STB SYSTEMS INC
SC 13D, 1998-12-23
COMPUTER PERIPHERAL EQUIPMENT, NEC
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<PAGE>


                          Securities and Exchange Commission

                               Washington, D.C.  20549

                                     SCHEDULE 13D

                    Under the Securities and Exchange Act of 1934

                                  STB Systems, Inc.
- --------------------------------------------------------------------------------
                                   (Name of Issuer)

                                     Common Stock
- --------------------------------------------------------------------------------
                            (Title of Class of Securities)

                                     784741 10 0
- --------------------------------------------------------------------------------
                                    (CUSIP Number)

                                   William E. Ogle
                                c/o STB Systems, Inc.
                                3400 Waterview Parkway
                                  Richardson, Texas
                                    (972) 234-8750
- --------------------------------------------------------------------------------
                    (Name, Address and Telephone Number of Person
                  Authorized to Receive Notices and Communications)

                                  December 13, 1998
- --------------------------------------------------------------------------------
               (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box:

NOTE:  Six copies of this statement, including all exhibits, should be filed
with the Commission.  See Rule 13d-1(a) for other parties to whom copies are to
be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 (the "ACT") or otherwise subject to the liabilities of that section of the
Act but shall be subject to all other provisions of the Act (however, see the
Notes).

                         (Continued on the following page(s))


<PAGE>

- --------------------------------------------------------------------------------
          1          NAME OF REPORTING PERSON
                     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                     William E. Ogle
                     ###-##-####

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

          2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                     (a)

                     (b)
- --------------------------------------------------------------------------------

          3          SEC USE ONLY
- --------------------------------------------------------------------------------

          4          SOURCE OF FUNDS*

                     OO (See Item 3.)
- --------------------------------------------------------------------------------

          5          CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                     PURSUANT TO ITEMS 2(d) OR 2(e)
                                                                  / /
- --------------------------------------------------------------------------------

          6          CITIZENSHIP OR PLACE OF ORGANIZATION

                     United States
- --------------------------------------------------------------------------------

                               7            SOLE VOTING POWER

      NUMBER OF                             1,628,328 (Subject to the
       SHARES                               restrictions set forth in the
    BENEFICIALLY                            Voting Agreement dated December
      OWNED BY                              13, 1998, the form of which is
        EACH                                filed as Exhibit 2 to this
      REPORTING                             Schedule 13D)   (See Item 4).
       PERSON
        WITH
- --------------------------------------------------------------------------------

                               8            SHARED VOTING POWER

                                            0
- --------------------------------------------------------------------------------

                               9            SOLE DISPOSITIVE POWER

                                            1,638,272 (Subject to the
                                            restrictions set forth in the
                                            Voting Agreement dated December
                                            13, 1998, the form of which is
                                            filed as Exhibit 2 to this
                                            Schedule 13D) (See Item 4)
- --------------------------------------------------------------------------------

                               10           SHARED DISPOSITIVE POWER

                                            0


                                          2
<PAGE>

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

         11          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
                     PERSON

                     1,638,272 (See Item  4)
- --------------------------------------------------------------------------------

         12          CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
                     CERTAIN SHARES*
                                                                  / /
- --------------------------------------------------------------------------------

         13          PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                     12.2%
- --------------------------------------------------------------------------------

         14          TYPE OF REPORTING PERSON*

                     IN
- --------------------------------------------------------------------------------

                        *SEE INSTRUCTIONS BEFORE FILLING OUT!


<PAGE>

Item 1.   SECURITY AND ISSUER.

     This statement relates to shares of the common stock, par value $.01 per
share (the "STB COMMON STOCK"), of STB Systems, Inc., a Texas corporation
("ISSUER").  The principal executive offices of the Issuer are located at 3400
Waterview Parkway, Richardson, Texas 75080, and its telephone number at such
address is (972) 234-8750.

Item 2.   IDENTITY AND BACKGROUND.

     (a)-(c), (f)   The name of the person filing this Schedule 13D is William
E. Ogle (the "REPORTING PERSON").  The Reporting Person's occupation is that of
Chief Executive Officer of the Issuer.  The business address of the Reporting
Person is 3400 Waterview Parkway, Richardson, Texas 75080.   The Reporting
Person is a United States citizen.

     (d)-(e)   During the last five years the Reporting Person has not been
convicted in a criminal proceeding (excluding traffic violations or similar
misdemeanors).  Also, during the last five years the Reporting Person was not a
party to a civil proceeding of a judicial or administrative body of competent
jurisdiction as a result of which he was or is subject to a judgment, decree or
final order enjoining future violations of, or prohibiting or mandating
activities subject to, federal or state securities laws or finding any violation
with respect to such laws.

Item 3.   SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

     On December 13, 1998, 3Dfx Interactive, Inc. ("3DFX"), through its
wholly-owned subsidiary Voodoo Merger Sub, Inc., a Texas corporation ("MERGER
SUB"), agreed to acquire the Issuer by means of a merger (the "MERGER") pursuant
to the terms of the Agreement and Plan of Reorganization dated as of December
13, 1998 (the "MERGER AGREEMENT"), by and among 3Dfx, Merger Sub and Issuer, and
subject to the conditions set forth therein (including approval by the
shareholders of Issuer).  Pursuant to the Merger Agreement, Merger Sub will
merge with and into Issuer and Issuer will become a wholly-owned subsidiary of
3Dfx. The Merger is subject to the approval of the Merger Agreement by the
shareholders of 3Dfx and Issuer, the expiration of the applicable waiting period
under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and
the satisfaction or waiver of certain other conditions as more fully described
in the Merger Agreement. A copy of the form of Merger Agreement is attached
hereto as EXHIBIT 1 and are incorporated herein by this reference.

     Concurrently with the execution of the Merger Agreement, the Reporting
Person and certain shareholders of Issuer entered into voting agreements, dated
as of December 13, 1998 (each a "VOTING AGREEMENT," and collectively, the
"VOTING AGREEMENTS"), with 3Dfx which agreements are described in more detail in
Item 6 below.  Pursuant to the Voting Agreement the Reporting Person has granted
3Dfx an irrevocable proxy to vote the shareholder's shares of STB Common Stock
in favor of the Merger (the "IRREVOCABLE PROXY").  No capital of the Reporting
Person is expected to be expended by the Reporting Person in connection with the
grant of the voting rights


<PAGE>

to 3Dfx with respect to the approximately 1,638,272 shares of STB Common Stock
covered by the Reporting Person's Voting Agreement described in Item 6 below. A
copy of the form of Voting Agreement and the Irrevocable Proxy are attached
hereto as EXHIBIT 2 and are incorporated herein by this reference.

Item 4.   PURPOSE OF TRANSACTION.

     (a)-(b)   As further described in Item 3 above and Item 6 below, this
statement relates to the grant of the Reporting Person's voting rights in his
STB Common Stock to 3Dfx as relates to the Merger of Merger Sub with and into
Issuer in a statutory merger pursuant to the provisions of the Texas Business
Corporation Act.

     As an inducement to 3Dfx to enter into the Merger Agreement, and as further
described in Item 3 above and Item 6 below, the Reporting Person who is a party
to a Voting Agreement has, by executing a Voting Agreement, irrevocably
appointed 3Dfx (or any nominee of 3Dfx) as his lawful attorney and proxy.  Such
proxies give 3Dfx the limited right to vote the shares of STB Common Stock
beneficially owned by the Reporting Person (including any shares of STB Common
Stock that the Reporting Person acquires after the time he entered into the
Voting Agreements) (collectively, the "SHARES").  The Reporting Person
beneficially owns 1,638,272(1)(2) shares of STB Common Stock.

     The descriptions herein of the Merger Agreement and the Voting Agreements
are qualified in their entirety by reference to such agreements, copies of which
are attached hereto as EXHIBITS 1 and 2 respectively.

     (c)  Not applicable.

     (d)  It is anticipated that, upon consummation of the Merger, the directors
and the initial officers of the surviving corporation in the Merger (the
"SURVIVING CORPORATION") shall generally be the current directors and officers
of Merger Sub (each of whom is an executive officer of 3Dfx), until their
respective successors are duly elected or appointed and qualified.

     (e)  See the discussion of the Merger in Item 3 above.

     (f)  Other than as a result of the Merger described in Item 3 above, not
applicable.

     (g)  Upon consummation of the Merger, the Articles of Incorporation of
Merger Sub, as in effect immediately prior to the Merger, shall be the Articles
of Incorporation of the Surviving Corporation until thereafter amended as
provided by Texas Law and such Articles of Incorporation, except the name of the
Surviving Corporation shall be "STB Systems, Inc."  Upon consummation of the
Merger, the Bylaws of Merger Sub, as in effect immediately prior to the Merger,
shall be the Bylaws of the Surviving Corporation until thereafter amended.

     (h)  Upon consummation of the Merger, Issuer's common stock will be
de-listed from


<PAGE>

The Nasdaq Stock Market.

     (i)  Upon consummation of the Merger, Issuer's common stock will become
eligible for termination of registration under the Securities Exchange Act of
1934, as amended (the "ACT"), pursuant to Section 12(g)(4) of the Act.

     (j)  Other than as described above, the Reporting Person currently has no
plan or proposal for an action similar to or which relates to, or may result in,
any of the matters listed in Items 4(a) - (j) of this Schedule 13D (although the
Reporting Person reserves the right to develop such plans or proposals).

- -------------------------
(1) Mr. Ogle is a party to a Right of First Refusal Agreement (the "Right of
     First Refusal Agreement") between STB Systems, Inc. (the "Company"), Mark
     S. Sims, William D. Balthaser, Jr. and himself.  Pursuant to the terms of
     the Right of First Refusal Agreement, if Mr. Ogle, Mr. Sims or Mr.
     Balthaser proposes to sell any shares of common stock registered in his
     name as of the date of the closing of the Company's initial public
     offering, then Issuer will have a right of first refusal to purchase such
     shares on terms similar to those proposed. If the Issuer does not exercise
     its right to purchase all of the shares of common stock proposed to be sold
     by either Mr. Sims or Mr. Balthaser, then Mr. Ogle will have a right of
     first refusal to purchase those shares of common stock that the Issuer does
     not wish to purchase. If the foregoing rights of first refusal are not
     independently or collectively fully exercised, then the shares not
     purchased may be sold in accordance with the proposed terms of sale.
     Notwithstanding the foregoing, the Right of First Refusal Agreement does
     not restrict the ability of Messrs. Ogle, Sims or Balthaser to sell shares
     of common stock in the public market pursuant to Rule 144 promulgated under
     the Securities Act of 1933, as amended.

(2) Includes options to purchase 139,201 shares of common stock that are
     exercisable within 60 days of December 17, 1998.  Also includes 12,375
     shares held by Mr. Ogle pursuant to an Individual Retirement Account and
     9,944 shares held by him pursuant to Issuer's 401(k) Savings Plan.

Item 5.   INTEREST IN SECURITIES OF THE ISSUER.

          (a)-(b)   As a result and subject to the terms and restrictions of the
     Voting Agreement and the irrevocable proxy granted pursuant thereto, the
     Reporting Person has granted the sole power to vote an aggregate of
     approximately 1,628,328 shares of STB Common Stock to 3Dfx for the limited
     purposes described in Item 6 below.  Such shares constitute approximately
     12.2% of the issued and outstanding shares of STB Common Stock as of
     December 13, 1998.  Other than with respect to the provisions of the Voting
     Agreements, 3Dfx does not have the right to vote the Shares on any other
     matters.  The Reporting Person does not share voting power of any
     additional shares of STB Common Stock with regard to the limited purposes
     set forth in Item 6 below or otherwise.  Except as provided by the Voting
     Agreement and Irrevocable Proxy, and excluding shares held pursuant to
     Issuer's 401(k) Savings Plan, the Reporting Person has the


<PAGE>

     sole power to vote or to direct the vote or to dispose or direct the
     disposition of its shares of STB Common Stock.

     (c)  Except as describe herein, the Reporting Person has not effected any
transaction in the STB Common Stock during the past 60 days.

     (d)  Not applicable.

     (e)  Not applicable.

Item 6.   CONTRACT, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONS WITH RESPECT TO
SECURITIES OF THE ISSUER.

     Pursuant to the Merger Agreement and subject to the conditions set forth
therein, Merger Sub will merge with and into Issuer and Issuer will become a
wholly-owned subsidiary of 3Dfx.  Upon consummation of the Merger, Merger Sub
will cease to exist as a corporation and all of the business, assets,
liabilities and obligations of Merger Sub will be merged into Issuer with Issuer
remaining as the Surviving Corporation.  As a result of the Merger, each
outstanding share of STB Common Stock, other than shares owned by Issuer (i.e.
Issuer treasury shares), Merger Sub, 3Dfx or any wholly-owned subsidiary of
Issuer, will be converted into the right to receive 0.65 of a share of 3Dfx
Common Stock.  Outstanding options or warrants to purchase Issuer's common stock
will be treated in the manner described in the Merger Agreement.  The foregoing
summary of the Merger is qualified in its entirety by reference to the copy of
the Merger Agreement included as EXHIBIT 1 to this Schedule 13D and incorporated
herein in its entirety by reference.

     In exercising its right to vote the Shares as lawful attorney and proxy of
the Reporting Person pursuant to the Voting Agreement, 3Dfx (or any nominee of
3Dfx) will be limited, at every Issuer shareholders meeting and every written
consent in lieu of such meeting, to vote the shares of STB Common Stock (i) in
favor of approval of the Merger and the Merger Agreement and (ii) against
approval of any proposal made in opposition to or in competition with the
consummation of the Merger and against any merger, consolidation, sale of
assets, reorganization or recapitalization with any party other than 3Dfx and
any liquidation or winding up of the Issuer.  The Reporting Person may vote his
own shares on all other matters. The Voting Agreements terminate upon the
earlier to occur of (i)  such date and time as the Merger shall become effective
in accordance with the terms and provisions of the Merger Agreement or (ii) such
date as the Merger Agreement shall be terminated in accordance with its terms
(the "EXPIRATION DATE").  The Reporting Person has agreed not to transfer his
Shares prior to the Expiration Date.  Moreover, the Reporting Person has granted
3Dfx an irrevocable proxy to vote the shares beneficially owned by the Reporting
Person in favor of the Merger.  The terms of the Voting Agreements are more
fully described in the Merger Agreement, attached hereto as EXHIBIT 1, and the
Voting Agreement and the Irrevocable Proxy, attached hereto as EXHIBIT 2.  Each
of the Merger Agreement, the Voting Agreement and the Irrevocable Proxy is
incorporated herein by this reference.


<PAGE>

     Other than the Merger Agreement, the Voting Agreement the Right of First
Refusal Agreement and such other benefit and option plans as routinely entered
into between the Reporting Person and Issuer, to the best knowledge of the
Reporting Person, there are no contracts, arrangements, understandings, or
relationships (legal or otherwise) among the Reporting Person with respect to
any securities of the Issuer, including but not limited to transfer or voting of
any of the securities, finder's fees, joint ventures, loan or option
arrangements, puts or calls, guarantees of profits, division of profits or loss,
or the giving or withholding of proxies.

     The descriptions herein of the Merger Agreement and the Voting Agreements
are qualified in their entirety by reference to such agreements, copies of which
are attached hereto as EXHIBITS 1 and 2 respectively.

Item 7.   MATERIAL TO BE FILED AS EXHIBITS.

Exhibit No.
- -----------
     1         Agreement and Plan of Reorganizations, dated December 13, 1998,
               by and among 3Dfx Interactive, Inc., a California corporation,
               Voodoo Merger Sub, Inc., a Texas corporation and a wholly-owned
               subsidiary of 3Dfx Interactive, Inc., and STB Systems, Inc., a
               Texas corporation.

     2         Form of Voting Agreement, dated December 13, 1998, between 3Dfx
               Interactive, Inc., a California corporation, and certain
               shareholders of STB Systems, Inc., a Texas corporation.


<PAGE>

                                      SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this Statement is true, complete and
correct.




DATED:    December 22, 1998


                              ____________________________________
                              William E. Ogle


<PAGE>

                     AGREEMENT AND PLAN OF REORGANIZATION
                                       
                                 BY AND AMONG
                                       
                           3DFX INTERACTIVE, INC.,
                                       
                           VOODOO MERGER SUB, INC.
                                       
                                     AND
                                       
                              STB SYSTEMS, INC.
                                       
                                       
                                       
                        DATED AS OF DECEMBER 13, 1998

<PAGE>

                              TABLE OF CONTENTS
                                       
                                 (CONTINUED)

<TABLE>
<CAPTION>
                                                                                  PAGE
<S>         <C>                                                                   <C>
ARTICLE 1   THE MERGER . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
                                                                                    
     1.1    The Merger . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
                                                                                    
     1.2    Effective Time of the Merger . . . . . . . . . . . . . . . . . . . .   2
                                                                                    
     1.3    Closing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
                                                                                    
     1.4    Effect of the Merger . . . . . . . . . . . . . . . . . . . . . . . .   2
                                                                                    
     1.5    Articles of Incorporation and Bylaws of Surviving Corporation. . . .   2
                                                                                    
     1.6    Directors and Officers . . . . . . . . . . . . . . . . . . . . . . .   2
                                                                                    
     1.7    Tax-Free Reorganization; Accounting. . . . . . . . . . . . . . . . .   2
                                                                                    
ARTICLE 2   EFFECT OF THE MERGER ON THE CAPITAL STOCK OF THE CONSTITUENT            
            CORPORATIONS; EXCHANGE OF CERTIFICATES . . . . . . . . . . . . . . .   3
                                                                                    
     2.1    Effect on Capital Stock. . . . . . . . . . . . . . . . . . . . . . .   3
                                                                                    
     2.2    Exchange of Certificates . . . . . . . . . . . . . . . . . . . . . .   4
                                                                                    
     2.3    Taking of Necessary Action; Further Action . . . . . . . . . . . . .   6
                                                                                    
ARTICLE 3   REPRESENTATIONS AND WARRANTIES OF STB. . . . . . . . . . . . . . . .   6
                                                                                    
     3.1    Organization and Qualification; Subsidiaries . . . . . . . . . . . .   6
                                                                                    
     3.2    Articles of Incorporation and Bylaws . . . . . . . . . . . . . . . .   7
                                                                                    
     3.3    Capitalization . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
                                                                                    
     3.4    Authority Relative to this Agreement . . . . . . . . . . . . . . . .   7
                                                                                    
     3.5    No Conflict; Required Filings and Consents . . . . . . . . . . . . .   8
                                                                                    
     3.6    Compliance; Permits. . . . . . . . . . . . . . . . . . . . . . . . .   8
                                                                                    
     3.7    SEC Filings; Financial Statements. . . . . . . . . . . . . . . . . .   9
                                                                                    
     3.8    Absence of Certain Changes or Events . . . . . . . . . . . . . . . .   9

     3.9    No Undisclosed Liabilities . . . . . . . . . . . . . . . . . . . . .  10
                                                                                  
     3.10   Absence of Litigation. . . . . . . . . . . . . . . . . . . . . . . .  10
                                                                                  
     3.11   Employee Matters and Benefit Plans . . . . . . . . . . . . . . . . .  10
                                                                                  
     3.12   Labor Matters. . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
                                                                                  
     3.13   Registration Statement; Proxy Statement. . . . . . . . . . . . . . .  13
                                                                                  
     3.14   Restrictions on Business Activities. . . . . . . . . . . . . . . . .  14
</TABLE>


                                      i
<PAGE>

                              TABLE OF CONTENTS
                                       
                                 (CONTINUED)

<TABLE>
<CAPTION>
                                                                                  PAGE
<S>         <C>                                                                   <C>
     3.15   Title to Property. . . . . . . . . . . . . . . . . . . . . . . . . .  14
                                                                                  
     3.16   Taxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
                                                                                  
     3.17   Environmental Matters. . . . . . . . . . . . . . . . . . . . . . . .  15
                                                                                  
     3.18   Brokers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
                                                                                  
     3.19   Intellectual Property. . . . . . . . . . . . . . . . . . . . . . . .  16
                                                                                  
     3.20   Change of Control Payments . . . . . . . . . . . . . . . . . . . . .  16
                                                                                  
     3.21   Insurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
                                                                                  
     3.22   Opinion of Financial Advisor . . . . . . . . . . . . . . . . . . . .  17
                                                                                  
     3.23   Board Approval . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
                                                                                  
     3.24   Vote Required. . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
                                                                                  
     3.25   Year 2000 Compliance . . . . . . . . . . . . . . . . . . . . . . . .  17
                                                                                  
     3.26   Texas Business Combination Law Not Applicable. . . . . . . . . . . .  17
                                                                                  
ARTICLE 4   REPRESENTATIONS AND WARRANTIES OF 3DFX AND SUB . . . . . . . . . . .  17
                                                                                  
     4.1    Organization and Qualification; Subsidiaries . . . . . . . . . . . .  17
                                                                                  
     4.2    Articles of Incorporation and Bylaws . . . . . . . . . . . . . . . .  18
                                                                                  
     4.3    Capitalization . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
                                                                                  
     4.4    Authority Relative to this Agreement . . . . . . . . . . . . . . . .  19
                                                                                  
     4.5    No Conflict; Required Filings and Consents . . . . . . . . . . . . .  19
                                                                                  
     4.6    Compliance; Permits. . . . . . . . . . . . . . . . . . . . . . . . .  20
                                                                                  
     4.7    SEC Filings; Financial Statements. . . . . . . . . . . . . . . . . .  20
                                                                                  
     4.8    Absence of Certain Changes or Events . . . . . . . . . . . . . . . .  21
                                                                                  
     4.9    No Undisclosed Liabilities . . . . . . . . . . . . . . . . . . . . .  21
                                                                                  
     4.10   Absence of Litigation. . . . . . . . . . . . . . . . . . . . . . . .  21
                                                                                  
     4.11   Employee Matters and Benefit Plans . . . . . . . . . . . . . . . . .  22
                                                                                  
     4.12   Labor Matters. . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
                                                                                  
     4.13   Registration Statement; Proxy Statement. . . . . . . . . . . . . . .  25
                                                                                  
     4.14   Restrictions on Business Activities. . . . . . . . . . . . . . . . .  25
                                                                                  
     4.15   Title to Property. . . . . . . . . . . . . . . . . . . . . . . . . .  25
</TABLE>


                                      ii
<PAGE>

                              TABLE OF CONTENTS
                                       
                                 (CONTINUED)

<TABLE>
<CAPTION>
                                                                                  PAGE
<S>         <C>                                                                   <C>
     4.16   Taxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
                                                                                  
     4.17   Environmental Matters. . . . . . . . . . . . . . . . . . . . . . . .  26
                                                                                  
     4.18   Brokers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
                                                                                  
     4.19   Intellectual Property. . . . . . . . . . . . . . . . . . . . . . . .  27
                                                                                  
     4.20   Insurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
                                                                                  
     4.21   Opinion of Financial Advisor . . . . . . . . . . . . . . . . . . . .  27
                                                                                  
     4.22   Board Approval . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
                                                                                  
     4.23   Vote Required. . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
                                                                                  
     4.24   Interim Operations of Sub. . . . . . . . . . . . . . . . . . . . . .  28
                                                                                  
     4.25   Year 2000 Compliance . . . . . . . . . . . . . . . . . . . . . . . .  28
                                                                                  
     4.26   Change of Control Payments.. . . . . . . . . . . . . . . . . . . . .  28
                                                                                  
ARTICLE 5   CONDUCT AND TRANSACTIONS PRIOR TO EFFECTIVE TIME; ADDITIONAL          
            AGREEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
                                                                                  
