
location is (408) 943-1234.
 
MANAGEMENT AND ADDITIONAL INFORMATION
 
  Certain information relating to executive compensation, various benefit plans
(including stock option plans), voting securities and the principal holders
thereof, certain relationships and related transactions and other related
matters as to Cadence is incorporated by reference or set forth in Cadence's
Annual Report on Form 10-K for the year ended January 3, 1998, incorporated
herein by reference. Quickturn Stockholders desiring copies of such documents
may contact Cadence at its address or telephone number indicated under "Where
You Can Find More Information."
 
                                       64
INFORMATION ABOUT CADENCE
<PAGE>
 
                          INFORMATION ABOUT QUICKTURN
 
GENERAL
 
  Quickturn designs, manufactures, sells and supports products that verify the
design of ICs and electronic systems. Quickturn derives substantially all of
its revenue from its design verification products and related maintenance and
consulting services. Quickturn's principal design verification products include
System Realizer(TM) and CoBALT(TM) (Concurrent Broadcast Array Logic
Technology) and Mercury Design Verification System(TM) emulators, and
SpeedSim(TM) cycle-based simulation software. Emulation systems are sold in
modules of various system capacities measured in "logic gates," which are
measurement units that describe the design elements created and verified by
Quickturn's customers. As system capacity increases, the selling price of these
systems increases correspondingly. Cycle-based simulation revenue is charged on
a per-license basis. Cycle-based simulation products, which complement
Quickturn's emulation products, can be used by customers to verify digital
logic designs early in the design process, particularly when design changes
occur several times per day. Later, when designs become more stabilized,
customers may use in-circuit emulation to test the entire system that contains
the design and to help identify system-level bugs, which typically are more
difficult to find at this stage in the design process. Quickturn's products
serve the needs of IC and systems design engineers in a variety of industries
including microprocessors, computers, workstations and PCs, telecommunications
and networking, multimedia, and graphics.
 
  Quickturn was incorporated in California in July 1987 and reincorporated in
Delaware in December 1993. In January 1997, Quickturn commenced shipment of its
CoBALT emulation system which was co-developed with IBM. In February 1997,
Quickturn merged with SpeedSim, Inc., a provider of cycle-based simulation
software. In June 1997, Quickturn purchased from Synopsys, Inc. ("SYNOPSYS")
certain assets relating to Synopsys's emulation business of Arkos Design, Inc.
Also in June 1997, Quickturn extended its relationship with IBM to develop the
next generation of custom processor-based emulation systems. In November 1997,
Quickturn moved its corporate headquarters to San Jose, California. Late in
1997, Quickturn introduced release 5.1 of its Quest(TM) II emulation software,
which is designed to enable customers to more quickly and easily compile their
IC designs. In June 1998, Quickturn announced its new Mercury Design
Verification System, which is designed to replace certain of Quickturn's
existing emulation product offerings.
 
  Quickturn's principal executive offices are located at 55 W. Trimble Road,
San Jose, California, 95131, and its telephone number is (408) 914-6000.
 
MANAGEMENT AND ADDITIONAL INFORMATION
 
  Certain information relating to executive compensation, various benefit plans
(including stock option plans), voting securities and the principal holders
thereof, certain relationships and related transactions and other related
matters as to Quickturn is incorporated by reference or set forth in
Quickturn's Annual Report on Form 10-K for the year ended December 31, 1997,
incorporated herein by reference. Quickturn Stockholders desiring copies of
such documents may contact Quickturn at its address or telephone number
indicated under "Where You Can Find More Information."
 
(TM)System Realizer, CoBALT, Mercury Design Verification System, SpeedSim and
Quest are trademarks of Quickturn Design Systems, Inc.
 
                                       65
INFORMATION ABOUT QUICKTURN
<PAGE>
 
                           CADENCE CAPITAL STOCK AND
                        COMPARISON OF STOCKHOLDER RIGHTS
 
  As a result of the conversion of shares of Quickturn Common Stock to shares
of Cadence Common Stock at the Effective Time, Quickturn Stockholders will
become Cadence stockholders. The rights of Cadence stockholders are governed by
the Delaware Law, Cadence's Certificate of Incorporation (the "CADENCE
CERTIFICATE") and Cadence's By-Laws (the "CADENCE BY-LAWS").
 
  The following is a description of Cadence capital stock, including the
Cadence Common Stock to be issued in the Merger, reflecting the anticipated
state of affairs at the Effective Time, and a summary of the material
differences between the rights of holders of Cadence Common Stock and Quickturn
Common Stock.
 
DESCRIPTION OF CADENCE CAPITAL STOCK
 
  The authorized capital stock of Cadence consists of 600,000,000 shares of
common stock, $0.01 par value, and 400,000 shares of Preferred Stock, $0.01 par
value ("CADENCE PREFERRED STOCK").
 
 Cadence Common Stock. As of      , 1999, there were approximately   shares of
Cadence Common Stock outstanding held of record by approximately   persons.
Cadence Common Stock is listed on the NYSE under the symbol "CDN." Holders of
Cadence Common Stock are entitled to one vote per share on all matters to be
voted upon by Cadence stockholders. Cadence stockholders may not cumulate votes
in connection with the election of directors. The holders of Cadence Common
Stock are entitled to receive ratably such dividends, if any, as may be
declared from time to time by the Cadence Board out of funds legally available
for the payment of dividends. In the event of a liquidation, dissolution or
winding up of Cadence, the holders of Cadence Common Stock are entitled to
share ratably in all assets remaining after payment of liabilities. The Cadence
Common Stock has no preemptive or conversion rights or other subscription
rights. There are no redemption or sinking fund provisions applicable to the
Cadence Common Stock. All outstanding shares of Cadence Common Stock are fully
paid and non-assessable, and the shares of Cadence Common Stock to be
outstanding upon completion of the Merger will be fully paid and non-
assessable. Harris Trust and Savings Bank, 311 West Monroe Street, 14th Floor,
Chicago, Illinois, 60690 is the Transfer Agent and Registrar for the shares of
Cadence Common Stock.
 
 Cadence Preferred Stock. The Cadence Board has the authority to issue up to
400,000 shares of Cadence Preferred Stock in one or more series and, subject to
the Delaware Law, to (i) fix the rights, preferences, privileges and
restrictions granted to or imposed upon any wholly unissued shares of Cadence
Preferred Stock consistent with the limitations of the Cadence Certificate;
(ii) fix the number of shares constituting any series and the designations of
such series, within the limits and restrictions stated in any resolution of the
Cadence Board originally fixing the number of shares constituting any series;
and (iii) increase or decrease the number of shares (but not below the number
of shares of such series then outstanding) of any such series after the
issuance of shares of that series. As of the date of this Proxy
Statement/Prospectus, no shares of Cadence Preferred Stock were outstanding.
Although it presently has no intention of doing so, the Cadence Board at any
time and without stockholder approval, may issue Cadence Preferred Stock with
voting and conversion rights which could adversely affect the voting power or
other rights of the holders of Cadence Common Stock. The issuance of Cadence
Preferred Stock may have the effect of delaying, deferring or preventing a
change in control of Cadence.
 
  The Cadence Certificate designates 400,000 shares of Preferred Stock as
Series A Junior Participating Preferred Stock (the "CADENCE SERIES A PREFERRED
SHARES") pursuant to the Cadence Rights Agreement. See "--Cadence Rights Plan."
 
                                       66
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
CADENCE RIGHTS PLAN
 
  General. On February 9, 1996, the Cadence Board declared a dividend of one
Cadence Stockholder Right for each outstanding share of Cadence Common Stock.
The dividend was payable on February 20, 1996 (the "RIGHTS RECORD DATE") to the
Cadence Stockholders of record on that date. Each Cadence Stockholder Right
entitles the registered holder to purchase from Cadence one one-thousandth of a
share of Cadence Series A Preferred Shares at a price of $240 per one one-
thousandth of a share of Cadence Series A Preferred Shares (the "PURCHASE
PRICE"), subject to adjustment. The description and terms of the Cadence
Stockholder Rights are set forth in the Cadence Rights Agreement. The rights
issued under the old amended and restated rights agreement, dated as of June
20, 1989, between Cadence and the Rights Agent expired at the close of business
on February 9, 1996.
 
  Until the earlier to occur of (i) ten days following a public announcement
that a person or group of affiliated or associated persons (a "CADENCE
ACQUIRING PERSON") have acquired beneficial ownership of 15% or more of the
outstanding shares of Cadence Common Stock or (ii) ten business days (or such
later date as may be determined by action of the Cadence Board prior to such
time as any person or group of affiliated persons becomes an Acquiring Person)
following the commencement of, or announcement of an intention to make, a
tender offer or exchange offer the consummation of which would result in the
beneficial ownership by a person or group of 15% or more of such outstanding
shares of Cadence Common Stock (the earlier of such dates being called the
"CADENCE DISTRIBUTION DATE"), the Cadence Stockholder Rights will be evidenced,
with respect to any of the Cadence Common Stock certificates outstanding as of
the Rights Record Date, by such Cadence Common Stock certificate with a copy of
the Summary of Rights attached to the Cadence Rights Agreement as Exhibit C
(the "SUMMARY OF RIGHTS") attached to such certificate.
 
  The Cadence Rights Agreement provides that, until the Distribution Date (or
earlier redemption or expiration of Cadence Stockholder Rights), the Cadence
Stockholder Rights will be transferred only with the shares of Cadence Common
Stock. Until the Distribution Date (or earlier redemption or expiration of the
Cadence Stockholder Rights), new Cadence Common Stock certificates issued after
the Rights Record Date, upon transfer or new issuance of Cadence Common Stock,
will contain a notation incorporating the Cadence Rights Agreement by
reference. Until the Distribution Date (or earlier redemption or expiration of
the Cadence Stockholder Rights), the surrender for transfer of any certificates
for shares of Cadence Common Stock, outstanding as of the Rights Record Date,
even without such notation or a copy of the Summary of Rights being attached
thereto, will also constitute the transfer of the Cadence Stockholder Rights
associated with the shares of Cadence Common Stock represented by such
certificate. As soon as practicable following the Distribution Date, separate
certificates evidencing the Cadence Stockholder Rights ("CADENCE RIGHT
CERTIFICATES") will be mailed to holders of record of the shares of Cadence
Common Stock as of the close of business on the Distribution Date and such
separate Cadence Right Certificates alone will evidence the Cadence Stockholder
Rights.
 
  The Cadence Stockholder Rights are not exercisable until the Distribution
Date. The Cadence Stockholder Rights will expire on February 9, 2006 (the
"FINAL EXPIRATION DATE"), unless the Final Expiration Date is extended or
unless the Cadence Stockholder Rights are earlier redeemed or exchanged by
Cadence, in each case, as described below.
 
  The Purchase Price payable, and the number of Cadence Series A Preferred
Shares or other securities or property issuable, upon exercise of the Cadence
Stockholder Rights are subject to adjustment from time to time to prevent
dilution (i) in the event of a stock dividend on, or a subdivision, combination
or reclassification of, the Cadence Series A Preferred Shares, (ii) upon the
grant to holders of the Cadence Series A Preferred Shares of certain rights or
warrants to subscribe for or purchase Cadence Series A Preferred Shares at a
price, or securities convertible into Cadence Series A Preferred Shares with a
conversion price, less than the then current market price of the Cadence Series
A Preferred Shares or (iii) upon the distribution to holders of the Cadence
Series A Preferred Shares of evidences of indebtedness or assets (excluding
regular periodic cash dividends or
 
                                       67
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
dividends payable in Cadence Series A Preferred Shares) or of subscription
rights or warrants (other than those referred to above).
 
  The number of outstanding Cadence Stockholder Rights are also subject to
adjustment in the event of a stock split of the shares of Cadence Common Stock
or a stock dividend on the shares of Cadence Common Stock payable in shares of
Cadence Common Stock or subdivisions, consolidations or combinations of the
shares of Cadence Common Stock occurring, in any such case, prior to the
Distribution Date.
 
  Cadence Series A Preferred Shares purchasable upon exercise of the Cadence
Stockholder Rights will not be redeemable. Each Cadence Series A Preferred
Share will be entitled, when, as and if declared, to a minimum preferential
quarterly dividend payment of $1 per share but will be entitled to an aggregate
dividend of 1,000 times the dividend declared per share of Cadence Common
Stock. In the event of liquidation, the holders of the Cadence Series A
Preferred Shares will be entitled to a minimum preferential liquidation payment
of $1,000 per share (plus any accrued but unpaid dividends) but will be
entitled to an aggregate payment of 1,000 times the payment made per share of
Cadence Common Stock. Each Cadence Series A Preferred Share will have 1,000
votes, voting together with the shares of Cadence Common Stock. Finally, in the
event of any merger, consolidation or other transaction in which shares of
Cadence Common Stock are exchanged, each Cadence Series A Preferred Share will
be entitled to receive 1,000 times the amount received per share of Cadence
Common Stock. These rights are protected by customary antidilution provisions.
 
  Because of the nature of the Cadence Series A Preferred Shares' dividend,
liquidation and voting rights, the value of the one one-thousandth interest in
a Cadence Series A Preferred Share purchasable upon exercise of each Cadence
Stockholder Right should approximate the value of one share of Cadence Common
Stock.
 
  In the event that any person or group of affiliated persons becomes a Cadence
Acquiring Person, each holder of a Cadence Stockholder Right, other than
Cadence Stockholder Rights beneficially owned by the Cadence Acquiring Person
(which will thereupon become void), will thereafter have the right to receive,
upon the exercise thereof at the then current exercise price of the Cadence
Stockholder Right, that number of shares of Cadence Common Stock having a
market value of two times the exercise price of the Cadence Stockholder Right.
In the event that, after a person or group has become a Cadence Acquiring
Person, Cadence is acquired in a merger or other business combination
transaction or 50% or more of its consolidated assets or earning power are
sold, proper provision will be made so that each holder of a Cadence
Stockholder Right (other than Cadence Stockholder Rights beneficially owned by
a Cadence Acquiring Person which will have become void) will thereafter have
the right to receive upon the exercise thereof at the then current exercise
price of the Cadence Stockholder Right, that number of shares of common stock
of the person with whom Cadence has engaged in the foregoing transaction (or
its parent), which number of shares at the time of such transaction will have a
market value of two times the exercise price of the right.
 
  At any time after any person or group becomes a Cadence Acquiring Person, and
prior to the acquisition by such person or group of 50% or more of the
outstanding shares of Cadence Common Stock, or the occurrence of an event
described in the prior paragraph, the Cadence Board may exchange the Cadence
Stockholder Rights (other than Cadence Stockholder Rights owned by such person
or group which have become void), in whole or in part, at an exchange ratio of
one share of Cadence Common Stock, or one one-thousandth of a Cadence Series A
Preferred Share (or of a share of a class or series of Cadence Preferred Stock
having equivalent rights, preferences and privileges), per Cadence Stockholder
Right (subject to adjustment).
 
  With certain exceptions, no adjustment in the Purchase Price will be required
until cumulative adjustments require an adjustment of at least 1% in such
Purchase Price. No fractional Cadence Series A Preferred Shares will be issued
(other than fractions which are integral multiples of one one-thousandth of a
Cadence Series A Preferred Share, which may, at the election of Cadence, be
evidenced by depository receipts), and, in lieu thereof, an adjustment in cash
will be made based on the market price of the Cadence Series A Preferred Shares
on the last trading day prior to the date of exercise.
 
 
                                       68
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
  At any time prior to the time an Acquiring Person becomes such, the Cadence
Board may redeem the Cadence Stockholder Rights in whole, but not in part, at a
price of $.01 per Cadence Stockholder Right (the "RIGHTS REDEMPTION PRICE").
The redemption of the Cadence Stockholder Rights may be made effective at such
time on such basis and with such conditions as the Cadence Board, in its sole
discretion, may establish. Immediately upon any redemption of the Cadence
Stockholder Rights, the right to exercise the Cadence Stockholder Rights will
terminate and the only right of the holders of Cadence Stockholder Rights will
be to receive the Rights Redemption Price.
 
  For so long as the Cadence Stockholder Rights are redeemable, Cadence may,
except with respect to the Redemption Price, amend the Cadence Stockholder
Rights in any manner. After the Cadence Stockholder Rights are no longer
redeemable, Cadence may, except with respect to the Redemption Price, amend the
Cadence Stockholder Rights in any manner that does not adversely affect the
interests of holders of the Cadence Stockholder Rights. Until a Cadence
Stockholder Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of Cadence, including, without limitation, the right to
vote or to receive dividends.
 
  The Cadence Stockholder Rights Have Certain Anti-Takeover Effects. The
Cadence Stockholder Rights will cause substantial dilution to a person or group
that attempts to acquire Cadence on terms not approved by the Cadence Board,
except pursuant to an offer conditioned on a substantial number of Cadence
Stockholder Rights being acquired. The Cadence Stockholder Rights should not
interfere with any merger or other business combination approved by the Cadence
Board since the Cadence Stockholder Rights may be redeemed by Cadence at the
Rights Redemption Price prior to the time that a person or group has acquired
beneficial ownership of 15% or more of the shares of Cadence Common Stock.
 
  The Cadence Rights Agreement is currently scheduled to expire on February 9,
2006. Before then, Cadence is likely either to renew the Cadence Rights
Agreement or enter into a successor rights agreement, with similar terms and
effects as the Cadence Rights Agreement.
 
  The foregoing description of the Cadence Stockholder Rights is qualified in
its entirety by reference to the Cadence Rights Agreement, which is
incorporated herein by reference. See "Where You Can Find More Information."
 
COMPARISON OF RIGHTS OF CADENCE STOCKHOLDERS AND QUICKTURN STOCKHOLDERS
 
  The rights of holders of Cadence Common Stock ("CADENCE STOCKHOLDERS") are
currently governed by the Delaware Law and the Cadence Certificate and Cadence
By-Laws, while the rights of Quickturn Stockholders are currently governed by
the Delaware Law and the Quickturn Certificate and the Quickturn By-Laws. In
most respects, the rights of Quickturn Stockholders are similar to those of
Cadence Stockholders. The following is a summary of the material differences
between the Cadence Certificate and Cadence By-Laws, on the one hand, and the
Quickturn Certificate and the Quickturn By-Laws, on the other. This summary
does not purport to be a complete discussion of, and is qualified in its
entirety by reference to, the Cadence Certificate, the Cadence By-Laws, the
Quickturn Certificate, the Quickturn By-Laws and the Delaware Law.
 
  Capital Stock. The Cadence Certificate provides that the authorized capital
stock of Cadence consists of 600,000,000 shares of Cadence Common Stock and
400,000 shares of Cadence Preferred Stock. 400,000 of the authorized shares of
Preferred Stock are designated in the Cadence Certificate as "Series A Junior
Participating Preferred Stock."
 
  The Quickturn Certificate provides that the authorized capital stock of
Quickturn consists of 40,000,000 shares of Quickturn Common Stock and 2,000,000
shares of Quickturn Preferred Stock.
 
  As of      , 1999, there were   shares of Quickturn Common Stock outstanding
held of record by approximately    persons. Quickturn Common Stock is listed on
Nasdaq under the symbol "QKTN."
 
 
                                       69
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
  The holders of Quickturn Common Stock are entitled to one vote for each share
held of record on all matters submitted to a vote of Quickturn Stockholders.
Subject to preferences that may be applicable to any outstanding shares of
Quickturn Preferred Stock (no shares of Quickturn Preferred Stock are
outstanding as of the date of this proxy Statement/Prospectus), the holders of
Quickturn Common Stock are entitled to receive ratably such dividends, if any,
as may be declared by the Quickturn Board out of funds legally available for
the payment of dividends. In the event of a liquidation, dissolution or winding
up of Quickturn, the holders of Quickturn Common Stock are entitled to share
ratably in all assets remaining after payment of liabilities and liquidation
preferences of any outstanding shares of Preferred Stock. Holders of Quickturn
Common Stock have no preemptive rights or rights to convert their Quickturn
Common Stock into any other securities. There are no redemption or sinking fund
provisions applicable to the Quickturn Common Stock. All outstanding shares of
Quickturn Common Stock are fully paid and non-assessable.
 
  Directors. The Cadence By-Laws provide for the Cadence Board to consist of
five or more members, with the exact number to be designated by resolution of
the Cadence Board. The Cadence By-Laws provide that vacancies on the Cadence
Board may be filled by the affirmative vote of a majority of the remaining
directors then in office, though less than a quorum or by a sole remaining
director or by the Cadence Stockholders at a meeting or by written consent.
 
  The Quickturn By-Laws provide for the Quickturn Board to consist of eight
members, which number may be changed from time to time by a by-law adopted by
the Quickturn Stockholders or by the Quickturn Board. The Quickturn By-Laws
provide that vacancies on the Quickturn Board may be filled by the affirmative
vote of a majority of the remaining directors then in office, though less than
a quorum, or by a plurality of the votes cast at a meeting of the Quickturn
Stockholders.
 
  Stockholder Proposals. The Cadence By-Laws do not provide a procedure by
which a stockholder may bring business before any meeting of Cadence
Stockholders. However, the Cadence By-Laws provide that any stockholder of
record seeking to have the Cadence Stockholders authorize or take corporate
action by written consent must, by written notice to the secretary of Cadence,
request that the Cadence Board fix a record date for determining the
stockholders entitled to consent to corporate action in writing without a
meeting. The request must include a brief description of the action proposed to
be taken. The Cadence Board must, within 10 days of receipt of the request,
adopt a resolution fixing a record date. The record date may not precede the
date on which the Cadence Board adopts the resolution and may not be more than
10 days after the date upon which such resolution was adopted. If the Cadence
Board fails to adopt a record date within the required 10 days, and no prior
action by the board is required by Delaware law, the record date shall be the
first date on which a signed written consent setting forth the action taken or
proposed to be taken is delivered to Cadence. If no record date is fixed and
prior action is required by the Cadence Board under the Delaware Law, the
record date shall be at the close of business on the date on which the Cadence
Board adopts the resolution taking such prior action.
 
  The Quickturn By-Laws provide that in order to properly bring nominations for
the election of director or other business before an annual meeting or special
meeting, a stockholder must give timely notice in proper form of his or her
intent to bring such business before such meeting. To be timely the
stockholder's notice must be delivered to or mailed and received by the
secretary of Quickturn not less than 90 days prior to the meeting; provided
that in the event that less than 100 days notice or prior public disclosure of
the date of the meeting is given, notice must be so received not later than the
close of business on the tenth day following the day on which such notice of
the date of the meeting was mailed or such public disclosure was made. To be in
proper form, the stockholder's notice to the secretary must set forth: (i) the
name and address of the stockholder who seeks to bring the action and the
nature of the business to be proposed or the name and address of the person(s)
to be nominated; (ii) the stockholder's representation that he or she is a
holder of record of Quickturn stock entitled to vote at the meeting and that
the stockholder intends to appear at the meeting to present the nominee or
matter of business to be proposed; (iii) if applicable, a description of all
arrangements or understandings between the stockholder and each nominee; (iv)
other information regarding the nominee or matter of business to be proposed as
would be required to be included in a proxy statement
 
                                       70
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
under the proxy rules of the Commission had the nominee or business been
proposed by the Quickturn Board; and (v) if applicable, the consent of each
nominee to serve as a director if elected. The chairman of the meeting may
refuse to acknowledge any person or proposal not made in compliance with the
foregoing procedures.
 
  Right to Call Special Meetings of Stockholders. The Cadence By-Laws provide
that special meetings of Cadence Stockholders may be called by the Cadence
Board, the chairman, the chief executive officer or the president of Cadence or
by stockholders holding shares representing not less than 10% of the votes
entitled to vote at the meeting.
 
  The Quickturn By-Laws provide that special meetings of stockholders of
Quickturn may be called by the Quickturn Board, the chairman, the president or
the chief executive officer of Quickturn or one or more Quickturn Stockholders
holding shares representing not less than 10% of the votes entitled to vote at
the meeting.
 
  A stockholder entitled to call a special meeting must submit his or her
request in writing by registered mail to Quickturn's president or chief
executive officer. The Quickturn Board determines the place and time for the
meeting. The time set for the special meeting will not be less than 90 nor more
than 100 days after the receipt of the stockholder's request for the special
meeting and the determination of the validity of the request and the Quickturn
Board will set a record date pursuant to the Quickturn By-Laws to determine the
stockholders entitled to vote at the special meeting. Following the receipt of
the request, the secretary of Quickturn must give notice of the special meeting
to the stockholders entitled to vote at the meeting.
 
  Stockholder Rights Plans. Cadence has entered into the Cadence Rights
Agreement pursuant to which each share of Cadence Common Stock is issued a
Cadence Stockholder Right. See "--Description of Cadence Capital Stock--Cadence
Rights Plan."
 
  On January 10, 1996, pursuant to a Preferred Shares Rights Agreement dated
January 10, 1996 (the "QUICKTURN RIGHTS AGREEMENT"), the Quickturn Board
declared a dividend of one Quickturn Stockholder Right (a "QUICKTURN
STOCKHOLDER RIGHT") for each outstanding share of Quickturn Common Stock. Prior
to the Distribution Date referred to below, the Quickturn Stockholder Rights
are evidenced by and trade with the certificates for Quickturn Common Stock.
After the Distribution Date, the Quickturn Board will mail Quickturn
Stockholder Rights certificates to Quickturn Stockholders and the Quickturn
Stockholder Rights will become transferable apart from the Common Stock.
 
  Quickturn Stockholder Rights will separate from the Quickturn Common Stock
and become exercisable on the Distribution Date. The Distribution Date is the
earlier of (i) the tenth day (or such later date as may be determined by a
majority of the Quickturn Board not affiliated with the acquiring person or
group (the "Continuing Directors")) after a person or group acquires beneficial
ownership of 15% or more of Quickturn Common Stock or (ii) the tenth day (or
such later date as may be determined by the Continuing Directors of the
Quickturn Board then in office) after a person or group announces a tender or
exchange offer, the consummation of which would result in ownership by a person
or group of 15% or more of Quickturn's Common Stock.
 
  After the Distribution Date, each Quickturn Stockholder Right will entitle
the holder to purchase, for $50, a fraction of a share of Quickturn Preferred
Stock with economic terms similar to that of one share of Quickturn Common
Stock. If an acquiror obtains 15% or more of Quickturn's Common Stock (other
than pursuant to a tender offer deemed adequate and in the best interests of
Quickturn and its stockholders by the Quickturn Board (a "PERMITTED OFFER")),
thereby becoming a "QUICKTURN ACQUIRING PERSON," then each Quickturn
Stockholder Right (other than Quickturn Stockholder Rights owned by a Quickturn
Acquiring Person or its affiliates) will entitle the holder thereof to
purchase, for the exercise price, a number of shares of Quickturn's Common
Stock having a then current market value of twice the exercise price (a "FLIP-
IN"). If, after the first date of public announcement by Quickturn or a
Quickturn Acquiring Person that a Quickturn Acquiring Person has become such
(the "SHARES ACQUISITION DATE"), (a) Quickturn merges into another
 
                                       71
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
entity, (b) an acquiring entity merges into Quickturn or (c) Quickturn sells
more than 50% of Quickturn's assets or earning power, then each Quickturn
Stockholder Right (other than Quickturn Stockholder Rights owned by a Quickturn
Acquiring Person or its affiliates) will entitle the holder thereof to
purchase, for the exercise price, a number of shares of Common Stock of the
person engaging in the transaction having a then current market value of twice
the exercise price (unless the transaction satisfies certain conditions and is
consummated with a person who acquired shares pursuant to a Permitted Offer, in
which case the rights will expire) (a "FLIP-OVER").
 
  At any time after an event triggering the Flip-In or Flip-Over rights and
prior to the acquisition by the Quickturn Acquiring Person of 50% or more of
the outstanding Quickturn Common Stock, the Quickturn Board may exchange the
Quickturn Stockholder Rights (other than Quickturn Stockholder Rights owned by
the Quickturn Acquiring Person or its affiliates), in whole or in part, at an
exchange ratio of one share of Quickturn Common Stock per Quickturn Stockholder
Right (subject to adjustment). Quickturn Stockholder Rights are redeemable at
Quickturn's option for $0.01 per Quickturn Stockholder Right at any time on or
prior to the Distribution Date.
 
  The Quickturn Stockholder Rights expire on the earliest of (a) January 10,
2006, (b) exchange or redemption of the Quickturn Stockholder Rights as
described above or (c) consummation of a merger or consolidation resulting in
expiration of the Quickturn Stockholder Rights as described above. The terms of
the Quickturn Stockholder Rights and the Quickturn Rights Agreement may be
amended in any respect without the consent of the Quickturn Stockholder Rights
holders on or prior to the Distribution Date; thereafter, the terms of the
Quickturn Stockholder Rights and the Quickturn Rights Agreement may be amended
without the consent of the Quickturn Stockholder Rights holders to cure any
ambiguities or to make changes which do not adversely affect the interests of
Quickturn Stockholder Rights holders (other than the Acquiring Person).
Quickturn Stockholder Rights do not have any voting rights. Quickturn
Stockholder Rights have the benefit of certain customary anti-dilution
provisions.
 
  On August 25, 1998, the Quickturn Board adopted certain amendments to the
Quickturn Rights Agreement, including a "delayed redemption" provision ("DRP").
The DRP provides that if a majority of directors are replaced by stockholder
action, the newly elected board cannot redeem the Quickturn Stockholder Rights
for 180 days if the purpose or effect of the redemption would be to facilitate
a transaction with a certain interested person and its affiliates. On December
3, 1998, the Chancery Court issued an opinion invalidating the DRP provision.
Quickturn has appealed the Chancery Court's ruling.
 
  On December 8, 1998, in connection with the Merger, the Quickturn Board
amended the Quickturn Rights Agreement to provide that neither Cadence's
entering into the Merger Agreement, the Option Agreement or the consummation of
the Merger, nor exercise of Cadence's rights under such Option Agreement will
cause the Quickturn Stockholder Rights to become exercisable or cause Cadence
to become a Quickturn Acquiring Person.
 
  The combined company will be subject to the Cadence Rights Agreement until
the expiration thereof, and may be covered thereafter by a renewal thereof or a
successor rights agreement. See "--Description of Cadence Capital Stock--
Cadence Rights Plan."
 
  The foregoing is a summary of certain principal terms of the Quickturn
Stockholder Rights only and is qualified in its entirety by reference to the
detailed terms of the Quickturn Rights Agreement dated as of January 10, 1996,
as amended.
 
                                       72
CADENCE CAPITAL STOCK AND
COMPARISON OF STOCKHOLDER RIGHTS
<PAGE>
 
                          DISSENTERS' APPRAISAL RIGHTS
 
  Quickturn Stockholders will not be entitled to dissenters' appraisal rights
under the Delaware Law or any other statute in connection with the Merger.
 
                                 LEGAL MATTERS
 
  The validity of the Cadence Common Stock to be issued in connection with the
Merger will be passed upon by Gibson, Dunn & Crutcher LLP, San Francisco,
California.
 
                                    EXPERTS
 
  The consolidated audited financial statements and schedules of Cadence and
its subsidiaries incorporated by reference in this Proxy Statement/Prospectus
have been audited by Arthur Andersen LLP, independent public accountants, as
indicated in their reports with respect thereto and are incorporated herein in
reliance upon authority of said firm as experts in giving said reports.
 
  The consolidated financial statements of Quickturn and its subsidiaries
incorporated in this Proxy Statement/Prospectus by reference to the Quickturn
Annual Report on Form 10-K for the year ended December 31, 1997 have been so
incorporated by reference herein in reliance on the report with respect thereto
of PricewaterhouseCoopers LLP independent public accountants, given upon the
authority of said firm as experts in accounting and auditing.
 
                             STOCKHOLDER PROPOSALS
 
  Quickturn will hold a 1999 Annual Meeting of Stockholders only if the Merger
is not consummated before the time of such meeting. In the event that such a
meeting is held, any proposals of Quickturn Stockholders intended to be
presented at the 1999 Annual Meeting must be received by the secretary of
Quickturn no later than     , 1999 in order to be considered for inclusion in
the Quickturn proxy materials relating to such meeting. Any proposal from a
Quickturn Stockholder that is submitted outside the processes of Rule 14a-8
under the Exchange Act and that therefore will not be included in proxy
materials to be sent to Quickturn Stockholders by Quickturn, must be received
by the secretary of Quickturn not earlier than 90 days prior nor later than 120
days prior to the date of such meeting (unless less than 100 days' notice or
prior public disclosure of the date of such meeting is given or made to
Quickturn Stockholders, in which case a stockholder proposal must be received
no later than the close of business on the 10th day following the date on which
Quickturn's notice was mailed or public disclosure was made with respect to
such meeting) in order to be considered timely received under the Quickturn By-
Laws.
 
                                 OTHER MATTERS
 
  As of the date of this Proxy Statement/Prospectus, the Quickturn Board and
the Cadence Board know of no matters that will be presented for consideration
at the Quickturn Special Meeting other than as described in this Proxy
Statement/Prospectus. If any other matters shall properly come before the
Quickturn Special Meeting or any adjournment or postponement thereof and be
voted upon, the enclosed proxies will be deemed to confer discretionary
authority on the individuals named as proxies therein to vote the shares
represented by such proxies as to any such matters. The individuals named as
proxies intend to vote or not to vote in accordance with the recommendation of
the management of Quickturn.
 
                                       73
<PAGE>
 
                      WHERE YOU CAN FIND MORE INFORMATION
 
  Cadence has filed with the Securities and Exchange Commission (the
"COMMISSION") a Registration Statement under the Securities Act that registers
the distribution to Quickturn Stockholders of the shares of Cadence Common
Stock to be issued in connection with the Merger (the "REGISTRATION
STATEMENT"). The Registration Statement, including the attached exhibits and
schedules, contains additional relevant information about Cadence and Cadence
Common Stock. The rules and regulations of the Commission allow us to omit
certain information included in the Registration Statement from this Proxy
Statement/Prospectus.
 
  In addition, Cadence and Quickturn file reports, proxy statements and other
information with the Commission under the Exchange Act. You may read and copy
this information at the following locations of the Commission:
 
   Public Reference         New York Regional Office      Chicago Regional
         Room                 7 World Trade Center             Office
   450 Fifth Street,               Suite 1300              Citicorp Center
         N.W.               New York, New York 10048      500 West Madison
       Room 1024                                               Street
   Washington, D.C.                                          Suite 1400
         20549                                            Chicago, Illinois
                                                             60661-2511
 
  You may also obtain copies of this information by mail from the Public
Reference Section of the Commission, 450 Fifth Street, N.W., Room 1024,
Washington, D.C. 20549, at prescribed rates.
 
  The Commission also maintains an Internet world wide web site that contains
reports, proxy statements and other information about issuers, like Cadence and
Quickturn, who file electronically with the Commission. The address of that
site is http://www.sec.gov.
 
  The Commission allows Cadence and Quickturn to "incorporate by reference"
information into this Proxy Statement/Prospectus. This means that the companies
can disclose important information to you by referring you to another document
filed separately with the Commission. The information incorporated by reference
is considered to be a part of this Proxy Statement/Prospectus, except for any
information that is superseded by information that is included directly in this
document.
 
  This Proxy Statement/Prospectus incorporates by reference the documents
listed below that Cadence and Quickturn have previously filed with the
Commission. They contain important information about our companies and their
financial condition.
 