     5.1    Information and Access . . . . . . . . . . . . . . . . . . . . . . .  28
                                                                                  
     5.2    Conduct of Business of the Companies . . . . . . . . . . . . . . . .  28
                                                                                  
     5.3    Negotiation With Others. . . . . . . . . . . . . . . . . . . . . . .  30
                                                                                  
     5.4    Preparation of S-4 and the Proxy Statement; Other Filings. . . . . .  32
                                                                                  
     5.5    Advice of Changes; SEC Filings . . . . . . . . . . . . . . . . . . .  32
                                                                                  
     5.6    Letter of STB's Independent Auditors . . . . . . . . . . . . . . . .  32
                                                                                  
     5.7    Letter of 3Dfx's Independent Auditors. . . . . . . . . . . . . . . .  32
                                                                                  
     5.8    Shareholders Meetings. . . . . . . . . . . . . . . . . . . . . . . .  33
                                                                                  
     5.9    Agreements to Take Reasonable Action . . . . . . . . . . . . . . . .  33
                                                                                  
     5.10   Consents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
                                                                                  
     5.11   Nasdaq Additional Shares Listing . . . . . . . . . . . . . . . . . .  34
                                                                                  
     5.12   Public Announcements . . . . . . . . . . . . . . . . . . . . . . . .  34
                                                                                  
     5.13   Affiliates . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
                                                                                  
     5.14   STB Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
                                                                                  
     5.15   STB Employee Stock Purchase Plan . . . . . . . . . . . . . . . . . .  36
</TABLE>


                                      iii
<PAGE>

                               TABLE OF CONTENTS
                                       
                                  (CONTINUED)

<TABLE>
<CAPTION>
                                                                                  PAGE
<S>         <C>                                                                   <C>
     5.16   Indemnification and Insurance. . . . . . . . . . . . . . . . . . . .  36
                                                                                  
     5.17   Notification of Certain Matters. . . . . . . . . . . . . . . . . . .  36

     5.18   Tax-Free Reorganization. . . . . . . . . . . . . . . . . . . . . . .  37
                                                                                  
     5.19   STB 401(k) Plan. . . . . . . . . . . . . . . . . . . . . . . . . . .  37
                                                                                  
     5.20   Amended Employment Agreements. . . . . . . . . . . . . . . . . . . .  37
                                                                                  
ARTICLE 6   CONDITIONS PRECEDENT . . . . . . . . . . . . . . . . . . . . . . . .  37
                                                                                  
     6.1    Conditions to Each Party's Obligation to Effect the Merger . . . . .  37
                                                                                  
     6.2    Conditions of Obligations of 3Dfx and Sub. . . . . . . . . . . . . .  38
                                                                                  
     6.3    Conditions of Obligation of STB. . . . . . . . . . . . . . . . . . .  39
                                                                                  
ARTICLE 7   TERMINATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
                                                                                  
     7.1    Termination. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
                                                                                  
     7.2    Effect of Termination. . . . . . . . . . . . . . . . . . . . . . . .  41
                                                                                  
     7.3    Fees and Expenses. . . . . . . . . . . . . . . . . . . . . . . . . .  41
                                                                                  
ARTICLE 8   GENERAL PROVISIONS . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.1    Amendment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.2    Extension; Waiver. . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.3    Nonsurvival of Representations, Warranties and Agreements. . . . . .  42
                                                                                  
     8.4    Entire Agreement . . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.5    Severability . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.6    Notices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                  
     8.7    Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
                                                                                  
     8.8    Counterparts . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
                                                                                  
     8.9    Benefits; Assignment . . . . . . . . . . . . . . . . . . . . . . . .  44
                                                                                  
     8.10   Governing Law. . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
</TABLE>


                                      iv
<PAGE>

EXHIBITS

<TABLE>
<S>  <C>
A    Form of STB Option Agreement

B    Form of STB Voting Agreement

C    Form of 3Dfx Voting Agreement

D    Form of Articles of Merger

E    STB Affiliates

F    Form of STB Affiliate Agreement

G    3Dfx Board of Directors
</TABLE>




                                      -i-
<PAGE>

                      AGREEMENT AND PLAN OF REORGANIZATION

     THIS AGREEMENT AND PLAN OF REORGANIZATION (the "AGREEMENT") is dated as 
of December 13, 1998, among 3DFX INTERACTIVE, INC., a California corporation 
("3DFX"), VOODOO MERGER SUB, INC., a Texas corporation and wholly-owned 
subsidiary of 3Dfx ("SUB"), and STB SYSTEMS, INC., a Texas corporation 
("STB"). 3Dfx and STB are sometimes referred to individually as a "COMPANY" 
and collectively as the "COMPANIES."
                                          
                                     RECITALS:

     A.   The Boards of Directors of STB, 3Dfx and Sub have each approved the 
terms and conditions of the business combination between 3Dfx and STB to be 
effected by the merger (the "MERGER") of Sub with and into STB, pursuant to 
the terms and subject to the conditions of this Agreement and the Texas 
Business Corporation Act (the "TEXAS STATUTE").

     B.   Concurrently with the execution of this Agreement, and as a 
condition and inducement to 3Dfx's willingness to enter into this Agreement, 
3Dfx and STB are entering into a STB Stock Option Agreement in the form 
attached as EXHIBIT A (the "STB OPTION AGREEMENT"), pursuant to which STB is 
granting to 3Dfx an option to purchase shares of Common Stock of STB upon the 
occurrence of certain conditions. 

     C.   Concurrently with the execution of this Agreement, and as a 
condition and inducement to 3Dfx's and STB's willingness to enter into this 
Agreement, certain affiliates of  STB and 3Dfx are entering into Voting 
Agreements in substantially the forms attached hereto as EXHIBIT B, (the "STB 
VOTING AGREEMENT") and EXHIBIT C (the "3DFX VOTING AGREEMENT"), respectively.

     D.   The Boards of Directors of STB and 3Dfx have each approved the 
STB Option Agreement.

     E.   The parties intend, by executing this Agreement, to adopt a plan 
of reorganization within the meaning of Section 368 of the Internal Revenue 
Code of 1986, as amended (the "CODE").

     NOW, THEREFORE, in consideration of the covenants, promises and 
representations set forth in this Agreement, the parties agree as follows:

                                  ARTICLE 1
                                       
                                 THE MERGER

     1.1    THE MERGER.  Upon the terms and subject to the conditions of this 
Agreement and in accordance with the Texas Statute, Sub shall be merged with 
and into STB.  STB and Sub shall execute Articles of Merger, in substantially 
the form attached as EXHIBIT D (the "ARTICLES OF MERGER") immediately prior 
to the Closing.  Following the Merger, STB shall continue as the surviving 
corporation (the "SURVIVING 

<PAGE>

CORPORATION") and the separate corporate existence of Sub shall cease.  Sub 
and STB are collectively referred to as the "CONSTITUENT CORPORATIONS."

     1.2    EFFECTIVE TIME OF THE MERGER.  Subject to the provisions of this 
Agreement and the Articles of Merger, the Articles of Merger, together with 
any required certificates, shall be duly filed in accordance with the Texas 
Statute simultaneously with or as soon as practicable following the Closing 
(as defined in Section 1.3 below).  The Merger shall become effective (the 
"EFFECTIVE TIME") upon the filing of the Articles of Merger (together with 
any required certificates) with the Secretary of State of the State of Texas.

     1.3    CLOSING.  Unless this Agreement shall have been terminated 
pursuant to Section 7.1, the closing of the Merger (the "CLOSING") will take 
place at 10:00 a.m. on a date (the "CLOSING DATE") to be mutually agreed upon 
by the parties, which date shall be no later than the third Business Day (as 
defined below) after all of the conditions set forth in Article 6 shall have 
been satisfied (or waived in accordance with Section 8.2), unless another 
date is agreed to in writing by the parties.  The Closing shall take place at 
the offices of Wilson Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo 
Alto, California, 94304-1050, unless another place is agreed to in writing by 
the parties.  As used in this Agreement, "BUSINESS DAY" shall mean any day, 
other than a Saturday, Sunday or legal holiday on which banks are permitted 
to close in the City and State of New York.

     1.4    EFFECT OF THE MERGER.  At the Effective Time, the effect of the 
Merger shall be as provided in this Agreement and the applicable provisions 
of the Texas Statute.  Without limiting the generality of the foregoing, and 
subject thereto, at the Effective Time all the property, rights, privileges, 
powers and franchises of STB and Sub shall vest in the Surviving Corporation, 
and all debts, liabilities and duties of STB and Sub shall become the debts, 
liabilities and duties of the Surviving Corporation.

     1.5    ARTICLES OF INCORPORATION AND BYLAWS OF SURVIVING CORPORATION.  
At the Effective Time, (i) the Articles of Incorporation of Sub, as in effect 
immediately prior to the Effective Time shall be the Articles of 
Incorporation of the Surviving Corporation until thereafter altered, amended 
or repealed as provided in the Texas Statute and such Articles of 
Incorporation of Surviving Corporation provided that at the Effective Time 
the Articles of Incorporation of the Surviving Corporation shall be amended 
so that the name of the Surviving Corporation shall be "STB Systems, Inc." 
and (ii) the Bylaws of Sub shall become the Bylaws of the Surviving 
Corporation until thereafter altered, amended or repealed as provided in the 
Texas Statute or in the Articles of Incorporation or Bylaws of the Surviving 
Corporation.

     1.6    DIRECTORS AND OFFICERS.  The initial directors of the Surviving 
Corporation shall be the director's of Sub immediately prior to the Effective 
Time, until their respective successors are duly elected or appointed and 
qualified.  The initial officers of the Surviving Corporation shall be the 
officers of Sub immediately prior to the Effective Time, until their 
respective successors are duly appointed.

     1.7    TAX-FREE REORGANIZATION; ACCOUNTING.  The parties intend that the 
Merger be treated as a tax free reorganization under Section 368(a) of the 
Code, and to be accounted for as a purchase for accounting purposes.


                                      2
<PAGE>

                                  ARTICLE 2
                                       
                 EFFECT OF THE MERGER ON THE CAPITAL STOCK OF THE
                CONSTITUENT CORPORATIONS; EXCHANGE OF CERTIFICATES

     2.1    EFFECT ON CAPITAL STOCK.  At the Effective Time, subject and 
pursuant to the terms of this Agreement, by virtue of the Merger and without 
any action on the part of the Constituent Corporations or the holders of any 
shares of capital stock of the Constituent Corporations:

            (a)     CAPITAL STOCK OF SUB.  Each issued and outstanding share 
of the common stock, $.001 par value, of Sub shall be converted into one 
validly issued, fully paid and nonassessable share of common stock, $.001 par 
value, of the Surviving Corporation.  Each stock certificate of Sub 
evidencing ownership of any such shares shall continue to evidence ownership 
of such shares of common stock of the Surviving Corporation.

            (b)     CANCELLATION OF CERTAIN SHARES OF STB COMMON STOCK.  Each 
share of STB Common Stock (as defined in Section 2.1(c)) that is owned by STB 
as treasury stock and each share of STB Common Stock that is owned by 3Dfx, 
Sub or any other subsidiary of 3Dfx or STB shall be canceled and no capital 
stock of 3Dfx or other consideration shall be delivered in exchange therefor.

            (c)     EXCHANGE RATIO FOR STB COMMON STOCK.  Each share of 
common stock, $.01 par value, of STB ("STB COMMON STOCK") issued and 
outstanding immediately prior to the Effective Time (other than shares 
canceled pursuant to Section 2.1(b)), will be canceled and extinguished and 
automatically converted (subject to Sections 2.1(e) and (f)) into the right 
to receive .65 (the "EXCHANGE RATIO") share of common stock, no par value, of 
3Dfx ("3DFX COMMON STOCK") upon surrender of the certificate representing 
such share of STB Common Stock in the manner provided in Section 2.2 (or in 
the case of a lost, stolen, or destroyed certificate, upon delivery of an 
affidavit (and bond, if required) in the manner provided in Section 2.2(g)).

            (d)     STOCK OPTIONS; EMPLOYEE STOCK PURCHASE PLAN.  At the 
Effective Time: (x) all options to purchase STB Common Stock then outstanding 
under STB's 1995 Amended and Restated Long Term Incentive Plan (the "OPTION 
PLAN") and STB's Amended and Restated Stock Option Plan for Non-Employee 
Directors (the "DIRECTOR PLAN" and together with the Option Plan, the "STB 
STOCK OPTION PLANS") shall be treated as set forth in Section 5.14; and (y) 
rights outstanding under STB's 1996 Employee Stock Option Purchase Plan (the 
"STB ESPP") shall be treated as set forth in Section 5.15.

            (e)     WARRANTS.  At the Effective Time, that certain warrant to 
purchase up to an aggregate of 420,000 shares of Common Stock of STB (the 
"STB WARRANT"), shall be assumed by 3Dfx in accordance with the terms hereof. 
 In this regard, STB agrees to provide the holder of the STB Warrant with any 
and all notices required as a result of the Merger and the transactions 
contemplated thereby.

            (f)     ADJUSTMENT OF EXCHANGE RATIO.  If between the date of 
this Agreement and the Effective Time, the outstanding shares of 3Dfx Common 
Stock or STB Common Stock shall have been changed into a different number of 
shares or a different class by reason of any reclassification, 
recapitalization, split-up, stock dividend, stock combination, exchange of 
shares, readjustment or otherwise, 


                                      3
<PAGE>

then the Exchange Ratio shall be correspondingly adjusted; PROVIDED, HOWEVER, 
that any such changes shall be subject to Section 5.2 below.

            (g)     NO ISSUANCE OF FRACTIONAL SHARES.  No certificates or 
scrip for fractional shares of 3Dfx Common Stock shall be issued, but in lieu 
thereof each holder of shares of STB Common Stock who would otherwise be 
entitled to receive certificates or scrip for a fraction of a share of 3Dfx 
Common Stock shall receive from 3Dfx, at such time as such holder shall 
receive a certificate representing shares of 3Dfx Common Stock,  an amount of 
cash equal to the per share market value of 3Dfx Common Stock determined by 
multiplying (i) the closing price of one share of 3Dfx Common Stock as 
reported on the NASDAQ National Market ("NASDAQ") on the last full trading 
day prior to the Effective Time by (ii) the fraction of a share of 3Dfx 
Common Stock to which such holder would otherwise be entitled.  The 
fractional share interests of each shareholder of STB shall be aggregated, so 
that no STB shareholder shall receive cash in an amount equal to or greater 
than the value of one full share of 3Dfx Common Stock.

     2.2    EXCHANGE OF CERTIFICATES.

            (a)     EXCHANGE AGENT.  Prior to the Closing Date, 3Dfx shall 
select a bank or trust company to act as exchange agent (the "EXCHANGE 
AGENT") in the Merger.  Immediately following the Effective Time, 3Dfx shall 
deposit with the Exchange Agent, for the benefit of the holders of shares of 
STB Common Stock, for exchange in accordance with this Article 2, 
certificates representing the shares of 3Dfx Common Stock (such shares of 
3Dfx Common Stock, together with any dividends or distributions with respect 
thereto, are referred to as the "EXCHANGE FUND") issuable pursuant to this 
Article 2 in exchange for outstanding shares of STB Common Stock, and cash in 
an amount sufficient for payment in lieu of fractional shares pursuant to 
Section 2.2(e). 

            (b)     EXCHANGE PROCEDURES.  As soon as practicable after the 
Effective Time, the Exchange Agent shall mail to each holder of record (other 
than STB, any subsidiary of STB, Sub, 3Dfx and any other subsidiary of 3Dfx) 
(including holders of record pursuant to purchases made under the STB 
Purchase Plan (as defined in Section 3.3) immediately prior to the Effective 
Time pursuant to Section 5.15) of a certificate or certificates which 
immediately prior to the Effective Time represented issued and outstanding 
shares of STB Common Stock (collectively, the "CERTIFICATES") whose shares 
are being converted into 3Dfx Common Stock pursuant to Section 2.1(c) of this 
Agreement, (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 3Dfx and STB may reasonably 
specify) and (ii) instructions for use in effecting the surrender of the 
Certificates in exchange for certificates representing 3Dfx Common Stock.  
Upon surrender of a Certificate for cancellation to the Exchange Agent, 
together with a duly executed letter of transmittal and such other documents 
as may be reasonably required by the Exchange Agent, the holder of such 
Certificate shall be entitled to receive in exchange therefor a certificate 
representing that number of whole shares of 3Dfx Common Stock which such 
holder has the right to receive pursuant to the provisions of this Article 2 
and the Certificate so surrendered shall forthwith be canceled.  In the event 
of a transfer of ownership of shares of STB Common Stock which is not 
registered on the transfer records of STB, a certificate representing the 
proper number of shares of 3Dfx Common Stock may be issued to a transferee if 
the Certificate representing such STB Common Stock 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 


                                      4
<PAGE>

Section 2.2, each Certificate shall be deemed, on and after the Effective 
Time, to represent only the right to receive upon such surrender the 
certificate representing shares of 3Dfx Common Stock and cash in lieu of any 
fractional shares of 3Dfx Common Stock as contemplated by this Article 2, and 
the Texas Statute.

            (c)     DISTRIBUTIONS WITH RESPECT TO UNSURRENDERED CERTIFICATES. 
No dividends or other distributions declared or made after the Effective 
Time with respect to 3Dfx 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 3Dfx Common Stock represented thereby and no cash 
payment in lieu of fractional shares shall be paid to any such holder 
pursuant to Section 2.1(f) until the holder of record of such Certificate 
shall surrender such Certificate. Subject to the effect, if any, of 
applicable laws, following surrender of any such Certificate, there shall be 
paid to the record holder of the certificates representing whole shares of 
3Dfx Common Stock issued in exchange therefor, without interest, (i) at the 
time of such surrender, the amount of any cash payable in lieu of a 
fractional share of 3Dfx Common Stock to which such holder is entitled 
pursuant to Section 2.1(f) and the amount of dividends or other distributions 
with a record date after the Effective Time theretofore paid with respect to 
such whole shares of 3Dfx 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 3Dfx Common Stock.

            (d)     NO FURTHER OWNERSHIP RIGHTS IN STB COMMON STOCK.  All 
shares of 3Dfx Common Stock issued upon the surrender for exchange of shares 
of STB Common Stock in accordance with the terms of this Article 2 (including 
any cash paid pursuant to Section 2.2(c) or 2.2(e)) shall be deemed to have 
been issued in full satisfaction of all rights pertaining to such shares of 
STB Common Stock.  There shall be no further registration of transfers on the 
stock transfer books of the Surviving Corporation of the shares of STB Common 
Stock which 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 2.

            (e)     TERMINATION OF EXCHANGE FUND.  Any portion of the 
Exchange Fund which remains undistributed to the shareholders of STB for 
twelve months after the Effective Time shall be delivered to 3Dfx, upon 
demand, and any former shareholders of STB who have not previously complied 
with this Article 2 shall thereafter look only to 3Dfx for payment of their 
claim for 3Dfx Common Stock, any cash in lieu of fractional shares of 3Dfx 
Common Stock and any dividends or distributions with respect to 3Dfx Common 
Stock.

            (f)     NO LIABILITY.  Neither the Exchange Agent, 3Dfx, Sub nor 
STB shall be liable to any holder of shares of STB Common Stock or 3Dfx 
Common Stock, as the case may be, for shares (or dividends or distributions 
with respect thereto) from the Exchange Fund delivered to a public official 
pursuant to any applicable abandoned property, escheat or similar law.

            (g)     LOST, STOLEN OR DESTROYED CERTIFICATES.  In the event any 
Certificates evidencing shares of STB Common Stock shall have been lost, 
stolen or destroyed, the holder of such lost, stolen or destroyed 
Certificate(s) shall execute an affidavit of that fact upon request.  The 
holder of any such lost, stolen or destroyed Certificate(s) shall also 
deliver a bond in such sum as 3Dfx may reasonably require as indemnity 
against any claim that may be made against 3Dfx or the Exchange Agent with 
respect to the Certificate(s) alleged to have been lost, stolen or destroyed. 
The affidavit and any bond which may be required hereunder 


                                      5
<PAGE>

shall be delivered to the Exchange Agent, who shall be responsible for making 
payment for such lost, stolen or destroyed Certificate(s).

     2.3    TAKING OF NECESSARY ACTION; FURTHER ACTION.  If, at any time 
after the Effective Time, any such further action is necessary or desirable 
to carry out the purposes of this Agreement and to vest the Surviving 
Corporation with full right, title and possession to all assets, property, 
rights, privileges, powers and franchises of STB and Sub, the officers and 
directors of STB and Sub are fully authorized in the name of their respective 
corporations or otherwise to take, and will take, all such lawful and 
necessary action.

                                   ARTICLE 3
                                       
                      REPRESENTATIONS AND WARRANTIES OF STB

     STB represents and warrants to 3Dfx and Sub, except as set forth in the 
STB SEC Reports (as defined in Section 3.7), as follows:

     3.1    ORGANIZATION AND QUALIFICATION; SUBSIDIARIES.  (i) Each of STB 
and its subsidiaries is a corporation duly organized, validly existing and in 
good standing under the laws of the jurisdiction of its incorporation and has 
the requisite corporate power and authority to own, lease and operate its 
assets and properties and to carry on its business as it is now being 
conducted.  Each of STB and its subsidiaries is in possession of all 
franchises, grants, authorizations, licenses, permits, easements, consents, 
certificates, approvals and orders ("APPROVALS") necessary to own, lease and 
operate the properties it purports to own, operate or lease and to carry on 
its business as it is now being conducted, except where the failure to have 
such Approvals would not, individually or in the aggregate, have a Material 
Adverse Effect (as defined below).  Each of STB and its subsidiaries is duly 
qualified or licensed as a foreign corporation to do business, and is in good 
standing, in each jurisdiction where the character of the properties owned, 
leased or operated by it or the nature of its activities makes such 
qualification or licensing necessary, except for such failures to be so duly 
qualified or licensed and in good standing that would not, either 
individually or in the aggregate, have a Material Adverse Effect.  When used 
in connection with STB or any of its subsidiaries, the term "MATERIAL ADVERSE 
EFFECT" means any change, event or effect that is materially adverse to the 
business, assets (including intangible assets), liabilities, financial 
condition or results of operations of STB and its subsidiaries taken as a 
whole; PROVIDED, HOWEVER, that a "Material Adverse Effect" shall not include 
any (i) adverse effect on the results of operations or financial condition of 
STB that is attributable to the transactions or resulting business enterprise 
contemplated by this Agreement, including, without limitation, delay of, 
reduction in, or cancellation or change in the terms of product orders by 
customers of STB or an increase in the price of, a delay of, reduction in or 
cancellation of or change in terms with respect to products or components 
supplied by, or any deterioration in or termination of a relationship by, 
vendors of STB,  (ii) change arising out of conditions in or affecting the 
industries in which the parties to this Agreement compete or (iii) decline in 
STB's stock price.  Other than wholly-owned subsidiaries and except as 
permitted after the date of this Agreement under Section 5.2 of this 
Agreement and except with respect to investments of less than a twenty 
percent (20%) interest in any corporation, partnership, joint venture or 
other business, association or entity, STB does not directly or indirectly 
own any equity or similar interest in, or any interest convertible or 
exchangeable or exercisable for, any equity or similar interest in, any 
corporation, partnership, joint venture or other business, association or 
entity.


                                      6
<PAGE>

     3.2    ARTICLES OF INCORPORATION AND BYLAWS.  STB has previously 
furnished to 3Dfx a complete and correct copy of its Articles of 
Incorporation and Bylaws as amended to date.  Such Articles of Incorporation, 
Bylaws and equivalent organizational documents of each of its subsidiaries 
are in full force and effect.  Neither STB nor any of its subsidiaries is in 
violation of any of the provisions of its Articles of Incorporation or Bylaws 
or equivalent organizational documents.

     3.3    CAPITALIZATION.  The authorized capital stock of STB consists of 
25,000,000 shares of STB Common Stock and 2,000,000 shares of Preferred Stock 
("STB PREFERRED STOCK"), each having a par value of $.01 per share.  At the 
close of business on December 11, 1998, (i) approximately 12,605,887 shares 
of STB Common Stock were issued and outstanding all of which are validly 
issued, fully paid and nonassessable, (ii) 696,800 shares of STB Common Stock 
were held in treasury by STB or by subsidiaries of STB, (iii) approximately 
422,088 shares of STB Common Stock were available for future issuance 
pursuant to STB's 1995 Employee Stock Option Purchase Plan (the "STB PURCHASE 
PLAN"), (iv) approximately 2,084,529 shares and approximately 71,250 shares 
of STB Common Stock were reserved for issuance upon the exercise of 
outstanding options to purchase STB Common Stock under the Option Plan and 
the Director Plan, respectively, (v) approximately 330,396 shares and 
approximately 153,750 shares of STB Common Stock were available for future 
grant under the Option Plan and the Director Plan, respectively, (vii) 
1,890,883 shares of STB Common Stock were reserved for future issuance 
pursuant to the STB Option Agreement, and (viii) 420,000 shares were reserved 
for issuance upon exercise of the STB Warrant.  As of the date hereof, no 
shares of STB Preferred Stock were issued or outstanding.  No change in such 
capitalization has occurred between December  31, 1998 and the date hereof 
except (A) the issuance of shares of STB Common Stock pursuant to the 
exercise of outstanding options, (B) shares issued under the STB Purchase 
Plan, and (C)  the issuance of options as permitted under Section 5.2(c) 
hereof (and exercise of such options).  As of the date of this Agreement, 
there are no options, warrants or other rights, agreements, arrangements or 
commitments of any character relating to the issued or unissued capital stock 
of STB or any of its subsidiaries or obligating STB or any of its 
subsidiaries to issue or sell any shares of capital stock of, or other equity 
interests in, STB or any of its subsidiaries.  All shares of STB Common Stock 
subject to issuance as aforesaid, upon issuance on the terms and conditions 
specified in the instruments pursuant to which they are issuable, shall be 
duly authorized, validly issued, fully paid and nonassessable.  Other than 
with respect to such actions as are permitted under Section 5.2, there are no 
obligations, contingent or otherwise, of STB or any of its subsidiaries to 
repurchase, redeem or otherwise acquire any shares of STB Common Stock or the 
capital stock of any subsidiary or to provide funds to or make any investment 
(in the form of a loan, capital contribution or otherwise) in any such 
subsidiary or any other entity other than guarantees of obligations of 
subsidiaries entered into in the ordinary course of business.  All of the 
outstanding shares of capital stock (other than directors' qualifying shares) 
of each of STB's subsidiaries is duly authorized, validly issued, fully paid 
and nonassessable and all such shares (other than directors' qualifying 
shares) are owned by STB or another subsidiary free and clear of all security 
interests, liens, claims, pledges, agreements, limitations in STB's voting 
rights, charges or other encumbrances of any nature whatsoever.

     3.4    AUTHORITY RELATIVE TO THIS AGREEMENT.  STB has all necessary 
corporate power and authority to execute and deliver this Agreement and the 
STB Option Agreement and to perform its obligations hereunder and thereunder 
and, subject to obtaining the approval of the shareholders of STB of the 
Merger, to consummate the transactions contemplated hereby and thereby.  The 
execution and delivery of this Agreement and the STB Option Agreement by STB 
and the consummation by STB of the transactions contemplated hereby and 
thereby have been duly and validly authorized by all necessary corporate 
action on 


                                      7
<PAGE>

the part of STB and no other corporate proceedings on the part of STB are 
necessary to authorize this Agreement, the STB Option Agreement or to 
consummate the transactions so contemplated (other than, with respect to the 
Merger, the approval and adoption of this Agreement by holders of a majority 
of the outstanding shares of STB Common Stock in accordance with the Texas 
Statute and STB's Articles of Incorporation and Bylaws).  This Agreement and 
the STB Option Agreement have been duly and validly executed and delivered by 
STB and, assuming the due authorization, execution and delivery by 3Dfx and 
Sub, constitute legal and binding obligations of STB, enforceable against STB 
in accordance with their respective terms, subject to (i) bankruptcy, 
insolvency, reorganization, moratorium or other similar laws affecting or 
relating to creditors rights generally and (ii) the availability of 
injunctive relief and other equitable remedies.

     3.5    NO CONFLICT; REQUIRED FILINGS AND CONSENTS.  

            (a)     The execution and delivery of this Agreement and the STB 
Option Agreement by STB do not, and the performance of this Agreement and the 
STB Option Agreement by STB shall not, (i) conflict with or violate the 
Articles of Incorporation or Bylaws or equivalent organizational documents of 
STB or any of its subsidiaries, (ii) subject to obtaining the approval of 
STB's shareholders of the Merger and compliance with the requirements set 
forth in Section 3.5(b) below, conflict with or violate any law, rule, 
regulation, order, judgment or decree applicable to STB or any of its 
subsidiaries or by which its or any of their respective properties is bound 
or affected, or (iii) result in any breach of or constitute a default (or an 
event that with notice or lapse of time or both would become a default) 
under, or impair STB's rights or alter the rights or obligations of any third 
party under, or give to others any rights of termination, amendment, 
acceleration or cancellation of, or result in the creation of a lien or 
encumbrance on any of the properties or assets of STB or any of its 
subsidiaries pursuant to, any material note, bond, mortgage, indenture, 
contract, agreement, lease, license, permit, franchise or other instrument or 
obligation to which STB or any of its subsidiaries is a party or by which STB 
or any of its subsidiaries or its or any of their respective properties are 
bound or affected, except for any such breaches, defaults or other 
occurrences that could not reasonably be expected to have, individually or in 
the aggregate, a Material Adverse Effect.  

            (b)     The execution and delivery of this Agreement and the STB 
Option Agreement by STB do not, and the performance of this Agreement by STB 
shall not, require any consent, approval, authorization or permit of, or 
filing with or notification to, any court, administrative agency, commission, 
governmental or regulatory authority, domestic or foreign (a "GOVERNMENTAL 
ENTITY"), except (A) for applicable requirements, if any, of the Securities 
Act of 1933, as amended (the "SECURITIES ACT"), the Securities Exchange Act 
of 1934, as amended (the "EXCHANGE ACT"), state securities laws ("BLUE SKY 
LAWS"), the pre-merger notification requirements (the "HSR APPROVAL") of the 
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR 
ACT") and of foreign Governmental Entities and the rules and regulations 
thereunder, the rules and regulations of Nasdaq and the filing and 
recordation of the Articles of Merger as required by the Texas Statute and 
(B) where the failure to obtain such consents, approvals, authorizations or 
permits, or to make such filings or notifications, (i) would not prevent 
consummation of the Merger or otherwise prevent STB from performing its 
obligations under this Agreement or (ii) could not, individually or in the 
aggregate, reasonably be expected to have a Material Adverse Effect.


                                      8
<PAGE>

     3.6    COMPLIANCE; PERMITS.  

            (a)     Neither STB nor any of its subsidiaries is in conflict 
with, or in default or violation of, (i) any law, rule, regulation, order, 
judgment or decree applicable to STB or any of its subsidiaries or by which 
its or any of their respective properties is bound or affected, or (ii) any 
note, bond, mortgage, indenture, contract, agreement, lease, license, permit, 
franchise or other instrument or obligation to which STB or any of its 
subsidiaries is a party or by which STB or any of its subsidiaries or its or 
any of their respective properties is bound or affected, except for any 
conflicts, defaults or violations which could not reasonably be expected to 
have, individually or in the aggregate, a Material Adverse Effect.  To the 
best knowledge of STB, no investigation or review by any governmental or 
regulatory body or authority is pending or threatened against STB or its 
subsidiaries, nor has any governmental or regulatory body or authority 
indicated an intention to conduct the same, other than, in each such case, 
those the outcome of which could not, individually or in the aggregate, 
reasonably be expected to have a Material Adverse Effect.

            (b)     STB and its subsidiaries hold all permits, licenses, 
variances, exemptions, orders and approvals from governmental authorities 
which are material to operation of the business of STB and its subsidiaries 
taken as a whole (collectively, the "STB PERMITS").  STB and its subsidiaries 
are in compliance with the terms of the STB Permits, except where the failure 
to so comply could not, individually or in the aggregate,  reasonably be 
expected to have a Material Adverse Effect.

     3.7    SEC FILINGS; FINANCIAL STATEMENTS.  

            (a)     STB has made available to 3Dfx a correct and complete 
copy of each report, schedule, registration statement and definitive proxy 
statement filed by STB with the Securities and Exchange Commission ("SEC") on 
or after January 1, 1997 and prior to the date of this Agreement (the "STB 
SEC REPORTS"), which are all the forms, reports and documents required to be 
filed by STB with the SEC since January 1, 1997.  The STB SEC Reports (A) 
were prepared in accordance with the requirements of the Securities Act or 
the Exchange Act, as the case may be, and (B) did not at the time they were 
filed (or if amended or superseded by a filing prior to the date of this 
Agreement then on the date of such filing) contain any untrue statement of a 
material fact or omit to state a material fact required to be stated therein 
or necessary in order to make the statements therein, in light of the 
circumstances under which they were made, not misleading.  None of STB's 
subsidiaries is required to file any reports or other documents with the SEC.

            (b)     Each set of consolidated financial statements (including, 
in each case, any related notes thereto) contained in the STB SEC Reports was 
prepared in accordance with generally accepted accounting principles ("GAAP") 
applied on a consistent basis throughout the periods involved (except as may 
be indicated in the notes thereto) and each fairly presents the consolidated 
financial position of STB and its subsidiaries as at the respective dates 
thereof and the consolidated results of its operations and cash flows for the 
periods indicated, except that the unaudited interim financial statements 
were or are subject to adjustments which were not or are not expected to be 
material in amount.

            (c)     STB has previously furnished to 3Dfx a complete and 
correct copy of any amendments or modifications, which have not yet been 
filed with the SEC but which are required to be filed, to agreements, 
documents or other instruments which previously had been filed by STB with 
the SEC pursuant to the Securities Act or the Exchange Act.


                                      9
<PAGE>

     3.8    ABSENCE OF CERTAIN CHANGES OR EVENTS.  Since July 31, 1998, STB 
and its subsidiaries have conducted their businesses only in the ordinary 
course and in a manner consistent with past practice and, since such date, 
there has not been (i) any Material Adverse Effect (provided, however, that 
for the purposes of this Section 3.8, "Material Adverse Effect" shall not 
include any Material Adverse Effect arising out of financial results of STB 
for the quarter ended October 31, 1998) or (ii) any material change by STB in 
its accounting methods, principles or practices except as required by 
concurrent changes in GAAP.

     3.9    NO UNDISCLOSED LIABILITIES.  Neither STB nor any of its 
subsidiaries has any liabilities (absolute, accrued, contingent or otherwise) 
of a nature required to be disclosed on a balance sheet or in the related 
notes to the consolidated financial statements prepared in accordance with 
GAAP which are, individually or in the aggregate, material to the business, 
results of operations or financial condition of STB and its subsidiaries 
taken as a whole, except liabilities (i) provided for in STB's balance sheet 
or in the related notes as of July 31, 1998, or (ii) incurred since July 31, 
1998 in the ordinary course of business, none of which are material to the 
business, results of operations or financial condition of STB and its 
subsidiaries, taken as a whole.

     3.10   ABSENCE OF LITIGATION.  Except for that certain class action 
shareholder litigation instituted on October 9, 1998 (Matt Brody, et al. v. 
STB Systems, Inc., et al.) and as set forth in Section 3.19, there are no 
claims, actions, suits or proceedings pending or, to the best knowledge of 
STB, threatened (or, to the best knowledge of STB, any investigation pending 
or threatened) against STB or any of its subsidiaries, or any properties or 
rights of STB or any of its subsidiaries, before any court, arbitrator or 
administrative, governmental or regulatory authority or body, domestic or 
foreign, that, individually or in the aggregate, could reasonably be expected 
to have a Material Adverse Effect.

     3.11   EMPLOYEE MATTERS AND BENEFIT PLANS.  

            (a)     DEFINITIONS.  With the exception of the definitions of 
"Affiliate" and "International Employee Plan" set forth in Section 3.11(a)(i) 
and (iii) below (such definitions shall only apply to this Section 3.11), for 
purposes of this Agreement, the following terms shall have the meanings set 
forth below:

                    (i)  "AFFILIATE," as used in this Section 3.11, shall 
mean any other person or entity under common control with STB within the 
meaning of Section 414(b), (c), (m) or (o) of the Code and the regulations 
thereunder;

                   (ii)  "ERISA" shall mean the Employee Retirement Income 
Security Act of 1974, as amended;

                  (iii)  "INTERNATIONAL EMPLOYEE PLAN" shall mean each STB 
Employee Plan that has been adopted or maintained by STB, whether informally 
or formally, for the benefit of STB Employees outside the United States;

                   (iv)  "STB EMPLOYEE PLAN" shall refer to any plan, 
program, policy, practice, contract, agreement or other arrangement providing 
for compensation, severance, termination pay, performance awards, stock or 
stock-related awards, fringe benefits or other employee benefits or 
remuneration of any kind, whether formal or informal, funded or unfunded, 
including without limitation, each "employee benefit plan," within the 
meaning of Section 3(3) of ERISA, which is or has been maintained, 


                                     10
<PAGE>

contributed to, or required to be contributed to, by STB or any Affiliate for 
the benefit of any "STB Employee" (as defined below), and pursuant to which 
STB or any Affiliate has or may have any material liability contingent or 
otherwise;

                    (v)  "STB EMPLOYEE" shall mean any current, former or
retired employee, officer, or director of STB or any Affiliate;

                   (vi)  "STB EMPLOYEE AGREEMENT" shall refer to each
management, employment, severance, consulting, relocation, repatriation,
expatriation, visa, work permit or similar agreement or contract between STB or
any Affiliate and any STB Employee or consultant;

                  (vii)  "IRS" shall mean the Internal Revenue Service;

                 (viii)  "MULTIEMPLOYER PLAN" shall mean any "Pension Plan" 
(as defined below) which is a "multiemployer plan," as defined in Section 
3(37) of ERISA; and

                   (ix)  "STB PENSION PLAN" shall refer to each STB Employee 
Plan which is an "employee pension benefit plan," within the meaning of 
Section 3(2) of ERISA.

            (b)     SCHEDULE.  STB does not have any plan or commitment to 
establish any new STB Employee Plan or STB Employee Agreement, to modify any 
STB Employee Plan or STB Employee Agreement (except to the extent required by 
law or to conform any such STB Employee Plan or STB Employee Agreement to the 
requirements of any applicable law, in each case as previously disclosed to 
3Dfx in writing, or as required by this Agreement), or to enter into any STB 
Employee Plan or STB Employee Agreement, nor does it have any intention or 
commitment to do any of the foregoing.

            (c)     DOCUMENTS.  STB has provided to 3Dfx (i) correct and 
complete copies of all documents embodying or relating to each STB Employee 
Plan and each STB Employee Agreement including all amendments thereto and 
written interpretations thereof; (ii) the most recent annual actuarial 
valuations, if any, prepared for each STB Employee Plan; (iii) the three most 
recent annual reports (Series 5500 ad all schedules thereto), if any, 
required under ERISA or the Code in connection with each STB Employee Plan or 
related trust; (iv) if STB Employee Plan is funded, the most recent annual 
and period accounting of STB Employee Plan assets; (v) the most recent 
summary plan description together with the most recent summary of material 
modifications, if any, required under ERISA with respect to each STB Employee 
Plan; (vi) all IRS determination letters and rulings relating to STB Employee 
Plans and copies of all applications and correspondence to or from the IRS or 
the Department of Labor ("DOL") with respect to any STB Employee Plan; (vii) 
all communications material to any STB Employee or STB Employees relating to 
any STB Employee Plan and any proposed STB Employee Plans, in each case, 
relating to any amendments, terminations, establishments, increases or 
decreases in benefits, acceleration of payments or vesting schedules or other 
events which would result in any material liability to STB; and (viii) all 
registration statements and prospectuses prepared in connection with each STB 
Employee Plan.

            (d)     STB EMPLOYEE PLAN COMPLIANCE. (i) STB has performed in 
all material respects all obligations required to be performed by it under 
each STB Employee Plan and each STB Employee Plan has been established and 
maintained in all material respects in accordance with its terms and in 
compliance with all applicable laws, statutes, orders, rules and regulations, 
including but not limited to ERISA or the Code; (ii) 


                                     11
<PAGE>

to STB's knowledge no "prohibited transaction," within the meaning of Section 
4975 of the Code or Section 406 of ERISA, has occurred with respect to any 
STB Employee Plan; (iii) there are no actions, suits or claims pending, or, 
to the knowledge of STB, threatened or anticipated (other than routine claims 
for benefits) against any STB Employee Plan or against the assets of any STB 
Employee Plan; (iv) each STB Employee Plan can be amended, terminated or 
otherwise discontinued after the Effective Time in accordance with its terms, 
without liability to STB, the Surviving Corporation, 3Dfx or any Affiliates 
(other than ordinary administration expenses typically incurred in a 
termination event); (v) there are no inquiries or proceedings pending or, to 
the knowledge of STB or any Affiliates, threatened by the IRS or DOL with 
respect to any STB Employee Plan; and (vi) neither STB nor any Affiliate is 
subject to any penalty or tax with respect to any STB Employee Plan under 
Section 402(i) of ERISA or Section 4975 through 4980 of the Code.

            (e)     STB PENSION PLANS.  STB does not now, nor has it ever, 
maintained, established, sponsored, participated in, or contributed to, any 
STB Pension Plan which is subject to Part 3 of Subtitle B of Title I of 
ERISA, Title IV of ERISA or Section 412 of the Code.

            (f)     MULTIEMPLOYER PLANS.  At no time has STB contributed to 
or been requested to contribute to any Multiemployer Plan.

            (g)     NO POST-EMPLOYMENT OBLIGATIONS.  No STB Employee Plan 
provides, or has any liability to provide, life insurance, medical or other 
medical benefits to any STB Employee upon his or her retirement or 
termination of employment for any reason, except as may be required by 
statute, and STB has never represented, promised or contracted (whether in 
oral or written form) to any STB Employee (either individually or to STB 
Employees as a group) that such STB Employee(s) would be provided with life 
insurance, medical or other employee welfare benefits upon their retirement 
or termination of employment, except to the extent required by statute.

            (h)     EFFECT OF TRANSACTION.

                    (i)  Except as provided in Section 2.1 of this 
Agreement, the execution of this agreement and the consummation of the 
transactions contemplated hereby will not (either along or upon the 
occurrence of any additional or subsequent events) constitute an event under 
any STB Employee Plan (except the Option Plan, the Director Plan and any 
stock option agreements entered into thereunder), STB Employee Agreement, 
trust or loan that will or may result in any payment (whether of severance 
pay or otherwise), acceleration, forgiveness of indebtedness, vesting, 
distribution, increase in benefits or obligations to fund benefits with 
respect to any STB Employee.

                   (ii)  No payment or benefit which will or may be made by 
STB or 3Dfx or any of their respective Affiliates with respect to any STB 
Employee will be characterized as an "excess parachute payment," within the 
meaning of Section 280G(b)(1) of the Code.

            (i)     EMPLOYMENT MATTERS.  STB and each of its subsidiaries (i) 
is in compliance in all material respects with all applicable foreign, 
federal, state and local laws, rules and regulations respecting employment, 
employment practices, terms and conditions of employment and wages and hours, 
in each case, in each location in which STB or any of its subsidiaries 
employs persons; (ii) has withheld all amounts required by law or by 
agreement to be withheld from the wages, salaries and other payments to STB 
Employees; (iii) is not liable for any material arrears of wages or any 
material taxes or any material penalty 


                                     12
<PAGE>

for failure to comply with any of the foregoing; and (iv) is not liable for 
any material payment to any trust or other fund or to any governmental or 
administrative authority, with respect to unemployment compensation benefits, 
social security or other benefits or obligations for STB Employees (other 
than routine payments to be made in the normal course of business and 
consistent with past practice).

            (j)     VIOLATIONS.  To STB's knowledge and reasonable belief, no 
employee of STB has violated any employment contract, patent disclosure 
agreement or non-competition agreement between such employee and any former 
employer of such employee due to such employee being employed by STB and 
disclosing to STB trade secrets or proprietary information of such employer. 
STB and its subsidiaries are in compliance in all material respects with all 
applicable laws regarding employment practices, terms and conditions of 
employment, and wages and hours (including, without limitation, ERISA, WARN 
or any similar state or local law).

            (k)     INTERNATIONAL EMPLOYEE PLAN.  Each International Employee 
Plan has been established, maintained and administered in material compliance 
with its terms and conditions and with the requirements prescribed by any and 
all statutory or regulatory laws that are applicable to such International 
Employee Plan.  Furthermore, no International Employee Plan has unfunded 
liabilities, that as of the Effective Time, will not be offset by insurance 
or fully accrued. Except as required by law, no condition exists that would 
prevent STB or 3Dfx from terminating or amending any International Employee 
Plan at any time for any reason.

     3.12   LABOR MATTERS.  (i) There are no controversies pending or, to the 
best knowledge of each of STB and its respective subsidiaries, threatened, 
between STB or any of its subsidiaries and any of their respective employees, 
which controversies have or could reasonably be expected to have a Material 
Adverse Effect; (ii) as of the date of this Agreement, neither STB nor any of 
subsidiaries is a party to any collective bargaining agreement or other labor 
union contract applicable to persons employed by STB or its subsidiaries nor 
does STB or its subsidiaries know of any activities or proceedings of any 
labor union to organize any such employees (A) as of the date of this 
Agreement and (B) which, as of the Closing Date, have or could reasonably be 
expected to have a Material Adverse Effect on STB and its subsidiaries; and 
(iii) as of the date of this Agreement, neither STB nor any of its 
subsidiaries has any knowledge of any strikes, slowdowns, work stoppages or 
lockouts, or threats thereof, by or with respect to any employees of STB or 
any of its subsidiaries (X) as of the date of this Agreement and (Y) which, 
as of the Closing Date, have or could reasonably be expected to have a 
Material Adverse Effect on STB and its subsidiaries.