                                       74
WHERE YOU CAN FIND
MORE INFORMATION
<PAGE>
 
<TABLE>
<CAPTION>
CADENCE SEC FILINGS                                             PERIOD
- -------------------                                             ------
<S>                                              <C>
Annual Report on Form 10-K...................... Year ended January 3, 1998
Quarterly Reports on Form 10-Q.................. Quarters ended April 4, 1998, July
                                                 4, 1998 and October 3, 1998
The description of Cadence Common Stock set
 forth in the Registrant's Registration
 Statement on Form 8-A.......................... Filed: August 29, 1990
The description of Cadence Preferred Stock
 Purchase Rights set forth in Exhibit 1A, 1B and
 1C to the Registrant's Current Report on Form
 8-K.......................................      Filed: February 16, 1996
Current Reports on Form 8-K..................... Filed:
                                                  . August 4, 1998
                                                  . October 13, 1998 (as amended by
                                                     Form 8-K/A filed December 11,
                                                     1998)
                                                  . October 13, 1998
                                                  . December 10, 1998 (as amended by
                                                     Form 8-K/A filed December 22,
                                                     1998)
<CAPTION>
QUICKTURN SEC FILINGS                                           PERIOD
- ---------------------                                           ------
<S>                                              <C>
Annual Report on Form 10-K...................... Year ended December 31, 1997
Quarterly Reports on Form 10-Q.................. Quarters ended March 31, 1998, June
                                                 30, 1998, and September 30, 1998
The description of Quickturn Common Stock set
 forth in Quickturn's Registration Statement on
 Form 8-A....................................... Filed: October 29, 1993
The description of Quickturn Preferred Stock
 Purchase Rights set forth in Quickturn's
 Registration Statement on Form 8-A............. Filed: January 17, 1996
Amendment No. 1 to the Preferred Share Purchase
 Rights set forth in Amendment No. 1 to
 Quickturn's Registration Statement on Form 8-
 A/A............................................ Filed: August 25, 1998
Amendment No. 2 to the Preferred Share Purchase
 Rights set forth in Amendment No. 2 to
 Quickturn's Registration Statement on Form 8-
 A/A............................................ Filed: December 16, 1998
Current Reports on Form 8-K..................... Filed:
                                                  . April 6, 1998
                                                  . December 16, 1998 (as amended by
                                                     Form 8-K/A filed December 22,
                                                     1998)
</TABLE>
 
  Cadence and Quickturn incorporate by reference additional documents that
either company may file with the Commission between the date of this Proxy
Statement/Prospectus and the date of the Quickturn Special Meeting. These
documents include periodic reports, such as Annual Reports on Form 10-K,
Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, as well as
proxy statements.
 
  Cadence has supplied all information contained or incorporated by reference
in this Proxy Statement/Prospectus relating to Cadence, as well as all pro
forma financial information, and Quickturn has supplied all such information
relating to Quickturn.
 
  You can obtain any of the documents incorporated by reference in this
document through Cadence or Quickturn, as the case may be, or from the
Commission through the Commission's web site at the address described above.
Documents incorporated by reference are available from the companies without
charge, excluding any exhibits to those documents unless the exhibit is
specifically incorporated by reference as an exhibit in this Proxy
Statement/Prospectus. You can obtain documents incorporated by reference in
this Proxy
 
                                       75
WHERE YOU CAN FIND
MORE INFORMATION
<PAGE>
 
Statement/Prospectus by requesting them in writing or by telephone from the
appropriate company at the following addresses:
 
           CADENCE                                        QUICKTURN
     Investor Relations                                Investor/Public
   Cadence Design Systems,                                Relations
            Inc.                                      Quickturn Design
      2655 Seely Avenue                                 Systems, Inc.
    San Jose, California                             55 W. Trimble Road
            95134                                   San Jose, California
    Telephone: (408) 943-                                   95131
            1234
 
                                                    Telephone: (408) 914-
                                                            6000
  If you would like to request documents, please do so by      , 1999 to
receive them before the Quickturn Special Meeting. If you request any
incorporated documents from us, we will mail them to you by first class mail,
or another equally prompt means, within one business day after we receive your
request.
 
  We have not authorized anyone to give any information or make any
representation about the Merger or our companies that is different from, or in
addition to, that contained in this Proxy Statement/Prospectus or in any of the
materials that we've incorporated into this document. Therefore, if anyone does
give you information of this sort, you should not rely on it. If you are in a
jurisdiction where offers to exchange or sell, or solicitations of offers to
exchange or purchase, the securities offered by this document or the
solicitation of proxies is unlawful, or if you are a person to whom it is
unlawful to direct these types of activities, then the offer presented in this
document does not extend to you. The information contained in this document
speaks only as of the date of this document unless the information specifically
indicates that another date applies.
 
                                       76
WHERE YOU CAN FIND
MORE INFORMATION
<PAGE>
 
          UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION
 
  The following unaudited pro forma condensed combined financial statements
give effect to the proposed Merger and Cadence's acquisition of Ambit, which
was consummated in the quarter ended October 3, 1998, and should be read in
conjunction with the historical financial statements and accompanying notes
incorporated by reference. The Merger is subject to approval by the Quickturn
Stockholders.
 
  The unaudited pro forma condensed combined balance sheet has been prepared as
if the Merger (which will be accounted for as a pooling-of-interests) had been
completed as of October 3, 1998. The acquisition of Ambit is reflected in the
historical unaudited condensed balance sheet of Cadence as of October 3, 1998.
The unaudited pro forma combined statements of operations for the nine-month
period ended October 3, 1998, and the fiscal year ended January 3, 1998, give
effect to the proposed Merger and the acquisition of Ambit (which was accounted
for as a purchase in the quarter ended October 3, 1998) as if these
transactions had been completed at the beginning of the periods presented. The
unaudited pro forma combined statements of operations for the two fiscal years
in the period ended December 28, 1996 give effect to the proposed Merger as if
the Merger had been completed at the beginning of the period presented.
 
  The pro forma information is presented for illustrative purposes only and is
not necessarily indicative of the operating results or financial position that
would have occurred if these transactions had been consummated at the beginning
of the earliest period presented, nor is it necessarily indicative of future
operating results or financial position.
 
                                       77
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                             CADENCE AND QUICKTURN
              UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET
                                OCTOBER 3, 1998
                                   (IN 000S)
 
<TABLE>
<CAPTION>
                                 CADENCE    QUICKTURN  ADJUSTMENTS     TOTAL
                                ----------  ---------  -----------   ----------
<S>                             <C>         <C>        <C>           <C>
            ASSETS
Current Assets:
  Cash and cash investments.... $  207,727  $ 25,182                 $  232,909
  Short-term investments.......     38,231    12,610                     50,841
  Accounts receivable, net.....    236,866    17,486                    254,352
  Inventories..................        --      6,932                      6,932
  Prepaid expenses and other...     86,582    12,697                     99,279
                                ----------  --------                 ----------
    Total current assets.......    569,406    74,907                    644,313
Marketable securities..........        --     20,995                     20,995
Property, plant and equipment,
 net...........................    248,019    12,838                    260,857
Software development costs,
 net...........................     13,548       --                      13,548
Purchased software and
 intangibles, net..............     91,154       --                      91,154
Installment contract
 receivables...................     95,269       --                      95,269
Other assets...................    165,826     9,330                    175,156
                                ----------  --------                 ----------
                                $1,183,222  $118,070                 $1,301,292
                                ==========  ========                 ==========
        LIABILITIES AND
      STOCKHOLDERS' EQUITY
Current Liabilities:
  Current portion of long-term
   debt........................ $    1,105       --                  $    1,105
  Accounts payable and accrued
   liabilities.................    161,831  $ 24,754     $10,000 (1)    196,585
  Payable to Ambit
   shareholders................    252,990       --                     252,990
  Income taxes payable.........     35,480       --                      35,480
  Deferred revenue.............    109,431     8,460                    117,891
                                ----------  --------                 ----------
    Total current liabilities..    560,837    33,214                    604,051
                                ----------  --------                 ----------
Long-Term Liabilities:
  Long-term debt...............      1,461       --                       1,461
  Minority interest liability..        325       --                         325
  Other long-term liabilities..     30,167       --                      30,167
                                ----------  --------                 ----------
    Total long-term
     liabilities...............     31,953       --                      31,953
                                ----------  --------                 ----------
Stockholders' Equity:
  Common stock and capital in
   excess of par value.........    626,602    93,769                    720,371
  Treasury stock at cost.......   (205,781)   (1,461)                  (207,242)
  Deferred compensation........        --       (382)                      (382)
  Retained earnings (deficit)..    177,080    (6,150)    (10,000)(1)    160,930
  Accumulated other
   comprehensive loss..........     (7,469)     (920)                    (8,389)
                                ----------  --------                 ----------
    Total stockholders'
     equity....................    590,432    84,856                    665,288
                                ----------  --------                 ----------
                                $1,183,222  $118,070                 $1,301,292
                                ==========  ========                 ==========
</TABLE>
- --------
(1) Reflects anticipated expenses of the merger with Quickturn.
 
                                       78
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                         CADENCE, QUICKTURN AND AMBIT
 
        UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS
                       NINE MONTHS ENDED OCTOBER 3, 1998
                      (IN 000S, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                         CADENCE   AMBIT   ADJUSTMENTS   SUBTOTAL QUICKTURN  ADJUSTMENTS    TOTAL
                         -------- -------  -----------   -------- ---------  -----------   --------
<S>                      <C>      <C>      <C>           <C>      <C>        <C>           <C>
REVENUE
  Product............... $489,865 $ 8,562                $498,427 $ 45,297                 $543,724
  Services..............  184,733     381                 185,114    6,381                  191,495
  Maintenance...........  196,020   1,873                 197,893   21,411                  219,304
                         -------- -------                -------- --------                 --------
   Total revenue........  870,618  10,816                 881,434   73,089                  954,523
                         -------- -------                -------- --------                 --------
COSTS AND EXPENSES
  Cost of product.......   40,325     189    $3,912 (1)    44,426   20,160                   64,586
  Cost of services......  138,066   1,363                 139,429    2,563                  141,992
  Cost of maintenance...   32,869      --                  32,869    6,326                   39,195
  Marketing and sales...  216,663   8,432                 225,095   28,493                  253,588
  Research and
   development..........  129,522   4,519                 134,041   17,811                  151,852
  General and
   administrative.......   49,484   2,578                  52,062   13,596                   65,658
  Unusual items.........  149,890      --                 149,890      --                   149,890
                         -------- -------                -------- --------                 --------
   Total costs and
    expenses............  756,819  17,081                 777,812   88,949                  866,761
                         -------- -------                -------- --------                 --------
Income (loss) from
 operations.............  113,799  (6,265)                103,622  (15,860)                  87,762
Other income, net.......    6,523     435                   6,958    2,221                    9,179
                         -------- -------                -------- --------                 --------
Income (loss) before
 provision for income
 taxes..................  120,322  (5,830)                110,580  (13,639)                  96,941
Provision (benefit) for
 income taxes...........   57,776      25    (1,565)(2)    56,236   (5,592)                  50,644
                         -------- -------                -------- --------                 --------
  Net income (loss)..... $ 62,546 $(5,855)               $ 54,344 $ (8,047)                $ 46,297
                         ======== =======                ======== ========                 ========
  Basic net income
   (loss) per share..... $   0.30                        $   0.26 $  (0.45)                $   0.21
                         ========                        ======== ========                 ========
  Diluted net income
   (loss) per share..... $   0.27                        $   0.23 $  (0.45)                $   0.19
                         ========                        ======== ========                 ========
  Weighted average
   common shares
   outstanding..........  211,505                         211,505   17,772     (9,597)(3)   219,680
                         ========                        ======== ========     ======      ========
  Weighted average
   common and potential
   common shares
   outstanding-assuming
   dilution.............  234,385                         234,385   17,772     (9,275)(3)   242,882
                         ========                        ======== ========     ======      ========
</TABLE>
- --------
(1) Reflects amortization of goodwill and identified intangible assets for
    nine month period ended October 3, 1998 ($5.2 million per year for 7
    years).
(2) Reflects tax benefit relating to the Ambit loss.
(3) Converts Quickturn's weighted average common and potential common shares
    outstanding to Cadence Common Stock based on an assumed Exchange Ratio of
    0.46 to 1.00.
 
                                      79
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                         CADENCE, QUICKTURN AND AMBIT
 
        UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS
                       FISCAL YEAR ENDED JANUARY 3, 1998
                      (IN 000S, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                         CADENCE   AMBIT   ADJUSTMENTS   SUBTOTAL QUICKTURN  ADJUSTMENTS     TOTAL
                         -------- -------  -----------   -------- ---------  -----------   ----------
<S>                      <C>      <C>      <C>           <C>      <C>        <C>           <C>
REVENUE
 Product................ $530,513 $ 2,361                $532,874 $ 80,850                 $  613,724
 Services...............  160,890      14                 160,904    7,899                    168,803
 Maintenance............  224,490     538                 225,028   21,655                    246,683
                         -------- -------                -------- --------                 ----------
   Total revenue........  915,893   2,913                 918,806  110,404                  1,029,210
                         -------- -------                -------- --------                 ----------
COSTS AND EXPENSES
 Cost of product........   41,509     119    $5,216 (1)    46,844   23,984                     70,828
 Cost of services.......  114,747     439                 115,186    2,696                    117,882
 Cost of maintenance....   26,840     --                   26,840    6,200                     33,040
 Marketing and sales....  257,867   4,207                 262,074   36,775                    298,849
 Research and
  development...........  140,375   2,811                 143,186   23,499                    166,685
 General and
  administrative........   56,495   2,814                  59,309   11,485                     70,794
 Unusual items..........   44,053     --                   44,053   19,231                     63,284
                         -------- -------                -------- --------                 ----------
   Total costs and
    expenses............  681,886  10,390                 697,492  123,870                    821,362
                         -------- -------                -------- --------                 ----------
Income (loss) from
 operations.............  234,007  (7,477)                221,314  (13,466)                   207,848
Other income, net.......   25,624     294                  25,918    2,175                     28,093
                         -------- -------                -------- --------                 ----------
Income (loss) before
 provision for income
 taxes..................  259,631  (7,183)                247,232  (11,291)                   235,941
Provision (benefit) for
 income taxes...........   77,889     --     (2,086)(2)    75,803   (5,945)                    69,858
                         -------- -------                -------- --------                 ----------
  Net income (loss)
   before cumulative
   effect of change in
   accounting method.... $181,742 $(7,183)               $171,429 $ (5,346)                $  166,083
                         ======== =======                ======== ========                 ==========
  Basic net income
   (loss) per share
   before cumulative
   effect of change in
   accounting method.... $   0.93                        $   0.88 $  (0.31)                $     0.82
                         ========                        ======== ========                 ==========
  Diluted net income
   (loss) per share
   before cumulative
   effect of change in
   accounting method.... $   0.83                        $   0.78 $  (0.31)                $     0.73
                         ========                        ======== ========                 ==========
  Weighted average
   common shares
   outstanding..........  194,900                         194,900   17,110     (9,239)(3)     202,771
                         ========                        ======== ========                 ==========
  Weighted average
   common and potential
   common shares
   outstanding-assuming
   dilution.............  219,552                         219,552   17,110     (8,485)(3)     228,177
                         ========                        ======== ========                 ==========
</TABLE>
- --------
(1) Reflects amortization of goodwill and identified intangible assets for
    twelve month period ended January 3, 1998 ($5.2 million per year for 7
    years).
(2) Reflects tax benefit relating to the Ambit loss.
(3) Converts Quickturn's weighted average common and potential common shares
    outstanding to Cadence Common Stock based on an assumed Exchange Ratio of
    0.46 to 1.00.
 
                                      80
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                             CADENCE AND QUICKTURN
        UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS
                         YEAR ENDED DECEMBER 28, 1996
                      (IN 000S, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                      CADENCE   QUICKTURN ADJUSTMENTS    TOTAL
                                      --------  --------- -----------   --------
<S>                                   <C>       <C>       <C>           <C>
REVENUE
  Product............................ $414,029   $88,090                $502,119
  Services...........................  114,620     4,846                 119,466
  Maintenance........................  212,810    16,642                 229,452
                                      --------   -------                --------
    Total revenue....................  741,459   109,578                 851,037
                                      --------   -------                --------
COSTS AND EXPENSES
  Cost of product....................   48,383    26,050                  74,433
  Cost of services...................   80,963     1,575                  82,538
  Cost of maintenance................   24,127     5,038                  29,165
  Marketing and sales................  226,496    31,982                 258,478
  Research and development...........  115,301    19,706                 135,007
  General and administrative.........   54,387     7,254                  61,641
  Unusual items......................  100,543       --                  100,543
                                      --------   -------                --------
    Total costs and expenses.........  650,200    91,605                 741,805
                                      --------   -------                --------
Income from operations...............   91,259    17,973                 109,232
Other income (expense), net..........     (782)    1,879                   1,097
                                      --------   -------                --------
Income before provision for income
 taxes...............................   90,477    19,852                 110,329
Provision for income taxes...........   61,439     5,721                  67,160
                                      --------   -------                --------
  Net income......................... $ 29,038   $14,131                $ 43,169
                                      ========   =======                ========
  Basic net income per share......... $   0.19   $  0.87                $   0.26
                                      ========   =======                ========
  Diluted net income per share....... $   0.16   $  0.79                $   0.22
                                      ========   =======                ========
  Weighted average common shares
   outstanding.......................  156,773    16,323    (8,814)(1)   164,282
                                      ========   =======                ========
  Weighted average common and
   potential common shares
   outstanding-assuming dilution.....  183,789    17,912    (9,672)(1)   192,029
                                      ========   =======                ========
</TABLE>
- --------
(1) Converts Quickturn's weighted average common and potential common shares
    outstanding to Cadence Common Stock based on an assumed Exchange Ratio of
    0.46 to 1.00.
 
                                      81
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                             CADENCE AND QUICKTURN
         UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS
                          YEAR ENDED DECEMBER 30, 1995
                      (IN 000S, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                        CADENCE  QUICKTURN ADJUSTMENTS    TOTAL
                                        -------- --------- -----------   --------
<S>                                     <C>      <C>       <C>           <C>
REVENUE
  Product.............................  $292,198  $68,321                $360,519
  Services............................    65,860    2,534                  68,394
  Maintenance.........................   190,360   11,587                 201,947
                                        --------  -------                --------
    Total revenue.....................   548,418   82,442                 630,860
                                        --------  -------                --------
COSTS AND EXPENSES
  Cost of product.....................    44,793   20,776                  65,569
  Cost of services....................    54,988      703                  55,691
  Cost of maintenance.................    16,749    3,627                  20,376
  Marketing and sales.................   185,025   25,809                 210,834
  Research and development............    88,566   15,436                 104,002
  General and administrative..........    40,437    5,006                  45,443
                                        --------  -------                --------
    Total costs and expenses..........   430,558   71,357                 501,915
                                        --------  -------                --------
Income from operations................   117,860   11,085                 128,945
Other income, net.....................    17,237      781                  18,018
                                        --------  -------                --------
Income before provision for income
 taxes................................   135,097   11,866                 146,963
Provision (benefit) for income taxes..    37,827     (612)                 37,215
                                        --------  -------                --------
  Net income..........................  $ 97,270  $12,478                $109,748
                                        ========  =======                ========
  Basic net income per share..........  $   0.59  $  0.81                $   0.64
                                        ========  =======                ========
  Diluted net income per share........  $   0.51  $  0.74                $   0.55
                                        ========  =======                ========
  Weighted average common shares
   outstanding........................   165,510   15,497    (8,368)(1)   172,639
                                        ========  =======                ========
  Weighted average common and
   potential common shares
   outstanding-assuming dilution......   191,114   16,806    (9,075)(1)   198,845
                                        ========  =======                ========
</TABLE>
- --------
(1) Converts Quickturn's weighted average common and potential common shares
    outstanding to Cadence Common Stock based on an assumed Exchange Ratio of
    0.46 to 1.00.
 
                                       82
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                          CADENCE, AMBIT AND QUICKTURN
 
    NOTES TO UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS OF
                          CADENCE, QUICKTURN AND AMBIT
 
BASIS OF PRESENTATION
 
  The unaudited pro forma condensed combined financial statements combine the
historical financial statements of Cadence and Quickturn for all periods
presented following the pooling-of-interests method of accounting. No
adjustments were necessary to conform the accounting policies of the combining
companies. The unaudited pro forma condensed combined statements of operations
for the nine months ended October 3, 1998 and the year ended January 3, 1998
include Cadence's acquisition of Ambit which has been accounted for under the
purchase method of accounting.
 
  The unaudited pro forma condensed combined financial statements included
herein have been prepared by Cadence and Quickturn, without audit, pursuant to
the rules and regulations of the Securities and Exchange Commission. Certain
information and footnote disclosures normally included in consolidated
financial statements prepared in accordance with generally accepted accounting
principles have been condensed or omitted pursuant to such rules and
regulations. However, Cadence and Quickturn believe that the disclosures are
adequate to make the information presented not misleading.
 
  The preparation of unaudited pro forma condensed combined financial
statements in conformity with generally accepted accounting principles requires
management to make estimates and assumptions that affect the reported amounts
of assets and liabilities and disclosure of contingent assets and liabilities
at the date of the unaudited pro forma condensed combined financial statements
and the reported amounts of revenues and expenses during the reporting period.
Actual results could differ from those estimates.
 
PRO FORMA NET INCOME (LOSS) PER SHARE
 
  The net income (loss) per share is based on the combined weighted average
number of common and dilutive potential common shares of Cadence and Quickturn
based upon an assumed exchange ratio of 0.46 shares of Cadence Common Stock for
each share of Quickturn Common Stock and outstanding Quickturn stock options
and warrants.
 
MERGER RELATED EXPENSES OF CADENCE AND QUICKTURN
 
  Cadence and Quickturn estimate that they will incur merger-related expenses,
consisting primarily of transaction costs for investment bankers, attorneys,
accountants, financial printing, and other related charges, of approximately
$10 million. This estimate is preliminary and is therefore subject to change.
These non-recurring expenses will be charged to operations during the period in
which the Merger is consummated. The pro forma condensed combined balance sheet
gives effect to such expenses as if they had been incurred as of October 3,
1998, but the pro forma condensed combined statements of operations do not give
effect to such expenses as such expenses are non-recurring.
 
PURCHASE PRICE
 
  The purchase price for the acquisition of Ambit is computed as follows (in
thousands):
 
<TABLE>
   <S>                                                                 <C>
   Cash payment to Ambit shareholders................................. $252,990
   Cadence ownership prior to acquisition.............................    2,000
                                                                       --------
     Total purchase price............................................. $254,990
                                                                       ========
</TABLE>
 
                                       83
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
IN-PROCESS TECHNOLOGY
 
  Cadence's acquisition of Ambit was accounted for as a purchase, allocating
the purchase price based upon the estimated fair value of the assets acquired
and the liabilities assumed. In connection with the acquisition, net
intangibles of $250.9 million were acquired. Cadence's management estimates
that $214.4 million of the purchased intangibles was purchased in-process
technology that had not yet reached technological feasibility and has no
alternative future use. This amount was expensed in the period ended October 3,
1998, but has been excluded from the historical financial information included
in the pro forma condensed combined statement of operations for that period
included herein as it is a non-recurring expense. The value assigned to
purchased in-process technology, based on a valuation prepared by a third-party
appraisal company, was determined by identifying research projects in areas for
which technological feasibility has not been established. The remaining
intangible assets of $36.5 million were assigned to purchased software and
intangibles, net and will be amortized on a straight-line basis over their
estimated useful lives of seven years. Cadence management believes that the
unamortized balance is recoverable through future operating results. If these
projects are not successfully developed, the business, operating results, and
financial condition of Cadence may be adversely affected. Additionally, the
value of the other intangible assets acquired may become impaired.
 
                                       84
UNAUDITED PRO FORMA
FINANCIAL CONDENSED
COMBINED INFORMATION
<PAGE>
 
                             INDEX OF DEFINED TERMS
 
<TABLE>
<CAPTION>
                                                                        PAGE NO.
                                                                        --------
<S>                                                                     <C>
Ambit..................................................................    14
Arthur Andersen........................................................    46
Cadence................................................................    28
Cadence Acquiring Person...............................................    67
Cadence Board..........................................................    30
Cadence By-Laws........................................................    66
Cadence Certificate....................................................    66
Cadence Distribution Date..............................................    67
Cadence Common Stock...................................................    30
Cadence Preferred Stock................................................    66
Cadence Right Certificates.............................................    67
Cadence Rights Agent...................................................    30
Cadence Rights Agreement...............................................    30
Cadence Series A Preferred Shares......................................    66
Cadence Stockholder Rights.............................................    30
Cadence Stockholders...................................................    69
Cancellation Amount....................................................    57
CCT....................................................................    12
Chancery Court.........................................................    31
Chancery Court Decision................................................    31
Closing Date...........................................................    42
Closing Opinions.......................................................    49
Code...................................................................    47
Commission.............................................................    74
Company Acquisition....................................................    57
Comparable M&A Transactions............................................    38
DBR....................................................................    32
Delaware District Court................................................    31
Delaware Law...........................................................    24
Delaware Supreme Court.................................................    31
DOJ....................................................................    48
DRP....................................................................    72
EBIT...................................................................    37
EDA....................................................................    19
Effective Time.........................................................    30
Employees..............................................................    54
Employment Agreements..................................................    33
Employment Period......................................................    54
EPS....................................................................    38
Exchange Agent.........................................................    41
Exchange Fund..........................................................    41
Exchange Ratio.........................................................    30
Exercise Date..........................................................    58
Exercise Notice........................................................    57
Expiration Date........................................................    57
Final Date.............................................................    51
Final Expiration Date..................................................    67
Flip-In................................................................    71
</TABLE>
<TABLE>
<CAPTION>
                                                                        PAGE NO.
                                                                        --------
<S>                                                                     <C>
Flip-Over..............................................................    72
FPGAs..................................................................    25
FTC....................................................................    48
GDC....................................................................    32
Goldman Sachs..........................................................    32
Hambrecht & Quist......................................................    30
HLDS...................................................................    12
Holder.................................................................    56
HSR Act................................................................    48
IBM....................................................................    26
ICs....................................................................     4
IRS....................................................................    49
LTM....................................................................    38
Mentor.................................................................    17
Mentor Delaware Complaint..............................................    31
Mentor Federal Complaint...............................................    31
Mentor Offer...........................................................    30
Merger.................................................................    28
Merger Agreement.......................................................    28
Merger Sub.............................................................    28
Merger Sub Common Stock................................................    30
MGZ....................................................................    30
NASD...................................................................    28
Nasdaq.................................................................    63
Notice of Superior Proposal............................................    45
Notional Total Payment.................................................    58
NYSE...................................................................    44
Option.................................................................    56
Option Agreement.......................................................    30
Option Price...........................................................    56
Option Shares..........................................................    56
Permitted Offer........................................................    71
Permitted Offering.....................................................    59
PricewaterhouseCoopers.................................................    32
Purchase Period........................................................    58
Purchase Price.........................................................    67
Quickturn..............................................................    28
Quickturn 14D-9........................................................    31
Quickturn Acquiring Person.............................................    71
Quickturn Benefit Plans................................................    54
Quickturn Board........................................................    28
Quickturn By-Laws......................................................    28
Quickturn Call.........................................................    58
Quickturn Call Price...................................................    58
Quickturn Certificate..................................................    29
Quickturn Common Stock.................................................    28
Quickturn Record Date..................................................    29
Quickturn Rights Agreement.............................................    71
</TABLE>
 
                                      G-1
INDEX OF DEFINED TERMS
<PAGE>
 
                      INDEX OF DEFINED TERMS--(CONTINUED)
 
<TABLE>
<CAPTION>
                                                                        PAGE NO.
                                                                        --------
<S>                                                                     <C>
Quickturn Special Meeting..............................................    28
Quickturn Stock Plans..................................................    40
Quickturn Stockholder Right............................................    71
Quickturn Stockholders.................................................    28
Registrable Securities.................................................    59
Registration Expenses..................................................    59
Registration Period....................................................    59
Registration Statement.................................................    74
Reorganization.........................................................    49
Requisite Regulatory Approvals.........................................    46
Rights Record Date.....................................................    67
Rights Redemption Price................................................    69
Securities Act.........................................................    46
Shapiro I Complaint....................................................    32
Shapiro II Complaint...................................................    34
</TABLE>
<TABLE>
<CAPTION>
                                                                        PAGE NO.
                                                                        --------
<S>                                                                     <C>
Share Acquisition......................................................    57
Shares Acquisition Date................................................    71
Solicitation...........................................................    31
Summary of Rights......................................................    67
Superior Proposal......................................................    46
Surviving Corporation..................................................    30
Synopsys...............................................................    65
Tax Opinions...........................................................    49
Tax Representations....................................................    49
Third Party............................................................    46
Third Party Acquisition................................................    45
Total Payment..........................................................    58
Triggering Event.......................................................    57
TtME(TM)...............................................................     4
WSGR...................................................................    32
</TABLE>
 
                                      G-2
INDEX OF DEFINED TERMS
<PAGE>
 
                                                                      APPENDIX A
- --------------------------------------------------------------------------------
 
                          AGREEMENT AND PLAN OF MERGER
                                   AS AMENDED
 
                          DATED AS OF DECEMBER 8, 1998
 
                                     AMONG
 
                         CADENCE DESIGN SYSTEMS, INC.,
 
                        QUICKTURN DESIGN SYSTEMS, INC.,
 
                                      AND
 
                             CDSI ACQUISITION, INC.
 
- --------------------------------------------------------------------------------
<PAGE>
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       ----
<S>                                                                                   <C>
ARTICLE 1 THE MERGER.................................................................   1
  Section 1.1.  The Merger...........................................................   1
  Section 1.2.  Effective Time.......................................................   1
  Section 1.3.  Closing of the Merger................................................   2
  Section 1.4.  Effects of the Merger................................................   2
  Section 1.5.  Certificate of Incorporation and Bylaws..............................   2
  Section 1.6.  Directors............................................................   2
  Section 1.7.  Officers.............................................................   2
  Section 1.8.  Conversion of Shares.................................................   2
  Section 1.9.  Dissent and Appraisal Rights.........................................   2
  Section 1.10. Exchange of Certificates.............................................   3
  Section 1.11. Stock Options........................................................   4

ARTICLE 2 REPRESENTATIONS AND WARRANTIES OF THE COMPANY..............................   5
  Section 2.1.  Organization and Qualification; Subsidiaries; Investments............   5
  Section 2.2.  Capitalization of the Company and its Subsidiaries...................   6
  Section 2.3.  Authority Relative to this Agreement; Recommendation.................   7
  Section 2.4.  SEC Reports; Financial Statements....................................   7
  Section 2.5.  Information Supplied.................................................   7
  Section 2.6.  Consents and Approvals; No Violations................................   8
  Section 2.7.  No Default...........................................................   8
  Section 2.8.  No Undisclosed Liabilities; Absence of Changes.......................   8
  Section 2.9.  Litigation...........................................................   9
  Section 2.10. Compliance with Applicable Law.......................................  10
  Section 2.11. Employee Benefit Plans; Labor Matters................................  10
  Section 2.12. Environmental Laws and Regulations...................................  11
  Section 2.13. Taxes................................................................  11
  Section 2.14. Intellectual Property................................................  12
  Section 2.15. Insurance............................................................  16
  Section 2.16. Certain Business Practices...........................................  16
  Section 2.17. Product Warranties...................................................  16
  Section 2.18. Suppliers and Customers..............................................  16
  Section 2.19. Vote Required........................................................  16
  Section 2.20. Tax Treatment; Pooling...............................................  16
  Section 2.21. Affiliates...........................................................  17
  Section 2.22. Opinion of Financial Adviser.........................................  17
  Section 2.23. Brokers..............................................................  17
  Section 2.24. Company Rights Agreement.............................................  17

ARTICLE 3 REPRESENTATIONS AND WARRANTIES OF PARENT AND ACQUISITION...................  17
  Section 3.1.  Organization.........................................................  17
  Section 3.2.  Capitalization of Parent and its Subsidiaries........................  18
  Section 3.3.  Authority Relative to this Agreement.................................  18
  Section 3.4.  SEC Reports; Financial Statements....................................  19
  Section 3.5.  Information Supplied.................................................  19
  Section 3.6.  Consents and Approvals; No Violations................................  19
  Section 3.7.  No Default...........................................................  20
  Section 3.8.  No Undisclosed Liabilities; Absence of Changes.......................  20
</TABLE>
 
                                       i
<PAGE>
 
<TABLE>
<S>                                                                          <C>
  Section 3.9.  Litigation..................................................  20
  Section 3.10. Compliance with Applicable Law..............................  20
  Section 3.11. Tax Treatment; Pooling......................................  20
  Section 3.12. Opinion of Financial Adviser................................  21
  Section 3.13. Brokers.....................................................  21
  Section 3.14. No Prior Activities.........................................  21
  Section 3.15 Environmental Laws and Regulations...........................  21
ARTICLE 4 COVENANTS.........................................................  21
  Section 4.1.  Conduct of Business of the Company..........................  21
  Section 4.2.  Conduct of Business of Parent...............................  23
  Section 4.3.  Preparation of S-4 and the Proxy Statement..................  23
  Section 4.4.  Other Potential Acquirers...................................  24
  Section 4.5.  Comfort Letters.............................................  25
  Section 4.6.  Meeting of Stockholders.....................................  25
  Section 4.7.  Stock Exchange Listing......................................  25
  Section 4.8.  Access to Information.......................................  25
  Section 4.9.  Certain Filings; Reasonable Efforts.........................  26
  Section 4.10. Public Announcements........................................  27
  Section 4.11. Indemnification and Directors' and Officers' Insurance......  27
  Section 4.12. Notification of Certain Matters.............................  28
  Section 4.13. Affiliates; Pooling; Tax-Free Reorganization................  28
  Section 4.14. Additions to and Modification of Company Disclosure
   Schedule.................................................................  28
  Section 4.15. Company Rights Agreement....................................  29
ARTICLE 5 CONDITIONS TO CONSUMMATION OF THE MERGER..........................  29
  Section 5.1.  Conditions to Each Party's Obligations to Effect the
   Merger...................................................................  29
  Section 5.2.  Conditions to the Obligations of the Company................  29
  Section 5.3.  Conditions to the Obligations of Parent and Acquisition.....  30
ARTICLE 6 TERMINATION; AMENDMENT; WAIVER....................................  31
  Section 6.1.  Termination.................................................  31
  Section 6.2.  Effect of Termination.......................................  32
  Section 6.3.  Fees and Expenses...........................................  32
  Section 6.4.  Amendment...................................................  33
  Section 6.5.  Extension; Waiver...........................................  33
ARTICLE 7 MISCELLANEOUS.....................................................  33
  Section 7.1.  Nonsurvival of Representations and Warranties...............  33
  Section 7.2.  Entire Agreement; Assignment................................  33
  Section 7.3.  Validity....................................................  33
  Section 7.4.  Notices.....................................................  33
  Section 7.5.  Governing Law...............................................  34
  Section 7.6.  Descriptive Headings........................................  34
  Section 7.7.  Parties in Interest.........................................  34
  Section 7.8.  Certain Definitions.........................................  34
  Section 7.9.  Personal Liability..........................................  35
  Section 7.10. Specific Performance........................................  35
  Section 7.11. Counterparts................................................  35
</TABLE>
 
                                       ii
<PAGE>
 
                               TABLE OF EXHIBITS
 
<TABLE>
 <C>                             <S>
 Exhibit A-1.................... Form of Letter Agreement with Company
                                  Affiliates
 Exhibit A-2.................... Form of Letter Agreement with Parent
                                  Affiliates
 Exhibit B-1.................... Form of Representations related to Tax
                                  Matters of the Company
 Exhibit B-2.................... Form of Representations Related to Tax
                                  Matters of Parent and Acquisition
 Exhibit C ..................... Matters to be Covered by Opinion of Legal
                                  Counsel to the Company
 Exhibit D...................... Matters to be Covered by Opinion of Legal
                                  Counsel to Parent and Acquisition
 Exhibit E...................... Form of Certificate of Merger
</TABLE>
 
                               TABLE OF CONTENTS
                                       TO
                          COMPANY DISCLOSURE SCHEDULE
 
<TABLE>
<S>                               <C>
Section 2.1(a)................... Subsidiaries
Section 2.1(c)................... Equity Investments
Section 2.6...................... Consents and Approval
Section 2.7...................... Defaults
Section 2.8...................... Undisclosed Liabilities; Absence of Changes
Section 2.9...................... Litigation
Section 2.11(a).................. Employee Plans
Section 2.11(b).................. Employment and Related Agreements
Section 2.11(c).................. Employee Benefits Affected by this Transaction
Section 2.11(d).................. Employee Benefits to Former Employees
Section 2.11(e).................. Employee Matters
Section 2.13(b).................. Delinquent or Inaccurate Tax Returns
Section 2.13(c).................. All Taxes Paid
Section 2.13(d).................. Tax Claims
Section 2.13(e).................. Excess Parachute Payments
Section 2.14(a).................. Intellectual Property
Section 2.14(e)(1)............... Inbound License Agreements
Section 2.14(e)(2)............... Outbound License Agreements
Section 2.14(i).................. Pending or Threatened Infringement Claims
Section 2.14(j).................. Infringement Matters
Section 2.14(k).................. Existing Software Products
Section 2.14(l).................. Non Company Intellectual Property Rights
Section 2.14(m).................. Existing and Currently Manufactured Software
Section 2.14(o).................. Year 2000 Compliance
Section 2.17..................... Product Warranties
Section 2.18..................... Suppliers and Customers
Section 2.21..................... Affiliates
Section 4.1...................... Conduct of Business
Section 5.3(i)................... Third Party Consents
</TABLE>
 
                                      iii
<PAGE>
 
                             TABLE OF DEFINED TERMS
 
<TABLE>
<CAPTION>
                                                    CROSS REFERENCE
TERM                                                 IN AGREEMENT          PAGE
- ----                                                ---------------        ----
<S>                                          <C>                           <C>
Acquisition................................. Preamble....................    1
affiliate................................... Section 7.8(a)..............   46
Agreement................................... Preamble....................    1
business day................................ Section 7.8(b)..............   46
Business System............................. Section 2.14(o)(i)..........   21
capital stock............................... Section 7.8(c)..............   47
Certificate of Merger....................... Section 1.2.................    2
Certificates................................ Section 1.10(b).............    4
Closing Date................................ Section 1.3.................    2
Closing..................................... Section 1.3.................    2
Code........................................ Preamble....................    1
Company..................................... Preamble....................    1
Company Acquisition......................... Section 7.8(d)..............   47
Company Affiliates.......................... Section 2.21................   22
Company Board............................... Section 2.3(a)..............    9
Company Financial Adviser................... Section 2.22................   22
Company Permits............................. Section 2.10................   13
Company Plans............................... Section 1.11(a).............    6
Company Rights Agreement.................... Section 2.2(a)..............    8
Company Rights.............................. Section 2.2(a)..............    8
Company SEC Reports......................... Section 2.4(a)..............   10
Company Securities.......................... Section 2.2(a)..............    8
Company Stock Option or Options............. Section 1.11(a).............    5
DGCL........................................ Section 1.1.................    1
Effective Time.............................. Section 1.2.................    2
Employee Plans.............................. Section 2.11(a).............   14
Environmental Claim......................... Section 2.12(a).............   15
Environmental Laws.......................... Section 2.12(a).............   15
ERISA Affiliate............................. Section 2.11(a).............   14
ERISA....................................... Section 2.11(a).............   14
Exchange Act................................ Section 2.2(c)..............    9
Exchange Agent.............................. Section 1.10(a).............    3
Exchange Fund............................... Section 1.10(a).............    3
Exchange Ratio.............................. Section 1.8(b)..............    3
Governmental Entity......................... Section 2.6.................   11
HSR Act..................................... Section 2.6.................   11
include..................................... Section 7.8(e)..............   47
Indemnified Liabilities..................... Section 4.11................   37
Indemnified Persons......................... Section 4.11................   36
Insurance Policies.......................... Section 2.15................   21
IRS......................................... Section 2.11(a).............   14
ISOs........................................ Section 1.11(a).............    6
knowledge or known.......................... Section 7.8(d)..............   47
Lien........................................ Section 2.2(b)..............    9
Material Adverse Effect on Parent........... Section 3.1(b)..............   23
Material Adverse Effect on the Company...... Section 2.1(b)..............    7
</TABLE>
 
                                       iv
<PAGE>
 
<TABLE>
<CAPTION>
                                                     CROSS REFERENCE
TERM                                                  IN AGREEMENT          PAGE
- ----                                                 ---------------        ----
<S>                                           <C>                           <C>
Merger Consideration......................... Section 1.8(a)..............    3
Merger....................................... Section 1.1.................    1
Notice of Superior Proposal.................. Section 4.4(b)..............   33
Other Interests.............................. Section 2.1(b)..............    8
Parent....................................... Preamble....................    1
Parent Common Stock.......................... Section 1.8(a)..............    3
Parent Financial Adviser..................... Section 3.12................   28
Parent Permits............................... Section 3.10................   27
Parent Rights................................ Section 3.2(a)..............   24
Parent SEC Reports........................... Section 3.4(a)..............   25
Parent Securities............................ Section 3.2(a)..............   24
person....................................... Section 7.8(f)..............   47
Pooling Transaction.......................... Section 2.20................   22
Proxy Statement.............................. Section 2.5.................   10
S-4.......................................... Section 2.5.................   10
SEC.......................................... Section 2.4(a)..............   10
Securities Act............................... Section 2.4(a)..............   10
Share........................................ Section 1.8(a)..............    2
Shares....................................... Section 1.8(a)..............    2
Stock Option Agreement....................... Section 5.2(a)..............   40
subsidiary or subsidiaries................... Section 7.8(g)..............   47
Superior Proposal............................ Section 4.4(c)..............   33
Surviving Corporation........................ Section 1.1.................    1
Tax or Taxes................................. Section 2.13(a)(i)..........   16
Tax Return................................... Section 2.13(a)(ii).........   16
Third Party Acquisition...................... Section 4.4(c)..............   33
Third Party.................................. Section 4.4(c)..............   33
Year 2000 Compliant.......................... Section 2.14(o)(i)..........   21
</TABLE>
 
 
                                       v
<PAGE>
 
                          AGREEMENT AND PLAN OF MERGER
 
  THIS AGREEMENT AND PLAN OF MERGER (this "Agreement") dated as of December 8,
1998, is by and among Quickturn Design Systems, Inc., a Delaware corporation
(the "Company"), Cadence Design Systems, Inc., a Delaware corporation
("Parent"), and CDSI ACQUISITION, INC., a Delaware corporation and a wholly
owned subsidiary of Parent ("Acquisition").
 