     3.13   REGISTRATION STATEMENT; PROXY STATEMENT.  None of the information 
supplied or to be supplied by STB for inclusion or incorporation by reference 
in (i) the registration statement on Form S-4 to be filed with the SEC by 
3Dfx in connection with the issuance of the 3Dfx Common Stock in or as a 
result of the Merger (the "S-4") will, at the time the S-4 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 in 
order to make the statements therein, in light of the circumstances under 
which they are made, not misleading; and (ii) the Proxy Statement (the "PROXY 
STATEMENT") to be filed with the SEC by 3Dfx and STB pursuant to Section 5.4 
hereof will, at the dates mailed to the shareholders of 3Dfx and STB, at the 
times of the shareholders meetings of 3Dfx and STB (each a "SHAREHOLDERS 
MEETING" and collectively, the "SHAREHOLDERS MEETINGS") in connection with 
the transactions contemplated hereby and as of the Effective Time, 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 


                                     13
<PAGE>

are made, not misleading.  The Proxy Statement will comply as to form in all 
material respects with the provisions of the Exchange Act and the rules and 
regulations promulgated by the SEC thereunder.

     3.14   RESTRICTIONS ON BUSINESS ACTIVITIES.  Other than as may be 
permitted under Section 5.9, there is no material agreement, judgment, 
injunction, order or decree binding upon STB or any of its subsidiaries which 
has or could reasonably be expected to have the effect of prohibiting or 
materially impairing any business practice of STB or any of its subsidiaries, 
any acquisition of property by STB or any of its subsidiaries or the conduct 
of business by STB or any of its subsidiaries as currently conducted.

     3.15   TITLE TO PROPERTY.  STB owns no material real property. STB and 
each of its subsidiaries have good and defensible title to all of their 
material properties and assets, free and clear of all liens, charges and 
encumbrances except liens for taxes not yet due and payable and such liens or 
other imperfections of title, if any, as do not materially detract from the 
value of or interfere with the present use of the property affected thereby 
or which, individually or in the aggregate, could not reasonably be expected 
to have a Material Adverse Effect; and all leases pursuant to which STB or 
any of its subsidiaries lease from others material amounts of real or 
personal property are in good standing, valid and effective in accordance 
with their respective terms, and there is not, under any of such leases, any 
existing material default or event of default (or any event which with notice 
or lapse of time, or both, would constitute a material default and in respect 
of which STB or subsidiary has not taken adequate steps to prevent such 
default from occurring) except where the lack of such good standing, validity 
and effectiveness or the existence of such default or event of default could 
not, individually or in the aggregate, reasonably be expected to have a 
Material Adverse Effect.  All the plants, structures and equipment of STB and 
its subsidiaries, except such as may be under construction, are in good 
operating condition and repair, except where the failure of such plants, 
structures and equipment to be in such good operating condition and repair 
could not, individually or in the aggregate, reasonably be expected to have a 
Material Adverse Effect.

     3.16   TAXES.  STB and each of its subsidiaries, and any consolidated, 
combined, unitary or aggregate group for Tax (as defined below) purposes of 
which STB or any of its subsidiaries is or has been a member, have timely 
filed all Tax Returns required to be filed by them and have paid all Taxes 
shown thereon to be due.  STB has provided adequate accruals in accordance 
with generally accepted accounting principles in its financial statements for 
any Taxes that have not been paid, whether or not shown as being due on any 
Tax Returns.  There is (i) no material claim for Taxes that is a lien against 
the property of STB or any of its subsidiaries or is being asserted against 
STB or any of its subsidiaries other than liens for Taxes not yet due and 
payable, (ii) no audit of any Tax Return of STB or any of its subsidiaries 
being conducted by a Tax authority, (iii) no extension of the statute of 
limitations on the assessment of any Taxes granted by STB or any of its 
subsidiaries and currently in effect, and (iv) no agreement, contract or 
arrangement to which STB or any of its subsidiaries is a party that may 
result in the payment of any amount that would not be deductible by reason of 
Sections 162(m), 280G or 404 of the Code. STB has not been and will not be 
required to include any material adjustment in Taxable income for any Tax 
period (or portion thereof) pursuant to Section 481 or 263A of the Code or 
any comparable provision under state or foreign Tax laws as a result of 
transactions, events or accounting methods employed prior to the Merger.  
Neither STB nor any of its subsidiaries has ever been a member of any 
combined, controlled, consolidated or affiliated group (other than the group 
of which STB is the parent) for Tax purposes.  Neither STB nor any of its 
subsidiaries is a party to any tax sharing or tax allocation agreement nor 
does STB or any of its subsidiaries owe any amount under any such agreement.  
Neither STB nor any of its subsidiaries has been at any time, a "United 
States real


                                      14
<PAGE>

property holding corporation" with he meaning of Section 897(c)(2) of the 
Code. For purposes of this Agreement, the following terms have the following 
meanings: "TAX" (and, with correlative meaning, "TAXES" and "TAXABLE") means 
(i) any net income, alternative or add-on minimum tax, gross income, gross 
receipts, sales, use, ad valorem, transfer, franchise, profits, license, 
withholding, payroll, employment, excise, severance, stamp, occupation, 
premium, property, environmental or windfall profit tax, custom, duty or 
other tax governmental fee or other like assessment or charge of any kind 
whatsoever, together with any interest or any penalty, addition to tax or 
additional amount imposed by any Governmental Entity (a "TAX AUTHORITY") 
responsible for the imposition of any such tax (domestic or foreign), (ii) 
any liability for the payment of any amounts of the type described in (i) as 
a result of being a member of an affiliated, consolidated, combined or 
unitary group for any Taxable period and (iii) any liability for the payment 
of any amounts of the type described in (i) or (ii) as a result of any 
express or implied obligation to indemnify any other person.  As used herein, 
"TAX RETURN" shall mean any return, statement, report or form (including, 
without limitation,) estimated Tax Returns and reports, withholding Tax 
Returns and reports and information reports and Returns required to be filed 
with respect to Taxes.

     3.17   ENVIRONMENTAL MATTERS.
  
            (a)     HAZARDOUS MATERIAL.  Except as would result in any 
material liability to STB under Environmental Laws (as defined below), no 
underground storage tanks and no amount of any substance that has been 
designated by any Governmental Entity or by applicable Environmental Laws to 
be radioactive, toxic, hazardous or otherwise a danger to health or the 
environment, including, without limitation, PCBs, asbestos, petroleum, 
urea-formaldehyde and all substances listed as hazardous substances pursuant 
to the Comprehensive Environmental Response, Compensation, and Liability Act 
of 1980, as amended, or defined as a hazardous waste pursuant to the Resource 
Conservation and Recovery Act of 1976, as amended, and the regulations 
promulgated pursuant to Environmental Laws, but excluding office and 
janitorial supplies maintained in accordance with Environmental Laws (a 
"HAZARDOUS MATERIAL") are present, as a result of the actions of STB or any 
of its subsidiaries or any affiliate of STB, or, to STB's knowledge, as a 
result of any action of any third party or otherwise, in, on or under any 
property, including the land and the improvements, ground water and surface 
water thereof, that STB or any of its subsidiaries has at any time owned, 
operated, occupied or leased.  For the purposes of this Agreement, 
"ENVIRONMENTAL LAWS" shall mean all federal, state, local and foreign laws, 
ordinances, treaties, rules, regulations, guidelines and permit conditions 
relating to contamination, pollution or the environment (including ambient 
air, surface water, ground water, land surface or subsurface strata) or the 
protection of human health and worker safety, including, without limitation, 
laws and regulations relating to Hazardous Materials Activities (as 
hereinafter defined) or emissions, discharges, releases or threatened 
releases of Hazardous Materials.

            (b)     HAZARDOUS MATERIALS ACTIVITIES.  Neither STB nor any of 
its subsidiaries has (i) transported, stored, used, manufactured, disposed 
of, released or exposed its employees or others to Hazardous Materials in 
violation of Environmental Laws, or (ii) disposed of, transported, sold, 
used, released, exposed its employees or others to or manufactured any 
product contained a Hazardous Material (collectively "HAZARDOUS MATERIALS 
ACTIVITIES") in violation of any Environmental Laws in effect prior to or as 
of the date hereof except for which violation has not heretofore been cured 
or for which there is any remaining liability.


                                     15
<PAGE>

            (c)     PERMITS.  STB and its subsidiaries hold all environmental 
approvals, permits, licenses, clearances and consents (the "STB ENVIRONMENTAL 
PERMITS") necessary for the conduct of STB's and its subsidiaries' Hazardous 
Material Activities and other businesses of STB and its subsidiaries as such 
activities and businesses are currently being conducted.  STB and its 
subsidiaries are and at all times have been in compliance in all material 
respects with the terms of the STB Environmental Permits except for which 
noncompliance has heretofore been cured or for which there is any remaining 
liability.

            (d)     ENVIRONMENTAL LIABILITIES.  No action, proceeding, 
revocation proceeding, amendment procedure, writ, claim or injunction is 
pending, and to STB's knowledge, no action, proceeding, revocation 
proceeding, amendment procedure, writ, claim or injunction has been 
threatened by any Governmental Entity against STB or any of its subsidiaries 
concerning any STB Environmental Permit, Hazardous Material or any Hazardous 
Materials Activities of STB or any of its subsidiaries.

     3.18   BROKERS.  No broker, finder or investment banker (other than Hoak 
Breedlove Wesneski & Co. ("HOAK BREEDLOVE")) 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 STB.

     3.19   INTELLECTUAL PROPERTY.  STB or its subsidiaries owns each of the 
patents and patent applications referred to in the STB SEC Reports and, 
except as disclosed in the STB SEC Reports, (i) each of STB and its 
subsidiaries owns or possesses, or could obtain ownership or possession of 
(on terms not materially adverse to the consolidated financial position, 
shareholders' equity, results of operations of STB and its subsidiaries taken 
as a whole) adequate and enforceable rights to use all other patent 
applications, patents, trademarks, trademark applications, trade names, 
service marks, copyrights, copyright applications, licenses, know-how and 
other similar rights and proprietary knowledge (collectively with the patents 
and patent applications described in the STB SEC Reports, the "Intangibles") 
necessary for the conduct of their businesses and (ii) neither STB nor any 
subsidiary, to its knowledge, has infringed, is infringing, or has received 
any notice of infringement of any Intangible of any other person that, if the 
subject of an unfavorable decision, ruling or finding, could reasonably be 
expected to (or, with respect to pending patent litigation as of the date 
hereof, STB does not believe will) have a Material Adverse Effect and STB 
knows of no basis therefor.  The expiration of any Intangibles would not have 
a Material Adverse Effect on STB and its subsidiaries taken as a whole.  
Except as set forth in the STB SEC Reports, STB has received no notice of 
potential indemnity claims from customers based upon a notice of infringement 
any such customer has received from a patent owner relating to an assertion 
of infringement of a patent other than potential indemnity claims which 
individually or in the aggregate would not reasonably be expected to have a 
Material Adverse Effect.

     3.20   CHANGE OF CONTROL PAYMENTS. Other than as excepted in Section 3.18 
hereof or contemplated by Section 5.14, there are no amounts that will become 
payable (whether currently or in the future) to current or former employees, 
officers and directors of STB under any plan or agreement of STB  as a result 
of or in connection with the Merger.

     3.21   INSURANCE.  STB maintains insurance policies and fidelity bonds 
covering the assets, business, equipment, properties, operations, employees, 
officers and directors of STB and its subsidiaries (collectively, the 
"INSURANCE POLICIES") which are of the type and in amounts customarily 
carried by persons conducting businesses similar to those of STB and its 
subsidiaries.  There is no material claim by STB or any 


                                     16
<PAGE>

of its subsidiaries pending under any of the material Insurance Policies as 
to which coverage has been questioned, denied or disputed by the underwriters 
of such policies or bonds.

     3.22   OPINION OF FINANCIAL ADVISOR.  STB has been advised in writing by 
its financial advisor, Hoak Breedlove, that in its opinion, as of the date 
hereof, the Exchange Ratio is fair from a financial point of view, to the 
shareholders of STB.

     3.23   BOARD APPROVAL.  The Board of Directors of STB has, as of the 
date of this Agreement (i) approved this Agreement and the STB Option 
Agreement and the transactions contemplated hereby and thereby, (ii) 
determined that the Merger is in the best interests of the shareholders of 
STB and is on terms that are fair to such shareholders and (iii) recommended 
that the shareholders of STB approve this Agreement and the Merger.

     3.24   VOTE REQUIRED.  The affirmative vote of a majority of the votes 
that holders of the outstanding shares of STB Common Stock are entitled to 
vote thereon is the only vote of the holders of any class or series of STB's 
capital stock necessary to approve this Agreement and the transactions 
contemplated hereby.

     3.25   YEAR 2000 COMPLIANCE. Except as would not reasonably be expected 
to have a Material Adverse Effect on STB, all of STB's Information Technology 
(as defined below) effectively addresses the Year 2000 issue, and will not 
cause an interruption in the ongoing operations of STB's business on or after 
January 1, 2000.  For purposes of the foregoing, the term "INFORMATION 
TECHNOLOGY" shall mean and include all software, hardware, firmware, 
telecommunications systems, network systems, embedded systems and other 
systems, components and/or services that are owned or used by STB in the 
conduct of its business, or purchased by STB from third party suppliers.

     3.26   TEXAS BUSINESS COMBINATION LAW NOT APPLICABLE.  The STB Board has 
taken all actions so that the restrictions contained in the Texas Business 
Combination Law ("TBCL") applicable to  entering into or engaging in a 
"business combination" (as defined in such the TBCL) will not apply to the 
execution, delivery or performance of this Agreement, the STB Option 
Agreement, or to the consummation of the Merger or the other transactions 
contemplated by this Agreement.

                                   ARTICLE 4
                                       
                  REPRESENTATIONS AND WARRANTIES OF 3DFX AND SUB

     3Dfx and Sub jointly and severally represent and warrant to STB, except 
as set forth in the 3Dfx SEC Reports (as defined in Section 4.7), as follows:

     4.1    ORGANIZATION AND QUALIFICATION; SUBSIDIARIES.  Each of 3Dfx and 
its subsidiaries is a corporation duly organized, validly existing and in 
good standing under the laws of the jurisdiction of its incorporation and has 
the requisite corporate power and authority to own, lease and operate its 
assets and properties and to carry on its business as it is now being 
conducted.  Each of 3Dfx and its subsidiaries is in possession of all 
Approvals necessary to own, lease and operate the properties it purports to 
own, operate or lease and to carry on its business as it is now being 
conducted, except where the failure to have such Approvals would not, 
individually or in the aggregate, have a Material Adverse Effect (as defined 
below).


                                     17
<PAGE>

Each of 3Dfx and its subsidiaries is duly qualified or licensed as a foreign 
corporation to do business, and is in good standing, in each jurisdiction 
where the character of the properties owned, leased or operated by it or the 
nature of its activities makes such qualification or licensing necessary, 
except for such failures to be so duly qualified or licensed and in good 
standing that would not, either individually or in the aggregate, have a 
Material Adverse Effect.  When used in connection with 3Dfx or any of its 
subsidiaries, the term "MATERIAL ADVERSE EFFECT" means any change, event or 
effect that is materially adverse to the business, assets (including 
intangible assets), liabilities, financial condition or results of operations 
of 3Dfx and its subsidiaries taken as a whole; PROVIDED, HOWEVER, that a 
"Material Adverse Effect" shall not include any (i) adverse effect on the 
results of operations or financial condition of 3Dfx that is attributable to 
the transactions or resulting business enterprise contemplated by this 
Agreement, including, without limitation, delay of, reduction in, or 
cancellation or change in the terms of product orders by customers of 3Dfx or 
an increase in the price of, a delay of, reduction in or cancellation of or 
change in terms with respect to products or components supplied by, or a 
deterioration in or termination of a relationship by, vendors of 3Dfx, (ii) 
change arising out of conditions in or affecting the industries in which the 
parties to this Agreement compete or (iii) decline in 3Dfx's stock price.  
Other than wholly-owned subsidiaries and except as permitted after the date 
of this Agreement under Section 5.2 of this Agreement and except with respect 
to an investment of less than a twenty percent (20%) interest in any 
corporation, partnership, joint venture or other business, association or 
entity, 3Dfx does not directly or indirectly own any equity or similar 
interest in, or any interest convertible or exchangeable or exercisable for, 
any equity or similar interest in, any corporation, partnership, joint 
venture or other business, association or entity.

     4.2    ARTICLES OF INCORPORATION AND BYLAWS.  3Dfx has previously 
furnished to STB a complete and correct copy of its Articles of Incorporation 
and Bylaws as amended to date.  Such Articles of Incorporation, Bylaws and 
equivalent organizational documents of each of its subsidiaries are in full 
force and effect.  Neither 3Dfx nor any of its subsidiaries is in violation 
of any of the provisions of its Articles of Incorporation or Bylaws or 
equivalent organizational documents.

     4.3    CAPITALIZATION.  The authorized capital stock of 3Dfx consists of 
(i) 50,000,000 shares of 3Dfx Common Stock and of (ii) 5,000,000 shares of 
Preferred Stock, no par value per share ("3DFX PREFERRED STOCK"), 60,000 of 
which have been designated as 3Dfx Series A Participating Preferred.  At the 
close of business on November 30, 1998, (i) approximately 15,592,912 shares 
of 3Dfx Common Stock were issued and outstanding, all of which are validly 
issued, fully paid and nonassessable, (ii) approximately 349,919 shares of 
3Dfx Common Stock were reserved for future issuance pursuant to 3Dfx's 
employee stock purchase plan, (iii) approximately 3,422,609 shares of 3Dfx 
Common Stock were reserved for issuance upon the exercise of outstanding 
options ("3DFX OPTIONS") to purchase 3Dfx Common Stock, approximately 
1,287,185 shares of 3Dfx Common Stock were reserved for future grant under 
the 1995 Stock Option Plan, the 1997 Supplemental Stock Option Plan and the 
1997 Director Option Plan and (iv) 93,636 shares of 3Dfx Common Stock were 
reserved for issuance upon exercise of warrants.  No change in such 
capitalization has occurred between September 30, 1998 and the date hereof 
except issuances of 3Dfx Common Stock that would be permitted pursuant to 
Section 5.2(c) hereof.  As of the date hereof, no shares of 3Dfx Preferred 
Stock were issued or outstanding.  The authorized capital stock of Sub 
consists of 10,000 shares of common stock, par value $0.10 per share, 100 
shares of which, as of the date hereof, are issued and outstanding. All of 
the outstanding shares of 3Dfx's and Sub's respective capital stock have been 
duly authorized and validly issued and are fully paid and nonassessable. 
Except as set forth in this Section 4.3, as of the date of this Agreement, 
there are no options, warrants or other rights, agreements, arrangements or 
commitments of any 


                                     18
<PAGE>

character relating to the issued or unissued capital stock of 3Dfx or any of 
its subsidiaries or obligating 3Dfx or any of its subsidiaries to issue or 
sell any shares of capital stock of, or other equity interests in, 3Dfx or 
any of its subsidiaries.  All shares of 3Dfx Common Stock subject to issuance 
as aforesaid, upon issuance on the terms and conditions specified in the 
instruments pursuant to which they are issuable, shall, and the shares of 
3Dfx Common Stock to be issued pursuant to the Merger will be, duly 
authorized, validly issued, fully paid and nonassessable.  Except for such 
actions as are permitted under Section 5.2, there are no obligations, 
contingent or otherwise, of 3Dfx or any of its subsidiaries to repurchase, 
redeem or otherwise acquire any shares of 3Dfx Common Stock or the capital 
stock of any subsidiary or to provide funds to or make any investment (in the 
form of a loan, capital contribution or otherwise) in any such subsidiary or 
any other entity other than guarantees of obligations of subsidiaries entered 
into in the ordinary course of business.  All of the outstanding shares of 
capital stock (other than directors' qualifying shares) of each of 3Dfx's 
subsidiaries is duly authorized, validly issued, fully paid and nonassessable 
and all such shares (other than directors' qualifying shares) are owned by 
3Dfx or another subsidiary free and clear of all security interests, liens, 
claims, pledges, agreements, limitations in 3Dfx's voting rights, charges or 
other encumbrances of any nature whatsoever.

     4.4    AUTHORITY RELATIVE TO THIS AGREEMENT.  Each of 3Dfx and Sub has 
all necessary corporate power and authority to execute and deliver this 
Agreement and the STB Option Agreement, and to perform its obligations 
hereunder and thereunder, subject to obtaining the approval of 3Dfx's 
shareholders of the issuance of 3Dfx Common Stock in the Merger, to 
consummate the transactions contemplated hereby and thereby.  The execution 
and delivery of this Agreement and the STB Option Agreement by 3Dfx and Sub 
and the consummation by 3Dfx and Sub of the transactions contemplated hereby 
and thereby have been duly and validly authorized by all necessary corporate 
action on the part of 3Dfx and Sub and no other corporate proceedings on the 
part of 3Dfx or Sub are necessary to authorize this Agreement and the STB 
Option Agreement, or to consummate the transactions so contemplated (other 
than with respect to the Merger, the approval by the holders of a majority of 
the outstanding shares of 3Dfx Common Stock of the issuance of 3Dfx Common 
Stock in the Merger in accordance with the applicable rules of Nasdaq and 
3Dfx's Articles of Incorporation and Bylaws). This Agreement and the STB 
Option Agreement have been duly and validly executed and delivered by 3Dfx 
and Sub and, assuming the due authorization, execution and delivery by STB, 
constitute legal and binding obligations of 3Dfx and Sub, enforceable against 
3Dfx and Sub in accordance with their respective terms, subject to (i) 
bankruptcy, insolvency, reorganization, moratorium or other similar laws 
affecting or relating to creditors rights generally and (ii) the availability 
of injunctive relief and other equitable remedies.

     4.5    NO CONFLICT; REQUIRED FILINGS AND CONSENTS.

            (a)     The execution and delivery of this Agreement by 3Dfx and 
Sub and the STB Option Agreement by 3Dfx do not, and the performance of this 
Agreement by 3Dfx and Sub and the STB Option Agreement by 3Dfx shall not, (i) 
conflict with or violate the Articles of Incorporation, Bylaws or equivalent 
organizational documents of 3Dfx or any of its subsidiaries, (ii) subject to 
obtaining 3Dfx's shareholders approval of the issuance of the shares of 3Dfx 
Common Stock in the Merger and compliance with the requirements set forth in 
Section 4.5(b) below, conflict with or violate any law, rule, regulation, 
order, judgment or decree applicable to 3Dfx or any of its subsidiaries or by 
which it or their respective properties are bound or affected, or (iii) 
result in any breach of or constitute a default (or an event that with notice 
or lapse of time or both would become a default) under, or impair 3Dfx's or 
any such subsidiary's rights or alter 


                                     19
<PAGE>

the rights or obligations of any third party under, or give to others any 
rights of termination, amendment, acceleration or cancellation of, or result 
in the creation of a lien or encumbrance on any of the properties or assets 
of 3Dfx or any of its subsidiaries pursuant to, any material note, bond, 
mortgage, indenture, contract, agreement, lease, license, permit, franchise 
or other instrument or obligation to which 3Dfx or any of its subsidiaries is 
a party or by which 3Dfx or any of its subsidiaries or its or any of their 
respective properties are bound or affected, except for any such breaches, 
defaults or other occurrences that could not reasonably be expected to have, 
individually or in the aggregate, a Material Adverse Effect.  