  WHEREAS, the Boards of Directors of the Company, Parent and Acquisition have
each (i) determined that the Merger (as defined below) is advisable and fair
and in the best interests of their respective stockholders and (ii) approved
the Merger upon the terms and subject to the conditions set forth in this
Agreement;
 
  WHEREAS, for Federal income tax purposes it is intended that the Merger
qualify as a reorganization under the provisions of Section 368(a) of the
Internal Revenue Code of 1986, as amended (the "Code");
 
  WHEREAS, certain officers and employees of the Company have entered into
employment and non-competition agreements, effective upon consummation of the
Merger, as an inducement to Parent to enter into this Agreement; and
 
  WHEREAS, the Merger is intended to be treated as a "pooling of interests" for
financial accounting purposes.
 
  NOW, THEREFORE, in consideration of the foregoing premises and the
representations, warranties, covenants and agreements herein contained, and
intending to be legally bound hereby, the Company, Parent and Acquisition
hereby agree as follows:
 
                                   ARTICLE 1
 
                                   THE MERGER
 
  SECTION 1.1. The Merger. At the Effective Time (as defined below) and upon
the terms and subject to the conditions of this Agreement and in accordance
with the Delaware General Corporation Law (the "DGCL"), Acquisition shall be
merged with and into the Company (the "Merger"). Following the Merger, the
Company shall continue as the surviving corporation (the "Surviving
Corporation") and the separate corporate existence of Acquisition shall cease.
At the election of the parties, the Merger may be structured so that the
Company shall be merged with and into Acquisition with the result that
Acquisition shall become the "Surviving Corporation." The Merger is intended to
qualify as a tax-free reorganization under Section 368(a) of the Code. Parent,
as the sole stockholder of Acquisition, hereby approves the Merger and this
Agreement.
 
  SECTION 1.2. Effective Time. Subject to the terms and conditions set forth in
this Agreement, on the Closing Date (as defined in Section 1.3), a Certificate
of Merger substantially in the form of Exhibit E (the "Certificate of Merger")
shall be duly executed and acknowledged by Acquisition and the Company and
thereafter delivered to the Secretary of State of the State of Delaware for
filing pursuant to Section 251 of the DGCL. The Merger shall become effective
at such time as a properly executed copy of the Certificate of Merger is duly
filed with the Secretary of State of the State of Delaware in accordance with
Section 251 of the DGCL or such later time as Parent and the Company may agree
upon and as set forth in the Certificate of Merger (the time the Merger becomes
effective being referred to herein as the "Effective Time").
 
  SECTION 1.3. Closing of the Merger. The closing of the Merger (the "Closing")
will take place at a time and on a date (the "Closing Date") to be specified by
the parties, which shall be no later than the second business day after
satisfaction of the latest to occur of the conditions set forth in Article 5,
at the offices of Gibson, Dunn & Crutcher LLP, One Montgomery Street, San
Francisco, California 94104, unless another time, date or place is agreed to in
writing by the parties hereto.
 
                                      A-1
<PAGE>
 
  SECTION 1.4. Effects of the Merger. The Merger shall have the effects set
forth in the DGCL. Without limiting the generality of the foregoing and subject
thereto, at the Effective Time, all the properties, rights, privileges, powers
and franchises of the Company and Acquisition shall vest in the Surviving
Corporation and all debts, liabilities and duties of the Company and
Acquisition shall become the debts, liabilities and duties of the Surviving
Corporation.
 
  SECTION 1.5. Certificate of Incorporation and Bylaws. The Certificate of
Incorporation of Acquisition in effect at the Effective Time shall be the
Certificate of Incorporation of the Surviving Corporation until amended in
accordance with applicable law. The bylaws of Acquisition in effect at the
Effective Time shall be the bylaws of the Surviving Corporation until amended
in accordance with applicable law.
 
  SECTION 1.6. Directors. The directors of Acquisition at the Effective Time
shall be the initial directors of the Surviving Corporation, each to hold
office in accordance with the Certificate of Incorporation and bylaws of the
Surviving Corporation until such director's successor is duly elected or
appointed and qualified.
 
  Section 1.7. Officers. The officers of Acquisition at the Effective Time
shall be the initial officers of the Surviving Corporation, each to hold office
in accordance with the Certificate of Incorporation and bylaws of the Surviving
Corporation until such officer's successor is duly elected or appointed and
qualified.
 
  Section 1.8. Conversion of Shares.
 
  (a) At the Effective Time, each share of common stock, $0.001 par value per
share, of the Company (individually a "Share" and collectively the "Shares")
issued and outstanding immediately prior to the Effective Time (other than (i)
Shares held in the Company's treasury or by any of the Company's subsidiaries
and (ii) Shares held by Parent, Acquisition or any other subsidiary of Parent)
shall, by virtue of the Merger and without any action on the part of
Acquisition, the Company or the holder thereof, be converted into and shall
become a number of fully paid and nonassessable shares of common stock, par
value $.01 per share, of Parent ("Parent Common Stock") equal to the Exchange
Ratio (as defined below) (the "Merger Consideration"). Unless the context
otherwise requires, each reference in this Agreement to shares of Parent Common
Stock and to the Shares shall include the associated Parent Rights (as such
term is defined in Section 3.2(a) hereof) and associated Company Rights (as
defined in Section 2.2(a)), respectively. Notwithstanding the foregoing, if,
between the date of this Agreement and the Effective Time, the outstanding
shares of Parent Common Stock or the Shares shall have been changed into a
different number of shares or a different class by reason of any stock
dividend, subdivision, reclassification, recapitalization, split, combination
or exchange of shares then the Exchange Ratio shall be correspondingly adjusted
to reflect such stock dividend, subdivision, reclassification,
recapitalization, split, combination or exchange of shares.
 
  (b) The "Exchange Ratio" shall be (i) $14.00 divided by (ii) the average
closing price of one share of Parent Common Stock (as reported on the NYSE
Composite Transactions reporting system) during the five trading days
immediately preceding the second business day prior to the Closing Date.
 
  (c) At the Effective Time, each outstanding share of the common stock, $0.01
par value per share, of Acquisition shall be converted into one share of common
stock, $0.01 par value per share, of the Surviving Corporation.
 
  (d) At the Effective Time, each Share held in the treasury of the Company and
each Share held by Parent, Acquisition or any subsidiary of Parent, Acquisition
or the Company immediately prior to the Effective Time shall, by virtue of the
Merger and without any action on the part of Acquisition, the Company or the
holder thereof, be canceled, retired and cease to exist and no shares of Parent
Common Stock shall be delivered with respect thereto.
 
  Section 1.9. Dissenters and Appraisal Rights. The holders of the Shares will
not be entitled to dissenters and appraisal rights in accordance with Section
262 of the DGCL.
 
                                      A-2
<PAGE>
 
  Section 1.10. Exchange of Certificates.
 
  (a) From time to time following the Effective Time, as required by
subsections (b) and (c) below, Parent shall deliver to its transfer agent, or a
depository or trust institution of recognized standing selected by Parent and
Acquisition (the "Exchange Agent") for the benefit of the holders of Shares for
exchange in accordance with this Article I: (i) certificates representing the
appropriate number of shares of Parent Common Stock issuable pursuant to
Section 1.8, and (ii) cash to be paid in lieu of fractional shares of Parent
Common Stock (such shares of Parent Common Stock and such cash are hereinafter
referred to as the "Exchange Fund"), in exchange for outstanding Shares.
 
  (b) As soon as reasonably practicable after the Effective Time, the Exchange
Agent shall mail to each holder of record of a certificate or certificates that
immediately prior to the Effective Time represented outstanding Shares (the
"Certificates") and whose shares were converted into the right to receive
shares of Parent Common Stock pursuant to Section 1.8: (i) a letter of
transmittal (which shall specify that delivery shall be effected and risk of
loss and title to the Certificates shall pass only upon delivery of the
Certificates to the Exchange Agent and shall be in such form and have such
other provisions as Parent and the Company may reasonably specify) and (ii)
instructions for use in effecting the surrender of the Certificates in exchange
for certificates representing shares of Parent Common Stock. Upon surrender of
a Certificate for cancellation to the Exchange Agent together with such letter
of transmittal duly executed, the holder of such Certificate shall be entitled
to receive in exchange therefor a certificate representing that number of whole
shares of Parent Common Stock and, if applicable, a check representing the cash
consideration to which such holder may be entitled on account of a fractional
share of Parent Common Stock that such holder has the right to receive pursuant
to the provisions of this Article I and the Certificate so surrendered shall
forthwith be canceled. In the event of a transfer of ownership of Shares that
is not registered in the transfer records of the Company, a certificate
representing the proper number of shares of Parent Common Stock may be issued
to a transferee if the Certificate representing such Shares is presented to the
Exchange Agent accompanied by all documents required to evidence and effect
such transfer and by evidence that any applicable stock transfer taxes have
been paid. Until surrendered as contemplated by this Section 1.10, each
Certificate shall be deemed at any time after the Effective Time to represent
only the right to receive upon such surrender the certificate representing
shares of Parent Common Stock and cash in lieu of any fractional shares of
Parent Common Stock as contemplated by this Section 1.10.
 
  (c) No dividends or other distributions declared or made after the Effective
Time with respect to Parent Common Stock with a record date after the Effective
Time shall be paid to the holder of any unsurrendered Certificate with respect
to the shares of Parent Common Stock represented thereby, and no cash payment
in lieu of fractional shares shall be paid to any such holder pursuant to
Section 1.10(f), until the holder of record of such Certificate shall surrender
such Certificate. Subject to the effect of applicable laws, following surrender
of any such Certificate there shall be paid to the record holder of the
certificates representing whole shares of Parent Common Stock issued in
exchange therefor without interest (i) the amount of any cash payable in lieu
of a fractional share of Parent Common Stock to which such holder is entitled
pursuant to Section 1.10(f) and the amount of dividends or other distributions
with a record date after the Effective Time theretofore paid with respect to
such number of whole shares of Parent Common Stock and (ii) at the appropriate
payment date the amount of dividends or other distributions with a record date
after the Effective Time but prior to surrender and a payment date subsequent
to surrender payable with respect to such whole shares of Parent Common Stock.
 
  (d) In the event that any Certificate for Shares shall have been lost, stolen
or destroyed, the Exchange Agent shall issue in exchange therefor upon the
making of an affidavit of that fact by the holder thereof such shares of Parent
Common Stock and cash in lieu of fractional shares, if any, as may be required
pursuant to this Agreement; provided, however, that Parent or the Exchange
Agent may, in its discretion, require the delivery of a suitable bond or
indemnity.
 
  (e) All shares of Parent Common Stock issued upon the surrender for exchange
of Shares in accordance with the terms hereof (including any cash paid pursuant
to Section 1.10(c) or 1.10(f)) shall be deemed to have
 
                                      A-3
<PAGE>
 
been issued in full satisfaction of all rights pertaining to such Shares;
subject, however, to the Surviving Corporation's obligation to pay any
dividends or make any other distributions with a record date prior to the date
hereof that remain unpaid at the Effective Time, and there shall be no further
registration of transfers on the stock transfer books of the Surviving
Corporation of the Shares that were outstanding immediately prior to the
Effective Time. If, after the Effective Time, Certificates are presented to the
Surviving Corporation for any reason, they shall be canceled and exchanged as
provided in this Article I.
 
  (f) No fractions of a share of Parent Common Stock shall be issued in the
Merger but in lieu thereof each holder of Shares otherwise entitled to a
fraction of a share of Parent Common Stock shall upon surrender of his or her
Certificate or Certificates be entitled to receive an amount of cash (without
interest) determined by multiplying the average closing price for Parent Common
Stock as reported on the NYSE Composite Transactions reporting system for the
five (5) business days prior to the Effective Time by the fractional share
interest to which such holder would otherwise be entitled. The parties
acknowledge that payment of the cash consideration in lieu of issuing
fractional shares was not separately bargained for consideration, but merely
represents a mechanical rounding off for purposes of simplifying the corporate
and accounting complexities that would otherwise be caused by the issuance of
fractional shares.
 
  (g) Any portion of the Exchange Fund that remains undistributed to the
stockholders of the Company upon the expiration of twelve (12) months after the
Effective Time shall be delivered to Parent upon demand and any stockholders of
the Company who have not theretofore complied with this Article I shall
thereafter look only to Parent for payment of their claim for Parent Common
Stock and cash in lieu of fractional shares as the case may be and any
applicable dividends or distributions with respect to Parent Common Stock.
 
  (h) Neither Parent nor the Company shall be liable to any holder of Shares or
Parent Common Stock as the case may be for such shares (or dividends or
distributions with respect thereto) or cash from the Exchange Fund delivered to
a public official pursuant to any applicable abandoned property, escheat or
similar law.
 
  Section 1.11. Stock Options.
 
  (a) At the Effective Time, each outstanding option or warrant to purchase
Shares (a "Company Stock Option" or collectively "Company Stock Options")
issued pursuant to the Company's 1988 Stock Option Plan, 1990 Stock Option
Plan, 1992 Key Executive Stock Option Plan, 1993 Employee Qualified Stock
Purchase Plan, 1996 Supplemental Stock Plan, as amended, 1997 Stock Option
Plan, as amended, 1994 Outside Director Stock Option Plan, Key Executive Stock
Option Plan, SpeedSim, Inc. 1995 Incentive and Nonqualified Stock Option Plan,
or other agreement or arrangement, whether vested or unvested, shall be
converted as of the Effective Time into options or warrants, as applicable, to
purchase shares of Parent Common Stock in accordance with the terms of this
Section 1.11. All plans or agreements described above pursuant to which any
Company Stock Option has been issued or may be issued other than outstanding
warrants are referred to collectively as the "Company Plans." Each Company
Stock Option shall be deemed to constitute an option to acquire, on the same
terms and conditions as were applicable under such Company Stock Option, a
number of shares of Parent Common Stock equal to the number of shares of Parent
Common Stock that the holder of such Company Stock Option would have been
entitled to receive pursuant to the Merger had such holder exercised such
option or warrant in full immediately prior to the Effective Time at a price
per share equal to (x) the aggregate exercise price for the Shares otherwise
purchasable pursuant to such Company Stock Option divided by (y) the product of
(i) the number of Shares otherwise purchasable pursuant to such Company Stock
Option, multiplied by (ii) the Exchange Ratio; provided, however, that in the
case of any option to which Section 421 of the Code applies by reason of its
qualification under Section 422 of the Code ("incentive stock options" or
"ISOs") the option price, the number of shares purchasable pursuant to such
option and the terms and conditions of exercise of such option shall be
determined in order to comply with Section 424(a) of the Code.
 
  (b) As soon as practicable after the Effective Time, Parent shall deliver to
the holders of Company Stock Options appropriate notices setting forth such
holders' rights pursuant to the Company Plan and that the agreements evidencing
the grants of such Options shall continue in effect on the same terms and
conditions
 
                                      A-4
<PAGE>
 
(subject to the adjustments required by this Section 1.11 after giving effect
to the Merger). Parent shall comply with the terms of the Company Plans and
ensure, to the extent required by and subject to the provisions of such Plans,
that Company Stock Options that qualified as incentive stock options prior to
the Effective Time continue to qualify as incentive stock options of Parent
after the Effective Time.
 
  (c) Parent shall take all corporate action necessary to reserve for issuance
a sufficient number of shares of Parent Common Stock for delivery upon exercise
of Company Stock Options assumed in accordance with this Section 1.11. As soon
as practicable after the Effective Time, Parent shall file a registration
statement on Form S-8 (or any successor or other appropriate forms) with
respect to the shares of Parent Common Stock subject to any Company Stock
Options held by persons who are directors, officers or employees of the Company
or its subsidiaries and shall use all reasonable efforts to maintain the
effectiveness of such registration statement or registration statements (and
maintain the current status of the prospectus or prospectuses contained
therein) for so long as such options remain outstanding.
 
  (d) At or before the Effective Time, the Company shall cause to be effected
any necessary amendments to the Company Plans to give effect to the foregoing
provisions of this Section 1.11.
 
                                   ARTICLE 2
 
                 REPRESENTATIONS AND WARRANTIES OF THE COMPANY
 
  The Company hereby represents and warrants to each of Parent and Acquisition,
subject to the exceptions set forth in the Disclosure Schedule (the "Company
Disclosure Schedule") delivered by the Company to Parent in accordance with
Section 4.15 (which exceptions shall specifically identify a Section,
Subsection or clause of a single Section or Subsection hereof, as applicable,
to which such exception relates) that:
 
  Section 2.1. Organization and Qualification; Subsidiaries; Investments.
 
  (a) Section 2.1(a) of the Company Disclosure Schedule sets forth, as of the
date of this Agreement, a true and complete list of all the Company's directly
or indirectly owned subsidiaries, together with the jurisdiction of
incorporation of each subsidiary and the percentage of each subsidiary's
outstanding capital stock or other equity interests owned by the Company or
another subsidiary of the Company. Each of the Company and its subsidiaries is
duly organized, validly existing and in good standing under the laws of the
jurisdiction of its incorporation or organization and has all requisite power
and authority to own, lease and operate its properties and to carry on its
businesses as now being conducted. The Company has heretofore delivered to
Acquisition or Parent accurate and complete copies of the Certificate of
Incorporation and bylaws (or similar governing documents), as currently in full
force and effect, of the Company and its subsidiaries. Section 2.1(a) of the
Company Disclosure Schedule identifies all the material subsidiaries of the
Company. The Company has no operating subsidiaries other than those
incorporated in a state of the United States.
 
  (b) Each of the Company and its subsidiaries is duly qualified or licensed
and in good standing to do business in each jurisdiction in which the property
owned, leased or operated by it or the nature of the business conducted by it
makes such qualification or licensing necessary, except in such jurisdictions
where the failure to be so duly qualified or licensed and in good standing
would not, individually or in the aggregate, have a Material Adverse Effect (as
defined below) on the Company. When used in connection with the Company or its
subsidiaries, the term "Material Adverse Effect on the Company" means any
circumstance, change in, or effect on (or circumstance, change in, or effect
involving a prospective change on) the Company and its subsidiaries, taken as a
whole, (a) that is, or is reasonably likely in the future to be, materially
adverse to the operations, assets or liabilities (including contingent
liabilities), earnings or results of operations, or the business (financial or
otherwise) of the Company and its subsidiaries, taken as a whole, excluding
from the foregoing the effect, if any, of (i) changes in general economic
conditions or changes affecting the industry in which the Company operates,
(ii) stockholder class action litigation arising from allegations of a breach
of fiduciary duty relating to this Agreement, (iii) of the public announcement
or pendency of the transactions contemplated hereby on
 
                                      A-5
<PAGE>
 
current or prospective customers or revenues of the Company (provided that such
effect is direct and that the Company shall have the burden of proving such
direct effect), or (iv) any action or inaction required of the Company by
Parent under Section 4.1, or (b) that would reasonably be expected to prevent
or materially delay or impair the ability of the Company to consummate the
transactions contemplated by this Agreement.
 
  (c) Section 2.1(c) of the Company Disclosure Schedule sets forth a true and
complete list of each equity investment in an amount of One Hundred Thousand
Dollars ($100,000) or more or that represents a five percent (5%) or greater
ownership interest in the subject of such investment made by the Company or any
of its subsidiaries in any other person other than the Company's subsidiaries
("Other Interests"). The Other Interests are owned by the Company, by one or
more of the Company's subsidiaries or by the Company and one or more of its
subsidiaries, in each case free and clear of all Lien (as defined below),
except for Liens that may be created by any partnership or joint venture
agreements for Other Interests.
 
  Section 2.2. Capitalization of the Company and its Subsidiaries.
 
  (a) The authorized capital stock of the Company consists of Forty Million
(40,000,000) Shares, of which, as of November 30, 1998, 18,095,580 Shares were
issued and outstanding and Two Million (2,000,000) shares of preferred stock,
$0.001 par value per share, no shares of which are outstanding. All of the
outstanding Shares have been validly issued and are fully paid, nonassessable
and free of preemptive rights. As of November 30, 1998, approximately 4,396,556
Shares were reserved for issuance and, as of December 5, 1998, 3,597,768 were
issuable upon or otherwise deliverable in connection with the exercise of
outstanding Company Stock Options issued pursuant to the Company Plans. Between
December 5, 1998 and the date hereof, no shares of the Company's capital stock
have been issued other than pursuant to Company Stock Options already in
existence on such date, and between December 5, 1998 and the date hereof no
stock options have been granted. Except as set forth above and for the rights
(the "Company Rights") issued pursuant to the Company's Preferred Shares Rights
Agreement, dated as of January 10, 1996, as amended between the Company and
BankBoston, N.A. (the "Company Rights Agreement"), as of the date hereof, there
are outstanding (i) no shares of capital stock or other voting securities of
the Company, (ii) no securities of the Company or any of its subsidiaries
convertible into or exchangeable or exercisable for shares of capital stock or
voting securities of the Company, (iii) no options or other rights to acquire
from the Company or any of its subsidiaries, and, except as described in the
Company SEC Reports (as defined below), no obligations of the Company or any of
its subsidiaries to issue any capital stock, voting securities or securities
convertible into or exchangeable or exercisable for capital stock or voting
securities of the Company and (iv) no equity equivalent interests in the
ownership or earnings of the Company or its subsidiaries or other similar
rights (collectively "Company Securities"). As of the date hereof, there are no
outstanding rights or obligations of the Company or any of its subsidiaries to
repurchase, redeem or otherwise acquire any Company Securities. There are no
stockholder agreements, voting trusts or other agreements or understandings to
which the Company is a party or by which it is bound relating to the voting or
registration of any shares of capital stock of the Company.
 
  (b) All of the outstanding capital stock of the Company's subsidiaries is
owned by the Company, directly or indirectly, free and clear of any Lien or any
other limitation or restriction (including any restriction on the right to vote
or sell the same except as may be provided as a matter of law). There are no
(i) securities of the Company or any of its subsidiaries convertible into or
exchangeable or exercisable for, (ii) options or (iii) except for the Company
Rights, other rights to acquire from the Company or any of its subsidiaries any
capital stock or other ownership interests in or any other securities of any
subsidiary of the Company, and there exists no other contract, understanding,
arrangement or obligation (whether or not contingent) providing for the
issuance or sale, directly or indirectly, of any such capital stock. There are
no outstanding contractual obligations of the Company or its subsidiaries to
repurchase, redeem or otherwise acquire any outstanding shares of capital stock
or other ownership interests in any subsidiary of the Company. For purposes of
this Agreement, "Lien" means, with respect to any asset (including any
security), any mortgage, lien, pledge, charge, security interest or encumbrance
of any kind in respect of such asset; provided, however, that the term "Lien"
shall not include (i) statutory liens for Taxes, which are not yet due and
payable or are being contested in good faith by appropriate proceedings and
disclosed in Section 2.13(d) of the Company Disclosure Schedule
 
                                      A-6
<PAGE>
 
or that are otherwise not material, (ii) statutory or common law liens to
secure landlords, lessors or renters under leases or rental agreements confined
to the premises rented, (iii) deposits or pledges made in connection with, or
to secure payment of, workers' compensation, unemployment insurance, old age
pension or other social security programs mandated under applicable laws, (iv)
statutory or common law liens in favor of carriers, warehousemen, mechanics and
materialmen, to secure claims for labor, materials or supplies and other like
liens, and (v) restrictions on transfer of securities imposed by applicable
state and federal securities laws.
 
  (c) The Company Rights and the Shares constitute the only class of equity
securities of the Company or its subsidiaries registered or required to be
registered under the Securities Exchange Act of 1934, as amended (the "Exchange
Act").
 
  Section 2.3. Authority Relative to this Agreement; Recommendation.
 
  (a) The Company has all necessary corporate power and authority to execute
and deliver this Agreement, to perform its obligations under this Agreement and
to consummate the transactions contemplated hereby. The execution and delivery
of this Agreement and the consummation of the transactions contemplated hereby
have been duly and validly authorized by the Board of Directors of the Company
(the "Company Board"), and no other corporate proceedings on the part of the
Company are necessary to authorize this Agreement or to consummate the
transactions contemplated hereby except the approval and adoption of this
Agreement by the holders of a majority of the outstanding Shares. This
Agreement has been duly and validly executed and delivered by the Company and
constitutes, assuming the due authorization, execution and delivery hereof by
Parent and Acquisition, a valid, legal and binding agreement of the Company,
enforceable against the Company in accordance with its terms, subject to any
applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
now or hereafter in effect relating to creditors' rights generally or to
general principles of equity.
 
  (b) The Company Board has unanimously resolved to recommend that the
stockholders of the Company approve and adopt this Agreement.
 
  Section 2.4. SEC Reports; Financial Statements.
 
  (a) The Company has filed all required forms, reports and documents ("Company
SEC Reports") with the Securities and Exchange Commission (the "SEC") since
January 1, 1997, each of which complied at the time of filing in all material
respects with all applicable requirements of the Securities Act of 1933, as
amended (the "Securities Act"), and the Exchange Act, each law as in effect on
the dates such forms, reports and documents were filed. None of such Company
SEC Reports, including, any financial statements or schedules included or
incorporated by reference therein, contained when filed any untrue statement of
a material fact or omitted to state a material fact required to be stated or
incorporated by reference therein or necessary in order to make the statements
therein in light of the circumstances under which they were made not
misleading, except to the extent superseded by a Company SEC Report filed
subsequently and prior to the date hereof. The audited consolidated financial
statements of the Company included in the Company SEC Reports fairly present,
in conformity in all material respects with generally accepted accounting
principles applied on a consistent basis (except as may be indicated in the
notes thereto), the consolidated financial position of the Company and its
consolidated subsidiaries as of the dates thereof and their consolidated
results of operations and changes in financial position for the periods then
ended.
 
  (b) The Company has heretofore made available or promptly will make available
to Acquisition or Parent a complete and correct copy of any amendments or
modifications that are required to be filed with the SEC but have not yet been
filed with the SEC to agreements, documents or other instruments that
previously had been filed by the Company with the SEC pursuant to the Exchange
Act.
 
  Section 2.5. Information Supplied. None of the information supplied or to be
supplied by the Company for inclusion or incorporation by reference in (i) the
registration statement on Form S-4 to be filed with the SEC by Parent in
connection with the issuance of shares of Parent Common Stock in the Merger
(the "S-4") will, at the time it becomes effective under the Securities Act,
contain any untrue statement of a material fact or
 
                                      A-7
<PAGE>
 
omit to state any material fact required to be stated therein or necessary to
make the statements therein not misleading or (ii) the proxy statement relating
to the meeting of the Company's stockholders to be held in connection with the
Merger (the "Proxy Statement") will, at the date mailed to stockholders of the
Company and at the time of the meeting of stockholders of the Company to be
held in connection with the Merger, contain any untrue statement of a material
fact or omit to state any material fact required to be stated therein or
necessary in order to make the statements therein in light of the circumstances
under which they are made not misleading. The Proxy Statement insofar as it
relates to the meeting of the Company's stockholders to vote on the Merger will
comply as to form in all material respects with the provisions of the Exchange
Act and the rules and regulations thereunder. Notwithstanding the foregoing,
the Company makes no representation, warranty or covenant with respect to any
information supplied or required to be supplied by Parent or Acquisition which
is contained in or omitted from any of the foregoing documents.
 
  Section 2.6. Consents and Approvals; No Violations. Except for filings,
permits, authorizations, consents and approvals as may be required under
applicable requirements of the Securities Act, the Exchange Act, state
securities or blue sky laws, and the Hart-Scott-Rodino Antitrust Improvements
Act of 1976, as amended (the "HSR Act"), any filings under similar merger
notification laws or regulations of foreign Governmental Entities and the
filing and recordation of the Certificate of Merger as required by the DGCL, no
filing with or notice to and no permit, authorization, consent or approval of
any United States or foreign court or tribunal, or administrative, governmental
or regulatory body, agency or authority (a "Governmental Entity") is necessary
for the execution and delivery by the Company of this Agreement or the
consummation by the Company of the transactions contemplated hereby, except
where the failure to obtain such permits, authorizations, consents or approvals
or to make such filings or give such notice would not, individually or in the
aggregate, materially and adversely affect the business operations of the
Company after the Merger or its ability to consummate the Merger. Neither the
execution, delivery and performance of this Agreement by the Company nor the
consummation by the Company of the transactions contemplated hereby will (i)
conflict with or result in any breach of any provision of the respective
Certificate of Incorporation or bylaws (or similar governing documents) of the
Company or any of its subsidiaries, (ii) except as set forth in Section 2.6 of
the Company Disclosure Schedule, result in a violation or breach of or
constitute (with or without due notice or lapse of time or both) a default (or
give rise to any right of termination, amendment, cancellation or acceleration
or Lien) under any of the terms, conditions or provisions of any note, bond,
mortgage, indenture, lease, license, contract, agreement or other instrument or
obligation to which the Company or any of its subsidiaries is a party or by
which any of them or any of their respective properties or assets may be bound
or (iii) except as set forth in Section 2.6 of the Company Disclosure Schedule,
violate any order, writ, injunction, decree, law, statute, rule or regulation
applicable to the Company or any of its subsidiaries or any of their respective
properties or assets except, in the case of clause (ii) or (iii), for
violations, breaches or defaults that would not, individually or in the
aggregate, have a Material Adverse Effect on the Company.
 
  Section 2.7. No Default. Except as set forth in Section 2.7 of the Company
Disclosure Schedule, neither the Company nor any of its subsidiaries is in
breach, default or violation (and no event has occurred that with notice or the
lapse of time or both would constitute a breach, default or violation) of any
term, condition or provision of (i) its Certificate of Incorporation or bylaws
(or similar governing documents), (ii) any note, bond, mortgage, indenture,
lease, license, contract, agreement or other instrument or obligation to which
the Company or any of its subsidiaries is now a party or by which it or any of
its properties or assets may be bound or (iii) any order, writ, injunction,
decree, law, statute, rule or regulation applicable to the Company or any of
its subsidiaries or any of its properties or assets, except, in the case of
clause (ii) or (iii), for violations, breaches or defaults that would not,
individually or in the aggregate, have a Material Adverse Effect on the
Company.
 
  Section 2.8. No Undisclosed Liabilities; Absence of Changes. Except as and to
the extent publicly disclosed by the Company in the Company SEC Reports or as
set forth in Section 2.8 of the Company Disclosure Schedule, neither the
Company nor any of its subsidiaries has any liabilities or obligations of any
nature, whether or not accrued, contingent or otherwise, that would be required
by generally accepted
 
                                      A-8
<PAGE>
 
accounting principles to be reflected on a consolidated balance sheet of the
Company (including the notes thereto), other than liabilities and obligations
which, individually or in the aggregate, will not have a Material Adverse
Effect on the Company. Except as publicly disclosed by the Company in the
Company SEC Reports or as set forth in Section 2.8 of the Company Disclosure
Schedule, since September 30, 1998, there have been no events, changes or
effects with respect to the Company or its subsidiaries that have had or
reasonably would be expected to have a Material Adverse Effect on the Company.
Without limiting the generality of the foregoing, except as and to the extent
publicly disclosed by the Company in the Company SEC Reports or as set forth in
Section 2.8 of the Company Disclosure Schedule, since September 30, 1998, the
Company and its subsidiaries have conducted their respective businesses in all
material respects only in, and have not engaged in any material transaction
other than according to, the ordinary and usual course of such businesses
consistent with past practices, and there has not been any (i) change in the
financial condition, properties, business or results of operations of the
Company and its subsidiaries, except for those changes that, individually or in
the aggregate, have not had and are not reasonably likely to have a Material
Adverse Effect on the Company; (ii) material damage, destruction or other
casualty loss with respect to any material asset or property owned, leased or
otherwise used by the Company or any of its subsidiaries, not covered by
insurance; (iii) declaration, setting aside or payment of any dividend or other
distribution in respect of the capital stock of the Company or any of its
subsidiaries (other than wholly-owned subsidiaries) or any repurchase,
redemption or other acquisition by the Company or any of its subsidiaries of
any outstanding shares of capital stock or other securities of, or other
ownership interests in, the Company or any of its subsidiaries; (iv) amendment
of any material term of any outstanding security of the Company or any of its
subsidiaries; (v) incurrence, assumption or guarantee by the Company or any of
its subsidiaries of any indebtedness for borrowed money other than in the
ordinary course of business and in amounts and on terms consistent with past
practices; (vi) creation or assumption by the Company or any of its
subsidiaries of any Lien on any material asset other than in the ordinary
course of business consistent with past practices; (vii) loan, advance or
capital contributions made by the Company or any of its subsidiaries to, or
investment in, any person other than (x) loans or advances to employees in
connection with business-related travel, (y) loans made to employees consistent
with past practices that are not in the aggregate in excess of Fifty Thousand
Dollars ($50,000), and (z) loans, advances or capital contributions to or
investments in wholly-owned subsidiaries, and in each case made in the ordinary
course of business consistent with past practices; (viii) transaction or
commitment made, or any contract or agreement entered into, by the Company or
any of its subsidiaries relating to its assets or business (including the
acquisition or disposition of any assets) or any relinquishment by the Company
or any of its subsidiaries of any contract, agreement or other right, in either
case, material to the Company and its subsidiaries, taken as a whole, other
than transactions and commitments in the ordinary course of business consistent
with past practices and those contemplated by this Agreement; (ix) labor
dispute, other than routine individual grievances, or any activity or
proceeding by a labor union or representative thereof to organize any employees
of the Company or any of its subsidiaries, or any lockouts, strikes, slowdowns,
work stoppages or threats thereof by or with respect to such employees; or (x)
change by the Company or any of its subsidiaries in its accounting principles,
practices or methods. Since September 30, 1998, except as disclosed in the
Company SEC Reports filed prior to the date hereof or increases in the ordinary
course of business consistent with past practices, there has not been any
increase in the compensation payable or that could become payable by the
Company or any of its subsidiaries to (a) officers of the Company or any of its
subsidiaries or (b) any employee of the Company or any of its Subsidiaries
whose annual cash compensation is One Hundred Thousand Dollars ($100,000) or
more.
 
  Section 2.9. Litigation. Except as publicly disclosed by the Company in the
Company SEC Reports or as set forth in Section 2.9 of the Company Disclosure
Schedule, there is no suit, claim, action, proceeding or investigation pending
or, to the knowledge of the Company, threatened against the Company or any of
its subsidiaries or any of their respective properties or assets before any
Governmental Entity that, individually or in the aggregate, would reasonably be
expected to have a Material Adverse Effect on the Company or would reasonably
be expected to prevent or delay the consummation of the transactions
contemplated by this Agreement. Except as publicly disclosed by the Company in
the Company SEC Reports, neither the Company nor any of its subsidiaries is
subject to any outstanding order, writ, injunction or decree that, insofar as
can be reasonably foreseen in the future, would reasonably be expected to have
a Material Adverse Effect on the
 
                                      A-9
<PAGE>
 
Company or could reasonably be expected to prevent or delay the consummation of
the transactions contemplated hereby.
 
  Section 2.10. Compliance with Applicable Law. Except as publicly disclosed by
the Company in the Company SEC Reports, the Company and its subsidiaries hold
all permits, licenses, variances, exemptions, orders and approvals of all
Governmental Entities necessary for the lawful conduct of their respective
businesses (the "Company Permits"), except for failures to hold such permits,
licenses, variances, exemptions, orders and approvals that would not,
individually or in the aggregate, have a Material Adverse Effect on the
Company. Except as publicly disclosed by the Company in the Company SEC
Reports, the Company and its subsidiaries are in compliance with the terms of
the Company Permits, except where the failure so to comply would not,
individually or in the aggregate, have a Material Adverse Effect on the
Company. Except as publicly disclosed by the Company in the Company SEC
Reports, the businesses of the Company and its subsidiaries are not being
conducted in violation of any law, ordinance or regulation of the United States
or any foreign country or any political subdivision thereof or of any
Governmental Entity, except (i) that no representation or warranty is made in
this Section 2.10 with respect to Environmental Laws (as defined in Section
2.12) and (ii) for violations or possible violations of any United States or
foreign laws, ordinances or regulations that do not and, insofar as reasonably
can be foreseen in the future, will not result in any charges, assessments,
levies, fines or other liabilities being imposed upon or incurred by the
Company that will equal or exceed Five Hundred Thousand Dollars ($500,000) for
any single violation or One Million Dollars ($1,000,000) in the aggregate.
Except as publicly disclosed by the Company in the Company SEC Reports, no
investigation or review by any Governmental Entity with respect to the Company
or any of its subsidiaries is pending or, to the knowledge of the Company,
threatened, nor, to the knowledge of the Company, has any Governmental Entity
indicated an intention to conduct the same, other than such investigations or
reviews as would not, individually or in the aggregate, have a Material Adverse
Effect on the Company.
 
  Section 2.11. Employee Benefit Plans; Labor Matters.
 
  (a) Section 2.11(a) of the Company Disclosure Schedule lists as of the date
hereof all employee benefit plans (as defined in Section 3(3) of the Employee
Retirement Income Security Act of 1974, as amended ("ERISA")), and all bonus,
stock option, stock purchase, incentive, deferred compensation, supplemental
retirement, health, life, or disability insurance, dependent care, severance
and other similar fringe or employee benefit plans, programs or arrangements
and any current or former employment or executive compensation or severance
agreements written or otherwise maintained or contributed to for the benefit of
or relating to any employee or former employee of the Company, any trade or
business (whether or not incorporated) that is a member of a controlled group
including the Company or that is under common control with the Company within
the meaning of Section 414 of the Code (an "ERISA Affiliate"), as well as each
plan with respect to which the Company or an ERISA Affiliate could incur
liability under Section 4069 (if such plan has been or were terminated) or
Section 4212(c) of ERISA (together the "Employee Plans"), excluding Employee
Plans under which the Company has no remaining obligations and any of the
foregoing that are required to be maintained by the Company under the laws of
any foreign jurisdiction. The Company has made available to Parent a copy of
(i) the most recent annual report on Form 5500 filed with the Internal Revenue
Service (the "IRS") for each disclosed Employee Plan where such report is
required and (ii) the documents and instruments governing each such Employee
Plan (other than those referred to in Section 4(b)(4) of ERISA). No event has
occurred and, to the knowledge of the Company, there currently exists no
condition or set of circumstances in connection with which the Company or any
of its subsidiaries could be subject to any liability under the terms of any
Employee Plans, ERISA, the Code or any other applicable law, including any
liability under Title IV of ERISA, that would have a Material Adverse Effect on
the Company.
 
  (b) Section 2.11(b) of the Company Disclosure Schedule sets forth a list as
of the date hereof of (i) all employment agreements with officers of the
Company; (ii) all agreements with consultants who are individuals obligating
the Company to make annual cash payments in an amount exceeding Fifty Thousand
Dollars ($50,000); (iii) all severance agreements, programs and policies of the
Company with or relating to its employees except such programs and policies
required to be maintained by law; and (iv) all plans, programs,
 
                                      A-10
<PAGE>
 
agreements and other arrangements of the Company with or relating to its
employees that contain change in control provisions whether or not listed in
other parts of the Company Disclosure Schedule. The Company has made available
to Parent copies (or descriptions in detail reasonably satisfactory to Parent)
of all such agreements, plans, programs and other arrangements.
 
  (c) Except as disclosed in Section 2.11(c) of the Company Disclosure
Schedule, there will be no payment, accrual of additional benefits,
acceleration of payments or vesting of any benefit under any Employee Plan or
any agreement or arrangement disclosed under this Section 2.11 solely by reason
of entering into or in connection with the transactions contemplated by this
Agreement.
 
  (d) No Employee Plan that is a welfare benefit plan within the meaning of
Section 3(1) of ERISA provides benefits to former employees of the Company or
its ERISA Affiliates other than pursuant to Section 4980B of the Code or
similar state laws.
 
  (e) There are no controversies relating to any Employee Plan or other labor
matters pending or, to the knowledge of the Company, threatened between the
Company or any of its subsidiaries and any of their respective employees, which
controversies, individually or in the aggregate, have or would reasonably be
expected to have a Material Adverse Effect of the Company. Neither the Company
nor any of its subsidiaries is a party to any collective bargaining agreement
or other labor union contract applicable to persons employed by the Company or
any of its subsidiaries except as disclosed in Section 2.11(e) of the Company
Disclosure Schedule, nor does the Company know of any activities or proceedings
of any labor union to organize any such employees. The Company has no knowledge
of any strikes, slowdowns, work stoppages, lockouts or threats thereof by or
with respect to any employees of the Company or any of its subsidiaries.
 
  Section 2.12. Environmental Laws and Regulations.
 
  (a) Except as publicly disclosed by the Company in the Company SEC Reports,
(i) each of the Company and its subsidiaries is in material compliance with all
applicable federal, state, local and foreign laws and regulations relating to
pollution or protection of human health or the environment (including ambient
air, surface water, ground water, land surface or subsurface strata)
(collectively "Environmental Laws") except for non-compliances that,
individually or in the aggregate, would not have a Material Adverse Effect on
the Company, which compliance includes, but is not limited to, the possession
by the Company and its subsidiaries of all material permits and other
governmental authorizations required under applicable Environmental Laws and
compliance with the terms and conditions thereof; (ii) neither the Company nor
any of its subsidiaries has received written notice of or, to the knowledge of
the Company, is the subject of any action, cause of action, claim,
investigation, demand or notice by any person alleging liability under or non-
compliance with any Environmental Law (an "Environmental Claim"); and (iii) to
the knowledge of the Company, there are no existing facts that are reasonably
likely to prevent or interfere with such material compliance in the future.
 
  (b) Except as disclosed in the Company SEC Reports, there are no
Environmental Claims that, individually or in the aggregate, would reasonably
be expected to have a Material Adverse Effect on the Company that are pending
or, to the knowledge of the Company, threatened against the Company or any of
its subsidiaries or, to the knowledge of the Company, against any person whose
liability for any Environmental Claim the Company or any of its subsidiaries
has or may have retained or assumed either contractually or by operation of
law.
 
  Section 2.13. Taxes.
 
  (a) Definitions. For purposes of this Agreement:
 
    (i) the term "Tax" (including "Taxes") means (A) all federal, state,
  local, foreign and other net income, gross income, gross receipts, sales,
  use, ad valorem, transfer, franchise, profits, license, lease, service,
  service use, withholding, payroll, employment, excise, severance, stamp,
  occupation, premium, property, windfall profits, customs, duties or other
  taxes, fees, assessments or charges of any kind
 
                                      A-11
<PAGE>
 
  whatsoever, together with any interest and any penalties, additions to tax
  or additional amounts with respect thereto, (B) any liability for payment
  of amounts described in clause (A) whether as a result of transferee
  liability, of being a member of an affiliated, consolidated, combined or
  unitary group for any period, or otherwise through operation of law, and
  (C) any liability for the payment of amounts described in clauses (A) or
  (B) as a result of any tax sharing, tax indemnity or tax allocation
  agreement or any other express or implied agreement to indemnify any other
  person; and
 
    (ii) the term "Tax Return" means any return, declaration, report,
  statement, information statement and other document required to be filed
  with respect to Taxes.
 
  (b) Except as set forth in Section 2.13(b) of the Company Disclosure
Schedule, the Company and its subsidiaries have timely filed all material Tax
Returns they are required to have filed; and such Tax Returns are accurate and
correct in all material respects and do not contain a disclosure statement
under Section 6662 of the Code (or any predecessor provision or comparable
provision of state, local or foreign law).
 
  (c) The Company and its subsidiaries have paid or adequately provided in the
financial statements included in the SEC Reports for all Taxes (whether or not
shown on any Tax Return) they are required to have paid or to pay, which
amounts are not material either individually or in the aggregate.
 
  (d) Except as set forth in Section 2.13(d) of the Company Disclosure
Schedule, no material claim for assessment or collection of Taxes is presently
being asserted against the Company or its subsidiaries and neither the Company
nor any of its subsidiaries is a party to any pending action, proceeding, or
investigation by any governmental taxing authority nor does the Company have
knowledge of any such threatened action, proceeding or investigation.
 
  (e) Except as set forth in Section 2.13(e) of the Company Disclosure
Schedule, neither the Company nor any of its subsidiaries is a party to any
agreement, contract, arrangement or plan that has resulted or would result,
individually or in the aggregate, in connection with this Agreement or any
change of control of the Company or any of its subsidiaries, in the payment of
any "excess parachute payments" within the meaning of Section 28OG of the Code.
 
  Section 2.14. Intellectual Property.
 
  (a) Section 2.14(a) of the Company Disclosure Schedule sets forth, for the
Intellectual Property owned, in whole or in part, including jointly with
others, by the Company or any of its subsidiaries, a complete and accurate list
of all United States and foreign (a) patents and patent applications; (b)
Trademark registrations and applications and material unregistered Trademarks;
and (c) copyright registrations and applications, indicating for each, the
applicable jurisdiction, registration number (or application number), and date
issued (or date filed). For purposes of this Agreement, "Intellectual Property"
means: trademarks and service marks (whether register or unregistered), trade
names, designs and general intangibles of like nature, together with all
goodwill related to the foregoing (collectively, "Trademarks"); patents
(including any continuations, continuations in part, renewals and applications
for any of the foregoing)(collectively "Patents"); copyrights (including any
registrations and applications therefor and whether registered or
unregistered)(collectively "Copyrights"); computer software; databases; works
of authorship; mask works; technology; trade secrets and other confidential
information, know-how, proprietary processes, formulae, algorithms, models,
user interfaces, customer lists, inventions, discoveries, concepts, ideas,
techniques, methods, source codes, object codes, methodologies and, with
respect to all of the foregoing, related confidential data or information
(collectively, "Trade Secrets").
 
  (b) Trademarks.
 
    (i) All Trademark registrations are currently in compliance in all
  material respects with all legal requirements (including the timely post-
  registration filing of affidavits of use and incontestability and renewal
  applications) other than any requirement that, if not satisfied, would not
  result in a cancellation of
 
                                      A-12
<PAGE>
 
  any such registration or otherwise materially affect the priority and
  enforceability of the Trademark in question.
 
    (ii) No registered Trademark has been within the last three (3) years or
  is now involved in any opposition or cancellation proceeding in the United
  States Patent and Trademark Office. To the Company's knowledge, no such
  action has been threatened in writing within the one (1)-year period prior
  to the date of this Agreement.
 
    (iii) To the knowledge of the Company and its subsidiaries, there has
  been no prior use of any material Trademark by any third party which would
  confer upon said third party superior rights in any such Trademark.
 
    (iv) All material Trademarks registered in the United States have been in
  continuous use by the Company or its subsidiaries.
 
    (v) The Company and its subsidiaries have adequately policed the
  Trademarks against third party infringement; and the material Trademarks
  registered in the United States have been continuously used in the form
  appearing in, and in connection with the goods and services listed in,
  their respective registration certificates.
 
    (c) Patents.
 
    (i) All Patents are currently in compliance with legal requirements
  (including payment of filing, examination, and maintenance fees and proofs
  of working or use) other than any requirement that, if not satisfied, would
  not result in a revocation or otherwise materially affect the
  enforceability of the Patent in question.
 
    (ii) No Patent has been or is now involved in any interference, reissue,
  reexamination or opposing proceeding in the United States Patent and
  Trademark Office. To the Company's knowledge, no such action has been
  threatened in writing within the one (1)-year period prior to the date of
  this Agreement.
 
    (iii) To the Company's knowledge, there is no patent or patent
  application of any person that conflicts in any material respect with any
  Patent.
 
    (d) Trade Secrets.
 
    (i) The Company has taken reasonable steps in accordance with normal
  industry practice to protect the Company's rights in confidential
  information and Trade Secrets of the Company.
 
    (ii) Without limiting the generality of Section 2.14(d)(i) and except as
  would not be materially adverse to the Company or its business, the Company
  enforces a policy of requiring each relevant employee, consultant and
  contractor to execute proprietary information, confidentiality and
  assignment agreements substantially in the Company's standard forms that
  assign to the Company all rights to any Intellectual Property rights
  relating to the Company's business and that otherwise appropriately protect
  the Intellectual Property of the Company, and, except under confidentiality
  obligations, there has been no disclosure by the Company or any subsidiary
  of material confidential information or Trade Secrets.
 
    (e) License Agreements.
 
    Section 2.14(e)(1) of the Company Disclosure Schedule sets forth a
  complete and accurate list of all license agreements granting to the
  Company or any of its subsidiaries any material right to use or practice
  any rights under any Intellectual Property other than office automation
  software used generally in the Company's or any of its subsidiaries'
  operations and other software that is not used in connection with the
  design, development, use, maintenance and support, testing, assembly and
  manufacture of the Company's or any such subsidiary's products and is
  commercially available on reasonable terms to any person for a
 
                                      A-13
<PAGE>
 
  license fee of no more than $100,000 (collectively, the "Inbound License
  Agreements"), indicating for each the title and the parties thereto and the
  amount of any future royalty or license fee payable thereunder. Section
  2.14(e)(2) of the Company Disclosure Schedule sets forth a complete and
  accurate list of all license agreements under which the Company or any of
  its subsidiaries licenses software or grants other rights in to use or
  practice any rights under any Intellectual Property, excluding licenses
  with customers that in the twelve-month period prior to the date hereof
  have purchased or licensed products for which the total payments to the
  Company and its subsidiaries did not exceed $100,000 (collectively, the
  "Outbound License Agreements"), indicating for each the title and the
  parties thereto. There is no material outstanding or, to the Company's
  knowledge, threatened dispute or disagreement with respect to any Inbound
  License Agreement or any Outbound License Agreement.
 
  (f) Ownership; Sufficiency of IP Assets. The Company or one of its
subsidiaries owns or possesses adequate licenses or other rights to use, free
and clear of Liens, orders and arbitration awards, all of its Intellectual
Property used in its business. The Intellectual Property identified in Section
2.14(a) of the Company Disclosure Schedule, together with the Company's and its
subsidiaries' unregistered copyrights and the Company's and such subsidiaries'
rights under the licenses granted to the Company or any of its subsidiaries
under the Inbound License Agreements, constitute all the material Intellectual
Property rights used in the operation of the Company's and its subsidiaries'
businesses as they are currently conducted and are all the Intellectual
Property rights necessary to operate such businesses after the Effective Time
in substantially the same manner as such businesses have been operated by the
Company prior thereto.
 
  (g) Protection of IP. The Company has taken reasonable steps to protect the
Intellectual Property of the Company and its subsidiaries.
 
  (h) No Infringement by the Company. To the Company's knowledge, the products
used, manufactured, marketed, sold or licensed by the Company, and all
Intellectual Property used in the conduct of the Company's and its
subsidiaries' businesses as currently conducted, do not infringe upon, violate
or constitute the unauthorized use of any rights owned or controlled by any
third party, including without limitation, any Intellectual Property of any
third party.
 
  (i) No Pending or Threatened Infringement Claims. Except and to the extent
publicly disclosed in the Company SEC Reports, no litigation is now or, within
the three (3) years prior to the date of this Agreement, was pending and, to
the Company's knowledge, no notice or other claim in writing has been received
by the Company within the one (1) year prior to the date of this Agreement, (A)
alleging that the Company any of its subsidiaries has engaged in any activity
or conduct that infringes upon, violates, or constitutes the unauthorized use
of the Intellectual Property rights of any third party or (B) challenging the
ownership, use, validity or enforceability of any Intellectual Property owned
or exclusively licensed by the Company. Except as specifically disclosed in one
or more Sections of the Company Disclosure Schedules pursuant to this Section
2.14, no Intellectual Property owned or licensed by the Company or any of its
subsidiaries is subject to any outstanding order, judgment, decree, stipulation
or agreement restricting the use thereof by the Company or any such subsidiary
or, in the case of any Intellectual Property licensed to others, restricting
the sale, transfer, assignment or licensing thereof by the Company or any of
its subsidiaries to any person.
 
  (j) No Infringement by Third Parties. Except as and to the extent publicly
disclosed in the Company SEC Reports or as set forth in Section 2.14(j) of the
Company Disclosure Schedule, to the knowledge of the Company, no third party is
misappropriating, infringing, diluting, or violating any Intellectual Property
owned or exclusively licensed by the Company or any of its subsidiaries, and no
such claims have been brought against any third party by the Company or any of
its subsidiaries.
 
  (k) Assignment; Change of Control. The execution, delivery and performance by
the Company of this Agreement, and the consummation of the transactions
contemplated hereby, will not result in the loss or impairment of, or give rise
to any right of any third party to terminate, any of the Company's or any of
its subsidiaries' rights to own any of its Intellectual Property or their
respective rights under the License
 
                                      A-14
<PAGE>
 
Agreements, nor require the consent of any Governmental Authority or third
party in respect of any such Intellectual Property.
 
  (l) Software. The Software owned or purported to be owned by the Company or
any of its subsidiaries, was either (i) developed by employees of Company or
any of its subsidiaries within the scope of their employment; (ii) developed by
independent contractors who have assigned their rights to the Company or any of
its subsidiaries pursuant to written agreements; or (iii) otherwise acquired by
the Company or a subsidiary from a third party. Except as set forth in Section
2.14(l) of the Company Disclosure Schedule, the Software does not contain any
programming code, documentation or other materials or development environments
that embody Intellectual Property rights of any person other than the Company
or any of its subsidiaries, except for such materials or development
environments obtained by the Company or any of its subsidiaries from other
persons who make such materials or development environments generally available
to all interested purchasers or end-users on standard commercial terms. For
purposes of this Section 2.14(l), "Software" means any and all (i) computer
programs, including any and all software implementations of algorithms, models
and methodologies, whether in source code or object code, (ii) databases and
compilations, including any and all data and collections of data, whether
machine readable or otherwise, (iii) descriptions, flow-charts and other work
product used to design, plan, organize and develop any of the foregoing, and
(iv) all documentation, including user manuals and training materials, relating
to any of the foregoing.
 
  (m) Performance of Existing Software Products. The Company's and its
subsidiaries' existing and currently manufactured and marketed Software
products listed and described on Section 2.14(m) of the Company Disclosure
Schedule perform in all material respects, free of significant bugs or
programming errors, the functions described in any agreed specifications or end
user documentation or other information provided to customers of the Company on
which such customers relied when licensing or otherwise acquiring such
products.
 
  (n) Documentation. The Company and its subsidiaries have taken all actions
customary in the software industry to document the Software and its operation,
such that the materials comprising the Software, including the source code and
documentation, have been written in a clear and professional manner so that
they may be understood, modified and maintained in an efficient manner by
reasonably competent programmers.
 
  (o) Year 2000 Compliance.
 
    (i) Except as set forth in Section 2.14(o) of the Company Disclosure
  Schedule, all of the Company's and its subsidiaries' material products
  (including products currently under development) will record, store,
  process and calculate and present calendar dates falling on and after
  December 31, 1998, and will calculate any information dependent on or
  relating to such dates in the same manner and with the same functionality,
  data integrity and performance as the products record, store, process,
  calculate and present calendar dates on or before December 31, 1998, or
  calculate any information dependent on or relating to such dates
  (collectively "Year 2000 Compliant"). Except as set forth in Section
  2.14(o) of the Company Disclosure Schedule, (A) all of the Company's and
  its subsidiaries' material products will lose no significant functionality
  with respect to the introduction of records containing dates falling on or
  after December 31, 1998; (B) all of the Company's and its subsidiaries'
  internal computer systems comprised of software, hardware, databases or
  embedded control systems (microprocessor controlled, robotic or other
  device) related to the Company's and its subsidiaries' businesses
  (collectively, a "Business System"), that constitutes any material part of,
  or is used in connection with the use, operation or enjoyment of, any
  material tangible or intangible asset or real property of the Company and
  its subsidiaries, including its accounting systems, are Year 2000
  Compliant. Except as set forth on Section 2.14(o) of the Company Disclosure
  Schedule, the current versions of the Company's and its subsidiaries'
  software and all other Intellectual Property may be used prior to, during
  and after December 31, 1998, such that such Software and Intellectual
  Property will operate prior to, during and after such time period without
  error caused by date data that represents or references different centuries
  or more than one century.
 
 
                                      A-15
<PAGE>
 
    (ii) To the knowledge of the Company, all of the Company's products and
  the conduct of the Company's business with customers and suppliers will not
  be materially adversely affected by the advent of the year 2000, the advent
  of the twenty-first century or the transition from the twentieth century
  through the year 2000 and into the twenty-first century. To the knowledge
  of the Company and except as set forth on Section 2.14(o) of the Company
  Disclosure Schedule, neither the Company nor any of its subsidiaries is
  reasonably likely to incur material expenses arising from or relating to
  the failure of any of its Business Systems or any products (including all
  products sold on or prior to the date hereof) as a result of the advent of
  the year 2000, the advent of the twenty-first century or the transition
  from the twentieth century through the year 2000.
 
  Section 2.15. Insurance. Each of the Company and its subsidiaries maintains
insurance policies (the "Insurance Policies") against all risks of a character
and in such amounts as are usually insured against by similarly situated
companies in the same or similar businesses. Each Insurance Policy is in full
force and effect and is valid, outstanding and enforceable, and all premiums
due thereon have been paid in full. None of the Insurance Policies will
terminate or lapse (or be affected in any other materially adverse manner) by
reason of the transactions contemplated by this Agreement. Each of the Company
and its subsidiaries has complied in all material respects with the provisions
of each Insurance Policy under which it is the insured party. No insurer under
any Insurance Policy has canceled or generally disclaimed liability under any
such policy or, to the Company's knowledge, indicated any intent to do so or
not to renew any such policy. All material claims under the Insurance Policies
have been filed in a timely fashion.
 
  Section 2.16. Certain Business Practices. None of the Company, any of its
subsidiaries or any directors, officers, agents or employees of the Company or
any of its subsidiaries has (i) used any funds for unlawful contributions,
gifts, entertainment or other unlawful expenses related to political activity,
(ii) made any unlawful payment to foreign or domestic government officials or
employees or to foreign or domestic political parties or campaigns or violated
any provision of the Foreign Corrupt Practices Act of 1977, as amended, or
(iii) made any other unlawful payment.
 
  Section 2.17. Product Warranties. Section 2.17 of the Company Disclosure
Schedule sets forth complete and accurate copies of the written warranties and
guaranties by the Company or any of its subsidiaries currently in effect with
respect to its products. There have not been any material deviations from such
warranties and guaranties, and neither the Company, any of its subsidiaries nor
any of their respective salesmen, employees, distributors and agents is
authorized to undertake obligations to any customer or to other third parties
in excess of such warranties or guaranties. Neither the Company nor any of its
subsidiaries has made any oral warranty or guaranty with respect to its
products.
 
  Section 2.18. Suppliers and Customers. The documents and information supplied
by the Company to Parent or any of its representatives in connection with this
Agreement with respect to relationships and volumes of business done with its
significant suppliers and customers are accurate in all material respects.
During the last twelve (12) months, the Company has received no notices of
termination or written threats of termination from any of the five (5) largest
suppliers or the five (5) largest customers of the Company and its
subsidiaries.
 
  Section 2.19. Vote Required. The affirmative vote of the holders of a
majority of the outstanding Shares is the only vote of the holders of any class
or series of the Company's capital stock necessary to approve and adopt this
Agreement.
 
  Section 2.20. Tax Treatment; Pooling. Neither the Company nor, to the
knowledge of the Company, any of its affiliates has taken or agreed to take
action that would prevent the Merger from (a) constituting a reorganization
qualifying under the provisions of Section 368(a) of the Code or (b) being
treated for financial accounting purposes as a pooling of interests in
accordance with generally accepted accounting principles and the rules
regulations and interpretations of the SEC (a "Pooling Transaction").
 
 
                                      A-16
<PAGE>
 
  Section 2.21. Affiliates. Except for the directors and executive officers of
the Company, each of whom is listed in Section 2.21 of the Company Disclosure
Schedule, there are no persons who, to the knowledge of the Company, may be
deemed to be affiliates of the Company under Rule 145 of the Securities Act
("Company Affiliates").
 
  Section 2.22. Opinion of Financial Adviser. Hambrecht & Quist LLC (the
"Company Financial Adviser") has delivered to the Company Board its written
opinion dated the date of this Agreement to the effect that as of such date the
Merger Consideration is fair, from a financial point of view, to the holders of
Shares.
 
  Section 2.23. Brokers. No broker, finder or investment banker (other than the
Company Financial Adviser, a true and correct copy of whose engagement
agreement has been provided to Acquisition or Parent) is entitled to any
brokerage finder's or other fee or commission in connection with the
transactions contemplated by this Agreement based upon arrangements made by or
on behalf of the Company.
 
  Section 2.24. Company Rights Agreement. The Company has taken all necessary
action to ensure that neither its entering into this Agreement or the Stock
Option Agreement, nor the consummation of the Merger, nor exercise of Parent's
rights under such Stock Option Agreement in accordance with its terms, will
cause the Company Rights to become exercisable, cause Parent or Acquisition to
become an "Acquiring Person" (each as defined in the Company Rights Agreement),
or cause there to occur a "Triggering Event" or a "Distribution Date" (each as
defined in the Company Rights Agreement).
 
                                   ARTICLE 3
 
                       REPRESENTATIONS AND WARRANTIES OF
                             PARENT AND ACQUISITION
 
  Parent and Acquisition hereby represent and warrant to the Company as
follows:
 
  Section 3.1. Organization.
 
  (a) Each of Parent and Acquisition is duly organized, validly existing and in
good standing under the laws of the State of Delaware, respectively, and has
all requisite power and authority to own, lease and operate its properties and
to carry on its businesses as now being conducted. Parent has heretofore made
available to the Company accurate and complete copies of the Certificate of
Incorporation and bylaws as currently in full force and effect, of Parent and
Acquisition.
 
  (b) Each of Parent and Acquisition is duly qualified or licensed and in good
standing to do business in each jurisdiction in which the property owned,
leased or operated by it or the nature of the business conducted by it makes
such qualification or licensing necessary, except in such jurisdictions where
the failure to be so duly qualified or licensed and in good standing would not
have a Material Adverse Effect on Parent. When used in connection with Parent
or Acquisition the term "Material Adverse Effect on Parent" means any
circumstance, change in, or effect on (or circumstance, change in, or effect
involving a prospective change on) Parent and its subsidiaries, taken as a
whole, (a) that is, or is reasonably likely in the future to be, materially
adverse to the operations, assets or liabilities (including contingent
liabilities), earnings or results of operations, or the business (financial or
otherwise) of Parent and its subsidiaries, taken as a whole, excluding from the
foregoing the effect, if any, of (i) changes in general economic conditions or
changes affecting the industry in which Parent operates, (ii) stockholder class
action litigation arising from allegations of a breach of fiduciary duty
relating to this Agreement, (iii) the public announcement or pendency of the
transactions contemplated hereby on current or prospective customers or
revenues of the Parent (provided that such effect is direct and that Parent
shall have the burden of proving such direct effect), or (iv) any action or
inaction required of Parent
 
                                      A-17
<PAGE>
 
by the Company under this Agreement, or (b) that would reasonably be expected
to prevent or materially delay or impair the ability of Parent and Acquisition
to consummate the transactions contemplated by this Agreement.
 
  Section 3.2. Capitalization of Parent and its Subsidiaries.
 
  (a) The authorized capital stock of Parent consists of 600,000,000 shares of
Parent Common Stock, of which, as of December 7, 1998, 218,140,000 shares of
Parent Common Stock were issued and outstanding (each together with a Parent
Common Stock purchase right (the "Parent Rights") issued pursuant to the Rights
Agreement dated as of February 9, 1996 between Parent and Harris Trust and
Savings Bank) and 400,000 shares of preferred stock, $.01 par value per share,
none of which are outstanding. All of the outstanding shares of Parent Common
Stock have been validly issued and are fully paid, nonassessable and free of
preemptive rights. As of December 7, 1998, 58,185,625 shares of Parent Common
Stock were reserved for issuance and 39,311,061 were issuable upon or otherwise
deliverable in connection with the exercise of outstanding options and
warrants. Between December 7, 1998 and the date hereof, no shares of Parent's
capital stock have been issued other than pursuant to stock options and
warrants already in existence on such date and except for grants of stock
options to employees, officers and directors in the ordinary course of business
consistent with past practice. Between December 7, 1998 and the date hereof, no
stock options or warrants have been granted. Except as set forth above and
except for the Parent Rights, as of the date hereof, there are outstanding (i)
no shares of capital stock or other voting securities of Parent (ii) no
securities of Parent or its subsidiaries convertible into or exchangeable for
shares of capital stock, or voting securities of Parent (iii) no options or
other rights to acquire from Parent or its subsidiaries and no obligations of
Parent or its subsidiaries to issue any capital stock, voting securities or
securities convertible into or exchangeable for capital stock or voting
securities of Parent and (iv) except for the Parent Rights, the Automated
Systems, Inc. 1983 Stock Option Plan, Cooper & Chyan Technology, Inc. 1989
Stock Option Plan, Cooper & Chyan Technology, Inc. 1993 Equity Incentive Plan,
Unicad, Inc. Stock Option Plan, Cadence Design Systems, Inc. 1997 Nonstatutory
Stock Option Plan, High Level Design Systems 1993 Stock Option Plan, High Level
Design Systems 1995 Special Nonstatutory Stock Option Plan, Ambit Design
Systems, Inc. 1994 Incentive Stock Option Plan, Ambit Design Systems, Inc. 1996
Incentive Stock Option Plan, Ambit OP (Shares Issued Outside Plans), Cadence
Design Systems, Inc. 1993 Non-Statutory Stock Option Plan, Cadence Design
Systems, Inc. 1993 Directors Stock Option Plan, Cadence Design Systems, Inc.
1995 Directors Stock Option Plan, Cadence Design Systems, Inc. 1997
Nonstatutory Stock Option Plan, OP Stock Option Plan (shares issued outside CDN
Directors Plan) and warrants issued to Comdisco and Goldman, Sachs & Co., no
equity equivalent interests in the ownership or earnings of Parent or its
subsidiaries or other similar rights (collectively, "Parent Securities"). As of
the date hereof, other than in connection with the Company's seasoned
authorized stock repurchase program, there are no outstanding obligations of
Parent or any of its subsidiaries to repurchase, redeem or otherwise acquire
any Parent Securities. There are no stockholder agreements, voting trusts or
other agreements or understandings to which Parent is a party or by which it is
bound relating to the voting of any shares of capital stock of Parent.
 
  (b) The Parent Rights and Parent Common Stock constitute the only classes of
equity securities of Parent or any of its subsidiaries registered or required
to be registered under the Exchange Act.
 
  Section 3.3. Authority Relative to this Agreement. Each of Parent and
Acquisition has all necessary corporate power and authority to execute and
deliver this Agreement, to perform its obligations under this Agreement and to
consummate the transactions contemplated hereby. The execution and delivery of
this Agreement and the consummation of the transactions contemplated hereby
have been duly and validly authorized by the boards of directors of Parent and
Acquisition and by Parent as the sole stockholder of Acquisition and no other
corporate proceedings on the part of Parent or Acquisition are necessary to
authorize this Agreement or to consummate the transactions contemplated hereby.
This Agreement has been duly and validly executed and delivered by each of
Parent and Acquisition and constitutes, assuming the due authorization,
execution and delivery hereof by the Company, a valid, legal and binding
agreement of each of Parent and Acquisition enforceable against each of Parent
and Acquisition in accordance with its terms, subject to any applicable
bankruptcy, insolvency, reorganization, moratorium or similar laws now or
hereafter in effect relating to creditors' rights generally or to general
principles of equity.
 
                                      A-18
<PAGE>
 
  Section 3.4. SEC Reports; Financial Statements.
 
  (a) Parent has filed all required forms, reports and documents ("Parent SEC
Reports) with the SEC since December 31, 1997, each of which, complied at the
time of filing in all material respects with all applicable requirements of the
Securities Act and the Exchange Act, each law as in effect on the dates such
forms reports and documents were filed. None of such Parent SEC Reports,
including any financial statements or schedules included or incorporated by
reference therein, contained when filed any untrue statement of a material fact
or omitted to state a material fact required to be stated or incorporated by
reference therein or necessary in order to make the statements therein in light
of the circumstances under which they were made not misleading, except to the
extent superseded by a Parent SEC Report filed subsequently and prior to the
date hereof. The audited consolidated financial statements of Parent included
in the Parent SEC Reports fairly present in conformity in all material respects
with generally accepted accounting principles applied on a consistent basis
(except as may be indicated in the notes thereto) the consolidated financial
position of Parent and its consolidated subsidiaries as of the dates thereof
and their consolidated results of operations and changes in financial position
for the periods then ended.
 