            (b)     The execution and delivery of this Agreement by 3Dfx and 
Sub and the STB Option Agreement by 3Dfx do not, and the performance of this 
Agreement by 3Dfx and Sub shall not, require any consent, approval, 
authorization or permit of, or filing with or notification to, any 
Governmental Entity except (i) for applicable requirements, if any, of the 
Securities Act, the Exchange Act, Blue Sky Laws, the pre-merger notification 
requirements of the HSR Act and of foreign governmental entities and the 
rules and regulations thereunder, the rules and regulations of Nasdaq, and 
the filing and recordation of the Articles of Merger as required by the Texas 
Statute and (ii) where the failure to obtain such consents, approvals, 
authorizations or permits, or to make such filings or notifications, (i) 
would not prevent consummation of the Merger or otherwise prevent 3Dfx or Sub 
from performing their respective obligations under this Agreement or (ii) 
could not, individually or in the aggregate, reasonably be expected to have a 
Material Adverse Effect.

     4.6    COMPLIANCE; PERMITS.

            (a)     Neither 3Dfx nor any of its subsidiaries is in conflict 
with, or in default or violation of, (i) any law, rule, regulation, order, 
judgment or decree applicable to 3Dfx or any of its subsidiaries or by which 
its or any of their respective properties is bound or affected, or (ii) any 
note, bond, mortgage, indenture, contract, agreement, lease, license, permit, 
franchise or other instrument or obligation to which 3Dfx or any of its 
subsidiaries is a party or by which 3Dfx or any of its subsidiaries or its or 
any of their respective properties is bound or affected, except for any such 
conflicts, defaults or violations which could not reasonably be expected to 
have, individually or in the aggregate, a Material Adverse Effect.  To the 
best knowledge of 3Dfx, no investigation or review by any governmental or 
regulatory body or authority is pending or threatened against 3Dfx or any of 
its subsidiaries, nor has any governmental or regulatory body or authority 
indicated an intention to conduct the same, other than, in each such case, 
those the outcome of which could not, individually or in the aggregate, 
reasonably be expected to have a Material Adverse Effect.
     
            (b)  3Dfx and its subsidiaries hold all permits, licenses, 
variances, exemptions, orders and approvals from governmental authorities 
which are material to the operation of the business of 3Dfx and its 
subsidiaries taken as a whole (collectively, the "3DFX PERMITS").  3Dfx and 
its subsidiaries are in compliance with the terms of the 3Dfx Permits, except 
where the failure to so comply could not, individually or in the aggregate, 
reasonably be expected to have a Material Adverse Effect.

     4.7    SEC FILINGS; FINANCIAL STATEMENTS.

            (a)    3Dfx has made available to STB a correct and complete copy 
of each report, schedule, registration statement and definitive proxy 
statement filed by 3Dfx with the SEC on or after June 25, 1997 and prior to 
the date of this Agreement (the "3DFX SEC REPORTS"), which are all the forms, 
reports and documents required to be filed by 3Dfx with the SEC since June 
25, 1997.  The 3Dfx SEC Reports (A) were 


                                     20
<PAGE>

prepared in accordance with the requirements of the Securities Act or the 
Exchange Act, as the case may be, and (B) did not at the time they were filed 
(or if amended or superseded by a filing prior to the date of this Agreement 
then on the date of such filing) contain any untrue statement of a material 
fact or omit to state a material fact required to be stated therein or 
necessary in order to make the statements therein, in light of the 
circumstances under which they were made, not misleading.  None of 3Dfx's 
subsidiaries is required to file any reports or other documents with the SEC.

            (b)     Each set of consolidated financial statements (including, 
in each case, any related notes thereto) contained in the 3Dfx SEC Reports 
was prepared in accordance with GAAP applied on a consistent basis throughout 
the periods involved (except as may be indicated in the notes thereto) and 
each fairly presents the consolidated financial position of 3Dfx and its 
subsidiaries as at the respective dates thereof and the consolidated results 
of its operations and cash flows for the periods indicated, except that the 
unaudited interim financial statements were or are subject to adjustments 
which were not or are not expected to be material in amount.

            (c)     3Dfx has previously furnished to STB a complete and 
correct copy of any amendments or modifications, which have not yet been 
filed with the SEC but which are required to be filed, to agreements, 
documents or other instruments which previously had been filed by 3Dfx with 
the SEC pursuant to the Securities Act or the Exchange Act.

     4.8    ABSENCE OF CERTAIN CHANGES OR EVENTS.  Since September 30, 1998, 
3Dfx and its subsidiaries have conducted their businesses only in the 
ordinary course and in a manner consistent with past practice and, since such 
date, there has not been (i) any Material Adverse Effect or (ii) any material 
change by 3Dfx in its accounting methods, principles or practices except as 
required by concurrent changes in GAAP.

     4.9    NO UNDISCLOSED LIABILITIES.  Neither 3Dfx nor any of its 
subsidiaries has any liabilities (absolute, accrued, contingent or otherwise) 
of a nature required to be disclosed on a balance sheet or in the related 
notes to the consolidated financial statements prepared in accordance with 
GAAP which are, individually or in the aggregate, material to the business, 
results of operations or financial condition of 3Dfx and its subsidiaries 
taken as a whole, except liabilities (i) provided for in 3Dfx's balance sheet 
or the related notes as of September 30, 1998 or (ii)  incurred since 
September 30, 1998 in the ordinary course of business, none of which are 
material to the business, results of operations or financial condition of 
3Dfx and its subsidiaries, taken as a whole.

     4.10   ABSENCE OF LITIGATION.  There are no claims, actions, suits or 
proceedings pending or, to the best knowledge of 3Dfx, threatened (or to the 
best knowledge of 3Dfx, any investigation pending or threatened) against 3Dfx 
or any of its subsidiaries, or any properties or rights of 3Dfx or any of its 
subsidiaries, before any court, arbitrator or administrative, governmental or 
regulatory authority or body, domestic or foreign, that, individually or in 
the aggregate, could reasonably be expected to have a Material Adverse Effect.

     4.11   EMPLOYEE MATTERS AND BENEFIT PLANS.

            (a)     DEFINITIONS.  With the exception of the definitions of 
"Affiliate" and "International Employee Plan" set forth in Section 4.11(a)(i) 
and (ii) below (such definitions shall only apply to this 


                                     21
<PAGE>

Section 4.11), for the purposes of this Agreement, the following terms shall 
have the meanings set forth below:

                    (i)  "AFFILIATE," as used in this Section 4.11, shall 
mean any other person or entity under common control with 3Dfx within the 
meaning of Section 414(b), (c), (m) or (o) of the Code and regulations 
thereunder;

                   (ii)  "INTERNATIONAL EMPLOYEE PLAN" shall mean each 3Dfx 
Employee Plan that has been adopted or maintained by 3Dfx, whether informally 
or formally, for the benefit of 3Dfx Employees outside the United States;

                  (iii)  "3Dfx EMPLOYEE PLAN" shall refer to any plan, 
program, policy, practice, contract, agreement or other arrangement providing 
for compensation, severance, termination pay, performance awards, stock or 
stock-related awards, fringe benefits or other employee benefits or 
remuneration of any kind, whether formal or informal, funded or unfunded, 
including without limitation, each "employee benefit plan," within the 
meaning of Section 3(3) of ERISA, which is or has been maintained, 
contributed to, or required to be contributed to, by 3Dfx or any Affiliate 
for the benefit of any "3Dfx Employee" (as defined below), and pursuant to 
which 3Dfx or any Affiliate has or may have any material liability contingent 
or otherwise;

                   (iv)  "3Dfx EMPLOYEE" shall mean any current, former, or 
retired employee, officer, or director of 3Dfx or any Affiliate;

                    (v)  "3Dfx EMPLOYEE AGREEMENT" shall refer to each 
management, employment, severance, consulting, relocation, repatriation, 
expatriation, visa, work permit or similar agreement or contact between 3Dfx 
or any Affiliates and any 3Dfx Employee or consultant; and

                   (vi)  "3Dfx PENSION PLAN" shall refer to each 3Dfx 
Employee Plan which is an "employee pension benefit plan," within the meaning 
of Section 3(2) of ERISA.

            (b)     SCHEDULE.  3Dfx does not have any plan or commitment to 
establish any new 3Dfx Employee Plan or 3Dfx Employee Agreement, to modify 
any 3Dfx Employee Plan or 3Dfx Employee Agreement (except to the extent 
required by law or to conform any such 3Dfx Employee Plan or 3Dfx Employee 
Agreement to the requirements of any applicable law, in each case as 
previously disclosed to STB in writing, or as required by this Agreement), or 
to enter into any 3Dfx Employee Plan or 3Dfx Employee Agreement, nor does it 
have any intention or commitment to do any of the foregoing.

            (c)     DOCUMENTS. 3Dfx has provided to STB (i) correct and 
complete copies of all documents embodying or relating to each 3Dfx Employee 
Plan and each 3Dfx Employee Agreement including all amendments thereto and 
written interpretations thereof, (ii) the most recent annual actuarial 
valuations, if any, prepared for each 3Dfx Employee Plan; (iii) the three 
most recent annual reports (Series 5500 and all schedules thereto), if any, 
required under ERISA or the Code in connection with each 3Dfx Employee Plan 
or related trust; (iv) if any 3Dfx Employee Plan is funded, the most recent 
annual and periodic accounting of 3Dfx Employee Plan assets; (v) the most 
recent summary plan description together with the most recent summary of 
material modifications, if any, required under ERISA with respect to each 
3Dfx Employee Plan; (vi) all IRS determination letters and rulings relating 
to 3Dfx Employee Plans and copies of all applications 


                                     22
<PAGE>

and correspondence to or from the IRS or the DOL with respect to any 3Dfx 
Employee Plan; (vii) all communications material to any 3Dfx Employee or 3Dfx 
Employees relating to any 3Dfx Employee Plan and any proposed 3Dfx Employee 
Plans, in each case, relating to any amendments, terminations, 
establishments, increases or decreases in benefits, acceleration of payments 
or vesting schedules or other events which would result in any material 
liability to 3Dfx; and (viii) all registration statements and prospectuses 
prepared in connection with each 3Dfx Employee Plan.

            (d)     3Dfx EMPLOYEE PLAN COMPLIANCE.  (i) 3Dfx has performed in 
all material respects all obligations required to be performed by it under 
each 3Dfx Employee Plan and each 3Dfx Employee Plan has been established and 
maintained in all material respects in accordance with its terms and in 
compliance with all applicable laws, statutes, orders, rules and regulations, 
including but not limited to ERISA or the Code; (ii) to 3Dfx's knowledge no 
"prohibited transaction," within the meaning of Section 4975 of the Code or 
Section 406 of ERISA, has occurred with respect to any 3Dfx Employee Plan; 
(iii) there are no actions, suits or claims pending, or, to the knowledge of 
3Dfx, threatened or anticipated (other than routine claims for benefits) 
against any 3Dfx Employee Plan or against the assets of any 3Dfx Employee 
Plan; (iv) each 3Dfx Employee Plan can be amended, terminated or otherwise 
discontinued after the Effective Time in accordance with its terms, without 
liability to 3Dfx, STB, the Surviving Corporation or any Affiliates (other 
than ordinary administration expenses typically incurred in a termination 
event); (v) there are no inquiries or proceedings pending or, to the 
knowledge of 3Dfx or any Affiliates, threatened by the IRS or DOL with 
respect to any 3Dfx Employee Plan; and (vi) to 3Dfx's knowledge neither 3Dfx 
nor any Affiliate is subject to any penalty or tax with respect to any 3Dfx 
Employee Plan under Section 402(i) of ERISA or Section 4975 through 4980 of 
the Code.

            (e)     3Dfx PENSION PLANS.  3Dfx does not now, nor has it ever, 
maintained, established, sponsored, participated in, or contributed to, any 
3Dfx Pension Plan which is subject to Part 3 of Subtitle B of Title I of 
ERISA, Title IV of ERISA or Section 412 of the Code.

            (f)     MULTIEMPLOYER PLANS.  At no time has 3Dfx contributed to 
or been requested to contribute to any Multiemployer Plan.

            (g)     NO POST-EMPLOYMENT OBLIGATIONS.  No 3Dfx Employee Plan 
provides, or has any liability to provide, life insurance, medical or other 
employee benefits to any 3Dfx Employee upon his or her retirement or 
termination of employment for any reason, except as may be required by 
statute, and 3Dfx has never represented, promised or contracted (whether in 
oral or written form) to any 3Dfx Employee (either individually or to 3Dfx 
Employees as a group) that such 3Dfx Employee(s) would be provided with life 
insurance, medical or other employee welfare benefits upon their retirement 
or termination of employment, except to the extent required by statute.

            (h)     EFFECT OF TRANSACTION.

                    (i)   The execution of this Agreement and the 
consummation of the transactions contemplated hereby will not (either alone 
or upon the occurrence of any additional or subsequent events) constitute an 
event under any 3Dfx Employee Plan, 3Dfx Employee Agreement, trust or loan 
that will or may result in any payment (whether of severance pay or 
otherwise), acceleration, forgiveness of indebtedness, vesting, distribution, 
increase in benefits or obligation to fund benefits with respect to any 3Dfx 
Employee.


                                     23
<PAGE>

                   (ii)   No payment or benefit which will or may be made by 
3Dfx or 3Dfx or any of their respective Affiliates with respect to any 3Dfx 
Employee will be characterized as an "excess parachute payment," within the 
meaning of Section 280G(b)(1) of the Code.

            (i)     EMPLOYMENT MATTERS.  3Dfx and each of its subsidiaries 
(i) is in compliance in all material respects with all applicable foreign, 
federal, state and local laws, rules and regulations respecting employment, 
employment practices, terms and conditions of employment and wages and hours, 
in each case, in each location in which 3Dfx or any of its subsidiaries 
employs persons; (ii) has withheld all amounts required by law or by 
agreement to be withheld from the wages, salaries and other payments to 3Dfx 
Employees; (iii) is not liable for any material arrears of wages or any 
material taxes or any material penalty for failure to comply with any of the 
foregoing; and (iv) is not liable for any material payment to any trust or 
other fund or to any governmental or administrative authority, with respect 
to unemployment compensation benefits, social security or other benefits or 
obligations for 3Dfx Employees (other than routine payments to be made in the 
normal course of business and consistent with past practice).

            (j)     VIOLATIONS.  To 3Dfx's knowledge and reasonable belief, 
no employee of 3Dfx has violated any employment contract, patent disclosure 
agreement or non competition agreement between such employee and any former 
employer of such employee due to such employee being employed by 3Dfx and 
disclosing to 3Dfx trade secrets or proprietary information of such employer. 
3Dfx is not, and has never been, a party to any collective bargaining 
agreement. 3Dfx and its subsidiaries are in compliance in all material 
respects with all applicable laws regarding employment practices, terms and 
conditions of employment, and wages and hours (including, without limitation, 
ERISA, WARN or any similar state or local law).

            (k)     INTERNATIONAL EMPLOYEE PLAN.  Each International Employee 
Plan has been established, maintained and administered in material compliance 
with its terms and conditions and with the requirements prescribed by any and 
all statutory or regulatory laws that are applicable to such International 
Employee Plan.  Furthermore, no International Employee Plan has unfunded 
liabilities, that as of the Effective Time, will not be offset by insurance 
or fully accrued. Except as required by law, no condition exists that would 
prevent 3Dfx from terminating or amending any International Employee Plan at 
any time for any reason.

     4.12   LABOR MATTERS.  (i) There are no controversies pending or, to the 
best knowledge of each of 3Dfx and its respective subsidiaries, threatened, 
between 3Dfx or any of its subsidiaries and any of their respective 
employees, which controversies have or could reasonably be expected to have a 
Material Adverse Effect; (ii) as of the date of this Agreement, neither 3Dfx 
nor any of its subsidiaries is a party to any collective bargaining agreement 
or other labor union contract applicable to persons employed by 3Dfx or its 
subsidiaries nor does 3Dfx or its subsidiaries know of any activities or 
proceedings of any labor union to organize any such employees (A) as of the 
date of this Agreement and (B) which, as of the Closing Date, have or could 
reasonably be expected to have a Material Adverse Effect on 3Dfx and its 
subsidiaries; and (iii) as of the date of this Agreement, neither 3Dfx nor 
any of its subsidiaries has any knowledge of any strikes, slowdowns, work 
stoppages or lockouts, or threats thereof, by or with respect to any 
employees of 3Dfx or any of its subsidiaries (X) as of the date of this 
Agreement and (Y) which, as of the Closing Date, have or could reasonably be 
expected to have a Material Adverse Effect on 3Dfx and its subsidiaries.

     4.13   REGISTRATION STATEMENT; PROXY STATEMENT.  None of the information 
supplied or to be supplied by 3Dfx for inclusion or incorporation by 
reference (i) in the S-4 will, at the time the S-4 becomes 


                                      24
<PAGE>

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 in order to make the statements therein, in light of the 
circumstances under which they are made, not misleading; and (ii) the Proxy 
Statement will, at the dates mailed to the shareholders of 3Dfx and STB, at 
the times of the Shareholders Meetings and as of the Effective Time, 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 will comply as to form in all material 
respects with the provisions of the Exchange Act and the rules and 
regulations promulgated by the SEC thereunder, and the S-4 will comply as to 
form in all material respects with the provisions of the Securities Act and 
the rules and regulations promulgated by the SEC thereunder.

     4.14   RESTRICTIONS ON BUSINESS ACTIVITIES.  Other than as may be 
permitted under Section 5.9, there is no material agreement, judgment, 
injunction, order or decree binding upon 3Dfx or any of its subsidiaries 
which has or could reasonably be expected to have the effect of prohibiting 
or materially impairing any business practice of 3Dfx or any of its 
subsidiaries, any acquisition of property by 3Dfx or any of its subsidiaries 
or the conduct of business by 3Dfx or any of its subsidiaries as currently 
conducted.

     4.15   TITLE TO PROPERTY.  3Dfx owns no material real property.  3Dfx 
and each of its subsidiaries have good and defensible title to all of their 
material properties and assets, free and clear of all liens, charges and 
encumbrances except liens for taxes not yet due and payable and such liens or 
other imperfections of title, if any, as do not materially detract from the 
value of or interfere with the present use of the property affected thereby 
or which, individually or in the aggregate, could not reasonably be expected 
to have a Material Adverse Effect; and all leases pursuant to which 3Dfx or 
any of its subsidiaries lease from others material amounts of real or 
personal property are in good standing, valid and effective in accordance 
with their respective terms, and there is not, under any of such leases, any 
existing material default or event of default (or any event which with notice 
or lapse of time, or both, would constitute a material default and in respect 
of which 3Dfx or its subsidiary has not taken adequate steps to prevent such 
default from occurring) except where the lack of such good standing, validity 
and effectiveness or the existence of such default or event of default could 
not, individually or in the aggregate, reasonably be expected to have a 
Material Adverse Effect.  All the plants, structures and equipment of 3Dfx 
and its subsidiaries, except such as may be under construction, are in good 
operating condition and repair, except where the failure of such plants, 
structures and equipment to be in such good operating condition and repair 
could not, individually or in the aggregate, reasonably be expected to have a 
Material Adverse Effect.

     4.16   TAXES.  3Dfx and each of its subsidiaries, and any consolidated, 
combined, unitary or aggregate group for Tax purposes of which 3Dfx or any of 
its subsidiaries is or has been a member, have timely filed all Tax Returns 
required to be filed by them and have paid all Taxes shown thereon to be due. 
3Dfx has provided adequate accruals in accordance with generally accepted 
accounting principles in its financial statements for any Taxes that have not 
been paid, whether or not shown as being due on any Tax Returns.  There is 
(i) no material claim for Taxes that is a lien against the property of 3Dfx 
or any of its subsidiaries or is being asserted against 3Dfx or any of its 
subsidiaries other than liens for Taxes not yet due and payable, (ii) no 
audit of any Tax Return of 3Dfx or any of its subsidiaries being conducted by 
a Tax authority, (iii) no extension of the statute of limitations on the 
assessment of any Taxes granted by 3Dfx or any of its subsidiaries and 
currently in effect, and (iv) no agreement, contract or arrangement to which 
3Dfx or any of its subsidiaries is a party that may result in the payment of 
any amount that would not be deductible 


                                     25
<PAGE>

by reason of Sections 162(m), 280G or 404 of the Code.  3Dfx has not been and 
will not be required to include any material adjustment in Taxable income for 
any Tax period (or portion thereof) pursuant to Section 481 or 263A of the 
Code or any comparable provision under state or foreign Tax laws as a result 
of transactions, events or accounting methods employed prior to the Merger. 
Neither 3Dfx nor any of its subsidiaries has ever been a member of any 
combined, controlled, consolidated or affiliated group (other than the group 
of which 3Dfx is the parent) for Tax purposes.  Neither 3Dfx nor any of its 
subsidiaries is a party to any tax sharing or tax allocation agreement nor 
does 3Dfx or any of its subsidiaries owe any amount under any such agreement. 
Neither 3Dfx nor any of its subsidiaries has been at any time, a "United 
States real property holding corporation" with the meaning of Section 
897(c)(2) of the Code. 

     4.17   ENVIRONMENTAL MATTERS. 

            (a)     HAZARDOUS MATERIAL.  Except as would not result in any 
material liability to 3Dfx under Environmental Laws, no underground storage 
tanks and no Hazardous Materials are present, as a result of the actions of 
3Dfx or any of its subsidiaries or any affiliate of 3Dfx, or, to 3Dfx's 
knowledge, as a result of any actions of any third party or otherwise, in, on 
or under any property, including the land and the improvements, ground water 
and surface water thereof, that 3Dfx or any of its subsidiaries has at any 
time owned, operated, occupied or leased.

            (b)     HAZARDOUS MATERIALS ACTIVITIES.  Neither 3Dfx nor any of 
its subsidiaries has (i) transported, stored, used, manufactured, disposed 
of, released or exposed its employees or others to Hazardous Materials in 
violation of Environmental Law, or (ii) engaged in any Hazardous Materials 
Activities in violation of any Environmental Law in effect prior to or as of 
the date hereof except for which violation has not heretofore been cured or 
for which there is any remaining liability.

            (c)     PERMITS.  3Dfx and its subsidiaries currently hold all 
environmental approvals, permits, licenses, clearances and consents (the 
"3DFX ENVIRONMENTAL PERMITS") necessary for the conduct of 3Dfx's and its 
subsidiaries' Hazardous Material Activities and other businesses of 3Dfx and 
its subsidiaries as such activities and businesses are currently being 
conducted. 3Dfx and its subsidiaries are in compliance in all material 
respects with the terms of the 3Dfx Environmental Permits, except for which 
noncompliance has not heretofore been cured or for which there is any 
remaining liability.

            (d)     ENVIRONMENTAL LIABILITIES.  No action, proceeding, 
revocation proceeding, amendment procedure, writ, claim or injunction is 
pending, and to 3Dfx's knowledge, no action, proceeding, revocation 
proceeding, amendment procedure, writ, claim or injunction has been 
threatened by any Governmental Entity against 3Dfx or any of its subsidiaries 
concerning any 3Dfx Environmental Permit, Hazardous Material or any Hazardous 
Materials Activities of 3Dfx or any of its subsidiaries. 