  (b) Parent has heretofore made available or promptly will make available to
the Company a complete and correct copy of any amendments or modifications that
are required to be filed with the SEC but have not yet been filed with the SEC
to agreements documents or other instruments that previously had been filed by
Parent with the SEC pursuant to the Exchange Act.
 
  Section 3.5. Information Supplied. None of the information supplied or to be
supplied by Parent or Acquisition for inclusion or incorporation by reference
to (i) the S-4 will at the time the S-4 is filed with the SEC and at the time
it becomes effective under the Securities Act contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein not misleading or (ii) the Proxy
Statement will at the date mailed to stockholders and at the times of the
meeting or meetings of stockholders of the Company to be held in connection
with the Merger contain any untrue statement of a material fact or omit to
state any material fact required to be stated therein or necessary in order to
make the statements therein in light of the circumstances under which they are
made not misleading. The S-4 will comply as to form in all material respects
with the provisions of the Securities Act and the rules and regulations
thereunder. Notwithstanding the foregoing, Parent makes no representation,
warranty or covenant with respect to any information supplied or required to be
supplied by the Company which is contained in or omitted from any of the
foregoing documents.
 
  Section 3.6. Consents and Approvals; No Violations. Except for filings,
permits, authorizations, consents, and approvals as may be required under and
other applicable requirements of the Securities Act, the Exchange Act, state
securities or blue sky laws, the HSR Act, and any filings under similar merger
notification laws or regulations of foreign Governmental Entities and the
filing and recordation of the Certificate of Merger as required by the DGCL, no
filing with or notice to, and no permit authorization consent or approval of
any Governmental Entity is necessary for the execution and delivery by Parent
or Acquisition of this Agreement or the consummation by Parent or Acquisition
of the transactions contemplated hereby, except where the failure to obtain
such permits, authorizations, consents or approvals or to make such filings or
give such notice would not, individually or in the aggregate, have a Material
Adverse Effect on Parent. Neither the execution, delivery and performance of
this Agreement by Parent or Acquisition nor the consummation by Parent or
Acquisition of the transactions contemplated hereby will (i) conflict with or
result in any breach of any provision of the respective Certificate or
Certificate of Incorporation or bylaws (or similar governing documents) of
Parent or Acquisition or any of Parent's other subsidiaries, (ii) result in a
violation or breach of or constitute (with or without due notice or lapse of
time or both) a default (or give rise to any right of termination, amendment,
cancellation or acceleration or Lien) under any of the terms, conditions or
provisions of any note, bond, mortgage, indenture, lease, license, contract,
agreement or other instrument or obligation to which Parent or Acquisition or
any of Parent's other subsidiaries is a party or by which any of them or any of
their respective properties or assets may be bound or (iii) violate any order,
writ, injunction, decree, law, statute, rule or regulation applicable to Parent
or Acquisition or any of Parent's other subsidiaries or any of their respective
 
                                      A-19
<PAGE>
 
properties or assets except, in the case of (ii) or (iii), for violations,
breaches or defaults that would not, individually or in the aggregate, have a
Material Adverse Effect on Parent.
 
  Section 3.7. No Default. Neither Parent nor any of its subsidiaries is in
breach, default or violation (and no event has occurred that with notice or the
lapse of time or both would constitute a breach, default or violation) of any
term, condition or provision of (i) its Certificate of Incorporation or bylaws
(or similar governing documents), (ii) any note, bond, mortgage, indenture,
lease, license, contract, agreement or other instrument or obligation to which
Parent or any of its subsidiaries is now a party or by which any of them or any
of their respective properties or assets may be bound or (iii) any order, writ,
injunction, decree, law, statute, rule or regulation applicable to Parent or
any of its subsidiaries or any of their respective properties or assets,
except, in the case of clause (ii) or (iii), for violations, breaches or
defaults that would not, individually or in the aggregate, have a Material
Adverse Effect on Parent.
 
  Section 3.8. No Undisclosed Liabilities; Absence of Changes. Except as and to
the extent publicly disclosed by Parent in the Parent SEC Reports, neither
Parent nor any of its subsidiaries has any liabilities or obligations of any
nature, whether or not accrued, contingent or otherwise that would be required
by generally accepted accounting principles to be reflected on a consolidated
balance sheet of Parent and its consolidated subsidiaries (including the notes
thereto), other than liabilities and obligations incurred in the ordinary
course of business since September 30, 1998, which, individually or in the
aggregate, will not have a Material Adverse Effect on Parent. Except as
publicly disclosed by Parent in the Parent SEC Reports, since September 30,
1998, there have been no events changes or effects with respect to Parent or
its subsidiaries having or that would reasonably be expected to have a Material
Adverse Effect on Parent.
 
  Section 3.9. Litigation. Except as publicly disclosed by Parent in the Parent
SEC Reports, there is no suit, claim, action, proceeding or investigation
pending or, to the knowledge of Parent threatened, against Parent or any of its
subsidiaries or any of their respective properties or assets before any
Governmental Entity that, individually or in the aggregate would reasonably be
expected to have a Material Adverse Effect or could reasonably be expected to
prevent or delay the consummation of the transactions contemplated by this
Agreement. Except as publicly disclosed by Parent in the Parent SEC Reports,
neither Parent nor any of its subsidiaries is subject to any outstanding order,
writ, injunction or decree that, insofar as can be reasonably foreseen in the
future would reasonably be expected to have a Material Adverse Effect on Parent
or could reasonably be expected to prevent or delay the consummation of the
transactions contemplated hereby.
 
  Section 3.10. Compliance with Applicable Law. Except as publicly disclosed by
Parent in the Parent SEC Reports, Parent and its subsidiaries hold all permits,
licenses, variances, exemptions, orders and approvals of all Governmental
Entities necessary for the lawful conduct of their respective businesses (the
"Parent Permits"), except for failures to hold such permits, licenses,
variances, exemptions, orders and approvals that would not, individually or in
the aggregate, have a Material Adverse Effect on Parent. Except as publicly
disclosed by Parent in the Parent SEC Reports, Parent and its subsidiaries are
in compliance with the terms of the Parent Permits, except where the failure so
to comply would not, individually or in the aggregate, have a Material Adverse
Effect on Parent. Except as publicly disclosed by Parent in the Parent SEC
Reports, the businesses of Parent and its subsidiaries are not being conducted
in violation of any law ordinance or regulation of any Governmental Entity
except that no representation or warranty is made in this Section 3.10 with
respect to Environmental Laws and except for violations or possible violations
that do not and, insofar as reasonably can be foreseen in the future, will not,
individually or in the aggregate, have a Material Adverse Effect on Parent.
Except as publicly disclosed by Parent in the Parent SEC Reports, no
investigation or review by any Governmental Entity with respect to Parent or
its subsidiaries is pending or, to the knowledge of Parent, threatened, nor, to
the knowledge of Parent, has any Governmental Entity indicated an intention to
conduct the same, other than in each case those that Parent reasonably believes
will not have a Material Adverse Effect on Parent.
 
  Section 3.11. Tax Treatment; Pooling. Neither Parent, Acquisition nor, to the
knowledge of Parent, any of its affiliates has taken, proposes to take, or has
agreed to take any action that would prevent the Merger
 
                                      A-20
<PAGE>
 
(a) from constituting a reorganization qualifying under the provisions of
Section 368(a) of the Code or (b) from being treated as a Pooling Transaction
for financial accounting purposes.
 
  Section 3.12. Opinion of Financial Adviser. Goldman, Sachs & Co. (the "Parent
Financial Adviser") has delivered to the Board of Directors of Parent its
opinion to the effect that, as of the date hereof, the Merger Consideration is
fair, from a financial point of view, to Parent.
 
  Section 3.13. Brokers. No broker finder or investment banker (other than the
Parent Financial Adviser) is entitled to any brokerage finder's or other fee or
commission in connection with the transactions contemplated by this Agreement
based upon arrangements made by or on behalf of Parent or Acquisition.
 
  Section 3.14. No Prior Activities. Except for obligations incurred in
connection with its incorporation or organization or the negotiation and
consummation of this Agreement and the transactions contemplated hereby,
Acquisition has neither incurred any obligation or liability nor engaged in any
business or activity of any type or kind whatsoever or entered into any
agreement or arrangement with any person.
 
  Section 3.15 Environmental Laws and Regulations.
 
  (a) Except as publicly disclosed by Parent in the Parent SEC Reports (i) each
of Parent and its subsidiaries is in material compliance with all Environmental
Laws, except for non-compliances that, individually or in the aggregate, would
not have a Material Adverse Effect on the Parent, which compliance includes,
but is not limited to, the possession by the Parent and its subsidiaries of all
material permits and other governmental authorizations required under
applicable Environmental Laws and compliance with the terms and conditions
thereof; (ii) neither Parent nor any of its subsidiaries has received written
notice of or, to the knowledge of Parent, is the subject of any Environmental
Claim, and (iii) to the knowledge of Parent, there are no existing facts that
are reasonably likely to prevent or interfere with such material compliance in
the future.
 
  (b) Except as disclosed in the Parent SEC Reports, there are no Environmental
Claims that, individually or in the aggregate, would reasonably be expected to
have a Material Adverse Effect on the Company that are pending or, to the
knowledge of Parent, threatened against Parent or any of its subsidiaries or,
to the knowledge of Parent, against any person whose liability for any
Environmental Claim the Parent or any of its subsidiaries has or may have
retained or assumed either contractually or by operation of law.
 
                                   ARTICLE 4
 
                                   COVENANTS
 
  Section 4.1. Conduct of Business of the Company. Except as contemplated by
this Agreement or as described in Section 4.1 of the Company Disclosure
Schedule, during the period from the date hereof to the Effective Time, the
Company will and will cause each of its subsidiaries to conduct its operations
in the ordinary course of business consistent with past practice and, to the
extent consistent therewith, with no less diligence and effort than would be
applied in the absence of this Agreement seek, to preserve intact its current
business organizations, keep available the service of its current officers and
employees and preserve its relationships with customers, suppliers and others
having business dealings with it with the intention that its goodwill and
ongoing businesses shall be unimpaired at the Effective Time. Without limiting
the generality of the foregoing, except as otherwise expressly provided in this
Agreement or as described in Section 4.1 of the Company Disclosure Schedule,
prior to the Effective Time, neither the Company nor any of its subsidiaries
will, without the prior written consent of Parent and Acquisition:
 
  (a) amend its Certificate or Articles of Incorporation or bylaws (or other
similar governing instrument);
 
  (b) authorize for issuance, issue, sell, deliver or agree or commit to issue
sell or deliver (whether through the issuance or granting of options, warrants,
commitments, subscriptions, rights to purchase or otherwise) any
 
                                      A-21
<PAGE>
 
stock of any class or any other securities (except bank loans) or equity
equivalents (including any stock options or stock appreciation rights) except
for the issuance and sale of Shares pursuant to options granted under the
Company Plans prior to the date hereof;
 
  (c) split, combine or reclassify any shares of its capital stock, declare,
set aside or pay any dividend or other distribution (whether in cash, stock or
property or any combination thereof) in respect of its capital stock, make any
other actual, constructive or deemed distribution in respect of its capital
stock or otherwise make any payments to stockholders in their capacity as such,
or redeem or otherwise acquire any of its securities or any securities of any
of its subsidiaries;
 
  (d) adopt a plan of complete or partial liquidation, dissolution, merger,
consolidation, restructuring, recapitalization or other reorganization of the
Company or any of its subsidiaries (other than the Merger);
 
  (e) alter through merger, liquidation, reorganization, restructuring or any
other fashion the corporate structure of ownership of any subsidiary;
 
  (f) (i) incur or assume any long-term or short-term debt or issue any debt
securities except for borrowings under existing lines of credit in the ordinary
course of business; (ii) assume, guarantee, endorse or otherwise become liable
or responsible (whether directly, contingently or otherwise) for the
obligations of any other person except for obligations of subsidiaries of the
Company incurred in the ordinary course of business; (iii) make any loans,
advances or capital contributions to or investments in any other person (other
than to subsidiaries of the Company or customary loans or advances to employees
in each case in the ordinary course of business consistent with past practice);
(iv) pledge or otherwise encumber shares of capital stock of the Company or any
of its subsidiaries; or (v) mortgage or pledge any of its material assets,
tangible or intangible, or create or suffer to exist any material Lien
thereupon;
 
  (g) except as may be required by law, enter into, adopt or amend or terminate
any bonus, profit sharing, compensation, severance, termination, stock option,
stock appreciation right, restricted stock, performance unit, stock equivalent,
stock purchase agreement, pension, retirement, deferred compensation,
employment, health, life, or disability insurance, dependent care, severance or
other employee benefit plan agreement, trust, fund or other arrangement for the
benefit or welfare of any director, officer or employee in any manner or
increase in any manner the compensation or fringe benefits of any director,
officer or employee or pay any benefit not required by any plan and arrangement
as in effect as of the date hereof (including the granting of stock
appreciation rights or performance units); provided, however, that this
paragraph (g) shall not prevent the Company or its subsidiaries from increasing
annual compensation and/or providing for or amending bonus arrangements for
employees for fiscal 1998 in the ordinary course of year-end compensation
reviews consistent with past practice (to the extent that such compensation
increases and new or amended bonus arrangements do not result in a material
increase in benefits or compensation expense to the Company or any such
subsidiary);
 
  (h) acquire, sell, lease or dispose of any assets in any single transaction
or series of related transactions having a fair market value in excess of One
Hundred Thousand Dollars ($100,000) in the aggregate, other than sales of its
products in the ordinary course of business consistent with past practices;
 
  (i) except as may be required as a result of a change in law or in generally
accepted accounting principles, change any of the accounting principles,
practices or methods used by it;
 
  (j) revalue in any material respect any of its assets, including writing down
the value of inventory or writing-off notes or accounts receivable, other than
in the ordinary course of business;
 
  (k) (i) acquire (by merger, consolidation or acquisition of stock or assets)
any corporation, partnership or other business organization or division thereof
or any equity interest therein; (ii) enter into any contract or agreement other
than in the ordinary course of business consistent with past practice that
would be material to the Company and its subsidiaries, taken as a whole; (iii)
amend, modify or waive any right under any material
 
                                      A-22
<PAGE>
 
contract of the Company or any of its subsidiaries; (iv) modify its standard
warranty terms for its products or amend or modify any product warranties in
effect as of the date hereof in any material manner that is adverse to the
Company or any of its subsidiaries; or (v) authorize any new capital
expenditure or expenditures that individually is in excess of One Hundred
Thousand Dollars ($100,000) or in the aggregate are in excess of Three Hundred
Thousand Dollars ($300,000); provided that nothing in the foregoing clause (v)
shall limit any capital expenditure required pursuant to existing customer
contracts;
 
  (l) make any tax election or settle or compromise any income tax liability
material to the Company and its subsidiaries taken as a whole;
 
  (m) settle or compromise any pending or threatened suit, action or claim that
(i) relates to the transactions contemplated hereby or (ii) the settlement or
compromise of which would have a Material Adverse Effect on the Company;
 
  (n) commence any material software development project or terminate any
material software development project that is currently ongoing, in either case
except pursuant to the terms of existing contracts with customers or except as
contemplated by the Company's project development budget previously provided to
Parent; or
 
  (o) take or agree in writing or otherwise to take any of the actions
described in Sections 4.1(a) through 4.1(n) (and it shall use all reasonable
efforts not to take any action that would make any of the representations or
warranties of the Company contained in this Agreement untrue or incorrect).
 
  Section 4.2. Conduct of Business of Parent. Except as contemplated by this
Agreement, during the period from the date hereof to the Effective Time, Parent
will and will cause each of its subsidiaries to conduct their operations in the
ordinary course of business consistent with past practice and, to the extent
consistent therewith, with no less diligence and effort than would be applied
in the absence of this Agreement, seek to preserve intact its current business
organizations, keep available the service of its current officers and employees
and preserve its relationships with customers, suppliers and others having
business dealings with it to the end that goodwill and ongoing businesses shall
be unimpaired at the Effective Time. Without limiting the generality of the
foregoing, except as otherwise expressly provided in this Agreement prior to
the Effective Time, neither Parent nor any of its subsidiaries will, without
the prior written consent of the Company:
 
  (a) knowingly take any action that would result in a failure to maintain the
trading of the Parent Common Stock on the New York Stock Exchange ("NYSE");
 
  (b) acquire or agree to acquire by merging or consolidating with by
purchasing an equity interest in or the assets of or by any other manner any
business or any corporation, partnership or other business organization or
division thereof or otherwise acquire or agree to acquire any assets of any
other entity (other than the purchase of assets from suppliers, clients or
vendors in the ordinary course of business and consistent with past practice)
if such transaction would prevent or materially delay the consummation of the
transactions contemplated by this Agreement;
 
  (c) adopt or propose to adopt any amendments to its charter documents that
would have an adverse impact on the consummation of the transactions
contemplated by this Agreement; or
 
  (d) take or agree in writing or otherwise to take any of the actions
described in Sections 4.2(a) through 4.2(c) or any action that would make any
of the representations or warranties of Parent contained in this Agreement
untrue or incorrect.
 
  Section 4.3. Preparation of S-4 and the Proxy Statement. The Company shall
promptly prepare and file with the SEC the Proxy Statement and Parent shall
promptly prepare and file with the SEC the S-4 in which the Proxy Statement
will be included as a prospectus. Each of Parent and the Company shall use all
reasonable efforts to have the S-4 declared effective under the Securities Act
as promptly as practicable after
 
                                      A-23
<PAGE>
 
such filing. Parent shall also take any action (other than qualifying to do
business in any jurisdiction in which it is now not so qualified) required to
be taken under any applicable state securities laws in connection with the
issuance of Parent Common Stock in the Merger and upon the exercise of Company
Stock Options and the Company shall furnish all information concerning the
Company and the holders of Shares as may be reasonably requested in connection
with any such action.
 
  Section 4.4. Other Potential Acquirers.
 
  (a) The Company, its affiliates (as reasonably determined by the Company) and
their respective officers and other employees with managerial responsibilities,
directors, representatives and agents shall immediately cease any discussions
or negotiations with any parties with respect to any Third Party Acquisition
(as defined below). Neither the Company nor any of its affiliates (as
reasonably determined by the Company) shall, nor shall the Company authorize or
permit any of its or their respective officers, directors, employees
representatives or agents to, directly or indirectly, encourage, solicit,
participate in or initiate discussions or negotiations with or provide any non-
public information to any person or group (other than Parent and Acquisition or
any designees of Parent and Acquisition) concerning any Third Party
Acquisition; provided, however, that nothing herein shall prevent the Company
Board from taking and disclosing to the Company's stockholders a position
contemplated by Rules 14d-9 and 14e-2 promulgated under the Exchange Act with
regard to any tender or exchange offer. The Company shall promptly notify the
Parent in the event it receives any proposal or inquiry concerning a Third
Party Acquisition, including the terms and conditions thereof and the identity
of the party submitting such proposal, and shall advise Parent from time to
time of the status and any material developments concerning the same.
 
  (b) Except as set forth in this Section 4.4(b), the Company Board shall not
withdraw its recommendation of the transactions contemplated hereby or approve
or recommend, or cause the Company to enter into any agreement with respect to,
any Third Party Acquisition. Notwithstanding the foregoing, if the Company
Board by a majority vote determines in its good faith judgment, after
consultation with and based upon the advice of legal counsel, that it is
required to do so in order to comply with its fiduciary duties, the Company
Board may withdraw its recommendation of the transactions contemplated hereby
or approve or recommend a Superior Proposal (as defined in subsection (c)
below), but in each case only (i) after providing written notice to Parent (a
"Notice of Superior Proposal") advising Parent that the Company Board has
received a Superior Proposal, specifying the material terms and conditions of
such Superior Proposal and identifying the person making such Superior Proposal
and (ii) if Parent does not, within five (5) business days of Parent's receipt
of the Notice of Superior Proposal, make an offer that the Company Board by a
majority vote determines in its good faith judgment (based on the written
advice of a financial adviser of nationally recognized reputation) to be at
least as favorable to the Company's stockholders as such Superior Proposal;
provided, however, that the Company shall not be entitled to enter into any
agreement with respect to a Superior Proposal unless and until this Agreement
is terminated by its terms pursuant to Section 6.1 and the Company has paid all
amounts due to Parent pursuant to Section 6.3. Any disclosure that the Company
Board may be compelled to make with respect to the receipt of a proposal for a
Third Party Acquisition or otherwise in order to comply with its fiduciary
duties or Rule 14d-9 or 14e-2 will not constitute a violation of this
Agreement, provided that such disclosure states that no action will be taken by
the Company Board in violation of this Section 4.4(b).
 
  (c) For the purposes of this Agreement, "Third Party Acquisition" means the
occurrence of any of the following events: (i) the acquisition of the Company
by merger or otherwise by any person (which includes a "person" as such term is
defined in Section 13(d)(3) of the Exchange Act) other than Parent, Acquisition
or any affiliate thereof (a "Third Party"); (ii) the acquisition by a Third
Party of any material portion of the assets of the Company and its subsidiaries
taken as a whole, other than the sale of its products in the ordinary course of
business consistent with past practices; (iii) the acquisition by a Third Party
of fifteen percent (15%) or more of the outstanding Shares; (iv) the adoption
by the Company of a plan of liquidation or the declaration or payment of an
extraordinary dividend; (v) the repurchase by the Company or any of its
subsidiaries of more than ten percent (10%) of the outstanding Shares; or (vi)
the acquisition by the Company or any of its subsidiaries by merger, purchase
of stock or assets, joint venture or otherwise of a direct or indirect
ownership
 
                                      A-24
<PAGE>
 
interest or investment in any business whose annual revenues, net income or
assets is equal or greater than ten percent (10%) of the annual revenues, net
income or assets of the Company. For purposes of this Agreement, a "Superior
Proposal" means any bona fide proposal to acquire directly or indirectly for
consideration consisting of cash and/or securities more than 50% of the Shares
then outstanding or all or substantially all the assets of the Company and
otherwise on terms that the Company Board by a majority vote determines in its
good faith judgment (based on the written advice of Hambrecht & Quist LLC or
another financial advisor of nationally recognized reputation) to be more
favorable to the Company's stockholders than the Merger.
 
  Section 4.5. Comfort Letters.
 
  (a) The Company shall use all reasonable efforts to cause
PricewaterhouseCoopers LLP to deliver a letter dated not more than five days
prior to the date on which the S-4 shall become effective and addressed to
itself and Parent and their respective Boards of Directors in form and
substance reasonably satisfactory to Parent and customary in scope and
substance for agreed-upon procedures letters delivered by independent public
accountants in connection with registration statements and proxy statements
similar to the S-4 and the Proxy Statement.
 
  (b) Parent shall use all reasonable efforts to cause Arthur Andersen LLP to
deliver a letter dated not more than five (5) days prior to the date of the S-4
shall become effective and addressed to itself and the Company and their
respective Boards of Directors in form and substance reasonably satisfactory to
the Company and customary in scope and substance for agreed-upon procedures
letters delivered by independent accountants in connection with registration
statements and proxy statements similar to the S-4 and the Proxy Statement.
 
  Section 4.6. Meeting of Stockholders. The Company shall take all actions
necessary in accordance with the DGCL and its Certificate of Incorporation and
bylaws to duly call, give notice of, convene and hold a meeting of its
stockholders as promptly as practicable to consider and vote upon the adoption
and approval of this Agreement and the transactions contemplated hereby. The
stockholder vote required for the adoption and approval of the transactions
contemplated by this Agreement shall be the vote required by the DGCL and the
Company's Certificate of Incorporation and bylaws. The Company will, through
the Company Board, recommend to its stockholders approval of such matters
subject to the provisions of Section 4.4(b). The Company shall promptly prepare
and file with the SEC the Proxy Statement for the solicitation of a vote of the
holders of Shares approving the Merger, which, subject to the provisions of
Section 4.4(b), shall include the recommendation of the Company Board that
stockholders of the Company vote in favor of the approval and adoption of this
Agreement and the written opinion of the Financial Advisor that the
consideration to be received by the stockholders of the Company pursuant to the
Merger is fair to such stockholders from a financial point of view. The Company
shall use all reasonable efforts to have the Proxy Statement cleared by the SEC
as promptly as practicable after such filing, and promptly thereafter mail the
Proxy Statement to the stockholders of the Company. Parent shall use all
reasonable efforts to obtain all necessary state securities law or "blue sky"
permits and approvals required in connection with the Merger and to consummate
the other transactions contemplated by this Agreement and will pay all expenses
incident thereto, provided that the Company shall cooperate with Parent in
obtaining such permits and approvals as reasonably requested.
 
  Section 4.7. Stock Exchange Listing. Parent shall use all reasonable efforts
to cause the shares of Parent Common Stock to be issued in the Merger and the
shares of Parent Common Stock to be reserved for issuance upon exercise of
Company Stock Options to be approved for listing on the NYSE, subject to
official notice of issuance, prior to the Effective Time.
 
  Section 4.8. Access to Information.
 
  (a) Between the date hereof and the Effective Time, the Company will give
Parent and its authorized representatives reasonable access to all employees,
plants, offices, warehouses and other facilities and to all books and records
of the Company and its subsidiaries as Parent may reasonably require, and will
cause its officers and those of its subsidiaries to furnish Parent with such
financial and operating data and other information with respect to the business
and properties of the Company and its subsidiaries as Parent may from
 
                                      A-25
<PAGE>
 
time to time reasonably request. Between the date hereof and the Effective
Time, Parent shall make available to the Company, as reasonably requested by
the Company, a designated officer of Parent to answer questions and make
available such information regarding Parent and its subsidiaries as is
reasonably requested by the Company taking into account the nature of the
transactions contemplated by this Agreement.
 
  (b) Between the date hereof and the Effective Time, the Company shall furnish
to Parent (1) within two (2) business days following preparation thereof (and
in any event within twenty (20) business days after the end of each calendar
month, commencing with December 1998), an unaudited balance sheet as of the end
of such month and the related statements of earnings, stockholders' equity
(deficit) and cash flows, (2) within two (2) business days following
preparation thereof (and in any event within twenty (20) business days after
the end of each fiscal quarter) an unaudited balance sheet as of the end of
such quarter and the related statements of earnings, stockholders' equity
(deficit) and cash flows for the quarter then ended, and (3) within two (2)
business days following preparation thereof (and in any event within ninety
(90) calendar days after the end of each fiscal year, an audited balance sheet
as of the end of such year and the related statements of earnings,
stockholders' equity (deficit) and cash flows, all of such financial statements
referred to in clauses (1), (2) and (3) to prepared in accordance with
generally accepted accounting principles in conformity with the practices
consistently applied by the Company with respect to such financial statements.
All the foregoing shall be in accordance with the books and records of the
Company and shall fairly present its financial position (taking into account
the differences between the monthly, quarterly and annual financial statements
prepared by the Company in conformity with its past practices) as of the last
day of the period then ended.
 
  (c) Each of the parties hereto will hold, and will cause its consultants and
advisers to hold, in confidence all documents and information furnished to it
by or on behalf of another party to this Agreement in connection with the
transactions contemplated by this Agreement pursuant to the terms of that
certain Confidentiality Agreement entered into between the Company and Parent
dated December 4, 1998.
 
  Section 4.9. Certain Filings; Reasonable Efforts.
 
  (a) Subject to the terms and conditions herein provided, including, without
limitation, Section 4.4(b), each of the parties hereto agrees to use all
reasonable efforts to take or cause to be taken all action and to do or cause
to be done all things reasonably necessary, proper or advisable under
applicable laws and regulations to consummate and make effective the
transactions contemplated by this Agreement, including using all reasonable
efforts to do the following, (i) cooperate in the preparation and filing of the
Proxy Statement and the S-4 and any amendments thereto, any filings that may be
required under the HSR Act and any filings under similar merger notification
laws or regulations of foreign Governmental Entities; (ii) obtain consents of
all third parties and Governmental Entities necessary, proper or advisable for
the consummation of the transactions contemplated by this Agreement; (iii)
contest any legal proceeding relating to the Merger; and (iv) execute any
additional instruments necessary to consummate the transactions contemplated
hereby. Subject to the terms and conditions of this Agreement, Parent and
Acquisition agree to use all reasonable efforts to cause the Effective Time to
occur as soon as practicable after the Company stockholder vote with respect to
the Merger. The Company agrees to use all reasonable efforts to encourage its
employees to accept any offers of employment extended by Parent. If at any time
after the Effective Time any further action is necessary to carry out the
purposes of this Agreement the proper officers and directors of each party
hereto shall take all such necessary action.
 
  (b) Parent and the Company will consult and cooperate with one another, and
consider in good faith the views of one another, in connection with any
analyses, appearances, presentations, letters, white papers, memoranda, briefs,
arguments, opinions or proposals made or submitted by or on behalf of any party
hereto in connection with proceedings under or relating to the HSR Act or any
other foreign, federal, or state antitrust, competition, or fair trade law. In
this regard but without limitation, each party hereto shall promptly inform the
other of any material communication between such party and the Federal Trade
Commission, the Antitrust Division of the United States Department of Justice,
or any other federal, foreign or state antitrust or competition Governmental
Entity regarding the transactions contemplated herein.
 
                                      A-26
<PAGE>
 
  Section 4.10. Public Announcements. Parent, Acquisition and the Company, as
the case may be, will consult with one another before issuing any press release
or otherwise making any public statements with respect to the transactions
contemplated by this Agreement, including the Merger, and shall not issue any
such press release or make any such public statement prior to such consultation
except (i) as may be required by applicable law, or by the rules and
regulations of, or pursuant to any listing agreement with, the NYSE or the
Nasdaq National Market, as determined by Parent, Acquisition or the Company, as
the case may be, or (ii) following a change, if any, of the Company Board's
recommendation of the Merger (in accordance with Section 4.4(b)), after which
event no such consultation shall be required. Notwithstanding the preceding
sentence, the first public announcement of this Agreement and the Merger shall
be a joint press agreed upon by Parent and the Company.
 
  Section 4.11. Indemnification and Directors' and Officers' Insurance.
 
  (a) After the Effective Time, Parent shall cause the Surviving Corporation to
indemnify and hold harmless (and shall also advance expenses as incurred to the
fullest extent permitted under applicable law to), to the extent not covered by
insurance, each person who is now or has been prior to the date hereof or who
becomes prior to the Effective Time an officer or director of the Company or
any of the Company's subsidiaries (the "Indemnified Persons") against (i) all
losses, claims, damages, costs, expenses (including counsel fees and expenses),
settlement, payments or liabilities arising out of or in connection with any
claim, demand, action, suit, proceeding or investigation based in whole or in
part on or arising in whole or in part out of the fact that such person is or
was an officer or director of the Company or any of its subsidiaries, whether
or not pertaining to any matter existing or occurring at or prior to the
Effective Time and whether or not asserted or claimed prior to or at or after
the Effective Time ("Indemnified Liabilities"); and (ii) all Indemnified
Liabilities based in whole or in part on or arising in whole or in part out of
or pertaining to this Agreement or the transactions contemplated hereby, in
each case to the fullest extent required or permitted under applicable law.
Nothing contained herein shall make Parent, Acquisition, the Company or the
Surviving Corporation, an insurer, a co-insurer or an excess insurer in respect
of any insurance policies which may provide coverage for Indemnified
Liabilities, nor shall this Section 4.11 relieve the obligations of any insurer
in respect thereto. The parties hereto intend, to the extent not prohibited by
applicable law, that the indemnification provided for in this Section 4.11
shall apply without limitation to negligent acts or omissions by an Indemnified
Person. Parent hereby guarantees the payment and performance of the Surviving
Corporation's obligations in this Section 4.11. Each Indemnified Person is
intended to be a third party beneficiary of this Section 4.11 and may
specifically enforce its terms. This Section 4.11 shall not limit or otherwise
adversely affect any rights any Indemnified Person may have under any agreement
with the Company or under the Company's Certificate of Incorporation or bylaws
as presently in effect.
 
  (b) From and after the Effective Time, Parent will fulfill and honor and will
cause the Surviving Corporation to fulfill and honor in all respects the
obligations of the Company pursuant to any indemnification agreements between
the Company and its directors and officers as of or prior to the date hereof
(or indemnification agreements in the Company's customary form for directors
joining the Company's Board of Directors prior to the Effective Time) and any
indemnification provisions under the Company's certificate of incorporation or
bylaws as in effect immediately prior to the Effective Time.
 
  (c) For a period of six years after the Effective Time, Parent will maintain
or cause the Surviving Corporation to maintain in effect, if available,
directors' and officers' liability insurance covering those persons who, as of
immediately prior to the Effective Time, are covered by the Company's
directors' and officers' liability insurance policy (the "Insured Parties") on
terms no less favorable to the Insured Parties than those of the Company's
present directors' and officers' liability insurance policy; provided, however,
that in no event will Parent or the Surviving Corporation be required to expend
in excess of 150% of the annual premium currently paid by the Company for such
coverage (or such coverage as is available for 150% of such annual premium);
provided further, that, in lieu of maintaining such existing insurance as
provided above, Parent may cause coverage to be provided under any policy
maintained for the benefit of Parent or any of its subsidiaries,
 
                                      A-27
<PAGE>
 
so long as the terms are not materially less advantageous to the intended
beneficiaries thereof than such existing insurance.
 
  (d) The provisions of this Section 4.11 are intended to be for the benefit
of, and will be enforceable by, each person entitled to indemnification
hereunder and the heirs and representatives of such person. Parent will not
permit the Surviving Corporation to merge or consolidate with any other Person
unless the Surviving Corporation will ensure that the surviving or resulting
entity assumes the obligations imposed by this Section 4.11.
 
  Section 4.12. Notification of Certain Matters. The Company shall give prompt
notice to Parent and Acquisition, and Parent and Acquisition shall give prompt
notice to the Company, of (i) the occurrence or nonoccurrence of any event the
occurrence or nonoccurrence of which has caused or would be likely to cause any
representation or warranty contained in this Agreement to be untrue or
inaccurate in any material respect at or prior to the Effective Time and (ii)
any material failure of the Company, Parent or Acquisition, as the case may be,
to comply with or satisfy in any material respect any covenant condition or
agreement to be complied with or satisfied by it hereunder; provided, however,
that the delivery of any notice pursuant to this Section 4.12 shall not cure
such breach or non-compliance or limit or otherwise affect the remedies
available hereunder to the party receiving such notice.
 
  Section 4.13. Affiliates; Pooling; Tax-Free Reorganization.
 
  (a) The Company shall use all reasonable efforts to obtain from all Company
Affiliates and from any person who may be deemed to have become a Company
Affiliate, after the date of this Agreement and on or prior to the Effective
Time, a letter agreement substantially in the form of Exhibit A-1 hereto as
soon as practicable.
 
  (b) Parent shall use all reasonable efforts to obtain from each of its
directors, officers and any other person who may be deemed to be an affiliate
of Parent pursuant to Rule 145 under the Securities Act, as soon as practicable
after the date of this Agreement and on or prior to the Effective Time, a
letter agreement substantially in the form of Exhibit A-2 hereto.
 
  (c) Parent shall not be required to maintain the effectiveness of the S-4 for
the purpose of resale of shares of Parent Common Stock by stockholders of the
Company who may be affiliates of the Company or Parent pursuant to Rule 145
under the Securities Act.
 
  (d) Each party hereto shall use all reasonable efforts to cause the Merger to
be treated for financial accounting purposes as a Pooling Transaction and shall
not take and shall use all reasonable efforts to prevent any affiliate of such
party from taking any actions that could prevent the Merger from being treated
for financial accounting purposes as a Pooling Transaction, and shall take all
reasonable actions to remedy the effects of any prior actions so as to permit
such treatment.
 
  (e) The Company, on the one hand, and Parent and Acquisition, on the other
hand, shall execute and deliver to legal counsel to the Company and Parent
certificates substantially in the form attached hereto as Exhibits B-1 and B-2,
respectively, at such time or times as reasonably requested by such legal
counsel in connection with its delivery of an opinion with respect to the
transactions contemplated hereby and the Company and Parent shall each provide
a copy thereof to the other parties hereto. Prior to the Effective Time, none
of the Company, Parent or Acquisition shall take or cause to be taken any
action that would cause to be untrue (or fail to take or cause not to be taken
any action that would cause to be untrue) any of the representations in
Exhibits B-1 or B-2.
 