     4.18   BROKERS.  No broker, finder or investment banker (other than 
BancBoston Robertson Stephens ("BANCBOSTON")) 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 3Dfx or Sub.

     4.19   INTELLECTUAL PROPERTY. 3Dfx or its subsidiaries owns each of the 
patents and patent applications referred to in the 3Dfx SEC Reports and, 
except as disclosed in the 3Dfx SEC Reports, (i) each of 3Dfx and its 
subsidiaries owns or possesses, or could obtain ownership or possession of 
(on terms not 


                                     26
<PAGE>

materially adverse to the consolidated financial position, shareholders' 
equity, results of operations of 3Dfx and its subsidiaries taken as a whole) 
adequate and enforceable rights to use all other patent applications, 
patents, trademarks, trademark applications, trade names, service marks, 
copyrights, copyright applications, licenses, know-how and other similar 
rights and proprietary knowledge (collectively with the patents and patent 
applications described in the 3Dfx SEC Reports, the "Intangibles") necessary 
for the conduct of their businesses and (ii) neither 3Dfx nor any subsidiary, 
to its knowledge, has infringed, is infringing, or has received any notice of 
infringement of any Intangible of any other person that, if the subject of an 
unfavorable decision, ruling or finding, could reasonably be expected to (or, 
with respect to pending patent litigation as of the date hereof, 3Dfx does 
not believe will) have a Material Adverse Effect and 3Dfx knows of no basis 
therefor.  The expiration of any Intangibles would not have a Material 
Adverse Effect on 3Dfx and its subsidiaries taken as a whole.  Except as set 
forth in the 3Dfx SEC Reports, 3Dfx has received no notice of potential 
indemnity claims from customers based upon a notice of infringement any such 
customer has received from a patent owner relating to an assertion of 
infringement of a patent other than potential indemnity claims which 
individually or in the aggregate would not reasonably be expected to have a 
Material Adverse Effect.

     4.20   INSURANCE.  3Dfx maintains insurance policies and fidelity bonds 
covering the assets, business, equipment, properties, operations, employees, 
officers and directors of 3Dfx and its subsidiaries ("3DFX INSURANCE 
POLICIES") which are of the type and in amounts customarily carried by 
persons conducting businesses similar to those of 3Dfx and its subsidiaries.  
There is no material claim by 3Dfx or any of its subsidiaries pending under 
any of the material 3Dfx Insurance Policies.

     4.21   OPINION OF FINANCIAL ADVISOR.  3Dfx has been advised in writing 
by its financial advisor, BancBoston, that in its opinion as of the date 
hereof, the Exchange Ratio is fair, from a financial point of view, to 3Dfx.

     4.22   BOARD APPROVAL.  The Board of Directors of 3Dfx has, as of the 
date hereof,  (i) approved this Agreement and the STB Option Agreement and 
the transactions contemplated hereby and thereby, (ii) determined that the 
Merger is in the best interests of the shareholders of 3Dfx and is on terms 
that are fair to such shareholders and (iii) recommended that the 
shareholders of 3Dfx approve the issuance of 3Dfx Common Stock in connection 
with the Merger.

     4.23   VOTE REQUIRED.  The affirmative vote of the holders of a majority 
of the shares of 3Dfx Common Stock present in person or represented by proxy 
at the meeting of 3Dfx's shareholders contemplated by Section 5.8 (provided 
that the shares so present or represented constitute a majority of the shares 
of 3Dfx Common Stock) is the only vote of the holders of any class or series 
of 3Dfx's capital stock necessary to approve the Merger and the issuance of 
3Dfx Common Stock in connection with the Merger.

     4.24   INTERIM OPERATIONS OF SUB.  Sub was formed solely for the purpose 
of engaging in the transactions contemplated hereby, has engaged in no other 
business activities and has conducted its operations only as contemplated 
hereby.

     4.25   YEAR 2000 COMPLIANCE.  Except as would not reasonably be expected 
to have a Material Adverse Effect on 3Dfx, all of 3Dfx's Information 
Technology (as defined below) is effectively addresses the Year 2000 issues 
Year, and will not cause an interruption in the ongoing operations of 3Dfx's 
business on or after January 1, 2000.  For purposes of the foregoing, the 
term "INFORMATION TECHNOLOGY" shall mean and 


                                     27
<PAGE>

include all software, hardware, firmware, telecommunications systems, network 
systems, embedded systems and other systems, components and/or services that 
are owned or used by 3Dfx in the conduct of its business, or purchased by 
3Dfx from third party suppliers.

     4.26   CHANGE OF CONTROL PAYMENTS.  Other than as excepted in Section 
4.18 hereof or contemplated by Section 5.14, there are no amounts that will 
become payable (whether currently or in the future) to current or former 
employees, officers and directors of 3Dfx under any plan or agreement of 3Dfx 
as a result of or in connection with the Merger.

                                  ARTICLE 5
                                       
                       CONDUCT AND TRANSACTIONS PRIOR TO
                     EFFECTIVE TIME; ADDITIONAL AGREEMENTS

     5.1    INFORMATION AND ACCESS.  Subject to and in accordance with the 
terms and conditions of those certain letter agreements dated December 5, 
1998 and December 7, 1998, between 3Dfx and STB (collectively the 
"CONFIDENTIALITY AGREEMENT"), from the date of this Agreement and continuing 
until the Effective Time, each Company shall afford and, with respect to 
clause (b) below, such Company shall cause its independent auditors to 
afford, (a) to the officers, independent auditors, counsel and other 
representatives of the other Company reasonable access to the properties, 
books, records (including Tax Returns filed and those in preparation) and 
personnel of such Company and its subsidiaries in order that the other 
Company may have a full opportunity to make such investigation as it 
reasonably desires to make of such Company and its subsidiaries and (b) to 
the independent auditors of the other Company, reasonable access to the audit 
work papers and other records of the independent auditors of such Company and 
its subsidiaries.  Additionally, subject to and in accordance with the 
Confidentiality Agreement, each Company and its subsidiaries will permit the 
other Company to make such reasonable inspections of such Company and its 
subsidiaries and their respective operations during normal business hours as 
the other Company may reasonably require and each Company and its 
subsidiaries will cause its officers and the officers of its subsidiaries to 
furnish the other Company with such financial and operating data and other 
information with respect to the business and properties of such Company and 
its subsidiaries as the other Company may from time to time reasonably 
request.  No investigation pursuant to this Section 5.1 shall affect or 
otherwise obviate or diminish any representations and warranties of any party 
or conditions to the obligations of any party.

     5.2    CONDUCT OF BUSINESS OF THE COMPANIES.  Except as contemplated by 
this Agreement, during the period from the date of this Agreement and 
continuing until the Effective Time or until the termination of this 
Agreement pursuant to Section 7.1, (i) each Company shall use reasonable 
efforts promptly to report to the other on the status of operational matters 
and changes of materiality (subject to the terms of the Confidentiality 
Agreement) and (ii) each Company and its subsidiaries shall conduct their 
respective businesses in the ordinary and usual course consistent with past 
practice and each Company and its subsidiaries shall use reasonable efforts 
to maintain and preserve intact its business organization, to keep available 
the services of its officers and employees and to maintain satisfactory 
relations with licensors, franchisees, licensees, suppliers, contractors, 
distributors, customers and others having business relationships with it.  
Without limiting the generality of the foregoing and except as provided in 
this Agreement, prior to the Effective Time, neither Company nor any of its 
subsidiaries shall, unless this Agreement is terminated 


                                     28
<PAGE>

pursuant to Section 7.1, without the prior written consent of the other 
Company (which consent shall not be unreasonably withheld):

            (a)     declare, set aside or pay any dividends on or make any 
other distribution in respect of any of its capital stock except (i) as 
permitted by subsection (c) below, (ii) dividends or distributions by 
subsidiaries of 3Dfx to 3Dfx or any subsidiary of 3Dfx, (iii) contributions 
or distributions by STB to a subsidiary of STB to support the operations of 
such subsidiary in the ordinary course of business consistent with past 
practice and (iv) the distributions of funds in satisfaction of STB 
obligations owed in respect of the STB Options as set forth in Section 5.14;

            (b)     split, combine or reclassify any of its capital stock or 
issue or authorize or propose the issuance or authorization of any other 
securities in respect of, in lieu of or in substitution for shares of its 
capital stock or repurchase, redeem (except in compliance with Section 5.2(n) 
below) or otherwise acquire any shares of its capital stock;

            (c)     issue, deliver, pledge, encumber or sell, or authorize or 
propose the issuance, delivery, pledge, encumbrance or sale of, or purchase 
or propose the purchase of, any shares of its capital stock or securities 
convertible into, or rights, warrants or options to acquire, any such shares 
of capital stock or other convertible securities (other than (i) the issuance 
of such capital stock upon the exercise or conversion of 3Dfx Options or STB 
Options (as defined in Section 5.14), as the case may be, outstanding on the 
date of this Agreement in accordance with their present terms or pursuant to 
the 3Dfx Employee Stock Purchase Plan or the STB Purchase Plan, as the case 
may be, in accordance with their present terms, (ii) the grant of 3Dfx 
Options in the ordinary course of business consistent with past practice, 
pursuant to 3Dfx Employee Plans in effect on the date of this Agreement, and 
the issuance of 3Dfx Common Stock upon exercise thereof, (iii) increases in 
the number of shares reserved for issuance under the 3Dfx Employee Plans 
provided that such increases are in connection with, or subject to, 
shareholder approval at an Annual or Special Meeting of shareholders, (iv) 
the grant of STB Options to purchase up to an aggregate of 50,000 shares of 
STB Common Stock in the ordinary course of business consistent with past 
practice, pursuant to STB Employee Plans in effect on the date of this 
Agreement or authorize or propose any change in its equity capitalization and 
(v) the purchase by 3Dfx of up to an aggregate of $20 million worth of its 
Common Stock in the open market pursuant to a stock repurchase program 
adopted by the 3Dfx Board of Directors and administered in compliance with 
Rule 10b-18 under the Exchange Act;

            (d)     except as otherwise provided in this Agreement, amend its 
Articles of Incorporation or Bylaws in any manner adverse to the other 
Company;

            (e)     acquire or agree to acquire by merging or consolidating 
with, or by purchasing any material portion of the capital stock or assets 
of, or by any other manner, any business or any corporation, partnership, 
association or other business organization or division thereof;

            (f)     sell, lease, pledge or otherwise dispose of or encumber 
any of its assets, except in the ordinary course of business (including, 
without limitation, any indebtedness owed to it or any claims held by it);

            (g)     transfer the stock of any subsidiary to any other 
subsidiary or any assets or liabilities to any new or, except in the ordinary 
course of business consistent with past practice, existing subsidiary, or in 


                                     29
<PAGE>

the case of 3Dfx, in connection with international subsidiaries established 
for the purposes of achieving tax benefits;

            (h)     incur any indebtedness for borrowed money or guarantee 
any such indebtedness or issue or sell any of its debt securities or 
guarantee, endorse or otherwise as an accommodation become responsible for 
the obligations of others, or make loans or advances, other than in the 
ordinary course of business consistent with past practice;

            (i)     pay, discharge or satisfy any material claims, 
liabilities or obligations (whether absolute, accrued, contingent or 
otherwise), other than (i) the payment, discharge or satisfaction of 
liabilities in the ordinary course of business and (ii) the payment of the 
fees and expenses of counsel and financial advisors relating to this 
Agreement and the transactions contemplated hereby;

            (j)     with respect to STB only, adopt or amend in any material 
respect any collective bargaining agreement or STB Employee Plan, enter into 
or amend any employment, severance, special pay arrangement with respect to 
termination of employment or other similar arrangements or agreements with 
any directors, officers or key employees of STB, or enter into or amend any 
severance or termination arrangement that provides for payments to any person 
other than as contemplated by this Agreement;

            (k)     change in any material respect the accounting methods or 
practices followed by such Company, including any material change in any 
assumption underlying, or method of calculating, any bad debt, contingency or 
other reserve, except as may be required by changes in GAAP; make any 
material Tax election or settle or compromise any material federal, state, 
local or foreign income tax liability or agree to an extension of a statute 
of limitations;

            (l)     enter into any material contract or agreement, except in 
the ordinary course of business, other than as expressly permitted in this 
Section 5.2 and other than renewals or replacements of leases scheduled to 
expire in the near-term in the ordinary course of business; or

            (m)     authorize or enter into any contract, agreement, 
commitment or arrangement to do any of the foregoing.

     Nothing contained herein shall restrict STB from entering into such 
reasonable contracts as are necessary in connection with furnishing the STB's 
headquarters.

     5.3    NEGOTIATION WITH OTHERS. 

            (a)     From and after the date of this Agreement until the 
earlier of the Effective Time or the termination of this Agreement in 
accordance with its terms, STB shall not, directly or indirectly, through any 
officer, director, employee, representative or agent of STB or any of its 
subsidiaries, solicit or encourage (including by way of furnishing nonpublic 
information) or take other action, either directly or indirectly,  to 
facilitate any inquiries or the making of any proposal that constitutes or 
may reasonably be expected to lead to an Acquisition Proposal (as defined 
below) from any person, or engage in any discussions or negotiations relating 
thereto or in furtherance thereof or accept any Acquisition Proposal.  For 
purposes of this Agreement, "ACQUISITION PROPOSAL" means any inquiries or 
proposals regarding (i) any merger, consolidation, sale of substantial assets 
or similar transactions involving STB or any subsidiaries of STB (other than 
sales of assets 


                                     30
<PAGE>

or inventory in the ordinary course of business), (ii) purchase of 20% or 
more of the outstanding shares of capital stock of STB (including without 
limitation by way of a tender offer or an exchange offer) or similar 
transactions involving STB or any subsidiaries of STB, (iii) the acquisition 
by any person of beneficial ownership or a right to acquire beneficial 
ownership of, or the formation of any "group" (as defined under Section 13(d) 
of the Exchange Act and the rules and regulations thereunder) which 
beneficially owns, or has the right to acquire beneficial ownership of 20% or 
more of the then outstanding shares of capital stock of STB; or (iv) any 
public announcement of a proposal, plan or intention to do any of the 
foregoing or any agreement to engage in any of the foregoing.

            (b)     Notwithstanding Section 5.3(a), the restrictions set 
forth in this Agreement shall not prevent the Board of Directors of STB, in 
the exercise of and as required by its fiduciary duties as determined by the 
Board of Directors of STB after consultation with its outside legal counsel, 
engaging in discussions or negotiations with, and furnishing information 
concerning STB and its business, properties and assets (but not directly or 
indirectly soliciting or initiating such discussions or negotiations or 
directly or indirectly encouraging inquiries or the making of any Acquisition 
Proposal), to a third party who makes a written, unsolicited, bona fide 
Acquisition Proposal that is reasonably capable of being consummated and is 
reasonably likely to be financially superior to the Merger, as determined in 
each case in good faith by STB's Board of Directors after consultation with 
STB's financial advisors (a "SUPERIOR PROPOSAL"), provided that 3Dfx shall 
have been notified in writing of such Acquisition Proposal, including the 
principal financial terms and conditions thereof and the identity of the 
person or group making such Acquisition Proposal.

     Upon compliance with the foregoing, STB shall be entitled to (1) 
withdraw, modify or refrain from making its recommendation referred to in 
Section 5.4 following receipt of a Superior Proposal, and approve and 
recommend to the shareholders of STB a Superior Proposal and (2) enter into 
an agreement with such third party concerning a Superior Proposal; PROVIDED, 
HOWEVER, that STB shall immediately make payment in full to 3Dfx of the 
Breakup Fee as defined in Section 7.3 below.

            (c)     If STB or any of its subsidiaries receives any 
unsolicited offer or proposal to enter negotiations relating to an 
Acquisition Proposal, STB shall immediately notify 3Dfx thereof, including 
information as to the identity of the offeror or the party making any such 
offer or proposal and the principal financial terms and conditions of such 
offer or proposal, as the case may be.

            (d)     Notwithstanding the foregoing, STB shall not provide any 
non-public information to a third party as described above unless STB 
provides such non-public information pursuant to a nondisclosure agreement 
with terms regarding the protection of confidential information at least as 
restrictive as such terms in the Confidentiality Agreement previously entered 
into between 3Dfx and STB. 

            (e)     STB shall immediately cease and cause to be terminated 
any existing discussions or negotiations with any parties (other than 3Dfx 
and Sub) conducted prior to the date of this Agreement with respect to any of 
the foregoing.

            (f)     3Dfx shall immediately cease and cause to be terminated 
any existing discussions or negotiations with any parties (other than STB) 
regarding any merger, consolidation, sale of substantial assets or similar 
transactions involving 3Dfx.


                                     31
<PAGE>

     5.4    PREPARATION OF S-4 AND THE PROXY STATEMENT; OTHER FILINGS.  As 
promptly as practicable after the date of this Agreement, 3Dfx and STB shall 
prepare and file with the SEC a preliminary Proxy Statement in form and 
substance satisfactory to each of 3Dfx and STB and 3Dfx shall prepare and 
file with the SEC the S-4, in which the Proxy Statement will be included as a 
prospectus.  Each of 3Dfx and STB shall use its reasonable efforts to respond 
to any comments of the SEC, to have the S-4 declared effective under the 
Securities Act as promptly as practicable after such filing and to cause the 
Proxy Statement to be mailed to such Company's shareholders at the earliest 
practicable time.  As promptly as practicable after the date of this 
Agreement, 3Dfx and STB shall prepare and file any other filings required 
under the Exchange Act, the Securities Act or any other federal or Blue Sky 
Laws relating to the Merger and the transactions contemplated by this 
Agreement and the Articles of Merger, including, without limitation, under 
the HSR Act and state takeover laws (the "OTHER FILINGS").  Each Company will 
notify the other Company promptly of the receipt of any comments from the SEC 
or its staff and of any request by the SEC or its staff or any other 
government officials for amendments or supplements to the S-4, the Proxy 
Statement or any Other Filing or for additional information and will supply 
the other Company with copies of all correspondence between such Company or 
any of its representatives, on the one hand, and the SEC, or its staff or any 
other government officials, on the other hand, with respect to the S-4, the 
Proxy Statement, the Merger or any Other Filing.  The Proxy Statement, the 
S-4 and the Other Filings shall comply in all material respects with all 
applicable requirements of law.  Whenever any event occurs which is required 
to be set forth in an amendment or supplement to the Proxy Statement, the S-4 
or any Other Filing, 3Dfx or STB, as the case may be, shall promptly inform 
the other Company of such occurrence and cooperate in filing with the SEC or 
its staff or any other government officials, and/or mailing to shareholders 
of 3Dfx and STB, such amendment or supplement.  The Proxy Statement shall 
include the recommendations of the Board of Directors of 3Dfx in favor of the 
issuance of 3Dfx Common Stock in connection with the Merger and of the Board 
of Directors of STB in favor of the Merger, provided that the recommendation 
of the Board of Directors of STB may not be included or may be withdrawn if 
previously included if  the Board of Directors of STB has accepted a Superior 
Proposal in accordance with the terms of Section 5.3.

     5.5    ADVICE OF CHANGES; SEC FILINGS.  Each Company shall promptly 
provide the other Company (or its counsel) copies of all filings made by such 
Company with any Governmental Entity in connection with this Agreement and 
the transactions contemplated hereby and thereby.

     5.6    LETTER OF STB'S INDEPENDENT AUDITORS.  STB shall use all 
reasonable efforts to cause to be delivered to 3Dfx a letter of 
PricewaterhouseCoopers, LLP, STB's independent auditors, dated a date within 
two Business Days before the date on which the S-4 shall become effective and 
addressed to 3Dfx, in form and substance reasonably satisfactory to 3Dfx and 
customary in scope and substance for letters delivered by independent 
auditors in connection with registration statements similar to the S-4.

     5.7    LETTER OF 3Dfx'S INDEPENDENT AUDITORS.  3Dfx shall use all 
reasonable efforts to cause to be delivered to STB a letter of 
PricewaterhouseCoopers, LLP, 3Dfx's independent auditors, dated a date within 
two Business Days before the date on which the S-4 shall become effective and 
addressed to STB, in form and substance reasonably satisfactory to STB and 
customary in scope and substance for letters delivered by independent 
auditors in connection with registration statements similar to the S-4.

     5.8    SHAREHOLDERS MEETINGS.  3Dfx and STB each shall call a meeting of 
its respective shareholders to be held as promptly as practicable for the 
purpose of voting upon, in the case of 3Dfx, the 


                                     32
<PAGE>

issuance of 3Dfx Common Stock in connection with the Merger and, in the case 
of STB, this Agreement.  3Dfx and STB shall coordinate and cooperate with 
respect to the timing of the Shareholders Meetings and shall use their 
respective reasonable efforts to hold the Shareholders Meetings on the same 
day as soon as practicable after the date of this Agreement.

     5.9    AGREEMENTS TO TAKE REASONABLE ACTION. 

            (a)     STB shall take, and shall cause its subsidiaries to take, 
all reasonable actions necessary to comply promptly with all legal 
requirements which may be imposed on STB or its subsidiaries with respect to 
the Merger (including furnishing the information required under the HSR Act) 
and shall take all reasonable actions necessary to cooperate promptly with 
and furnish information to 3Dfx in connection with any such requirements 
imposed upon 3Dfx or Sub or any subsidiary of 3Dfx or Sub in connection with 
the Merger.  STB shall take, and shall cause its subsidiaries to take, all 
reasonable actions necessary (i) to obtain (and will take all reasonable 
actions necessary to promptly cooperate with 3Dfx or Sub and their 
subsidiaries in obtaining) any clearance, consent, authorization, order or 
approval of, or any exemption by, any Governmental Entity, or other third 
party, required to be obtained or made by STB or any of its subsidiaries (or 
by 3Dfx or any of its subsidiaries) in connection with the Merger or the 
taking of any action contemplated by this Agreement; (ii) to lift, rescind or 
mitigate the effect of any injunction or restraining order or other order 
adversely affecting the ability of STB to consummate the transactions 
contemplated hereby; (iii) to fulfill all conditions applicable to STB or 
3Dfx pursuant to this Agreement reasonably within that party's control; and 
(iv) to prevent, with respect to a threatened or pending temporary, 
preliminary or permanent injunction or other order, decree or ruling or 
statute, rule, regulation or executive order, the entry, enactment or 
promulgation thereof, as the case may be; PROVIDED, HOWEVER, that with 
respect to clauses (i) through (iv) above, STB and its subsidiaries will take 
only such curative measures (such as licensing and divestiture) as 3Dfx and 
STB mutually determine, in good faith, to be reasonable.

            (b)     3Dfx and Sub shall take, and shall cause their 
subsidiaries to take, all reasonable actions necessary to comply promptly 
with all legal requirements which may be imposed on them or their 
subsidiaries with respect to the Merger (including furnishing the information 
required under the HSR Act) and shall take all reasonable actions necessary 
to cooperate promptly with and furnish information to STB in connection with 
any such requirements imposed upon STB or any subsidiary of STB in connection 
with the Merger.  3Dfx and Sub shall take, and shall cause their subsidiaries 
to take, all reasonable actions necessary (i) to obtain (and will take all 
reasonable actions necessary to promptly cooperate with STB and its 
subsidiaries in obtaining) any clearance, consent, authorization, order or 
approval of, or any exemption by, any Governmental Entity, or other third 
party, required to be obtained or made by 3Dfx or any of its subsidiaries (or 
by STB or any of its subsidiaries) in connection with the Merger or the 
taking of any action contemplated by this Agreement; (ii) to lift, rescind or 
mitigate the effect of any injunction or restraining order or other order 
adversely affecting the ability of 3Dfx or Sub to consummate the transactions 
contemplated hereby; (iii) to fulfill all conditions applicable to 3Dfx or 
Sub or STB pursuant to this Agreement; and (iv) to prevent, with respect to a 
threatened or pending temporary, preliminary or permanent injunction or other 
order, decree or ruling or statute, rule, regulation or executive order, the 
entry, enactment or promulgation thereof, as the case may be; PROVIDED, 
HOWEVER, that with respect to clauses (i) through (iv) above 3Dfx and its 
subsidiaries will take only such curative measures (such as licensing and 
divestiture) as 3Dfx determines, in good faith, to be reasonable.


                                     33
<PAGE>

            (c)     Subject to the terms and conditions of this Agreement, 
each of the parties shall use all reasonable efforts to take, or cause to be 
taken, all actions and to do, or cause to be done, all things necessary, 
proper or advisable under applicable laws and regulations to consummate and 
make effective as promptly as practicable the transactions contemplated by 
this Agreement, subject to the appropriate approval of the shareholders of 
3Dfx and STB.  3Dfx and STB will use their reasonable best efforts to resolve 
any competitive issues relating to or arising under the HSR Act or any other 
federal or state antitrust or fair trade law raised by any Governmental 
Entity including making offers of curative divestitures and/or licensing of 
technology which 3Dfx determines, in good faith, to be reasonable.  If such 
offers are not accepted by such Governmental Entity, 3Dfx (with STB's 
cooperation) shall pursue all litigation resulting from such issues.  The 
parties hereto will consult and cooperate with one another, and consider in 
good faith the views of one another, in connection with any analyses, 
appearances, presentations, memoranda, briefs, arguments, opinions and 
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 federal or 
state antitrust or fair trade law.

     5.10   CONSENTS.  3Dfx, Sub and STB shall each use best efforts to 
obtain the consent and approval of, or effect the notification of or filing 
with, each person or authority whose consent or approval is required of any 
of 3Dfx, STB or Sub in order to permit the consummation of the Merger and the 
transactions contemplated by this Agreement and to enable the Surviving 
Corporation to conduct and operate the business of STB and its subsidiaries 
substantially as presently conducted and as contemplated to be conducted.

     5.11   NASDAQ ADDITIONAL SHARES LISTING.  3Dfx will cause the shares of 
3Dfx Common Stock issuable to the shareholders of STB in the Merger to be 
listed for trading on the NASDAQ National Market.

     5.12   PUBLIC ANNOUNCEMENTS.  3Dfx, Sub and STB shall consult with each 
other before issuing any press release or otherwise making any public 
statements with respect to the Merger and shall not issue any such press 
release or make any such public statement prior to such consultation except 
as may be required by law.

     5.13   AFFILIATES.   Set forth on EXHIBIT E hereto is a list  of those 
persons who may be deemed to be, in STB's reasonable judgment, affiliates of 
STB within the meaning of Rule 145 promulgated under the Securities Act (each 
a "STB RULE 145 AFFILIATE").  STB will provide 3Dfx with such information and 
documents as 3Dfx reasonably requests for purposes of reviewing such list.  
STB will use its reasonable best efforts to deliver or cause to be delivered 
to 3Dfx, as promptly as practicable on or following the date hereof, from 
each STB Rule 145 Affiliate an executed affiliate agreement in substantially 
the form attached hereto as EXHIBIT F (the "STB AFFILIATE AGREEMENT"), each 
of which will be in full force and effect as of the Effective Time.  3Dfx 
will be entitled to place appropriate legends on the shares of 3Dfx Common 
Stock to be received by a STB Affiliate pursuant to the terms of this 
Agreement, and to issue appropriate stop transfer instructions to the 
transfer agent for the 3Dfx Common Stock, consistent with the terms of the 
STB Affiliate Agreement.

     5.14   STB OPTIONS. 

            (a)     At the Effective Time, each outstanding option to 
purchase shares of STB Common Stock issued pursuant to (i) the STB Option 
Plan that vested prior to the Merger other than Accelerated Options as 
defined in Section 5.14(d) and (ii) the STB Director Plan that is not 
exercised as described in Section 5.14(e) below, shall be assumed by 3Dfx 
(collectively, the "Converting STB Options").  Accordingly, each Converting 
STB Option so assumed shall be deemed to constitute an option to acquire, on 
the same 


                                     34
<PAGE>

terms and conditions as were applicable immediately prior to the Effective 
Time under such Converting STB Option, the number, rounded down to the 
nearest whole integer, of full shares of 3Dfx Common Stock equal to the 
product of the number of shares of STB Common Stock that were issuable upon 
the full exercise of such Converting STB Option multiplied by the Exchange 
Ratio at a price per share equal to (y) the exercise price per share for the 
shares of STB Common Stock otherwise purchasable pursuant to such Converting 
STB Option divided by (z) the Exchange Ratio, with such exercise price per 
share rounded up to the nearest whole cent.

            (b)     As soon as practicable after the Effective Time, 3Dfx 
shall deliver to each holder of a Converting STB Option a document evidencing 
the foregoing assumption of such Converting STB Option by 3Dfx.

            (c)     As soon as practicable after the Effective Time, 3Dfx 
shall file a registration statement on Form S-8 (or any successor or other 
appropriate form), or another appropriate form with respect to the shares of 
3Dfx Common Stock subject to such Converting STB Options and shall use its 
reasonable efforts to maintain the effectiveness of such registration 
statement (and maintain the current status of the prospectus or prospectuses 
contained therein) for so long as such Converting STB Options remain 
outstanding.  

              (d) STB agrees to solicit all of its employees who hold options 
granted under the STB Option Plan that will accelerate and become fully 
vested and exercisable as a result of the Merger (the "Accelerated Options") 
to make an election not less than five (5) Business Days prior to the 
Effective Date to either (i) exercise any or all of the Accelerated Options 
held by such employee upon the acceleration of such Accelerated Options and 
purchase the related shares of STB Common Stock (which shares shall convert 
into shares of 3Dfx Common Stock pursuant to the Merger upon the Effective 
Date) or (ii) receive a cash payment from STB on the Effective Date equal to 
the amount, if any, by which the exercise price of each of the Accelerated 
Options held by such employee that were not exercised is exceeded by the 
average of the per share closing prices of the STB Common Stock reported on 
the Nasdaq National Market for the ten (10) trading days immediately 
preceding the Effective Date.  STB shall on the Effective Date pay to each 
employee who elects to receive a cash payment the amount of such cash payment 
as provided above.  Except as addressed above, all Accelerated Options shall 
terminate on the Effective Date, and in any event shall not be assumed by 
3Dfx. 

              (e)  STB shall take all actions necessary to ensure that all 
options granted under the STB Director Plan shall become fully vested and 
exercisable five (5) Business Days prior to the Effective Date.  STB also 
agrees to solicit all of its directors who hold options granted under the STB 
Director Plan to provide notice not less than five (5) Business Days prior to 
the Effective Date of his intent to exercise any or all of such options and 
purchase shares of STB Common Stock (which shares shall convert into shares 
of 3Dfx Common Stock pursuant to the Merger upon the Effective Date), with 
any such options not so exercised becoming Converting STB Options that will 
be treated in accordance with Section 5.14(a) above.

     5.15   STB EMPLOYEE STOCK PURCHASE PLAN.  STB agrees that it shall not 
effect any new offering periods effective as of March 31, 1999 immediately 
after the exercise of all Options whose Exercise Period ends on March 31, 
1999; Participants in the STB Purchase Plan with outstanding Options whose 
12-month "Exercise Period" (as such term is defined in the STB Purchase Plan) 
commences April 1, 1999 and ends March 31, 2000 (the "Outstanding Purchase 
Options") shall not have their rights under such Plan impaired or affected.  
Holders of Outstanding  Purchase Options shall have such options assumed by 
3Dfx at the Effective 


                                     35
<PAGE>

Time.  Accordingly, each Outstanding Purchase Option shall be deemed to 
constitute an option to acquire, on the same terms and conditions as were 
applicable under the STB Purchase Plan, a number of full shares of 3Dfx 
Common Stock determined as provided in the STB Purchase Plan at a price per 
share equal to (y) the option price per share for the shares of STB Common 
Stock otherwise purchasable pursuant to such Plan divided by (z) the Exchange 
Ratio rounded up to the nearest whole cent.  3Dfx agrees that from and after 
the Effective Time, STB employees may participate in the 3Dfx Employee Stock 
Purchase Plan, subject to the terms and conditions of such plan.  
Notwithstanding anything to the contrary contained herein, in the event that 
the termination date of the offering period occurs on any date other than 
March 31, all dates in this Section 5.15 shall be adjusted accordingly.

     5.16   INDEMNIFICATION AND INSURANCE.   

            (a)     From and after the Effective Time, 3Dfx will, and will 
also cause the Surviving Corporation to, fulfill and honor in all respects 
the obligations of STB pursuant to any indemnification agreements between STB 
and its present and former directors and officers in effect immediately prior 
to the Effective Time (the "INDEMNIFIED PARTIES") and any indemnification 
provisions under STB's Articles of Incorporation or Bylaws as in effect on 
the date hereof. The Articles of Incorporation and Bylaws of the Surviving 
Corporation will contain provisions with respect to exculpation and 
indemnification that are at least as favorable to the Indemnified Parties as 
those contained in the Articles of Incorporation and Bylaws of STB as in 
effect on the date hereof, which provisions will not be amended, repealed or 
otherwise modified for a period of six years from the Effective Time in any 
manner that would adversely affect the rights thereunder of individuals who, 
immediately prior to the Effective Time, were directors, officers, employees 
or agents of STB, unless such modification is required by law.

            (b)     For a period of six years after the Effective Time, 3Dfx 
will, or will cause the Surviving Corporation to, use all commercially 
reasonable efforts to maintain in effect, if available, directors' and 
officers' liability insurance covering those persons who are currently 
covered by STB's directors' and officers' liability insurance policy on terms 
substantially similar to those applicable to the current directors and 
officers of STB; PROVIDED, HOWEVER, that in no event will 3Dfx or the 
Surviving Corporation be required to expend in excess of 125% of the annual 
premium currently paid by STB for such coverage (or such coverage as is 
available for such 125% of such annual premium).

            (c)     The provisions of this Section 5.16 are intended to be in 
addition to the rights otherwise available to the Indemnified Parties by law, 
charter, statute, bylaw, resolution of the Board of Directors of STB or 
agreement, and shall operate for the benefit of, and shall be enforceable by, 
each of the Indemnified Parties, their heirs and their representatives.

     5.17   NOTIFICATION OF CERTAIN MATTERS.  STB shall give prompt notice to 
3Dfx, and 3Dfx and Sub shall give prompt notice to STB, of the occurrence, or 
failure to occur, of any event, which occurrence or failure to occur would be 
likely to cause (a) any representation or warranty contained in this 
Agreement to be untrue or inaccurate in any material respect at any time from 
the date of this Agreement to the Effective Time, or (b) any material failure 
of STB or 3Dfx and Sub, as the case may be, or of any officer, director, 
employee or agent thereof, to comply with or satisfy any covenant, condition 
or agreement to be complied with or satisfied by it under this Agreement.  
Notwithstanding the above, the delivery of any notice pursuant to this 
Section shall not limit or otherwise affect the remedies available hereunder 
to the party receiving such notice.


                                     36
<PAGE>

     5.18   TAX-FREE REORGANIZATION.  From and after the date of this 
Agreement, each of 3Dfx, Sub and STB shall use best efforts to cause the 
Merger to qualify, and shall not, without the prior written consent of the 
other party hereto, knowingly take any actions or cause any actions to be 
taken which could prevent the Merger from qualifying as a reorganization 
under the provisions of Section 368(a) of the Code.  In particular, 3Dfx and 
Sub represent and warrant that they have no plan to cause the Surviving 
Corporation to issue additional shares of its Stock, or dispose of stock, 
that would result in 3Dfx or Surviving Corporation losing control of the 
Surviving Corporation within the meaning of Section 368(c) of the Code.

     5.19   STB 401(k) PLAN.  At the request of 3Dfx, STB shall take all 
necessary corporate action terminate, or cause its subsidiaries to terminate, 
as the case may be, all 401(k) plans maintained by STB or any of its 
subsidiaries. 

     5.20   AMENDED EMPLOYMENT AGREEMENTS.  3Dfx agrees to assume, and be 
bound by, each of the employment agreements between STB and each of Messrs. 
Ogle, Eisenbach, Hopkins and Long, as amended in contemplation of the Merger. 


                                   ARTICLE 6
                                       
                             CONDITIONS PRECEDENT

     6.1    CONDITIONS TO EACH PARTY'S OBLIGATION TO EFFECT THE MERGER.  The 
respective obligation of each party to effect the Merger is subject to the 
satisfaction prior to the Closing Date of the following conditions:

            (a)     HSR ACT.  Any waiting period applicable to the 
consummation of the Merger under the HSR Act shall have expired or been 
terminated, and no action shall have been instituted by the Department of 
Justice or Federal Trade Commission challenging or seeking to enjoin the 
consummation of the Merger, which action shall not have been withdrawn or 
terminated.

            (b)     SHAREHOLDER APPROVAL.  The issuance of 3Dfx Common Stock 
in connection with the Merger shall have been approved by the requisite vote 
of the shareholders of 3Dfx (as described in Section 4.25) and this Agreement 
shall have been approved and adopted by the requisite vote of the 
shareholders of STB (as described in Section 3.25), in each case in 
accordance with applicable law and the rules and, with respect to 3Dfx, in 
accordance with the regulations of Nasdaq.

            (c)     EFFECTIVENESS OF THE S-4.  The S-4 shall have been 
declared effective by the SEC under the Securities Act and shall not be the 
subject of any stop order or proceeding by the SEC seeking a stop order.

            (d)     GOVERNMENTAL ENTITY APPROVALS.  All material 
authorizations, consents, orders or approvals of, or declarations or filings 
with, or expiration of waiting periods imposed by, any Governmental Entity 
necessary for the consummation of the transactions contemplated by this 
Agreement shall have been filed, expired or been obtained, other than those 
that, individually or in the aggregate, the failure to be filed, 


                                     37
<PAGE>

expired or obtained would not, in the reasonable opinion of 3Dfx, have a 
Material Adverse Effect on STB or 3Dfx.

            (e)     NO INJUNCTIONS OR RESTRAINTS; ILLEGALITY.  No temporary 
restraining order, preliminary or permanent injunction or other order issued 
by any court of competent jurisdiction or other legal restraint or 
prohibition (an "INJUNCTION") preventing the consummation of the Merger shall 
be in effect, nor shall any proceeding brought by an administrative agency or 
commission or other governmental authority or instrumentality, domestic or 
foreign, seeking any of the foregoing be pending; and there shall not be any 
action taken, or any statute, rule, regulation or order (whether temporary, 
preliminary or permanent) enacted, entered or enforced which makes the 
consummation of the Merger illegal or prevents or prohibits the Merger.

            (f)     TAX OPINIONS.  3Dfx and STB shall each have received 
written opinions from their respective counsel Wilson Sonsini Goodrich & 
Rosati, Professional Corporation and Locke Purnell Rain Harrell in form and 
substance reasonably satisfactory to them to the effect that the Merger will 
constitute a reorganization within the meaning of Section 368(a) of the Code 
with respect to the 3Dfx Common Stock to be received by holders of STB Common 
Stock in the Merger.  In rendering such opinions, counsel may rely upon (and 
3Dfx, Sub and STB shall be required to make) reasonably requested 
representations of 3Dfx, Sub and STB.

            (g)     LISTING OF SHARES.  3Dfx will have amended its listing 
application with the NASDAQ Stock Market to include the shares of Common 
Stock issued under this Agreement.

     6.2    CONDITIONS OF OBLIGATIONS OF 3DFX AND SUB.  The obligations of 
3Dfx and Sub to effect the Merger are subject to the satisfaction of the 
following additional conditions, unless waived in writing by 3Dfx:

            (a)     REPRESENTATIONS AND WARRANTIES.  The representations and 
warranties of STB set forth in this Agreement shall be true and correct 
(determined without regard to any materiality qualifiers in any particular 
representation or warranty, including without limitation "Material Adverse 
Effect") (i) as of the date hereof and (ii) as of the Closing Date, as though 
made on and as of the Closing Date (provided that in the cases of clauses (i) 
and (ii) any such representation and warranty made as of a specific date 
shall be true and correct as of such specific date), except for such 
inaccuracies as individually or in the aggregate which would not have a 
Material Adverse Effect (x) in the case of clause (i) on STB and subsidiaries 
taken as a whole and (y) in the case of clause (ii) on 3Dfx, STB and their 
respective subsidiaries taken as a whole (as if the Merger were consummated); 
and 3Dfx shall have received a certificate signed by the chief executive 
officer and the chief financial officer of STB to such effect.

            (b)     PERFORMANCE OF OBLIGATIONS OF STB.  STB shall have 
performed in all material respects all obligations and covenants required to 
be performed by it under this Agreement prior to or as of the Closing Date, 
and 3Dfx shall have received a certificate signed by the chief executive 
officer and the chief financial officer of STB to such effect.

            (c)     CONSENTS.  3Dfx and Sub shall have received duly executed 
copies of all third-party consents and approvals contemplated by this 
Agreement in form and substance reasonably satisfactory to 3Dfx and Sub, 
except those consents that the failure to so receive would not, individually 
or in the aggregate, have a Material Adverse Effect on STB; provided, 
however, that this Section 6.2(c) shall not apply to any 


                                      38
<PAGE>

consent required under or in connection with the Participation Agreement 
dated as of November 14, 1997 among Asset XVII Holdings, L.L.C., as lessor, 
STB Systems, Inc., as lessee, and Bank One, Texas, N.A., as lender, required 
by other agreements related thereto, or contemplated in connection with 
transactions thereunder.

            (d)     SHAREHOLDER CONSENT.  This Agreement and the Merger shall 
have been approved by the affirmative vote of the holders of at least 
two-thirds of the outstanding shares of the STB Common Stock.

     6.3    CONDITIONS OF OBLIGATION OF STB. The obligation of STB to effect 
the Merger is subject to the satisfaction of the following conditions, unless 
waived in writing by STB:

            (a)     REPRESENTATIONS AND WARRANTIES.  The representations and 
warranties of 3Dfx and Sub set forth in this Agreement shall be true and 
correct (determined without regard to any materiality qualifiers in any 
particular representation or warranty, including without limitation "Material 
Adverse Effect")  (i) as of the date hereof and (ii) as of the Closing Date, 
as though made on and as of the Closing Date (provided that in the cases of 
clauses (i) and (ii) any such representation and warranty made as of a 
specific date shall be true and correct as of such specific date), except for 
such inaccuracies as individually or in the aggregate which would not have a 
Material Adverse Effect (x) in the case of clause (i) on 3Dfx and its 
subsidiaries taken as a whole and (y) in the case of clause (ii) on 3Dfx, STB 
and their respective subsidiaries taken as a whole (as if the Merger were 
consummated); and STB shall have received a certificate signed by the chief 
executive officer and the chief financial officer of 3Dfx and the president 
of Sub to such effect.

            (b)     PERFORMANCE OF OBLIGATIONS OF 3DFX AND SUB.  Each of 3Dfx 
and Sub shall have performed in all material respects all obligations and 
covenants required to be performed by it under this Agreement prior to or as 
of the Closing Date, and STB shall have received a certificate signed by the 
chief executive officer and the chief financial officer of 3Dfx and the 
president of Sub to such effect.

            (c)     CONSENTS.  STB shall have received duly executed copies 
of all material third-party consents and approvals contemplated by this 
Agreement in form and substance satisfactory to STB, except those consents 
that the failure to so receive, would not, individually or in the aggregate, 
have a Material Adverse Effect on 3Dfx.

            (d)     ELECTION OF BOARD.  3Dfx shall have reconstituted its 
Board, effective as of the Effective Time, such that its membership consists 
of those persons listed in EXHIBIT G to this Agreement.

                                   ARTICLE 7
                                       
                                  TERMINATION

     7.1    TERMINATION.  This Agreement may be terminated at any time prior 
to the Effective Time of the Merger, whether before or after approval of the 
Merger by the shareholders of 3Dfx and STB:

            (a)     by mutual written consent duly authorized by the Boards 
of Directors of 3Dfx and STB;

            (b)     by either 3Dfx or STB if the Merger shall not have been 
consummated by May 31, 1999 (PROVIDED that if the Merger shall not have been 
consummated due to the waiting period (or any extension 


                                     39
<PAGE>

thereof) under the HSR Act not having expired or been terminated, or due to 
an action having been instituted by the Department of Justice or Federal 
Trade Commission challenging or seeking to enjoin the consummation of the 
Merger, then such date shall be extended to July 31, 1999, and PROVIDED 
FURTHER that the right to terminate this Agreement under this Section 7.1(b) 
shall not be available to any party whose action or failure to act has been 
the cause of or resulted in the failure of the Merger to occur on or before 
such date and such action or failure to act constitutes a breach of this 
Agreement);

            (c)     by either 3Dfx or STB if a court of competent 
jurisdiction or governmental, regulatory or administrative agency or 
commission shall (i) have issued an order, decree or ruling or taken any 
other action, in any case having the effect of permanently restraining, 
enjoining or otherwise prohibiting the Merger, which order, decree or ruling 
is final and nonappealable or (ii) seek to enjoin the Merger and the 
terminating party reasonably believes that the time period required to 
resolve such governmental action and the related uncertainty is reasonably 
likely to have a Material Adverse Effect on either 3Dfx or STB; or

            (d)     by either 3Dfx or STB if the required approvals of the 
shareholders of 3Dfx or STB contemplated by this Agreement shall not have 
been obtained by reason of the failure to obtain the required vote upon a 
vote taken at a meeting of shareholders duly convened therefor or at any 
adjournment thereof (PROVIDED that the right to terminate this Agreement 
under this Section 7.1(d) shall not be available to any party where the 
failure to obtain shareholder approval of such party shall have been caused 
by the action or failure to act of such party in breach of this Agreement); or

            (e)     by either 3Dfx or STB, if STB (A) shall have accepted or 
recommended to the shareholders of STB a Superior Proposal, and (B) in the 
case of the termination of this Agreement by STB, STB shall have paid to 3Dfx 
all amounts owing by STB to 3Dfx under Section 7.3(b); or

            (f)     by 3Dfx, if the Board of Directors of STB shall have 
withdrawn,  modified or refrained from making its recommendation concerning 
the Merger referred to in Section 5.4 or if a third party other than 3Dfx or 
any of its affiliates (including a person or a group as defined under Section 
13(d) of the Exchange Act and the rules and regulations thereunder) acquires 
beneficial ownership of, or the right to acquire beneficial ownership of, at 
least thirty-three percent (33%) of STB's outstanding voting equity 
securities; or

            (g)     by STB, upon a breach of any representation, warranty, 
covenant or agreement on the part of 3Dfx set forth in this Agreement, or if 
any representation or warranty of 3Dfx shall have become untrue, in either 
case such that the conditions set forth in Section 6.3(a) or Section 6.3(b) 
would not be satisfied as of the time of such breach or as of the time such 
representation or warranty shall have become untrue, PROVIDED that if such 
inaccuracy in 3Dfx's representations and warranties or breach by 3Dfx is 
curable by 3Dfx through the exercise of its reasonable efforts and for so 
long as 3Dfx continues to exercise such reasonable efforts, STB may not 
terminate this Agreement under this Section 7.1(g); or

            (h)     by 3Dfx, upon a breach of any representation, warranty, 
covenant or agreement on the part of STB set forth in this Agreement, or if 
any representation or warranty of STB shall have become untrue, in either 
case such that the conditions set forth in Section 6.2(a) or Section 6.2(b) 
would not be satisfied as of the time of such breach or as of the time such 
representation or warranty shall have become untrue, PROVIDED, that if such 
inaccuracy in STB's representations and warranties or breach by STB is 
curable 


                                      40
<PAGE>

by STB through the exercise of its reasonable efforts and for so long as STB 
continues to exercise such reasonable efforts, 3Dfx may not terminate this 
Agreement under this Section 7.1(h).