  Section 4.14. Additions to and Modification of Company Disclosure
Schedule. Concurrently with the execution and delivery of this Agreement, the
Company has delivered a Company Disclosure Schedule that includes all of the
information required by the relevant provisions of this Agreement. In addition,
the Company shall deliver to Parent and Acquisition such additions to or
modifications of any Sections of the Company
 
                                      A-28
<PAGE>
 
Disclosure Schedule necessary to make the information set forth therein true,
accurate and complete in all material respects as soon as practicable after
such information is available to the Company after the date of execution and
delivery of this Agreement; provided, however, that such disclosure shall not
be deemed to constitute an exception to its representations and warranties
under Article 2, nor limit the rights and remedies of Parent and Acquisition
under this Agreement for any breach by the Company of such representation and
warranties.
 
  Section 4.15. Company Rights Agreement. The Company shall not redeem any of
the Company Rights issued pursuant to the Company Rights Agreement nor will the
Company take any action to amend the Company Rights Agreement to facilitate the
acquisition of Shares by any person other than Parent or Acquisition unless
this Agreement is first terminated in accordance with Article 6 of this
Agreement.
 
                                   ARTICLE 5
 
                    CONDITIONS TO CONSUMMATION OF THE MERGER
 
  Section 5.1. Conditions to Each Party's Obligations to Effect the Merger. The
respective obligations of each party hereto to effect the Merger are subject to
the satisfaction at or prior to the Effective Time of the following conditions:
 
  (a) this Agreement shall have been approved and adopted by the requisite vote
of the stockholders of the Company;
 
  (b) no statute, rule, regulation, executive order, decree, ruling or
injunction shall have been enacted, entered, promulgated or enforced by any
United States federal or state court or United States federal or state
Governmental Entity that prohibits, restrains, enjoins or restricts the
consummation of the Merger;
 
  (c) any waiting period applicable to the Merger under the HSR Act shall have
terminated or expired;
 
  (d) any governmental or regulatory notices, approvals or other requirements
necessary to consummate the transactions contemplated hereby and to operate the
Business after the Effective Time in all material respects as it was operated
prior thereto (other than under the HSR Act) shall have been given, obtained or
complied with, as applicable;
 
  (e) the S-4 shall have become effective under the Securities Act and shall
not be the subject of any stop order or proceedings seeking a stop order and
Parent shall have received all state securities laws or "blue sky" permits and
authorizations necessary to issue shares of Parent Common Stock in exchange for
Shares in the Merger; and
 
  (f) The Company shall have received from PricewaterhouseCoopers LLP and
Parent shall have received from Arthur Andersen LLP, independent accountants
for the Company and Parent, respectively, a copy of a letter addressed to the
Company and Parent, respectively, each dated the Closing Date, in substance
reasonably satisfactory to Parent and the Company (and which may contain
customary qualifications and assumptions), to the effect that such independent
accountants concur with the Company's and Parent's managements' conclusions
that no conditions exist related to the Company or Parent, respectively, that
would preclude Parent from accounting for the Merger as a "pooling of
interests."
 
  Section 5.2. Conditions to the Obligations of the Company. The obligation of
the Company to effect the Merger is subject to the satisfaction at or prior to
the Effective Time of the following conditions:
 
  (a) the representations and warranties of Parent and Acquisition contained in
this Agreement or in the Stock Option Agreement of even date herewith between
Parent and the Company (the "Stock Option Agreement") shall be true and correct
(except to the extent that the aggregate of all breaches thereof would not have
a Material Adverse Effect on Parent) at and as of the Effective Time with the
same effect as if made at
 
                                      A-29
<PAGE>
 
and as of the Effective Time (except to the extent such representations
specifically related to an earlier date, in which case such representations
shall be true and correct as of such earlier date, and in any event, subject to
the foregoing Material Adverse Effect qualification) and, at the Closing,
Parent and Acquisition shall have delivered to the Company a certificate to
that effect, executed by two (2) executive officers of Parent and Acquisition;
 
  (b) each of the covenants and obligations of Parent and Acquisition to be
performed at or before the Effective Time pursuant to the terms of this
Agreement shall have been duly performed in all material respects at or before
the Effective Time and, at the Closing, Parent and Acquisition shall have
delivered to the Company a certificate to that effect, executed by two (2)
executive officers of Parent and Acquisition;
 
  (c) the shares of Parent Common Stock issuable to the Company's stockholders
pursuant to this Agreement and such other shares required to be reserved for
issuance in connection with the Merger shall have been authorized for listing
on the NYSE upon official notice of issuance;
 
  (d) the Company shall have received the opinion of tax counsel to the Company
to the effect that (i) the Merger will be treated for Federal income tax
purposes as a reorganization within the meaning of Section 368(a) of the Code
and (ii) each of Parent, Acquisition and the Company will be a party to the
reorganization within the meaning of Section 368(b) of the Code, which opinion
may rely on the representations set forth in Exhibits B-1 and B-2 and such
other representations as such counsel reasonably deems appropriate and such
opinion shall not have been withdrawn or modified in any material respect;
 
  (e) the Company shall have received the opinion of legal counsel to Parent as
to the matters set forth in Exhibit C;
 
  (f) Parent shall have obtained the consent or approval of each person whose
consent or approval shall be required in connection with the transactions
contemplated hereby under any loan or credit agreement, note, mortgage,
indenture, lease, or other agreement or instrument, except those for which
failure to obtain such consents and approvals would not, in the reasonable
opinion of the Company, individually or in the aggregate, have a Material
Adverse Effect on Parent; and
 
  (g) there shall have been no events, changes or effects with respect to
Parent or its subsidiaries having or that would reasonably be expected to have
a Material Adverse Effect on Parent,
 
  Section 5.3. Conditions to the Obligations of Parent and Acquisition. The
respective obligations of Parent and Acquisition to effect the Merger are
subject to the satisfaction at or prior to the Effective Time of the following
conditions:
 
  (a) the representations and warranties of the Company contained in this
Agreement (other than those contained in Section 2.24) and in the Stock Option
Agreement shall be true and correct (except to the extent that the aggregate of
all breaches thereof would not have a Material Adverse Effect on the Company)
at and as of the Effective Time with the same effect as if made at and as of
the Effective Time (except to the extent such representations specifically
related to an earlier date, in which case such representations shall be true
and correct as of such earlier date, and in any event, subject to the foregoing
Material Adverse Effect qualification) and the representations and warranties
of the Company contained in Section 2.24 shall be true and correct in all
respects at and as of the Effective Time, and, at the Closing, the Company
shall have delivered to Parent and Acquisition a certificate to that effect,
executed by two (2) executive officers of the Company;
 
  (b) each of the covenants and obligations of the Company to be performed at
or before the Effective Time pursuant to the terms of this Agreement shall have
been duly performed in all material respects at or before the Effective Time
and, at the Closing, the Company shall have delivered to Parent and Acquisition
a certificate to that effect, executed by two (2) executive officers of the
Company;
 
 
                                      A-30
<PAGE>
 
  (c) Parent shall have received from each affiliate of the Company referred to
in Sections 2.21 and 4.13(a) an executed copy of the letter attached hereto as
Exhibit A-1;
 
  (d) there shall have been no events, changes or effects with respect to the
Company or its subsidiaries having or that, individually or in the aggregate,
would reasonably be expected to have, a Material Adverse Effect on the Company;
 
  (e) Parent shall have received the opinion of tax counsel to Parent to the
effect that (i) the Merger will be treated for Federal income tax purposes as a
reorganization within the meaning of Section 368(a) of the Code and (ii) each
of Parent, Acquisition and the Company will be a party to the reorganization
within the meaning of Section 368(b) of the Code, which opinion may rely on the
representations set forth in Exhibits B-1 and B-2 and such other
representations as such counsel reasonably deems appropriate, and such opinion
shall not have been withdrawn or modified in any material respect;
 
  (f) Parent shall have received the opinion of legal counsel to the Company as
to the matters set forth in Exhibit D;
 
  (g) the Company shall have obtained the consent or approval of each person
whose consent or approval shall be required in order to permit the succession
by the Surviving Corporation pursuant to the Merger to any obligation right or
interest of the Company or any subsidiary of the Company the agreements and
instruments, set forth in Section 5.3(g) of the Company Disclosure Schedule;
and
 
  (h) Keith R. Lobo shall not have questioned the validity or enforceability of
the employment or non-competition agreement dated the date hereof with Parent
or otherwise expressed his intent not to continue his employment with the
Surviving Corporation.
 
                                   ARTICLE 6
 
                         TERMINATION; AMENDMENT; WAIVER
 
  Section 6.1. Termination. This Agreement may be terminated and the Merger may
be abandoned at any time prior to the Effective Time whether before or after
approval and adoption of this Agreement by the Company's stockholders:
 
  (a) by mutual written consent of Parent, Acquisition and the Company;
 
  (b) by Parent and Acquisition or the Company if (i) any court of competent
jurisdiction in the United States or other United States federal or state
Governmental Entity shall have issued a final order, decree or ruling, or taken
any other final action, restraining, enjoining or otherwise prohibiting the
Merger and such order, decree, ruling or other action is or shall have become
nonappealable or (ii) the Merger has not been consummated by June 30, 1999 (the
"Final Date"); provided that no party may terminate this Agreement pursuant to
this clause (ii) if such party's failure to fulfill any of its obligations
under this Agreement shall have been the reason that the Effective Time shall
not have occurred on or before said date;
 
  (c) by the Company if (i) there shall have been a breach of any
representation or warranty on the part of Parent or Acquisition set forth in
this Agreement or if any representation or warranty of Parent or Acquisition
shall have become untrue such that the conditions set forth in Section 5.2(a)
would be incapable of being satisfied by the Final Date, provided that the
Company has not breached any of its obligations hereunder in any material
respect; (ii) there shall have been a breach by Parent or Acquisition of any of
their respective covenants or agreements hereunder having a Material Adverse
Effect on Parent or materially adversely affecting (or materially delaying) the
consummation of the Merger, and Parent or Acquisition, as the case may be, has
not cured such breach within twenty (20) business days after notice by the
Company thereof, provided that the Company has not breached any of its
obligations hereunder in any material respect; (iii) the Company
 
                                      A-31
<PAGE>
 
shall have convened a meeting of its stockholders to vote upon the Merger and
shall have failed to obtain the requisite vote of its stockholders at such
meeting (including any adjournments thereof); or (iv) the Company Board has
received a Superior Proposal, has complied with the provisions of Section
4.4(b), and has made the payment called for by Section 6.3(a); or
 
  (d) by Parent and Acquisition if (i) there shall have been a breach of any
representation or warranty on the part of the Company set forth in this
Agreement or if any representation or warranty of the Company shall have become
untrue such that the conditions set forth in Section 5.3(a) would be incapable
of being satisfied by the Final Date, provided that neither Parent nor
Acquisition has breached any of their respective obligations hereunder in any
material respect; (ii) there shall have been a breach by the Company of its
covenants or agreements hereunder having a Material Adverse Effect on the
Company or materially adversely affecting (or materially delaying) the
consummation of the Merger, and the Company has not cured such breach within
twenty (20) business days after notice by Parent or Acquisition thereof,
provided that neither Parent nor Acquisition has breached any of their
respective obligations hereunder in any material respect; (iii) the Company
Board shall have recommended to the Company's stockholders a Superior Proposal;
(iv) the Company Board shall have withdrawn or adversely modified its approval
or recommendation of this Agreement or the Merger; (v) the Company shall have
ceased using all reasonable efforts to call, give notice of, or convene or hold
a stockholders' meeting to vote on the Merger as promptly as practicable after
the date hereof or shall have adopted a resolution not to effect any of the
foregoing; or (vi) the Company shall have convened a meeting of its
stockholders to vote upon the Merger and shall have failed to obtain the
requisite vote of its stockholders at such meeting (including any adjournments
thereof).
 
  Section 6.2. Effect of Termination. In the event of the termination and
abandonment of this Agreement pursuant to Section 6.1, this Agreement shall
forthwith become void and have no effect without any liability on the part of
any party hereto or its affiliates, directors, officers or stockholders other
than the provisions of this Section 6.2 and Sections 4.8(c) and 6.3 hereof.
Nothing contained in this Section 6.2 shall relieve any party from liability
for any breach of this Agreement prior to such termination.
 
  Section 6.3. Fees and Expenses.
 
  (a) In the event that this Agreement shall be terminated pursuant to:
 
    (i) Section 6.1(c)(iv) or 6.1(d)(iii), (iv) or (v);
 
    (ii) Section 6.1(d)(i) or (ii) and within twelve (12) months thereafter
  the Company enters into an agreement with respect to a Company Acquisition
  or a Company Acquisition occurs involving any party (or any affiliate
  thereof) (x) with whom the Company (or its agents) had negotiations with a
  view to a Company Acquisition, (y) to whom the Company (or its agents)
  furnished information with a view to a Company Acquisition or (z) who had
  submitted a proposal or expressed an interest in a Company Acquisition, in
  the case of each of clauses (x), (y) and (z), prior to such termination; or
 
    (iii) Section 6.1(c)(iii) or 6.1(d)(vi) and at the time of the Company
  stockholders' meeting at which the Company failed to obtain the requisite
  vote there shall be outstanding at that time an offer by a Third Party to
  consummate, or a third party shall have publicly announced (and not
  withdrawn) a plan or proposal with respect to, a Company Acquisition;
 
    Parent and Acquisition would suffer direct and substantial damages, which
  damages cannot be determined with reasonable certainty. To compensate
  Parent and Acquisition for such damages the Company shall pay to Parent the
  amount of $10,557,000 as liquidated damages immediately upon the occurrence
  of the event described in this Section 6.3(a) giving rise to such damages.
  It is specifically agreed that the amount to be paid pursuant to this
  Section 6.3(a) represents liquidated damages and not a penalty. The Company
  hereby waives any right to set-off or counterclaim against such amount.
 
  (b) Upon the termination of this Agreement pursuant to Section 6.1(c)(iii),
(iv) or 6.1(d)(i), (ii), (iv), (v) or (vi), in addition to any other remedies
that Parent, Acquisition or their affiliates may have as a result of such
 
                                      A-32
<PAGE>
 
termination, the Company shall pay to Parent the amount of $3,500,000 as
reimbursement for the costs, fees and expenses incurred by any of them or on
their behalf in connection with this Agreement, the Merger and the consummation
of all transactions contemplated by this Agreement (including fees payable to
investment bankers, counsel to any of the foregoing and accountants).
 
  (c) Upon the termination of this Agreement pursuant to Section 6.1(c)(i) or
(ii), in addition to any other remedies that the Company or its affiliates may
have as a result of such termination, Parent shall pay to the Company the
amount of $3,500,000 as reimbursement for the costs, fees and expenses incurred
by any of them or on their behalf in connection with this Agreement, the Merger
and the consummation of all transactions contemplated by this Agreement
(including fees payable to investment bankers, counsel to any of the foregoing
and accountants).
 
  (d) Except as specifically provided in this Section 6.3, each party shall
bear its own expenses in connection with this Agreement and the transactions
contemplated hereby.
 
  Section 6.4. Amendment. This Agreement may be amended by action taken by the
Company, Parent and Acquisition at any time before or after approval of the
Merger by the stockholders of the Company but after any such approval no
amendment shall be made that requires the approval of such stockholders under
applicable law without such approval. This Agreement (including, subject to
Section 4.15, the Company Disclosure Schedule) may be amended only by an
instrument in writing signed on behalf of the parties hereto.
 
  Section 6.5. Extension; Waiver. At any time prior to the Effective Time, each
party hereto may (i) extend the time for the performance of any of the
obligations or other acts of the other party, (ii) waive any inaccuracies in
the representations and warranties of the other party contained herein or in
any document certificate or writing delivered pursuant hereto or (iii) waive
compliance by the other party with any of the agreements or conditions
contained herein. Any agreement on the part of any party hereto to any such
extension or waiver shall be valid only if set forth in an instrument, in
writing, signed on behalf of such party. The failure of any party hereto to
assert any of its rights hereunder shall not constitute a waiver of such
rights.
 
                                   ARTICLE 7
 
                                 MISCELLANEOUS
 
  Section 7.1. Nonsurvival of Representations and Warranties. The
representations and warranties made herein shall not survive beyond the
Effective Time or a termination of this Agreement. This Section 7.1 shall not
limit any covenant or agreement of the parties hereto that by its terms
requires performance after the Effective Time.
 
  Section 7.2. Entire Agreement; Assignment. This Agreement (including the
Company Disclosure Schedule) (a) constitutes the entire agreement between the
parties hereto with respect to the subject matter hereof and supersedes all
other prior agreements and understandings both written and oral between the
parties with respect to the subject matter hereof and (b) shall not be assigned
by operation of law or otherwise; provided, however, that Acquisition may
assign any or all of its rights and obligations under this Agreement to any
wholly owned subsidiary of Parent, but no such assignment shall relieve
Acquisition of its obligations hereunder if such assignee does not perform such
obligations.
 
  Section 7.3. Validity. If any provision of this Agreement or the application
thereof to any person or circumstance is held invalid or unenforceable, the
remainder of this Agreement and the application of such provision to other
persons or circumstances shall not be affected thereby and to such end the
provisions of this Agreement are agreed to be severable.
 
  Section 7.4. Notices. All notices, requests, claims, demands and other
communications hereunder shall be in writing and shall be given (and shall be
deemed to have been duly given upon receipt) by delivery in
 
                                      A-33
<PAGE>
 
person, by facsimile or by registered or certified mail (postage prepaid,
return receipt requested) to each other party as follows:
 
<TABLE>
 <C>                             <S>
    if to Parent or Acquisition: Cadence Design Systems,
                                 Inc.
                                 2655 Seely Road
                                 San Jose, California
                                 95134
                                 Telecopier: (408) 944-
                                 6855
                                 Attention: General
                                 Counsel
    with a copy to:              Gibson, Dunn & Crutcher
                                 LLP
                                 One Montgomery Street
                                 Telesis Tower
                                 San Francisco, CA 94104
                                 Telecopier: (415) 986-
                                 5309
                                 Attention: Kenneth R.
                                 Lamb
    if to the Company to:        Quickturn Design
                                 Systems, Inc.
                                 55 West Trimble Road
                                 San Jose, California
                                 95131
                                 Telecopier: (408) 914-
                                 6001
                                 Attention: President
    with a copy to:              Wilson, Sonsini, Rosati
                                 & Goodrich LLP
                                 650 Page Mill Road
                                 Palo Alto, CA 94304
                                 Telecopier: (650) 493-
                                 6811
                                 Attention: Larry Sonsini
</TABLE>
 
or to such other address as the person to whom notice is given may have
previously furnished to the others in writing in the manner set forth above.
 
  Section 7.5. Governing Law. This Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware without regard to the
principles of conflicts of law thereof.
 
  Section 7.6. Descriptive Headings. The descriptive headings herein are
inserted for convenience of reference only and are not intended to be part of
or to affect the meaning or interpretation of this Agreement.
 
  Section 7.7. Parties in Interest. This Agreement shall be binding upon and
inure solely to the benefit of each party hereto and its successors and
permitted assigns and, except as expressly provided herein, including in
Sections 4.12 and 7.2, nothing in this Agreement is intended to or shall confer
upon any other person any rights, benefits or remedies of any nature whatsoever
under or by reason of this Agreement.
 
  Section 7.8. Certain Definitions. For the purposes of this Agreement the
term:
 
  (a) "affiliate" means (except as otherwise provided in Sections 2.21 and
4.14) a person that, directly or indirectly, through one or more intermediaries
controls, is controlled by or is under common control with the first-mentioned
person;
 
  (b) "business day" means any day other than a day on which the NYSE is
closed;
 
  (c) "capital stock" means common stock, preferred stock, partnership
interests, limited liability company interests or other ownership interests
entitling the holder thereof to vote with respect to matters involving the
issuer thereof;
 
 
                                      A-34
<PAGE>
 
  (d) "Company Acquisition" means the occurrence of any of the following
events: (i) the acquisition of the Company by merger or otherwise by any Third
Party; (ii) the acquisition by a Third Party of any material portion of the
assets of the Company and its subsidiaries taken as a whole; or (iii) the
acquisition by a Third Party of thirty percent (30%) or more of the outstanding
Shares or any securities convertible into or exchangeable for such number of
Shares;
 
  (e) "knowledge" or "known" means, with respect to any matter in question, the
actual knowledge of such matter of any executive officer of the Company or
Parent, as the case may be;
 
  (f) "include" or "including" means "include, without limitation" or
"including, without limitation," as the case may be, and the language following
"include" or "including" shall not be deemed to set forth an exhaustive list.
 
  (g) "person" means an individual, corporation, partnership, limited liability
company, association, trust, unincorporated organization or other legal entity
including any Governmental Entity; and
 
  (h) "subsidiary" or "subsidiaries" of the Company, Parent, the Surviving
Corporation or any other person means any corporation, partnership, limited
liability company, association, trust, unincorporated association or other
legal entity of which the Company, Parent, the Surviving Corporation or any
such other person, as the case may be (either alone or through or together with
any other subsidiary), owns, directly or indirectly, 50% or more of the capital
stock the holders of which are generally entitled to vote for the election of
the board of directors or other governing body of such corporation or other
legal entity.
 
  Section 7.9. Personal Liability. This Agreement shall not create or be deemed
to create or permit any personal liability or obligation on the part of any
direct or indirect stockholder of the Company or Parent or Acquisition or any
officer, director, employee, agent, representative or investor of any party
hereto.
 
  Section 7.10. Specific Performance. The parties hereby acknowledge and agree
that the failure of any party to perform its agreements and covenants
hereunder, including its failure to take all actions as are necessary on its
part to the consummation of the Merger, will cause irreparable injury to the
other parties, for which damages, even if available, will not be an adequate
remedy. Accordingly, each party hereby consents to the issuance of injunctive
relief by any court of competent jurisdiction to compel performance of such
party's obligations and to the granting by any court of the remedy of specific
performance of its obligations hereunder; provided, however, that if a party
hereto is entitled to receive any payment or reimbursement of expenses pursuant
to Section 6.3(a), (b) or (c) it shall not be entitled to specific performance
to compel the consummation of the Merger.
 
  Section 7.11. Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original but all of which
shall constitute one and the same agreement.
 
                  (Remainder of page intentionally left blank)
 
                                      A-35
<PAGE>
 
  IN WITNESS WHEREOF, each of the parties has caused this Agreement to be duly
executed on its behalf as of the day and year first above written.
 
                                          CADENCE DESIGN SYSTEMS, INC.
 
                                          By:/s/ H. Raymond Bingham
                                            -----------------------------------
                                            Name: H. Raymond Bingham Title:
                                            Executive Vice President andChief
                                            Financial Officer
 
                                          QUICKTURN DESIGN SYSTEMS, INC.
 
                                          By:/s/ Keith R. Lobo
                                            -----------------------------------
                                            Name: Keith R. Lobo Title:
                                            President and Chief Executive
                                            Officer
 
                                          CDSI ACQUISITION, INC.
 
                                          By:/s/ H. Raymond Bingham
                                            -----------------------------------
                                            Name: H. Raymond Bingham Title:
                                            Executive Vice President andChief
                                            Financial Officer
 
 
                                      A-36
<PAGE>
 
                                                                      APPENDIX B
 
                             STOCK OPTION AGREEMENT
 
  THIS STOCK OPTION AGREEMENT is dated as of December 8, 1998, between Cadence
Design Systems, Inc., a Delaware corporation ("Grantee"), and Quickturn Design
Systems, Inc., a Delaware corporation ("Issuer").
 
                                    RECITALS
 
  A. Grantee, CDSI Acquisition, Inc. ("Acquisition") and Issuer are
simultaneously entering into an Agreement and Plan of Merger (the "Merger
Agreement") which provides, among other things, that, upon the terms and
subject to the conditions thereof, Acquisition will be merged with and into
Issuer (the "Merger").
 
  B. As a condition to its willingness to enter into the Merger Agreement,
Grantee has required that Issuer agree, and Issuer has agreed, to enter into
this Stock Option Agreement, which provides, among other things, that Issuer
grant to Grantee an option to purchase shares of Issuer's Common Stock, $.001
par value per share ("Issuer Common Stock"), upon the terms and subject to the
conditions provided for herein.
 
  NOW, THEREFORE, in consideration of the premises and mutual covenants and
agreements contained in this Stock Option Agreement and the Merger Agreement,
the parties agree as follows:
 
  1. GRANT OF OPTION. Subject to the terms and conditions of this Stock Option
Agreement, Issuer hereby grants to Grantee an irrevocable option (the "Option")
to purchase 3,619,100 shares of Issuer Common Stock (the "Option Shares"), in
the manner set forth below, at an exercise price of $14.00 per share of Issuer
Common Stock, subject to adjustment as provided below (the "Option Price").
Capitalized terms used herein but not defined herein shall have the meanings
set forth in the Merger Agreement.
 
  2. EXERCISE OF OPTION.
 
    (a) Subject to the satisfaction or waiver of the conditions set forth in
  Section 9 of this Stock Option Agreement, prior to the termination of this
  Stock Option Agreement in accordance with its terms, Grantee may exercise
  the Option, in whole or in part, at any time or from time to time on or
  after the occurrence of a Triggering Event. The Option shall terminate and
  not be exercisable at any time following the Expiration Date (as defined in
  Section 11). The term "Triggering Event" shall mean the time immediately
  prior to the occurrence of any of the events (or series of events)
  specified in Section 6.3(a) of the Merger Agreement giving rise to the
  obligation of the Company to pay the fee specified in Section 6.3(a). The
  Option will not be exercisable if Grantee willfully and materially breached
  the Merger Agreement.
 
    (b) In the event Grantee wishes to exercise the Option at such time as
  the Option is exercisable and has not terminated, Grantee shall deliver
  written notice (the "Exercise Notice") to Issuer specifying its intention
  to exercise the Option, the total number of Option Shares it wishes to
  purchase and a date and time for the closing of such purchase (a "Closing")
  not less than one (1) nor more than thirty (30) business days after the
  later of (i) the date such Exercise Notice is given and (ii) the expiration
  or termination of any applicable waiting period under the HSR Act. If prior
  to the Expiration Date (as defined in Section 11 below) any person or Group
  (other than Grantee and its affiliates) shall have acquired thirty percent
  (30%) or more of the then outstanding shares of Issuer Common Stock (a
  "Share Acquisition"), or Issuer shall have entered into a written
  definitive agreement with any person or group (other than Grantee and its
  affiliates) providing for a Company Acquisition, then Grantee, in lieu of
  exercising the Option, shall have the right at any time thereafter (for so
  long as the Option is exercisable under Section 2(a) hereof) to request in
  writing that Issuer pay, and promptly (but in any event not more than five
  (5) business days) after the giving by Grantee of such request, Issuer
  shall pay to Grantee, in cancellation of the Option, an amount in cash (the
  "Cancellation Amount") equal to (i) the lesser of
 
                                      B-1
<PAGE>
 
    (x) the excess over the Option Price of the greater of (A) the last
        sale price of a share of Issuer Common Stock as reported on the
        Nasdaq National Market System on the last trading day prior to the
        date of the Exercise Notice, and (B) (1) the highest price per
        share of Issuer Common Stock offered to be paid or paid by any such
        person or Group pursuant to or in connection with such Share
        Acquisition or Company Acquisition or (2) if such Company
        Acquisition consists of a purchase and sale of assets, the
        aggregate consideration offered to be paid or paid in any
        transaction or proposed transaction in connection with a Company
        Acquisition, divided by the number of shares of Issuer Common Stock
        then outstanding, and
 
    (y) $3.8890884474
 
  multiplied by (ii) the number of Option Shares then covered by the Option.
  If all or a portion of the price per share of Issuer Common Stock offered,
  paid or payable or the aggregate consideration offered, paid or payable for
  the stock or assets of Issuer, each as contemplated by the preceding
  sentence, consists of noncash consideration, such price or aggregate
  consideration shall be the cash consideration, if any, plus the fair market
  value of the non-cash consideration as determined by the investment bankers
  of Issuer and the investment bankers of Grantee.
 
    (c) Notwithstanding anything to the contrary contained herein, the
  economic benefit, if any, which Grantee may derive hereunder shall be
  limited as follows: (1) in no event shall Grantee's Total Payment (as
  defined below) exceed $14,075,000, and Grantee shall pay any excess over
  such amount to Issuer, and (2) the Option may not be exercised for a number
  of Option Shares as would, as of the date of exercise, result in a Notional
  Total Payment (as defined below), together with the actual Total Payment
  immediately preceding such exercise, exceeding $14,075,000. As used herein,
  (1) "Total Payment" shall mean the sum (before taxes) of the following: (i)
  any Cancellation Amount received by Grantee pursuant to Section 2(b)
  hereof, (ii)(x) the net cash amounts received by Grantee pursuant to the
  sale of Option Shares (or any other securities into which such Option
  Shares shall be converted or exchanged) pursuant to Section 12 or otherwise
  to any unaffiliated party, less (y) the aggregate Option Price for such
  shares, (iii) any amounts received by Grantee upon transfer of the Option
  (or any portion thereof) to any unaffiliated party, and (iv) the amount
  actually received by Grantee pursuant to Section 6.3(a) of the Merger
  Agreement; and (2) "Notional Total Payment" with respect to any number of
  Option Shares as to which Grantee may propose to exercise the Option shall
  be the Total Payment determined as of the date of such proposed exercise
  assuming that the Option were exercised on such date for such number of
  shares and assuming further that such shares, together with all other
  Option Shares held by Grantee as of such date, were sold for cash at the
  closing market price for the Issuer Common Stock as of the close of
  business on the preceding trading day (less customary brokerage
  commissions). For purposes of this Section 2, references to Grantee shall
  be deemed to include references to any affiliate of Grantee.
 
  3. PAYMENT OF OPTION PRICE AND DELIVERY OF CERTIFICATE. Any Closings under
Section 2 of this Stock Option Agreement shall be held at the principal
executive offices of Issuer, or at such other place as Issuer and Grantee may
agree. At any Closing hereunder, (a) Grantee or its designee will make payment
to Issuer of the aggregate price for the Option Shares being so purchased by
delivery of a certified check, official bank check or wire transfer of funds
pursuant to Issuer's instructions payable to Issuer in an amount equal to the
product obtained by multiplying the Option Price by the number of Option Shares
to be purchased, and (b) upon receipt of such payment Issuer will deliver to
Grantee or its designee a certificate or certificates representing the number
of validly issued, fully paid and non-assessable Option Shares so purchased, in
the denominations and registered in such names designated to Issuer in writing
by Grantee.
 
  4. REGISTRATION AND LISTING OF OPTION SHARES.
 
    (a) Issuer will, if requested by Grantee at any time or from time to time
  within two (2) years following a Triggering Event (the "Registration
  Period"), in order to permit the sale or other disposition of the Option
  Shares that have been acquired by or are issuable to Grantee upon exercise
  of the Option ("Registrable Securities"), register under the Securities Act
  of 1933, as amended (the "Act"), the
 
                                      B-2
<PAGE>
 
  offering, sale and delivery, or other disposition, of the Registrable
  Securities. In connection with any such sale or other disposition, Grantee
  shall use all reasonable efforts to prevent any person or group from
  purchasing through such offering shares of Issuer Common Stock representing
  more than five percent (5%) of the outstanding Common Stock of Issuer on a
  fully diluted basis at the time of such request. Any such Registration
  Notice must relate to a number of Registrable Securities equal to at least
  twenty percent (20%) of the Option Shares, unless the remaining number of
  Registrable Securities is less than such amount, in which case Grantee
  shall be entitled to exercise its rights hereunder but only for all of the
  remaining Registrable Securities (a "Permitted Offering"). Grantee's rights
  hereunder shall terminate at such time as Grantee shall be entitled to sell
  all of the remaining Registrable Securities pursuant to Rule 144(k) under
  the Act. Issuer will use all reasonable efforts to qualify any Registrable
  Securities Grantee desires to sell or otherwise dispose of under applicable
  state securities or "blue sky" laws; provided, however, that Issuer shall
  not be required to qualify to do business, or consent to general service of
  process, in any jurisdiction by reason of this provision. Without Grantee's
  prior written consent, no other securities may be included in any such
  registration. Issuer will use all reasonable efforts to cause each such
  registration statement to become effective, to obtain all consents or
  waivers of other parties that are required therefor and to keep such
  registration statement effective for a period of ninety (90) days from the
  day such registration statement first becomes effective. The obligations of
  Issuer hereunder to file a registration statement and to maintain its
  effectiveness may be suspended for one or more periods not exceeding ninety
  (90) days in the aggregate if the Board of Directors of Issuer shall have
  determined in good faith that the filing of such registration statement or
  the maintenance of its effectiveness would require disclosure of nonpublic
  information that would materially and adversely affect Issuer, or Issuer is
  required under the Act to include audited financial statements for any
  period in such registration statement and such financial statements are not
  yet available for inclusion in such registration statement. Grantee shall
  be entitled to make up to two (2) requests under this Section 4(a). For
  purposes of determining whether the two (2) requests have been made under
  this Section 4(a), only requests relating to a registration statement that
  has become effective under the Act will be counted.
 
    (b) If, during the Registration Period, Issuer shall propose to register
  under the Act the offering, sale and delivery of Issuer's Common Stock for
  cash for its own account or for any other stockholder of Issuer pursuant to
  a firm underwriting, it will, in addition to Issuer's other obligations
  under this Section 4, allow Grantee the right to participate in such
  registration provided that Grantee participates in such underwriting;
  provided, however, that, if the managing underwriter of such offering
  advises Issuer in writing that in its opinion the number of shares of
  Issuer's Common Stock requested to be included in such registration exceeds
  the number that it would be in the best interests of Issuer to sell in such
  offering, Issuer will, after fully including therein all shares of Issuer
  Common Stock to be sold by Issuer, include the shares of Issuer Common
  Stock requested to be included therein by Grantee pro rata (based on the
  number of shares of Issuer Common Stock requested to be included therein)
  with the shares of Issuer Common Stock requested to be included therein by
  persons other than Issuer and persons to whom Issuer owes a contractual
  obligation (other than any director, officer or employee of Issuer to the
  extent any such person is not currently owed such contractual obligation).
 
    (c) The expenses associated with the preparation and filing of any
  registration statement pursuant to this Section 4 and any sale covered
  thereby (including any fees related to blue sky qualifications and filing
  fees in respect of SEC or the National Association of Securities Dealers,
  Inc.) ("Registration Expenses") will be paid by Issuer, except for
  underwriting discounts or commissions or brokers' fees in respect of shares
  of Issuer's Common Stock to be sold by Grantee and the fees and
  disbursements of Grantee's counsel; provided, however, that Issuer will not
  be required to pay for any Registration Expenses with respect to such
  registration if the registration request is subsequently withdrawn at the
  request of Grantee unless Grantee agrees to forfeit its right to request
  one registration; provided further, however, that, if at the time of such
  withdrawal Grantee has learned of a material adverse change in the results
  of operations, condition, business or prospects of Issuer not known to
  Grantee at the time of the request and has withdrawn the request within a
  reasonable period of time following disclosure by Issuer to Grantee of
 
                                      B-3
<PAGE>
 
  such material adverse change, then Grantee shall not be required to pay any
  of such expenses and will retain all remaining rights to request
  registration. Grantee will provide all information reasonably requested by
  Issuer for inclusion in any registration statement to filed hereunder.
 
    (d) The registration rights granted under this Section 4 are subject to
  and are limited by any registration rights previously granted by Issuer,
  and Grantee acknowledges that the registration rights granted under this
  Section 4 shall be subject to any such limitations.
 
    (e) In connection with each registration under this Section 4, Issuer
  shall indemnify and hold each holder of Option or Option Shares
  participating in such offering (a "Holder"), its underwriters and each of
  their respective affiliates harmless against any and all losses, claims,
  damage, liabilities and expenses (including, without limitation,
  investigation expenses and fees and disbursements of counsel and
  accountants), joint or several, to which such Holder, its underwriters and
  each of their respective affiliates may become subject, under the Act or
  otherwise, insofar as such losses, claims, damages, liabilities or expenses
  (or actions in respect thereof) arise out of or are based upon an untrue
  statement or alleged untrue statement of a material fact contained in any
  registration statement (including any prospectus therein), or any amendment
  or supplement thereto, or arise out of or are based upon the omission or
  alleged omission to state therein a material fact required to be stated
  therein or necessary to make the statements therein not misleading, other
  than such losses, claims, damages, liabilities or expenses (or actions in
  respect thereof) which arise out of or are based upon an untrue statement
  or alleged untrue statement of a material fact contained in written
  information furnished by a Holder to Issuer expressly for use in such
  registration statement.
 