     7.2    EFFECT OF TERMINATION.  In the event of the termination of this 
Agreement as provided in Section 7.1, this Agreement shall be of no further 
force or effect, except (i) as set forth in this Section 7.2, Section 7.3 and 
Article 8, each of which shall survive the termination of this Agreement, and 
(ii) nothing herein shall relieve any party from liability for any breach of 
this Agreement.  No termination of this Agreement shall affect the 
obligations of the parties contained in the Confidentiality Agreement, all of 
which obligations shall survive the termination of this Agreement in 
accordance with its terms.

     7.3    FEES AND EXPENSES. 

            (a)     Except as set forth in this Section 7.3, all fees and 
expenses incurred in connection with this Agreement and the transactions 
contemplated hereby shall be paid by the party incurring such expenses, 
whether or not the Merger is consummated; PROVIDED, HOWEVER, that 3Dfx and 
STB shall share equally all fees and expenses, other than attorneys' fees, 
incurred in relation to the printing and filing of the Proxy Statement 
(including any preliminary materials related thereto) and the S-4 (including 
financial statements and exhibits) and any amendments or supplements thereto.

            (b)     Upon the occurrence of any of the following events, STB 
shall immediately make payment to 3Dfx (by wire transfer or cashiers check) 
of a breakup fee in the amount of $5.0 million (the "BREAKUP FEE"): (i) STB 
shall have accepted a Superior Proposal; (ii) the Board of Directors of STB 
shall have withdrawn, modified or refrained from making its recommendation 
concerning the Merger referred to in Section 5.4, or shall have disclosed 
publicly its intention to change such recommendation; or  (iii) a third party 
other than 3Dfx or its affiliates (including a person or a group as defined 
under Section 13(d) of the Exchange Act and the rules and regulations 
thereunder) acquires beneficial ownership of, or the right to acquire 
beneficial ownership of, at least thirty-three percent (33%) of STB's 
outstanding voting equity securities. Payment of the Breakup Fee shall be 
subject to offset as described in the STB Option Agreement. 

            (c)     Upon the occurrence of a termination pursuant to Sections 
7.1(d), (g) or (h), the terminating party shall be entitled to receive from 
the non-terminating party all fees and expenses incurred in connection with 
this Agreement and the transactions contemplated hereby; PROVIDED, HOWEVER, 
that this Section 7.3(c) shall not apply if, as a result of such termination 
by 3Dfx under Sections 7.1(d) or (h), STB shall become obligated to pay the 
Breakup Fee in accordance with Section 7.3(b).

            (d)     Payment of the fees described in Section 7.3(b) above 
shall not be in lieu of damages incurred in the event of breach of this 
Agreement. 

                                   ARTICLE 8
                                       
                              GENERAL PROVISIONS

     8.1    AMENDMENT.  This Agreement may be amended prior to the Effective 
Time by the parties, by action taken by their respective Boards of Directors, 
at any time before or after approval of the Merger by the shareholders of 
3Dfx and STB but, after any such approval, no amendment shall be made which 
by law 


                                      41
<PAGE>

requires further approval by such shareholders without such further approval. 
This Agreement may not be amended except by an instrument in writing signed 
on behalf of each of the parties.

     8.2    EXTENSION; WAIVER.  At any time prior to the Effective Time, the 
parties, by action taken by their respective Boards of Directors, may (i) 
extend the time for the performance of any of the obligations or other acts 
of the other parties, (ii) waive any inaccuracies in the representations and 
warranties contained in this Agreement or in any document delivered pursuant 
to this Agreement and (iii) waive compliance with any of the agreements or 
conditions contained in this Agreement.  Any agreement on the part of a party 
to any such extension or waiver shall be valid only if set forth in an 
instrument in writing signed on behalf of such party.

     8.3    NONSURVIVAL OF REPRESENTATIONS, WARRANTIES AND AGREEMENTS.  All 
representations, warranties and agreements in this Agreement or in any 
instrument delivered pursuant to this Agreement shall be deemed to be 
conditions to the Merger and shall not survive the Merger, except for the 
agreements contained in Sections 2.3 (further assurances) 5.14 (options), 
5.15 (employee stock purchase plan), 5.16 (indemnification), 5.18 (tax-free 
reorganization) and 7.3 (fees and expenses), each of which shall survive the 
Merger.

     8.4    ENTIRE AGREEMENT.  This Agreement, the STB Option Agreement, (and 
the other exhibits hereto), the Confidentiality Agreement and the other 
documents referenced herein contain the entire agreement between the parties 
with respect to the subject matter hereof and supersede all prior 
arrangements and understandings, both written and oral, with respect thereto.

     8.5    SEVERABILITY.  It is the desire and intent of the parties that 
the provisions of this 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 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 
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 to 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 
Agreement or affecting the validity or enforceability of such provision in 
any other jurisdiction.

     8.6    NOTICES .  All notices and other communications pursuant to this 
Agreement 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, faxed, sent by nationally-recognized, overnight courier or mailed 
by registered or certified mail (return receipt requested), postage prepaid, 
to the parties at the following addresses (or at such other address for a 
party as shall be specified by like notice):


                                      42
<PAGE>

            (a)   if to 3Dfx or Sub, to:

                         3Dfx Interactive, Inc.
                         4435 Fortran Drive
                         San Jose, California 95134
                         Attention:  Chief Financial Officer
                         Facsimile:  (408) 262-5551 

                  with a copy to:

                         Wilson Sonsini Goodrich & Rosati
                         650 Page Mill Road
                         Palo Alto, CA  94304-1050
                         Attention:  Robert P. Latta, Esq./Chris F. Fennell,
                         Esq.
                         Facsimile:  (650) 845-5000

          (b)     if to STB, to:

                         STB Systems, Inc.
                         3400 Waterview Parkway
                         Richardson, Texas 75080
                         Attention:  Chief Financial Officer
                         Facsimile:  (972) 680-7153
                         cc:  Legal Department

                  with a copy to:

                         Locke Purnell Rain Harrell
                         2200 Ross Avenue, Suite 2200
                         Dallas, Texas 75201
                         Attention:  John B. McKnight, Esq. 
                         Facsimile:  (214) 740-8800

All such notices and other communications shall be deemed to have been 
received (a) in the case of personal delivery, on the date of such delivery, 
(b) in the case of a fax, when the party receiving such fax shall have 
confirmed receipt of the communication, (c) in the case of delivery by 
nationally-recognized, overnight courier, on the Business Day following 
dispatch and (d) in the case of mailing, on the third Business Day following 
such mailing.

     8.7    HEADINGS.  The headings contained in this Agreement are for 
reference purposes only and shall not affect in any way the meaning or 
interpretation of this Agreement.

     8.8    COUNTERPARTS.  This Agreement may be executed in one or more 
counterparts, all of which shall be considered one and the same agreement and 
shall become effective when one or more counterparts have been signed by each 
of the parties and delivered to the other parties, it being understood that 
all parties need not sign the same counterpart.


                                      43
<PAGE>

     8.9    BENEFITS; ASSIGNMENT.  This Agreement is not intended to confer 
upon any person other than the parties any rights or remedies hereunder and 
shall not be assigned by operation of law or otherwise; PROVIDED, HOWEVER, 
that (i) the holders of STB Options and the participants under the STB 
Purchase Plan are intended beneficiaries of the covenants and agreements 
contained in Sections 5.14 and 5.15; (ii) the officers and directors of STB 
are intended beneficiaries of the covenants and agreements contained in 
Section 5.16; (iii) certain officers of STB are intended beneficiaries of the 
Agreements described in Section 5.20; and (iv) Sub may assign all or any 
portion of its rights hereunder to any other newly-formed, wholly-owned 
subsidiary of 3Dfx, and STB shall execute any amendment to this Agreement 
necessary to provide the benefits of this Agreement to any such assignee.

     8.10   GOVERNING LAW.  This Agreement shall be governed by and construed 
in accordance with the laws of the State of California where applicable to 
contracts made and to be performed therein except to the extent that the laws 
of the State of Texas shall govern the Merger.


                                      44
<PAGE>

     IN WITNESS WHEREOF, the parties have caused this Agreement to be signed 
by their respective officers thereunto duly authorized, as of the date first 
written above.

                                        3DFX INTERACTIVE, INC.


                                        By: 
                                            -----------------------------------

                                        Name:
                                              ---------------------------------

                                        Title:
                                               --------------------------------



                                        VOODOO MERGER SUB, INC. 


                                        By: 
                                            -----------------------------------

                                        Name:
                                              ---------------------------------

                                        Title:
                                               --------------------------------


                                        STB SYSTEMS, INC.


                                        By: 
                                            -----------------------------------

                                        Name:
                                              ---------------------------------

                                        Title:
                                               --------------------------------


           [SIGNATURE PAGE TO AGREEMENT AND PLAN OF REORGANIZATION]


                                      45
<PAGE>

                                  EXHIBIT A
                                       
                         FORM OF STB OPTION AGREEMENT



























                                      46
<PAGE>
                                       
                                  EXHIBIT B
                                       
                         FORM OF STB VOTING AGREEMENT



























                                      47
<PAGE>
                                       
                                  EXHIBIT C
                                       
                         FORM OF 3Dfx VOTING AGREEMENT



























                                      48
<PAGE>
                                       
                                  EXHIBIT D
                                       
                          FORM OF ARTICLES OF MERGER


                                      
























                                      49
<PAGE>

                                  EXHIBIT E
                                       
                              AFFILIATES OF STB

William E. Ogle

Randall D. Eisenbach

James L. Hopkins

J. Shane Long

Bryan F. Keyes

James J. Byrne

Dennis Sabo

Lawrence Wesneski

Twin Lakes Partners, L.P.









                                      50
<PAGE>

                                    
                                   EXHIBIT F
                                       
                        FORM OF STB AFFILIATE AGREEMENT



























                                      51
<PAGE>
                                       
                                   EXHIBIT G
                                        
                            3DFX BOARD OF DIRECTORS


L. Gregory Ballard

Gordon A. Campbell

James L. Hopkins

Alex Leupp

William E. Ogle 

Scott D. Sellers

Tony Sun

Philip Young

James Whims








                                      52

<PAGE>

                                  STB SYSTEMS, INC.
                                   VOTING AGREEMENT


     This Voting Agreement ("AGREEMENT") is made and entered into as of
December 13, 1998 between 3Dfx Interactive, Inc., a California corporation
("3Dfx"), and the undersigned shareholder ("SHAREHOLDER") of STB Systems, Inc. a
Texas corporation (the "STB").

                                       RECITALS

     A.   Concurrently with the execution of this Agreement, 3Dfx, STB and
Voodoo Merger Sub, a Texas corporation and a wholly owned subsidiary of 3Dfx
("MERGER SUB"), have entered into an Agreement and Plan of Reorganization of
even date herewith (the "MERGER AGREEMENT") which provides for the merger (the
"MERGER") of Merger Sub with and into STB.  Pursuant to the Merger, shares of
Common Stock of STB will be converted into the right to receive shares of Common
Stock of 3Dfx in the manner set forth in the Merger Agreement.

     B.   The Shareholder is the record holder and beneficial owner (as defined
in Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the
"EXCHANGE ACT")) of such number of shares of the outstanding Common Stock of STB
as is indicated on the final page of this Agreement (the "SHARES").

     C.   As a material inducement to enter into the Merger Agreement, 3Dfx
desires the Shareholder to agree, and the Shareholder is willing to agree, not
to transfer or otherwise dispose of any of the Shares, or any other shares of
capital stock of STB acquired hereafter and prior to the Expiration Date (as
defined in Section 1.1 below), except as otherwise permitted hereby, and to vote
the Shares and any other such shares of capital stock of STB so as to facilitate
consummation of the Merger.

     NOW, THEREFORE, in consideration of the covenants, promises and
representations set forth herein, the parties agree as follows:

     1.   AGREEMENT TO RETAIN SHARES.

          1.1  TRANSFER AND ENCUMBRANCE.  Shareholder agrees not to transfer
(except as may be specifically required by court order), sell, exchange, pledge
or otherwise dispose of or encumber any of the Shares or any New Shares as
defined in Section 1.2 below, or to make any offer or agreement relating
thereto, at any time prior to the Expiration Date.  As used herein, the term
"EXPIRATION DATE" shall mean the earlier to occur of (i) such date and time as
the Merger shall become effective in accordance with the terms and provisions of
the Merger Agreement and (ii) such date and time as the Merger Agreement shall
be terminated in accordance with its terms.


                                         -1-
<PAGE>

          1.2  ADDITIONAL PURCHASES.  Shareholder agrees that any shares of
capital stock of STB that Shareholder purchases or with respect to which
Shareholder otherwise acquires beneficial ownership (as such term is defined in
Rule 13d-3 under the Exchange Act) after the execution of this Agreement and
prior to the Expiration Date ("NEW SHARES") shall be subject to the terms and
conditions of this Agreement to the same extent as if they constituted Shares.

     2.   AGREEMENT TO VOTE SHARES.  At every meeting of the shareholders of STB
called with respect to any of the following, and at every adjournment thereof,
and on every action or approval by written consent of the shareholders of STB
with respect to any of the following, Shareholder shall vote the Shares and any
New Shares:  (i) in favor of approval of the Merger Agreement and the Merger and
any matter that could reasonably be expected to facilitate the Merger; and
(ii) against approval of any proposal made in opposition to or competition with
consummation of the Merger and against any merger, consolidation, sale of
assets, reorganization or recapitalization, with any party other than with 3Dfx
and its affiliates and against any liquidation or winding up of STB (each of the
foregoing is hereinafter referred to as an "OPPOSING PROPOSAL").  Shareholder
agrees not to take any actions contrary to Shareholder's obligations under this
Agreement.

     3.   IRREVOCABLE PROXY.  Concurrently with the execution of this Agreement,
Shareholder agrees to deliver to 3Dfx a proxy in the form attached hereto as
ANNEX A (the "PROXY"), which shall be irrevocable, with respect to the total
number of shares of capital stock of STB beneficially owned (as such term is
defined in Rule 13d-3 under the Exchange Act) by Shareholder set forth therein.

     4.   REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE SHAREHOLDER.
Shareholder hereby represents, warrants and covenants to 3Dfx as follows:

          4.1  OWNERSHIP OF SHARES.  Shareholder (i) is the beneficial owner of
the Shares, which at the date hereof and at all times up until the Expiration
Date will be free and clear of any liens, claims, options, charges or other
encumbrances; (ii) does not beneficially own any shares of capital stock of STB
other than the Shares (excluding shares as to which Shareholder currently
disclaims beneficial ownership in accordance with applicable law); and (iii) has
full power and authority to make, enter into and carry out the terms of this
Agreement and the Proxy.

          4.2  NO PROXY SOLICITATIONS.  Shareholder will not, and will not
permit any entity under Shareholder's control to:  (i) solicit proxies or become
a "participant" in a "solicitation" (as such terms are defined in Regulation 14A
under the Exchange Act) with respect to an Opposing Proposal or otherwise
encourage or assist any party in taking or planning any action that would
compete with, restrain or otherwise serve to interfere with or inhibit the
timely consummation of the Merger in accordance with the terms of the Merger
Agreement; (ii) initiate a shareholders' vote or action by consent of STB
shareholders with respect to an Opposing Proposal; or (iii) become a member of a
"group" (as such term is used in Section 13(d) of the Exchange Act) with respect
to any voting securities of STB with respect to an Opposing Proposal.


                                         -2-
<PAGE>

     5.   ADDITIONAL DOCUMENTS.  Shareholder hereby covenants and agrees to
execute and deliver any additional documents necessary or desirable, in the
reasonable opinion of 3Dfx and Shareholder, as the case may be, to carry out the
intent of this Agreement.

     6.   CONSENT AND WAIVER.  Shareholder hereby gives any consents or waivers
that are reasonably required for the consummation of the Merger under the terms
of any agreements to which Shareholder is a party or pursuant to any rights
Shareholder may have.

     7.   TERMINATION.  This Agreement and the Proxy delivered in connection
herewith shall terminate and shall have no further force or effect as of the
Expiration Date.

     8.   MISCELLANEOUS.

          8.1  SEVERABILITY.  If any term, provision, covenant or restriction of
this Agreement is held by a court of competent jurisdiction to be invalid, void
or unenforceable, then the remainder of the terms, provisions, covenants and
restrictions of this Agreement shall remain in full force and effect and shall
in no way be affected, impaired or invalidated.

          8.2  BINDING EFFECT AND ASSIGNMENT.  This Agreement and all of the
provisions hereof shall be binding upon and inure to the benefit of the parties
hereto and their respective successors and permitted assigns, but, except as
otherwise specifically provided herein, neither this Agreement nor any of the
rights, interests or obligations of the parties hereto may be assigned by either
of the parties without prior written consent of the other.

          8.3  AMENDMENTS AND MODIFICATION.  This Agreement may not be modified,
amended, altered or supplemented except upon the execution and delivery of a
written agreement executed by the parties hereto.

          8.4  SPECIFIC PERFORMANCE; INJUNCTIVE RELIEF.  The parties hereto
acknowledge that 3Dfx will be irreparably harmed and that there will be no
adequate remedy at law for a violation of any of the covenants or agreement of
Shareholder set forth herein.  Therefore, it is agreed that, in addition to any
other remedies that may be available to 3Dfx upon any such violation, 3Dfx shall
have the right to enforce such covenants and agreements by specific performance,
injunctive relief or by any other means available to 3Dfx at law or in equity.

          8.5  NOTICES.  All notices, requests, claims, demands and other
communications hereunder shall be in writing and sufficient if delivered in
person, by cable, telegram or telex, or sent by mail (registered or certified
mail, postage prepaid, return receipt requested) or overnight courier (prepaid)
to the respective parties as follows:

          If to 3Dfx:              3Dfx Interactive, Inc.


                                         -3-
<PAGE>

                                   4435 Fortran Drive
                                   San Jose, California 95134
                                   Attention: Chief Financial Officer
                                   Facsimile: (408) 262-5551


          With a copy to:          Wilson Sonsini Goodrich & Rosati
                                   650 Page Mill Road
                                   Palo Alto, California 94304-1050
                                   Attention: Robert P. Latta, Esq./Chris F.
                                   Fennell, Esq.

          If to the Shareholder:   At the address provided on the signature
                                   page hereto

          With a copy to:          Locke Purnell Rain Harrell
                                   2200 Ross Avenue, Suite 2200
                                   Dallas, Texas 75201
                                   Attention: John B. McKnight, Esq.
                                   Facsimile: (214) 740-8800

or to such other address as any party may have furnished to the other in writing
in accordance herewith, except that notices of change of address shall only be
effective upon receipt.

          8.6  GOVERNING LAW.  This Agreement shall be governed by and construed
and enforced in accordance with the laws of the State of California without
giving effect to the conflicts of laws principles thereof.

          8.7  ENTIRE AGREEMENT.  This Agreement contains the entire
understanding of the parties in respect of the subject matter hereof, and
supersedes all prior negotiations and understandings between the parties with
respect to such subject matter.

          8.8  COUNTERPARTS.  This Agreement may be executed in several
counterparts, each of which shall be an original, but all of which together
shall constitute one and the same agreement.

          8.9  EFFECT OF HEADINGS.  The section headings herein are for
convenience only and shall not affect the construction of interpretation of this
Agreement.


                  [Remainder of This Page Intentionally Left Blank]


                                         -4-
<PAGE>

     IN WITNESS WHEREOF, the parties have caused this Voting Agreement to be
duly executed on the date and year first above written.

                                   3DFX INTERACTIVE, INC.



                                   By:
                                      ------------------------------------------
                                   Name:
                                        ----------------------------------------
                                   Title:
                                         ---------------------------------------


                                   SHAREHOLDER


                                   ---------------------------------------------
                                   Name:

                                   Shareholder's Address for Notice:

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

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

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

                                   Number of Shares Beneficially Owned:

                                                     shares of Common Stock
                                   -----------------




                          [Voting Agreement Signature Page]


<PAGE>

                                       ANNEX A

                                  IRREVOCABLE PROXY

     The undersigned Shareholder of STB Systems, Inc., a Texas corporation
("STB"), hereby irrevocably appoints the directors on the Board of Directors of
3Dfx Interactive, Inc., a California corporation ("3Dfx"), and each of them, as
the sole and exclusive attorneys and proxies of the undersigned, with full power
of substitution and resubstitution, to the full extent of the undersigned's
rights with respect to the shares of capital stock of STB beneficially owned by
the undersigned, which shares are listed on the final page of this Irrevocable
Proxy (the "SHARES"), and any and all other shares or securities issued or
issuable in respect thereof on or after the date hereof, until the earlier to
occur of (i) such time as that certain Agreement and Plan of Reorganization
dated as of December 13, 1998 (the "MERGER AGREEMENT"), among 3Dfx, Voodoo
Merger Sub, Inc., a Texas corporation and a wholly-owned subsidiary of 3Dfx
("MERGER SUB"), and STB, shall be terminated in accordance with its terms or
(ii) the Merger (as defined in the Merger Agreement) is effective.  Upon the
execution hereof, all prior proxies given by the undersigned with respect to the
Shares and any and all other shares or securities issued or issuable in respect
thereof on or after the date hereof are hereby revoked and no subsequent proxies
will be given.

     This proxy is irrevocable, is granted pursuant to the Voting Agreement
dated as of December 13, 1998 between 3Dfx and the undersigned Shareholder (the
"VOTING AGREEMENT"), and is granted in consideration of 3Dfx entering into the
Merger Agreement.  3Dfx and the undersigned Shareholder agree and acknowledge
that the grant of this irrevocable proxy is a material inducement for 3Dfx to
enter into the Merger Agreement and is therefore coupled with an interest and
irrevocable.  The attorneys and proxies named above will be empowered at any
time prior to termination of the Merger Agreement to exercise all voting and
other rights (including, without limitation, the power to execute and deliver
written consents with respect to the Shares) of the undersigned at every annual,
special or adjourned meeting of STB shareholders, and in every written consent
in lieu of such a meeting, or otherwise, in favor of approval of the Merger and
the Merger Agreement and any matter that could reasonably be expected to
facilitate the Merger, and against any proposal made in opposition to or
competition with the consummation of the Merger and against