    (f) In connection with any registration statement pursuant to this
  Section 4, each Holder agrees to furnish Issuer with such information
  concerning itself and the proposed sale or distribution as shall reasonably
  be required in order to ensure compliance with the requirements of the Act
  and shall provide representations and warranties customary for selling
  shareholders who are unaffiliated with the issuer. In addition, Grantee and
  each Holder shall indemnify and hold Issuer, its underwriters and each of
  their respective affiliates harmless against any and all losses, claims,
  damages, liabilities and expenses (including, without limitation,
  investigation expenses and fees and disbursement of counsel and
  accountants), joint or several, to which Issuer, its underwriters and each
  of their respective affiliates may become subject under the Act or
  otherwise, insofar as such losses, claims, damages, liabilities or expenses
  (or actions in respect thereof) arise out of or are based upon an untrue
  statement or alleged untrue statement of a material fact contained in
  written information furnished by any Holder to Issuer expressly for use in
  such registration statement; provided, however, that in no event shall any
  indemnification amount contributed by a Holder hereunder exceed the
  proceeds of the offering received by such Holder.
 
    (g) Upon the issuance of Option Shares hereunder, Issuer will promptly
  list such Option Shares with the Nasdaq National Market System or on such
  national or other exchange on which the shares of Issuer Common Stock are
  at the time listed.
 
  5. REPRESENTATIONS AND WARRANTIES OF ISSUER. Issuer hereby represents and
warrants to Grantee as follows:
 
    (a) Issuer is a corporation duly organized, validly existing and in good
  standing under the laws of the State of Delaware and has requisite power
  and authority to enter into and perform its obligations under this Stock
  Option Agreement.
 
    (b) The execution and delivery of this Stock Option Agreement and the
  consummation of the transactions contemplated hereby have been duly and
  validly authorized by the Board of Directors of Issuer and no other
  corporate proceedings on the part of Issuer are necessary to authorized
  this Stock Option Agreement or to consummate the transactions contemplated
  hereby. The Board of Directors of Issuer has duly approved the issuance and
  sale of the Option Shares, upon the terms and subject to the
 
                                      B-4
<PAGE>
 
  conditions contained in this Stock Option Agreement, and the consummation
  of the transactions contemplated hereby. This Stock Option Agreement has
  been duly and validly executed and delivered by Issuer and, assuming this
  Stock Option Agreement has been duly and validly authorized, executed and
  delivered by Grantee, constitutes a valid and binding obligation of Issuer
  enforceable against Issuer in accordance with its terms, subject to
  bankruptcy, insolvency, reorganization, moratorium or other similar laws
  affecting or relating to creditors' rights generally; the availability of
  injunctive relief and other equitable remedies; and limitations imposed by
  law on indemnification for liability under federal securities laws.
 
    (c) Issuer has taken all necessary action to authorize and reserve for
  issuance and to permit it to issue, and at all times from the date of this
  Stock Option Agreement through the date of expiration of the Option will
  have reserved for issuance upon exercise of the Option, a sufficient number
  of authorized shares of Issuer Common Stock for issuance upon exercise of
  the Option, each of which, upon issuance pursuant to this Stock Option
  Agreement and when paid for as provided herein, will be validly issued,
  fully paid and nonassessable, and shall be delivered free and clear of all
  claims, liens, charges, encumbrances and security interests (other than
  those imposed by Grantee, its affiliate or by applicable law).
 
    (d) The execution, delivery and performance of this Stock Option
  Agreement by Issuer and the consummation by it of the transactions
  contemplated hereby except as required by the HSR Act and any material
  foreign competition authorities (if applicable), and, with respect to
  Section 4 hereof, compliance with the provisions of the Act and any
  applicable state securities laws, do not require the consent, waiver,
  approval, license or authorization of or result in the acceleration of any
  obligation under, or constitute a default under, any term, condition or
  provision of any charter or bylaw, or any indenture, mortgage, lien, lease,
  agreement, contract, instrument, order, judgment, ordinance, regulation or
  decree or any restriction to which Issuer or any property of Issuer or its
  subsidiaries is bound, except where failure to obtain such consents,
  waivers, approvals, licenses or authorizations or where such acceleration
  or defaults could not, individually or in the aggregate, reasonably be
  expected to have a Material Adverse Effect on Issuer.
 
  6. REPRESENTATIONS AND WARRANTIES OF GRANTEE. Grantee hereby represents and
warrants to Issuer that:
 
    (a) Grantee is a corporation duly organized, validly existing and in good
  standing under the laws of the State of Delaware, and has requisite power
  and authority to enter into and perform its obligations under this Stock
  Option Agreement.
 
    (b) The execution and delivery of this Stock Option Agreement and the
  consummation of the transactions contemplated hereby have been duly and
  validly authorized by the Board of Directors of Grantee and no other
  corporate proceedings on the part of Grantee are necessary to authorize
  this Stock Option Agreement or to consummate the transactions contemplated
  hereby. This Stock Option Agreement has been duly and validly executed and
  delivered by Grantee and, assuming this Stock Option Agreement has been
  duly executed and delivered by Issuer, constitutes a valid and binding
  obligation of Grantee enforceable against Grantee in accordance with its
  terms, subject to bankruptcy, insolvency, reorganization, moratorium or
  other similar laws affecting or relating to creditors' rights generally;
  the availability of injunctive relief and other equitable remedies; and
  limitations imposed by law on indemnification for liability under federal
  securities laws.
 
    (c) Grantee is acquiring the Option and it will acquire the Option Shares
  issuable upon the exercise thereof for its own account and not with a view
  to the distribution or resale thereof in any manner not in accordance with
  applicable law.
 
  7. COVENANTS OF GRANTEE. Grantee agrees not to transfer or otherwise dispose
of the Option or the Option Shares, or any interest therein, except that
Grantee may transfer or dispose of the Option Shares so long as such
transaction is in compliance with the Act and any applicable state securities
law. Grantee further agrees
 
                                      B-5
<PAGE>
 
to the placement of the following legend on the certificates) representing the
Option Shares (in addition to any legend required under applicable state
securities laws) and any legend referring to the provisions of Section 12
hereof:
 
  "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
  EITHER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
  APPLICABLE STATE LAW GOVERNING THE OFFER AND SALE OF SECURITIES. NO
  TRANSFER OR OTHER DISPOSITION OF THESE SHARES, OR OF ANY INTEREST THEREIN,
  MAY BE MADE EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER
  THE ACT AND SUCH OTHER STATE LAWS OR PURSUANT TO EXEMPTIONS FROM
  REGISTRATION UNDER THE ACT, SUCH OTHER STATE LAWS, AND THE RULES AND
  REGULATIONS PROMULGATED THEREUNDER."
 
  8. HSR COMPLIANCE EFFORTS. Grantee and Issuer shall take, or cause to be
taken, all reasonable action to consummate and make effective the transactions
contemplated by this Stock Option Agreement, including, without limitation,
reasonable efforts to obtain any necessary consents of third parties and
governmental agencies and the filing by Grantee and Issuer promptly after the
date hereof of any required HSR Act notification forms and the documents
required to comply with the HSR Act.
 
  9. CERTAIN CONDITIONS. The obligation of Issuer to issue Option Shares under
this Stock Option Agreement upon exercise of the Option shall be subject to the
satisfaction or waiver of the following conditions:
 
    (a) any waiting periods applicable to the acquisition of the Option
  Shares by Grantee pursuant to this Stock Option Agreement under the HSR Act
  and any material foreign competition laws shall have expired or been
  terminated;
 
    (b) the representations and warranties of Grantee made in Section 6 of
  this Stock Option Agreement shall be true and correct in all material
  respects as of the date of the Closing for the issuance of such Option
  Shares; and
 
    (c) no statute, rule or regulation shall be in effect, and no order,
  decree or injunction entered by any court of competent jurisdiction or
  governmental, regulatory or administrative agency or commission in the
  United States shall be in effect which prohibits the exercise of the Option
  or acquisition or issuance of Option Shares pursuant to this Stock Option
  Agreement.
 
  10. ADJUSTMENTS UPON CHANGES IN CAPITALIZATION. In the event of any change in
the number of issued and outstanding shares of Issuer Common Stock by reason of
any stock dividend, stock split, recapitalization, merger, rights offering,
share exchange or other change in the corporate or capital structure of Issuer,
Grantee shall receive, upon exercise of the Option, the stock or other
securities, cash or property to which Grantee would have been entitled if
Grantee had exercised the Option and had been a holder of record of shares of
Issuer Common Stock on the record date fixed for determination of holders of
shares of Issuer Common Stock entitled to receive such stock or other
securities, cash or property at the same aggregate price as the aggregate
Option Price of the Option Shares.
 
  11. EXPIRATION. The Option shall expire at the earlier of (y) the Effective
Time (as defined in the Merger Agreement) and (z) 5:00 p.m., California time,
on the day that is the twelve (12) month anniversary of the date on which the
Merger Agreement has been terminated in accordance with the terms thereof (such
expiration date is referred to as the "Expiration Date").
 
  12. ISSUER CALL. If Grantee has acquired Option Shares pursuant to exercise
of the Option (the date of any closing relating to any such exercise herein
referred to as an "Exercise Date"), then, at any time after the date thirteen
(13) months following such Exercise Date and prior to the date twenty-five (25)
months following such Exercise Date (the "Purchase Period"), Issuer may require
Grantee, upon delivery to Grantee of written
 
                                      B-6
<PAGE>
 
notice, to sell to Issuer any Option Shares held by Grantee as of the date that
is ten (10) business days after the date of such notice, up to a number of
shares equal to the number of Option Shares acquired by Grantee pursuant to
exercise of the Option in connection with such Exercise Date. The per share
purchase price for such sale (the "Issuer Call Price") shall be equal to the
higher of (i) the Option Price, less any dividends paid on the Option Shares to
be purchased by the Issuer pursuant to this Section 12, plus an amount equal to
a return at the rate of fifteen percent (15%) of the Option Price per year from
the Exercise Date and (b) an amount equal to the average of the high and low
trading prices per share of Issuer Common Stock for the thirty (30) trading day
period ending one day prior to the delivery of Issuer's notice exercising its
call rights pursuant to this Section 12. The closing of any sale of Option
Shares pursuant to this Section 12 shall take place at the principal offices of
Issuer at a time and on a date designated by Issuer in the aforementioned
notice to Grantee, which date shall be no more than thirty (30) and no less
than twelve (12) business days from the date of such notice. The Issuer Call
Price shall be paid in immediately available funds.
 
  13. GENERAL PROVISIONS.
 
    (a) Survival. All of the representations, warranties and covenants
  contained herein shall survive a Closing and shall be deemed to have been
  made as of the date hereof and as of the date of each Closing, except for
  the representations and warranties in Section 5(d) hereof which shall be
  deemed to have been made only as of the date hereof.
 
    (b) Further Assurances. If Grantee exercises the Option, or any portion
  thereof, in accordance with the terms of this Stock Option Agreement,
  Issuer and Grantee will execute and deliver all such further documents and
  instruments and use all reasonable efforts to take all such further action
  as may be necessary in order to consummate the transactions contemplated
  thereby.
 
    (c) Severability. It is the desire and intent of the parties that the
  provisions of this Stock Option Agreement be enforced to the fullest extent
  permissible under the law and public policies applied in each jurisdiction
  in which enforcement is sought. Accordingly, in the event that any
  provision of this Stock Option Agreement would be held in any jurisdiction
  to be invalid, prohibited or unenforceable for any reason, such provision,
  as to such jurisdiction, shall be ineffective, without invalidating the
  remaining provisions of this Stock Option Agreement or affecting the
  validity or enforceability of such provision in any other jurisdiction.
  Notwithstanding the foregoing, if such provision could be more narrowly
  drawn so as not be invalid, prohibited or unenforceable in such
  jurisdiction, it shall, as to such jurisdiction, be so narrowly drawn,
  without invalidating the remaining provisions of this Stock Option
  Agreement or affecting the validity or enforceability of such provision in
  any other jurisdiction.
 
    (d) Assignment; Transfer of Stock Option. This Stock Option Agreement
  shall be binding on and inure to the benefit of the parties hereto and
  their respective successors and permitted assigns; provided, however, that
  Issuer and Grantee, without the prior written consent of the other party,
  shall not be entitled to assign or otherwise transfer any of its rights or
  obligations hereunder and any such attempted assignment or transfer shall
  be void; provided, further, that Grantee shall be entitled to assign or
  transfer this Stock Option Agreement or any rights hereunder to any wholly-
  owned subsidiary of Grantee so long as such wholly-owned subsidiary agrees
  in writing to be bound by the terms and provisions hereof.
 
    (e) Specific Performance. The parties agree and acknowledge that in the
  event of a breach of any provision of this Stock Option Agreement, the
  aggrieved party would be without an adequate remedy at law. The parties
  therefore agree that in the event of a breach of any provision of this
  Stock Option Agreement, the aggrieved party may elect to institute and
  prosecute proceedings in any court of competent jurisdiction to enforce
  specific performance or to enjoin the continuing breach of such provisions,
  as well as to obtain damages for breach of this Stock Option Agreement. By
  seeking or obtaining any such relief, the aggrieved party will not be
  precluded from seeking or obtaining any other relief to which it may be
  entitled.
 
                                      B-7
<PAGE>
 
    (f) Amendments. This Stock Option Agreement may not be modified, amended,
  altered or supplemented except upon the execution and delivery of a written
  agreement executed by Grantee and Issuer.
 
    (g) Notices. All notices, requests, claims, demands and other
  communications hereunder shall be in writing and shall be deemed to be
  sufficient if contained in a written instrument and shall be deemed given
  if delivered personally, telecopied, sent by nationally-recognized,
  overnight courier or mailed by registered or certified mail (return receipt
  requested), postage prepaid, to the other party at the following addresses
  (or such other address for a party as shall be specified by like notice):
 
If to Grantee:
 
      Cadence Design Systems, Inc.
      2655 Seely Road
      San Jose, California 95134
      Telecopier: (408) 944-6855
      Attention: General Counsel
 
      with a copy to:
 
      Gibson, Dunn & Crutcher LLP
      One Montgomery Street
      Telesis Tower
      San Francisco, California 94104
      Telecopier: (415) 986-5309
      Attention: Kenneth R. Lamb
 
If to Issuer:
 
      Quickturn Design Systems, Inc.
      55 West Trimble Road
      San Jose, California 95131
      Telecopier: (408) 914-6001
      Attention: President
 
      with a copy to:
 
      Wilson, Sonsini, Rosati & Goodrich LLP
      650 Page Mill Road
      Palo Alto, CA 94304
      Telecopier: (650) 493-6811
      Attention: Larry Sonsini
 
  (h) Headings. The headings contained in this Stock Option Agreement are for
reference purposes only and shall not affect in any way the meaning or
interpretation of this Stock Option Agreement.
 
  (i) Counterparts. This Stock Option Agreement may be executed in one or more
counterparts, each of which shall be an original, but all of which together
shall constitute one and the same agreement.
 
  (j) Governing Law. This Stock Option Agreement shall be governed by and
construed in accordance with the laws of the State of Delaware without regard
to the principles of conflicts of law thereof.
 
  (k) Jurisdiction and Venue. Each of Issuer and Grantee hereby agrees that any
proceeding relating to this Stock Option Agreement shall be brought solely in a
court in the State of Delaware. Each of Issuer and Grantee hereby consents to
personal jurisdiction in any such action brought in any such Delaware court,
consents to service of process by registered mail made upon such party and such
party's agent and waives any objection to venue in any such Delaware court or
to any claim that any such Delaware court is an inconvenient forum.
 
 
                                      B-8
<PAGE>
 
  (l) Entire Agreement. This Stock Option Agreement and the Merger Agreement,
and any documents and instruments referred to herein and therein, constitute
the entire agreement between the parties hereto and thereto with respect to the
subject matter hereof and thereof and supersede all other prior agreements and
understandings, both written and oral, between the parties with respect to the
subject matter hereof and thereof. Nothing in this Stock Option Agreement shall
be construed to give any person other than the parties to this Stock Option
Agreement or their respective successors or permitted assigns any legal or
equitable right, remedy or claim under or in respect of this Stock Option
Agreement or any provision contained herein.
 
  (m) Expenses. Except as otherwise provided in this Stock Option Agreement,
each party shall pay its own expenses incurred in connection with this Stock
Option Agreement and the transactions contemplated hereby.
 
  IN WITNESS WHEREOF, the parties have caused this Stock Option Agreement to be
signed by their respective officers thereunto duly authorized as of the date
first written above.
 
                                          CADENCE DESIGN SYSTEMS, INC.
 
                                               /s/ H. Raymond Bingham
                                          By:
                                             ----------------------------------
                                          Name: H. Raymond Bingham
                                          Title: Executive Vice President and
                                               Chief Financial Officer
 
                                          QUICKTURN DESIGN SYSTEMS, INC.
 
                                               /s/ Keith R. Lobo
                                          By:
                                             ----------------------------------
                                          Name: Keith R. Lobo
                                          Title: President and Chief Executive
                                          Officer
 
                                      B-9
<PAGE>
 
                                                                      APPENDIX C
 
HAMBRECHT & QUIST LLC
 
                                                             ONE BUSH STREET
                                                            SAN FRANCISCO, CA
                                                                  94104
                                                             (415) 439-3000
 
December 8, 1998
 
CONFIDENTIAL
 
The Board of Directors
Quickturn Design Systems, Inc.
55 West Trimble Rd.
San Jose, CA 95131
 
Gentlemen:
 
  You have requested our opinion as to the fairness from a financial point of
view to the holders of the outstanding shares of common stock (the "Common
Stock") of Quickturn Design Systems Inc. ("Quickturn" or the "Company") of the
consideration to be received by such shareholders in connection with the
proposed merger of CDSI Acquisition, Inc. ("Merger Sub"), a wholly owned
subsidiary of Cadence Design Systems, Inc. ("Cadence"), with and into Quickturn
(the "Proposed Transaction") pursuant to the Agreement and Plan of Merger to be
dated as of December 8, 1998, among Cadence, Merger Sub, and Quickturn (the
"Agreement").
 
  We understand that the terms of the Agreement provide, among other things,
that each issued and outstanding share of Common Stock shall be converted into
the right to receive a number of shares of common stock of Cadence equal to
$14.00 per share, as more fully set forth in the Agreement. For purposes of
this opinion, we have assumed that the Proposed Transaction will qualify as a
tax-free reorganization under the United States Internal Revenue Code for the
shareholders of the Company and that the Proposed Transaction will be accounted
for as a pooling of interests.
 
  Hambrecht & Quist LLC ("Hambrecht & Quist"), as part of its investment
banking services, is regularly engaged in the valuation of businesses and their
securities in connection with mergers and acquisitions, strategic transactions,
corporate restructurings, negotiated underwritings, secondary distributions of
listed and unlisted securities, private placements and valuations for corporate
and other purposes. We have acted as a financial advisor to the Board of
Directors of Quickturn in connection with the Proposed Transaction, and we will
receive a fee for our services, which include the rendering of this opinion.
 
  In the past, we have provided investment banking and other financial advisory
services Quickturn and have received fees for rendering these services.
Hambrecht & Quist served as co-manager in the Company's December 15, 1993
initial public offering, advised the Company in the January 10, 1996 adoption
of its Shareholder Rights Plan, advised the Company in its February 1997 merger
with SpeedSim, Inc., and advised the Company in its June 1997 acquisition of
the assets of Arkos Design, Inc. In the ordinary course of business, Hambrecht
& Quist acts as a market maker and broker in the publicly traded securities of
Quickturn and receives customary compensation in connection therewith, and also
provides research coverage for Cadence and Quickturn. In the ordinary course of
business, Hambrecht & Quist actively trades in the equity and derivative
securities of Cadence and Quickturn for its own account and for the accounts of
its customers and, accordingly, may at any time hold a long or short position
in such securities. Moreover, Hambrecht & Quist and its affiliates own 40,000
shares of Common Stock of the Company. Hambrecht & Quist may in the future
provide investment banking or other financial advisory services to Cadence or
Quickturn.
 
                                      C-1
<PAGE>
 
In connection with our review of the Proposed Transaction, and in arriving at
our opinion, we have, among other things:
 
<TABLE>
 <C>       <S>
       (i) reviewed the publicly available consolidated financial statements of
           Cadence for recent years and interim periods to date and certain
           other relevant financial and operating data of Cadence (including
           its capital structure) made available to us from published sources;
      (ii) discussed the business, financial condition and prospects of Cadence
           with certain members of senior management;
     (iii) reviewed the publicly available consolidated financial statements of
           Quickturn for recent years and interim periods to date and certain
           other relevant financial and operating data of Quickturn made
           available to us from published sources and from the internal records
           of Quickturn;
      (iv) reviewed certain internal financial and operating information,
           relating to Quickturn prepared by the senior management of
           Quickturn;
       (v) discussed the business, financial condition and prospects of
           Quickturn with certain members of senior management;
      (vi) reviewed the recent reported prices and trading activity for the
           common stocks of Cadence and Quickturn and compared such information
           and certain financial information for Cadence and Quickturn with
           similar information for certain other companies engaged in
           businesses we consider comparable;
     (vii) reviewed the financial terms, to the extent publicly available, of
           certain comparable merger and acquisition transactions;
    (viii) reviewed a draft of the Agreement dated December 7, 1998; and
      (ix) performed such other analyses and examinations and considered such
           other information, financial studies, analyses and investigations
           and financial, economic and market data as we deemed relevant.
</TABLE>
 
  In rendering our opinion, we have assumed and relied upon the accuracy and
completeness of all of the information concerning Cadence or Quickturn
considered in connection with our review of the Proposed Transaction, and we
have not assumed any responsibility for independent verification of such
information. We have not prepared any independent valuation or appraisal of any
of the assets or liabilities of Cadence or Quickturn, nor have we conducted a
physical inspection of the properties and facilities of either company. With
respect to the financial forecasts made available to us and used in our
analysis, we have assumed that they reflect the best currently available
estimates and judgments of the expected future financial performance of
Quickturn. For purposes of this opinion, we have assumed that neither Cadence
nor Quickturn is a party to any pending transactions, including external
financings, recapitalizations or material merger discussions, other than the
Proposed Transaction and those activities undertaken in the ordinary course of
conducting their respective businesses. Our opinion is necessarily based upon
market, economic, financial and other conditions as they exist and can be
evaluated as of the date of this letter and any change in such conditions would
require a reevaluation of this opinion. We express no opinion as to the price
at which Cadence common stock will trade subsequent to the Effective Time (as
defined in the Agreement). In rendering our opinion, we have assumed that the
proposed merger will be consummated substantially on the terms described in the
Agreement, without any waiver of any material terms or conditions by any party
thereto. We were not requested to, and did not, solicit indications of interest
from any other parties in connection with a possible acquisition of, or
business combination with, Quickturn.
 
  It is understood that this letter is for the information of the Board of
Directors only and may not be used for any other purpose without our prior
written consent; provided, however, that this letter may be reproduced in full
in the Proxy Statement/Prospectus. This letter does not constitute a
recommendation to any stockholder as to how such stockholder should vote on the
Proposed Transaction.
 
                                      C-2
<PAGE>
 
  Based upon and subject to the foregoing and after considering such other
matters as we deem relevant, we are of the opinion that as of the date hereof
the consideration to be received by the holders of the Common Stock in the
Proposed Transaction is fair to such holders from a financial point of view.
 
                                          Very truly yours,
 
                                          Hambrecht & Quist LLC
 
                                                  /s/ Paul B. Cleveland
                                          By-----------------------------------
                                                     Paul B. Cleveland
                                                     Managing Director
 
                                      C-3
<PAGE>

                                                                      APPENDIX D
 
                       QUICKTURN DESIGN SYSTEMS, INC.

             PROXY SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS
                     FOR SPECIAL MEETING OF STOCKHOLDERS


                            ____________ ___ 1999

        The undersigned stockholder of Quickturn Design Systems, Inc. a
Delaware corporation (the "Company") acknowledges receipt of the Notice of
Special Meeting of Stockholders and Proxy Statement/Prospectus relating to the
Company's combination with Cadence Design Systems, Inc. through the merger of
CDSI Acquisition Inc. with and into the Company, pursuant to an Agreement and
Plan of Merger, dated as of December 8, 1998, as amended on December 16, 1998
and the transactions contemplated thereby and the undersigned revokes all
other proxies and appoints Glen Antle, Keith R. Lobo and Raymond K. Ostby, and
each of them, the attorneys and proxies for the undersigned each with full
power of substitution to attend and act for the undersigned at the Company's
Special Meeting of Stockholders and at any adjournments or postponements
thereof in connection therewith to vote and represent all of the shares of the
Company's Common Stock which the undersigned would be entitled to vote.

        1.    To adopt the Merger Agreement and to approve the transactions 
contemplated by the Merger Agreement.

        2.    To approve the postponement or adjournment of the Special 
Meeting to solicit additional votes to approve the Merger Agreement.


                                                  (change of address/comments)


                                            __________________________________

                                            __________________________________

                                            __________________________________

                                            __________________________________

                                            __________________________________
                                            (If you have written in the above 
                                            spaces please mark the 
                                            corresponding box on the reverse 
                                            side of this card.)

        This card provides voting instructions as applicable to (1) the
appointed proxies for shares held of record by the undersigned and (2)
[___________] as Trustee for shares held for the undersigned in the
[___________] Account. If registrations are not identical you may receive more
than one set of proxy materials. Please sign date and return all cards you
receive.
                                                    __________________________
THIS PROXY WILL BE VOTED AS DIRECTED ON THE         
REVERSE SIDE. IN THE ABSENCE OF ANY DIRECTION            SEE REVERSE SIDE
THIS PROXY WILL BE VOTED FOR PROPOSALS 1 AND 2.     __________________________


<PAGE>
 
    [X]       Please mark your
              votes as in this 
              example

         The Board of Directors recommends a vote FOR adoption of the Merger
         Agreement and approval of the transactions contemplated by the Merger
         Agreement.


1. Adoption of                 FOR           AGAINST         ABSTAIN
   the Merger                  [_]             [_]             [_]
   Agreement.
   (see reverse)


2. Approval of the             FOR           AGAINST         ABSTAIN
   adjournment or              [_]             [_]             [_]
   postponement of
   the Special
   Meeting.


                                                  Please check this    [_]
                                                  box if you plan to 
                                                  attend the special 
                                                  meeting.

                                                  Change of Address/   [_] 
                                                  Comments


         Signature(s) ______________________________   Date __________________

NOTE:    Please sign exactly as name appears above. Joint owners should each
         sign. Fiduciaries should add their full title to their signature.
         Corporations should sign in full corporate name by an authorized
         officer. Partnerships should sign in partnership name by an
         authorized person.

- --------------------------------------------------------------------------------

              DETACH & RETURN PROXY CARD; RETAIN ADMISSION CARD

                               ADMISSION CARD

                       SPECIAL MEETING OF STOCKHOLDERS
                           _____________  ___ 1999
                                 [__] __.M.
                                  [ADDRESS]

                    Presentation of this card is required
                    for admission to the Special Meeting

          PLEASE PRESENT THIS CARD TO THE QUICKTURN REPRESENTATIVE 
                   AT THE ENTRANCE TO THE SPECIAL MEETING

                        QUICKTURN DESIGN SYSTEMS, INC.


Name:  _______________________

Address: _____________________


<PAGE>
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 20. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
  Section 145 of the Delaware General Corporation Law permits a corporation to
indemnify any of its directors or officers who was or is a party or is
threatened to be made a party to any third party proceeding by reason of the
fact that such person is or was a director or officer of the corporation,
against expenses (including attorneys' fees), judgments, fines and amounts paid
in settlement actually and reasonably incurred by such person in connection
with such action, suit or proceeding, if such person acted in good faith and in
a manner such person reasonably believed to be in or not opposed to the best
interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe that such person's conduct was
unlawful. In a derivative action, i.e., one by or in the right of a
corporation, the corporation is permitted to indemnify any of its directors or
officers against expenses (including attorneys' fees) actually and reasonably
incurred by such person in connection with the defense or settlement of such
action or suit if such person acted in good faith and in a manner such person
reasonably believed to be in or not opposed to the best interests of the
corporation, except that no indemnification shall be made if such person shall
have been adjudged liable to the corporation, unless and only to the extent
that the court in which such action or suit was brought shall determine upon
application that such person is fairly and reasonably entitled to indemnity for
such expenses despite such adjudication of liability.
 
  Article VII of the Registrant's currently effective Certificate of
Incorporation eliminates the personal liability of its directors for monetary
damages for breach of fiduciary duty as a director, except for liability
(i) for any breach of the director's duty of loyalty to the corporation or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174
of the Delaware General Corporation Law, or (iv) for any transaction from which
the director derived an improper personal benefit. In addition, as permitted by
Section 145 of the Delaware General Corporation Law, the Bylaws of the
Registrant provide that: (a) the Registrant is required to indemnify its
directors, officers and employees, and persons serving in such capacities in
other business enterprises (including, for example, subsidiaries of the
Registrant) at the Registrant's request, to the fullest extent permitted by
Delaware law, including those circumstances in which indemnification would
otherwise be discretionary; (b) the Registrant is required to advance expenses,
as incurred, to such directors, officers and employees in connection with
defending a proceeding (except that it is not required to advance expenses to a
person against whom the Registrant brings a claim for breach of the duty of
loyalty, failure to act in good faith, intentional misconduct, knowing
violation of law or deriving an improper personal benefit); (c) the rights
conferred in the Bylaws are not exclusive and the Registrant is authorized to
enter into indemnification agreements with such directors, officers and
employees; (d) the Registrant is required to maintain director and officer
liability insurance to the extent reasonably available; and (e) the Registrant
may not retroactively amend the Bylaws indemnification provision in a way that
is adverse to such directors, officers and employees.
 
  The Registrant's policy is to enter into indemnity agreements with each of
its executive officers and directors that provide the maximum indemnity allowed
to officers and directors by Section 145 of the Delaware General Corporation
Law and the Bylaws, as well as certain additional procedural protections. The
Registrant also maintains a limited amount of director and officer insurance.
The indemnification provision in the Bylaws, and the indemnity agreements
entered into between the Registrant and its officers or directors, may be
sufficiently broad to permit indemnification of the Registrant's officers and
directors for liability arising under the Securities Act.
 
                                      II-1
<PAGE>
 
ITEM 21. EXHIBITS
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
  2.01   Agreement and Plan of Merger dated as of December 8, 1998 among
         Cadence Design Systems, Inc., Quickturn Design Systems, Inc. and CDSI
         Acquisition, Inc., as amended on December 16, 1998 (included as
         Appendix A to the Prospectus/Proxy Statement included as a part of
         this Registration Statement. The Disclosure Schedules relating to the
         Merger Agreement have been omitted but will be provided to the
         Commission upon its request pursuant to Item 601(b)(2) of Regulation
         S-K.)
  3.01   Restated Certificate of Incorporation of Registrant dated May 13, 1998
         (incorporated by reference to Exhibit 3.01(h) of the Registrant's Form
         10-Q for the quarter ended July 4, 1998).
  3.02   Bylaws of Registrant as currently in effect (incorporated by reference
         to Exhibit 3.02 to the Registrant's Registration Statement on Form S-1
         (No. 33-13845) and Exhibit 3-b to the Registrant's Current Report on
         Form 8-K filed June 12, 1989).
  4.01   Specimen Certificate of the Registrant's Common Stock (incorporated by
         reference to Exhibit 4.01 to the Registrant's Registration Statement
         on Form S-4 (No. 33-43400)).
  4.02   Rights Agreement dated as of February 9, 1996 between the Registrant
         and Harris Trust and Savings Bank which includes as exhibits thereto
         the Certificate of Designation for the Series A Junior Participating
         Preferred Stock, the form of Rights Certificate and the Summary of
         Rights to Purchase Preferred Shares (incorporated by reference to
         Exhibits 1A, 1B and 1C to the Registrant's Current Report on Form 8-K
         filed February 16, 1996).
  5.01   Opinion of Gibson, Dunn & Crutcher LLP.
  8.01*  Opinion of Gibson, Dunn & Crutcher LLP as to tax matters.
  8.02*  Opinion of Wilson Sonsini Goodrich & Rosati Professional Corporation
         as to tax matters.
 10.01   1987 Stock Option Plan as amended and restated on February 23, 1998
         (incorporated by reference to the Registrant's Preliminary Proxy
         Statement filed on March 16, 1998 (the "1998 Preliminary Proxy
         Statement")).
 10.02   Form of Stock Option Agreement and Form of Stock Option Exercise
         Request as currently in effect under the Registrant's 1987 Stock
         Option Plan (incorporated by reference to Exhibit 4.01 to the
         Registrant's Registration Statement on Form S-8 (No. 33-22652)).
 10.03   1988 Directors Stock Option Plan as amended to date including the
         Stock Option Grant and Form of Stock Option Exercise Notice and
         Agreement (the first document is incorporated by reference to Exhibit
         4.02 to the Registrant's Registration Statement on Form S-8 (No. 33-
         53913) (the "1994 Form S-8") and the latter two documents are
         incorporated by reference to Exhibits 10.08--10.10 to the Registrant's
         Registration Statement on Form S-1 (No. 33-23107)).
 10.04   1993 Directors Stock Option Plan including the Form of Stock Option
         Grant (incorporated by reference to Exhibit 10.04 to the 1994 Form S-
         8).
 10.05   1995 Directors Stock Option Plan including the Form of Stock Option
         Grant (incorporated by reference to Exhibit 10.05 to the Registrant's
         Form 10-K for the fiscal year ended December 30, 1995 (the "1995 Form
         10-K")).
 10.06   1990 Employee Stock Purchase Plan as amended on March 4, 1997
         (incorporated by reference to Exhibit 10.07 to the Registrant's Form
         10-K for the fiscal year ended December 28, 1996).
 10.07   Senior Executive Bonus Plan for 1995 (incorporated by reference to
         Exhibit 10.08 of the Registrant's Form 10-K for the fiscal year ended
         December 31, 1994 (the "1994 Form 10-K")).
 10.08   Senior Executive Bonus Plan for 1996 (incorporated by reference to
         Exhibit 10.08 to the 1995 Form 10-K).
 10.09   Senior Executive Bonus Plan (previously the Chief Executive Officer
         Bonus Plan for 1996) as amended January 1, 1998 (incorporated by
         reference to the 1998 Preliminary Proxy Statement).
</TABLE>
 
                                      II-2
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.10   Deferred Compensation Plan for 1994 (incorporated by reference to
         Exhibit 10.09 to the 1994 Form 10-K).
 10.11   1996 Deferred Compensation Venture Investment Plan (incorporated by
         reference to Exhibit 10.11 to the 1995 Form 10-K).
 10.12   Amended and Restated Lease dated June 29, 1989 by and between River
         Oaks Place Associates (ROPA), a California limited partnership, and
         the Registrant for the Registrant's offices at 555 River Oaks Parkway,
         San Jose, California (incorporated by reference to Exhibit 10.14 to
         the Registrant's Form 10-K for the year ended December 31, 1990 (the
         "1990 Form 10-K")).
 10.13   Lease dated June 29, 1989 by and between ROPA and the Registrant for
         the Registrant's offices at 575 River Oaks Parkway, San Jose,
         California (incorporated by reference to Exhibit 10.16 to the 1990
         Form 10-K).
 10.14   Lease dated June 29, 1989 by and between ROPA and the Registrant for
         the Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California (incorporated by reference to Exhibit 10.17 to the 1990
         Form 10-K).
 10.15   Lease dated December 19, 1988 by and among the Richard T. Peery and
         John Arrillaga Separate Trusts and Valid Logic Systems Incorporated
         (Valid) (which merged into the Registrant) for the Registrant's
         offices at 2835 North First Street, San Jose, California (incorporated
         by reference to Exhibit 10.18 to Valid's Form 10-K for the fiscal year
         ended December 30, 1990).
 10.16   Form of Executive Compensation Agreement dated May 1989 between the
         Registrant and Mr. Joseph B. Costello (incorporated by reference to
         Exhibit 10.20 to the Registrant's Registration Statement on Form S-4
         (No. 33-31673)).
 10.17   Offer letter to H. Raymond Bingham dated May 12, 1993 (incorporated by
         reference to Exhibit 10.24 to the Registrant's Form 10-K for the year
         ended December 31, 1993 (the "1993 Form 10-K")).
 10.18   Offer letter to M. Robert Leach dated May 17, 1993 (incorporated by
         reference to Exhibit 10.25 to the 1993 Form 10-K).
 10.19   The 1993 Non-Statutory Stock Option Plan (incorporated by reference to
         Exhibit 4.05 to the 1994 Form S-8).
 10.20   Consulting Agreement dated October 26, 1993 with Alberto Sangiovanni-
         Vincentelli (incorporated by reference to Exhibit 10.29 to the
         Registrant's Form 10-Q for the second quarter ended June 30, 1994).
 10.21   Amended and restated 401(k) Plan (incorporated by reference to Exhibit
         10.29 of the Registrant's Form 10-Q for the first quarter ended March
         30, 1996 (the "1996 First Quarter Form 10-Q")).
 10.22   Amendment dated May 3, 1996 to the Registrant's 1993 Non-Statutory
         Stock Option Plan (incorporated by reference to Exhibit 10.30 to the
         1996 First Quarter Form 10-Q).
 10.23   Revolving Credit Agreement dated April 11, 1996 by and between the
         Registrant and Credit Lyonnais (incorporated by reference to Exhibit
         10.31 to the 1996 First Quarter Form 10-Q).
 10.24   Term Loan Agreement dated May 31, 1996 by and between Credit Lyonnais
         and River Oaks Place Associates L.P. (ROPA), a California limited
         partnership (the Term Loan) (incorporated by reference to Exhibit
         10.32 to the Registrant's Form 10-Q for the second quarter ended June
         29, 1996 (the "1996 Second Quarter Form 10-Q")).
 10.25   Deed of Trust Security Agreement Assignment of Leases and Rents
         Fixture Filing and Financing Statement dated May 31, 1996 Schedule to
         Term Loan (incorporated by reference to Exhibit 10.33 to the 1996
         Second Quarter Form 10-Q).
 10.26   Assignment of Leases and Rents dated May 31, 1996 Schedule to Term
         Loan (incorporated by reference to Exhibit 10.34 to the 1996 Second
         Quarter Form 10-Q).
 10.27   Assignment of Partnership Interests by Seeley Properties Inc. dated
         May 31, 1996 Schedule to Term Loan (incorporated by reference to
         Exhibit 10.35 to the 1996 Second Quarter Form 10-Q).
 10.28   Assignment of Partnership Interests by the Registrant dated May 31,
         1996 Schedule to Term Loan (incorporated by reference to Exhibit 10.36
         to the 1996 Second Quarter Form 10-Q).
 10.29   Environmental Indemnity dated May 31, 1996 Schedule to Term Loan
         (incorporated by reference to Exhibit 10.37 to the 1996 Second Quarter
         Form 10-Q).
</TABLE>
 
                                      II-3
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.30   Amendment dated August 2, 1996 to the Registrant's 1993 Non-Statutory
         Stock Option Plan (incorporated by reference to Exhibit 10.39 to the
         1996 Second Quarter Form 10-Q).
 10.31   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 555 River Oaks Parkway, San Jose, California,
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.40 to the 1996 Second Quarter Form 10-Q and Exhibit 10.14
         to the 1990 Form 10-K).
 10.32   Amendment Number 2 dated May 31,1996 to Lease Agreement for the
         Registrant's offices at 555 River Oaks Parkway, San Jose, California,
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.41 to the 1996 Second Quarter Form 10-Q and Exhibit 10.14
         to the 1990 Form 10-K).
 10.33   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 575 River Oaks Parkway, San Jose, California
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.42 to the 1996 Second Quarter Form 10-Q and Exhibit 10.16
         to the 1990 Form 10-K).
 10.34   Amendment Number 2 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 575 River Oaks Parkway, San Jose, California
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.43 to the 1996 Second Quarter Form 10-Q and Exhibit 10.16
         to the 1990 Form 10-K).
 10.35   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California, by and between ROPA and the Registrant (incorporated by
         reference to Exhibit 10.44 to the 1996 Second Quarter Form 10-Q and
         Exhibit 10.17 to the 1990 Form 10-K).
 10.36   Amendment Number 2 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California, by and between ROPA and the Registrant (incorporated by
         reference to Exhibit 10.45 to the 1996 Second Quarter Form 10-Q and
         Exhibit 10.17 to the 1990 Form 10-K).
 10.37   Agreement and Plan of Merger and Reorganization dated as of October 3,
         1996 among the Registrant, High Level Design Systems Inc., a Delaware
         corporation, and Harbor Acquisition Sub Inc., a Delaware corporation,
         (incorporated by reference to Exhibit 2.1 to the Registrant's Current
         Report on Form 8-K filed November 7, 1996 (the "November 7, 1996 Form
         8-K")).
 10.38   Distribution Agreement dated April 28, 1997 among Cadence Design
         Systems (Ireland) Ltd., Cadence Design Systems K.K. and Cadence Design
         Systems (Japan) B.V. (incorporated by reference to Exhibit 10.48 to
         the Registrant's Form 10-Q for the second quarter ended June 28,
         1997).
 10.39   Agreement and Plan of Merger and Reorganization dated as of October
         28, 1996 among Registrant, Cooper & Chyan Technology Inc. ("CCT") and
         Wyoming Acquisition Sub Inc. (incorporated by reference to Exhibit 2.2
         to the November 7, 1996 Form 8-K).
 10.40   CCT 1993 Equity Incentive Plan, Form of Equity Incentive Plan Stock
         Option Agreement, Form of Exercise of Equity Incentive Plan Stock
         Option and Form of Equity Incentive Plan Stock Option Exercise
         Agreement (incorporated by reference to Exhibit 10.49 to the
         Registrant's Form S-4 Registration Statement (No. 333-16779)).
 10.41   Employment Agreement dated October, 19, 1997 between the Registrant
         and John R. Harding (incorporated by reference to Exhibit 10.41 to the
         Registrant's Form 10-K for the year ending January 3, 1998 (the
         "January 3, 1998 Form 10-K")).
 10.42   Letter Agreement dated December 5, 1997 between the Registrant and
         Joseph B. Costello (incorporated by reference to Exhibit 10.42 to the
         Registrant's 1997 Form 10-K).
 10.43   Form of Executive Severance Agreement (incorporated by reference to
         Exhibit 10.43 to the Registrant's January 3, 1998 Form 10-K).
 10.44   Indemnity Agreement dated October, 19, 1997 by and between the
         Registrant and John R. Harding (incorporated by reference to Exhibit
         10.44 to the Registrant's January 3, 1998 Form 10-K).
</TABLE>
 
                                      II-4
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.45   Revolving Credit Agreement dated September 30, 1998 by and between
         ABN-AMRO Bank and the Registrant (incorporated by reference to Exhibit
         10.45 to the Registrant's Form 10-Q for the third quarter ended
         October 3, 1998 ("1997 Third Quarter 10-Q")).
 10.46   Amendment dated October 16, 1998 to the Revolving Credit Agreement by
         and between ABN-AMRO Bank and the Registrant (incorporated by
         reference to Exhibit 10.46 to the Registrant's 1997 Third Quarter Form
         10-Q).
 10.47   Agreement and Plan of Reorganization dated September 3, 1998 by and
         among the Registrant, Ambit Design Systems Inc. and Adirondack
         Transaction Corp. (incorporated by reference to Exhibit 2.01 to the
         Registrant's Form 8-K filed September 30, 1998).
 10.48   Stock Option Agreement between the Registrant and Quickturn dated
         December 8, 1998 (included as Appendix B to the Prospectus/Proxy
         Statement included as a part of this Registration Statement).
 21.01   Subsidiaries of the Registrant.
 23.01   Consent of Arthur Andersen LLP.
 23.02   Consent of PricewaterhouseCoopers LLP.
 23.03   Consent of Hambrecht & Quist LLC.
 23.04   Consent of Gibson, Dunn & Crutcher LLP (included in its opinion filed
         herewith as Exhibit 5.01).
 23.05*  Consent of Wilson, Sonsini, Goodrich & Rosati, Professional
         Corporation (included in its opinion to be filed by amendment as
         Exhibit 8.02).
 24.01   Power of Attorney (see signature page of this Registration Statement).
 99.01   Form of Proxy for holders of Quickturn Design Systems, Inc. common
         stock (included as Appendix D to the Proxy Statement/Prospectus
         included as part of this Registration Statement).
</TABLE>
- --------
* To be filed by amendment.
 
ITEM 22. UNDERTAKINGS.
 
  (a) The undersigned registrant hereby undertakes:
 
    (1) That for purposes of determining any liability under the Securities
  Act of 1933 each filing of the Registrant's annual report pursuant to
  Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (and where
  applicable each filing of an employee benefit plan's annual report pursuant
  to Section 15(d) of the Securities Exchange Act of 1934) that is
  incorporated by reference in the registration statement shall be deemed to
  be a new registration statement relating to the securities offered therein
  and the offering of such securities at that time shall be deemed to be the
  initial bona fide offering thereof.
 
    (2) That prior to any public reoffering of the securities registered
  hereunder through use of a prospectus which is a part of this registration
  statement by any person or party who is deemed to be an underwriter within
  the meaning of Rule 145(c) such reoffering prospectus will contain the
  information called for by the applicable registration form with respect to
  reofferings by persons who may be deemed underwriters in addition to the
  information called for by the other items of the applicable form.
 
    (3) That every prospectus (i) that is filed pursuant to paragraph (2)
  immediately preceding or (ii) that purports to meet the requirements of
  Section 10(a)(3) of the Securities Act of 1933 and is used in connection
  with an offering of securities subject to Rule 415 will be filed as a part
  of an amendment to the registration statement and will not be used until
  such amendment is effective and that for purposes of determining any
  liability under the Securities Act of 1933 each such post-effective
  amendment shall be deemed to be a new registration statement relating to
  the securities offered therein and the offering of such securities at that
  time shall be deemed to be the initial bona fide offering thereof.
 
 
                                      II-5
<PAGE>
 
  (b) The undersigned registrant hereby undertakes to respond to requests for
information that is incorporated by reference into the Proxy
Statement/Prospectus pursuant to Item 4 10(b) 11 or 13 of this Form within one
business day of receipt of such request and to send the incorporated documents
by first class mail or other equally prompt means. This includes information
contained in documents filed subsequent to the effective date of the
registration statement through the date of responding to the request.
 
  (c) The undersigned registrant hereby undertakes to supply by means of a
post-effective amendment all information concerning a transaction and the
company being acquired involved therein that was not the subject of and
included in the registration statement when it became effective.
 
  (d) Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act of 1933 and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than the payment by
the registrant of expenses incurred or paid by a director, officer or
controlling person of the registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act of 1933 and will be governed by the final adjudication of such
issue.
 
                                      II-6
<PAGE>
 
                                   SIGNATURES
 
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THE
REGISTRANT HAS DULY CAUSED THIS REGISTRATION STATEMENT TO BE SIGNED ON ITS
BEHALF BY THE UNDERSIGNED THEREUNTO DULY AUTHORIZED IN THE CITY OF SAN JOSE,
STATE OF CALIFORNIA, ON DECEMBER 22, 1998.
 
                                          CADENCE DESIGN SYSTEMS INC.
 
                                                    /s/ JOHN R. HARDING
                                          By___________________________________
                                                      JOHN R. HARDING
                                            PRESIDENT, CHIEF EXECUTIVE OFFICER
                                                       AND DIRECTOR
 
                               POWER OF ATTORNEY
 
  Each person whose individual signature appears below hereby constitutes and
appoints John R. Harding, H. Raymond Bingham and R.L. Smith McKeithen and each
of them severally, as his or her true and lawful attorney-in-fact with full
power of substitution to execute in the name and on behalf of such person,
individually and in each capacity stated below, and to file any and all
amendments to this Registration Statement, including any and all post-effective
amendments.
 
  Pursuant to the requirements of the Securities Act of 1933, this Registration
Statement has been signed below by the following persons in the capacities
indicated below on the 22nd day of December 1998.
 
             SIGNATURES                                  TITLE
 
         /s/ John R. Harding             President, Chief Executive Officer and
- -------------------------------------    Director (Principal Executive Officer)
           JOHN R. HARDING
 
       /s/ H. Raymond Bingham               Executive Vice President, Chief
- -------------------------------------        Financial Officer and Director
         H. RAYMOND BINGHAM                  (Principal Financial Officer)
 
         /s/ William Porter               Vice President, Corporate Controller
- -------------------------------------      and Assistant Secretary (Principal
           WILLIAM PORTER                         Accounting Officer)
 
         /s/ Carol A. Bartz                             Director
- -------------------------------------
           CAROL A. BARTZ
 
      /s/ Dr. Leonard Y.W. Liu                          Director
- -------------------------------------
        DR. LEONARD Y.W. LIU
 
 
                                      II-7
<PAGE>
 
             SIGNATURES                                  TITLE
 
         /s/ Donald L. Lucas                            Director
- -------------------------------------
           DONALD L. LUCAS
 
    /s/ Dr. Alberto Sangiovanni-                        Director
             Vincentelli
- -------------------------------------
 DR. ALBERTO SANGIOVANNI-VINCENTELLI
 
        /s/ George M. Scalise                           Director
- -------------------------------------
          GEORGE M. SCALISE
 
       /s/ Dr. John B. Shoven                           Director
- -------------------------------------
         DR. JOHN B. SHOVEN
 
                                      II-8
<PAGE>
 
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
  2.01   Agreement and Plan of Merger dated as of December 8, 1998 among
         Cadence Design Systems, Inc., Quickturn Design Systems, Inc. and CDSI
         Acquisition, Inc., as amended on December 16, 1998 (included as
         Appendix A to the Prospectus/Proxy Statement included as a part of
         this Registration Statement. The Disclosure Schedules relating to the
         Merger Agreement have been omitted but will be provided to the
         Commission upon its request pursuant to Item 601(b)(2) of Regulation
         S-K.)
  3.01   Restated Certificate of Incorporation of Registrant dated May 13, 1998
         (incorporated by reference to Exhibit 3.01(h) of the Registrant's Form
         10-Q for the quarter ended July 4, 1998).
  3.02   Bylaws of Registrant as currently in effect (incorporated by reference
         to Exhibit 3.02 to the Registrant's Registration Statement on Form S-1
         (No. 33-13845) and Exhibit 3-b to the Registrant's Current Report on
         Form 8-K filed June 12, 1989).
  4.01   Specimen Certificate of the Registrant's Common Stock (incorporated by
         reference to Exhibit 4.01 to the Registrant's Registration Statement
         on Form S-4 (No. 33-43400)).
  4.02   Rights Agreement dated as of February 9, 1996 between the Registrant
         and Harris Trust and Savings Bank which includes as exhibits thereto
         the Certificate of Designation for the Series A Junior Participating
         Preferred Stock, the form of Rights Certificate and the Summary of
         Rights to Purchase Preferred Shares (incorporated by reference to
         Exhibits 1A, 1B and 1C to the Registrant's Current Report on Form 8-K
         filed February 16, 1996).
  5.01   Opinion of Gibson, Dunn & Crutcher LLP.
  8.01*  Opinion of Gibson, Dunn & Crutcher LLP as to tax matters.
  8.02*  Opinion of Wilson Sonsini Goodrich & Rosati Professional Corporation
         as to tax matters.
 10.01   1987 Stock Option Plan as amended and restated on February 23, 1998
         (incorporated by reference to the Registrant's Preliminary Proxy
         Statement filed on March 16, 1998 (the "1998 Preliminary Proxy
         Statement")).
 10.02   Form of Stock Option Agreement and Form of Stock Option Exercise
         Request as currently in effect under the Registrant's 1987 Stock
         Option Plan (incorporated by reference to Exhibit 4.01 to the
         Registrant's Registration Statement on Form S-8 (No. 33-22652)).
 10.03   1988 Directors Stock Option Plan as amended to date including the
         Stock Option Grant and Form of Stock Option Exercise Notice and
         Agreement (the first document is incorporated by reference to Exhibit
         4.02 to the Registrant's Registration Statement on Form S-8 (No. 33-
         53913) (the "1994 Form S-8") and the latter two documents are
         incorporated by reference to Exhibits 10.08--10.10 to the Registrant's
         Registration Statement on Form S-1 (No. 33-23107)).
 10.04   1993 Directors Stock Option Plan including the Form of Stock Option
         Grant (incorporated by reference to Exhibit 10.04 to the 1994 Form S-
         8).
 10.05   1995 Directors Stock Option Plan including the Form of Stock Option
         Grant (incorporated by reference to Exhibit 10.05 to the Registrant's
         Form 10-K for the fiscal year ended December 30, 1995 (the "1995 Form
         10-K")).
 10.06   1990 Employee Stock Purchase Plan as amended on March 4, 1997
         (incorporated by reference to Exhibit 10.07 to the Registrant's Form
         10-K for the fiscal year ended December 28, 1996).
 10.07   Senior Executive Bonus Plan for 1995 (incorporated by reference to
         Exhibit 10.08 of the Registrant's Form 10-K for the fiscal year ended
         December 31, 1994 (the "1994 Form 10-K")).
 10.08   Senior Executive Bonus Plan for 1996 (incorporated by reference to
         Exhibit 10.08 to the 1995 Form 10-K).
 10.09   Senior Executive Bonus Plan (previously the Chief Executive Officer
         Bonus Plan for 1996) as amended January 1, 1998 (incorporated by
         reference to the 1998 Preliminary Proxy Statement).
 10.10   Deferred Compensation Plan for 1994 (incorporated by reference to
         Exhibit 10.09 to the 1994 Form 10-K).
 10.11   1996 Deferred Compensation Venture Investment Plan (incorporated by
         reference to Exhibit 10.11 to the 1995 Form 10-K).
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.12   Amended and Restated Lease dated June 29, 1989 by and between River
         Oaks Place Associates (ROPA), a California limited partnership, and
         the Registrant for the Registrant's offices at 555 River Oaks Parkway,
         San Jose, California (incorporated by reference to Exhibit 10.14 to
         the Registrant's Form 10-K for the year ended December 31, 1990 (the
         "1990 Form 10-K")).
 10.13   Lease dated June 29, 1989 by and between ROPA and the Registrant for
         the Registrant's offices at 575 River Oaks Parkway, San Jose,
         California (incorporated by reference to Exhibit 10.16 to the 1990
         Form 10-K).
 10.14   Lease dated June 29, 1989 by and between ROPA and the Registrant for
         the Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California (incorporated by reference to Exhibit 10.17 to the 1990
         Form 10-K).
 10.15   Lease dated December 19, 1988 by and among the Richard T. Peery and
         John Arrillaga Separate Trusts and Valid Logic Systems Incorporated
         (Valid) (which merged into the Registrant) for the Registrant's
         offices at 2835 North First Street, San Jose, California (incorporated
         by reference to Exhibit 10.18 to Valid's Form 10-K for the fiscal year
         ended December 30, 1990).
 10.16   Form of Executive Compensation Agreement dated May 1989 between the
         Registrant and Mr. Joseph B. Costello (incorporated by reference to
         Exhibit 10.20 to the Registrant's Registration Statement on Form S-4
         (No. 33-31673)).
 10.17   Offer letter to H. Raymond Bingham dated May 12, 1993 (incorporated by
         reference to Exhibit 10.24 to the Registrant's Form 10-K for the year
         ended December 31, 1993 (the "1993 Form 10-K")).
 10.18   Offer letter to M. Robert Leach dated May 17, 1993 (incorporated by
         reference to Exhibit 10.25 to the 1993 Form 10-K).
 10.19   The 1993 Non-Statutory Stock Option Plan (incorporated by reference to
         Exhibit 4.05 to the 1994 Form S-8).
 10.20   Consulting Agreement dated October 26, 1993 with Alberto Sangiovanni-
         Vincentelli (incorporated by reference to Exhibit 10.29 to the
         Registrant's Form 10-Q for the second quarter ended June 30, 1994).
 10.21   Amended and restated 401(k) Plan (incorporated by reference to Exhibit
         10.29 of the Registrant's Form 10-Q for the first quarter ended March
         30, 1996 (the "1996 First Quarter Form 10-Q")).
 10.22   Amendment dated May 3, 1996 to the Registrant's 1993 Non-Statutory
         Stock Option Plan (incorporated by reference to Exhibit 10.30 to the
         1996 First Quarter Form 10-Q).
 10.23   Revolving Credit Agreement dated April 11, 1996 by and between the
         Registrant and Credit Lyonnais (incorporated by reference to Exhibit
         10.31 to the 1996 First Quarter Form 10-Q).
 10.24   Term Loan Agreement dated May 31, 1996 by and between Credit Lyonnais
         and River Oaks Place Associates L.P. (ROPA), a California limited
         partnership (the Term Loan) (incorporated by reference to Exhibit
         10.32 to the Registrant's Form 10-Q for the second quarter ended June
         29, 1996 (the "1996 Second Quarter Form 10-Q")).
 10.25   Deed of Trust Security Agreement Assignment of Leases and Rents
         Fixture Filing and Financing Statement dated May 31, 1996 Schedule to
         Term Loan (incorporated by reference to Exhibit 10.33 to the 1996
         Second Quarter Form 10-Q).
 10.26   Assignment of Leases and Rents dated May 31, 1996 Schedule to Term
         Loan (incorporated by reference to Exhibit 10.34 to the 1996 Second
         Quarter Form 10-Q).
 10.27   Assignment of Partnership Interests by Seeley Properties Inc. dated
         May 31, 1996 Schedule to Term Loan (incorporated by reference to
         Exhibit 10.35 to the 1996 Second Quarter Form 10-Q).
 10.28   Assignment of Partnership Interests by the Registrant dated May 31,
         1996 Schedule to Term Loan (incorporated by reference to Exhibit 10.36
         to the 1996 Second Quarter Form 10-Q).
 10.29   Environmental Indemnity dated May 31, 1996 Schedule to Term Loan
         (incorporated by reference to Exhibit 10.37 to the 1996 Second Quarter
         Form 10-Q).
 10.30   Amendment dated August 2, 1996 to the Registrant's 1993 Non-Statutory
         Stock Option Plan (incorporated by reference to Exhibit 10.39 to the
         1996 Second Quarter Form 10-Q).
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.31   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 555 River Oaks Parkway, San Jose, California,
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.40 to the 1996 Second Quarter Form 10-Q and Exhibit 10.14
         to the 1990 Form 10-K).
 10.32   Amendment Number 2 dated May 31,1996 to Lease Agreement for the
         Registrant's offices at 555 River Oaks Parkway, San Jose, California,
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.41 to the 1996 Second Quarter Form 10-Q and Exhibit 10.14
         to the 1990 Form 10-K).
 10.33   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 575 River Oaks Parkway, San Jose, California
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.42 to the 1996 Second Quarter Form 10-Q and Exhibit 10.16
         to the 1990 Form 10-K).
 10.34   Amendment Number 2 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 575 River Oaks Parkway, San Jose, California
         by and between ROPA and the Registrant (incorporated by reference to
         Exhibit 10.43 to the 1996 Second Quarter Form 10-Q and Exhibit 10.16
         to the 1990 Form 10-K).
 10.35   Amendment Number 1 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California, by and between ROPA and the Registrant (incorporated by
         reference to Exhibit 10.44 to the 1996 Second Quarter Form 10-Q and
         Exhibit 10.17 to the 1990 Form 10-K).
 10.36   Amendment Number 2 dated May 31, 1996 to Lease Agreement for the
         Registrant's offices at 535 and 545 River Oaks Parkway, San Jose,
         California, by and between ROPA and the Registrant (incorporated by
         reference to Exhibit 10.45 to the 1996 Second Quarter Form 10-Q and
         Exhibit 10.17 to the 1990 Form 10-K).
 10.37   Agreement and Plan of Merger and Reorganization dated as of October 3,
         1996 among the Registrant, High Level Design Systems Inc., a Delaware
         corporation, and Harbor Acquisition Sub Inc., a Delaware corporation,
         (incorporated by reference to Exhibit 2.1 to the Registrant's Current
         Report on Form 8-K filed November 7, 1996 (the "November 7, 1996 Form
         8-K")).
 10.38   Distribution Agreement dated April 28, 1997 among Cadence Design
         Systems (Ireland) Ltd., Cadence Design Systems K.K. and Cadence Design
         Systems (Japan) B.V. (incorporated by reference to Exhibit 10.48 to
         the Registrant's Form 10-Q for the second quarter ended June 28,
         1997).
 10.39   Agreement and Plan of Merger and Reorganization dated as of October
         28, 1996 among Registrant, Cooper & Chyan Technology Inc. ("CCT") and
         Wyoming Acquisition Sub Inc. (incorporated by reference to Exhibit 2.2
         to the November 7, 1996 Form 8-K).
 10.40   CCT 1993 Equity Incentive Plan, Form of Equity Incentive Plan Stock
         Option Agreement, Form of Exercise of Equity Incentive Plan Stock
         Option and Form of Equity Incentive Plan Stock Option Exercise
         Agreement (incorporated by reference to Exhibit 10.49 to the
         Registrant's Form S-4 Registration Statement (No. 333-16779)).
 10.41   Employment Agreement dated October, 19, 1997 between the Registrant
         and John R. Harding (incorporated by reference to Exhibit 10.41 to the
         Registrant's Form 10-K for the year ending January 3, 1998 (the
         "January 3, 1998 Form 10-K")).
 10.42   Letter Agreement dated December 5, 1997 between the Registrant and
         Joseph B. Costello (incorporated by reference to Exhibit 10.42 to the
         Registrant's 1997 Form 10-K).
 10.43   Form of Executive Severance Agreement (incorporated by reference to
         Exhibit 10.43 to the Registrant's January 3, 1998 Form 10-K).
 10.44   Indemnity Agreement dated October, 19, 1997 by and between the
         Registrant and John R. Harding (incorporated by reference to Exhibit
         10.44 to the Registrant's January 3, 1998 Form 10-K).
 10.45   Revolving Credit Agreement dated September 30, 1998 by and between
         ABN-AMRO Bank and the Registrant (incorporated by reference to Exhibit
         10.45 to the Registrant's Form 10-Q for the third quarter ended
         October 3, 1998 ("1997 Third Quarter 10-Q")).
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                               EXHIBIT TITLE
 -------                              -------------
 <C>     <S>
 10.46   Amendment dated October 16, 1998 to the Revolving Credit Agreement by
         and between ABN-AMRO Bank and the Registrant (incorporated by
         reference to Exhibit 10.46 to the Registrant's 1997 Third Quarter Form
         10-Q).
 10.47   Agreement and Plan of Reorganization dated September 3, 1998 by and
         among the Registrant, Ambit Design Systems Inc. and Adirondack
         Transaction Corp. (incorporated by reference to Exhibit 2.01 to the
         Registrant's Form 8-K filed September 30, 1998).
 10.48   Stock Option Agreement between the Registrant and Quickturn dated
         December 8, 1998 (included as Appendix B to the Prospectus/Proxy
         Statement included as a part of this Registration Statement).
 21.01   Subsidiaries of the Registrant.
 23.01   Consent of Arthur Andersen LLP.
 23.02   Consent of PricewaterhouseCoopers LLP.
 23.03   Consent of Hambrecht & Quist LLC.
 23.04   Consent of Gibson, Dunn & Crutcher LLP (included in its opinion filed
         herewith as Exhibit 5.01).
 23.05*  Consent of Wilson, Sonsini, Goodrich & Rosati, Professional
         Corporation (included in its opinion to be filed by amendment as
         Exhibit 8.02).
 24.01   Power of Attorney (see signature page of this Registration Statement).
 99.01   Form of Proxy for holders of Quickturn Design Systems, Inc. common
         stock (included as Appendix D to the Proxy Statement/Prospectus
         included as part of this Registration Statement).
</TABLE>
- --------
* To be filed by amendment.

<PAGE>
 
                                                                    EXHIBIT 5.01

                  [Letterhead of Gibson, Dunn & Crutcher LLP]


                               December 23, 1998



(415) 393-8200                                                       18861-00007


Cadence Design Systems, Inc.
2655 Seely Avenue
San Jose, California  95134

     Re:  Registration Statement on Form S-4 of Cadence Design Systems, Inc.

Gentlemen:

     We refer to the registration statement on Form S-4 (the "Registration
Statement"), under the Securities Act of 1933, as amended (the "Securities
Act"), filed by Cadence Design Systems, Inc., a Delaware corporation (the
"Corporation"), with respect to the issuance by the Corporation of up to
11,800,000 shares (the "Shares") of its common stock, par value $.01 per share
("Common Stock"), and associated preferred stock purchase rights (the "Rights"),
upon consummation of the proposed merger of CDSI Acquisition, Inc., a wholly-
owned subsidiary of the Corporation, with Quickturn Design Systems, Inc. (the
"Merger").

     We have examined the originals or certified copies of such corporate
records, certificates of officers of the Corporation and/or public officials and
such other documents, and have made such other factual and legal investigations,
as we have deemed relevant and necessary as the basis for the opinions set forth
below.  In such examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, the conformity
to original documents of all documents submitted to us as conformed or
photostatic copies and the authenticity of the originals of such copies.

     Based on our examination described above, subject to the assumptions stated
above and relying on the statements of fact contained in the documents that we
have examined, we are of 
<PAGE>
 
Cadence Design Systems, Inc.
December 23, 1998
Page 2


the opinion that (i) the issuance by the Corporation of the Shares and the
Rights in connection with the Merger has been duly authorized and (ii) when
issued as described in the Registration Statement, the Shares and Rights will be
legally and validly issued, fully paid and non-assessable shares of Common Stock
and Rights, respectively.

     This opinion is limited to the laws of the State of California and United
States federal law.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our name under the captions
"Background of the Merger," "Material Federal Income Tax Consequences," and
"Legal Matters" in the Proxy Statement/Prospectus which forms a part of the
Registration Statement.  In giving this consent, we do not admit that we are
within the category of persons whose consent is required under Section 7 of the
Securities Act or the General Rules and Regulations of the Securities and
Exchange Commission.


                              Very truly yours,

                              /s/ Gibson, Dunn & Crutcher LLP

                              GIBSON, DUNN & CRUTCHER LLP

KRL/GJC/LAF


<PAGE>
 
                                                                   EXHIBIT 21.01

                         SUBSIDIARIES OF THE REGISTRANT

     The Registrant's subsidiaries and the state or country in which each is
incorporated or organized, are as follows:

<TABLE>
<S>                                                                    <C>
Accent S.r.l.........................................................  Italy
Cadence China Ltd....................................................  Hong Kong
Cadence Design Systems (Canada) Ltd..................................  Canada
Cadence Design Systems (India) Private Ltd...........................  India
Cadence Design Systems (Ireland), Ltd................................  Ireland
Cadence Design Systems (Israel) Ltd..................................  Israel
Cadence Design Systems (Japan) B.V...................................  Netherlands
Cadence Design Systems (S) Pte Ltd...................................  Singapore
Cadence  Design Systems I B.V........................................  Netherlands
Cadence Design Systems III B.V.......................................  Netherlands
Cadence Design Systems AB............................................  Sweden
Cadence Design Systems AG............................................  Switzerland
Cadence Design Systems Asia Ltd......................................  Hong Kong
Cadence Design Systems B.V...........................................  Netherlands
Cadence Design Systems GmbH..........................................  Germany
Cadence Design Systems, Ltd..........................................  United Kingdom
Cadence Design Systems S.A.S.........................................  France
Cadence Design Systems S.r.l.........................................  Italy
Cadence International Sales Corporation..............................  U.S. Virgin Islands
Cadence Korea Ltd....................................................  Korea
Cadence Taiwan, Inc..................................................  Taiwan
Castlewilder.........................................................  Ireland
Cooper & Chyan Technology FSC, Inc...................................  Barbados
Cooper & Chyan Technology GmbH.......................................  Germany
Cooper & Chyan Technology, Inc.......................................  U.S.
Cooper & Chyan Technology KK.........................................  Japan
Cooper & Chyan Technology, Ltd.......................................  United Kingdom
Cooper & Chyan Technology S.A.R.L....................................  France
European CAD Developments Ltd........................................  Germany
High Level Designs Systems, Ltd......................................  United Kingdom
Integrated Measurement Systems, Inc..................................  U.S.
Redwood Design Automation, Ltd.......................................  United Kingdom
River Oaks Place Association.........................................  U.S.
Seeley Properties, Inc...............................................  U.S.
Simon Software, Inc..................................................  U.S.
Synthesia AB.........................................................  Sweden
Telos Venture Partners...............................................  U.S.
Unicad, Inc..........................................................  U.S.
UVW Ltd..............................................................  United Kingdom
Valid Europe BVBA....................................................  Belgium
3005353 Nova Scotia..................................................  Nova Scotia
Ambit Designs Systems, Inc...........................................  California
Ditente Technology, Inc..............................................  California
Adirondack Transaction Corp..........................................  Delaware
Cadence Design Systems, Finland......................................  Finland
Excellent Design, Inc................................................  Japan
Esperan Ltd..........................................................  United Kingdom
</TABLE> 
<PAGE>
 
<TABLE>
<S>                                                                    <C>
Symbionics Communications Ltd........................................  United Kingdom
Symbionics Developments Ltd..........................................  United Kingdom
Symbionics Group Ltd.................................................  United Kingdom
Symbionics Networks Ltd..............................................  United Kingdom
Symbionics Video Ltd.................................................  United Kingdom
Cadence Credit Corporation...........................................  Delaware
Cadence Receivables Corporation......................................  Delaware
</TABLE>

                                       2

<PAGE>
 
                                                                   EXHIBIT 23.01
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
  As independent public accountants, we hereby consent to the incorporation by
reference in this Registration Statement of our report dated January 23, 1998
included in Cadence Design Systems, Inc.'s Form 10-K for the year ended January
3, 1998 and to all references to our Firm included in this Registration
Statement.
 
                                          /s/ Arthur Andersen LLP
                                          Arthur Andersen LLP
 
San Jose, California
December 23, 1998

<PAGE>
 
                                                                   EXHIBIT 23.02
 
                       CONSENT OF INDEPENDENT ACCOUNTANTS
 
  We consent to the incorporation by reference in the registration statement of
Cadence Design Systems, Inc. on Form S-4 (File No. 333-       ) of our reports
dated January 20, 1998, on our audits of the consolidated financial statements
and financial statement schedule of Quickturn Design Systems, Inc.
("Quickturn") as of December 31, 1997 and 1996 and for each of the three years
in the period ended December 31, 1997, which reports are incorporated by
reference from the Quickturn 1997 Annual Report to Stockholders or included in
the Quickturn Annual Report on Form 10-K for the year ended December 31, 1997.
We also consent to the references to our firm under the Captions "Experts" and
"Selected Financial Data". However, it should be noted that
PricewaterhouseCoopers LLP has not prepared or certified such Selected
Financial Statement Data.
 
  We also consent to the incorporation by reference in the registration
statement of Cadence Design Systems, Inc. on Form S-4 (File No. 333-     ) of
our report dated August 7, 1998, on our audit of the consolidated financial
statements of Ambit Design Systems, Inc. as of June 30, 1997 and 1998 and for
the years then ended, which report is incorporated by reference from the Form
8-K filed by Cadence Design Systems, Inc. on December 10, 1998.
 
                                          /s/ PricewaterhouseCoopers LLP
                                          PricewaterhouseCoopers LLP
 
San Jose, California
December 23, 1998

<PAGE>
 
                                                                   EXHIBIT 23.03
 
                        CONSENT OF HAMBRECHT & QUIST LLC
 
  We hereby consent to the use of our opinion letter dated December 8, 1998 to
the Board of Directors of Quickturn Design Systems, Inc. ("Quickturn"),
included as Appendix C to the Proxy Statement/Prospectus of Quickturn which
forms a part of the Registration Statement dated as of the date hereof on Form
S-4 relating to the proposed merger of CDSI Acquisition, Inc., a wholly-owned
subsidiary of Cadence Design Systems, Inc. with and into Quickturn, and to the
references therein to such opinion under the captions "Summary--Opinion of
Quickturn's Financial Advisor" and "The Merger--Opinion of Quickturn's
Financial Advisor."
 
  In giving such consent, we do not admit that we come within the category of
persons whose consent is required under Section 7 of the Securities Act of
1933, as amended, or the rules and regulations of the Securities and Exchange
Commission thereunder, nor do we thereby admit that we are experts with respect
to any part of such Registration Statement within the meaning of the term
"experts" as used in the Securities Act of 1933, as amended, or the rules and
regulations of the Securities and Exchange Commission thereunder.
 
                                          Hambrecht & Quist LLC
 
                                                    /s/ Paul Cleveland
                                          By: _________________________________
                                            Name: Paul Cleveland
                                            Title: Managing Director
 
December 23, 1998


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission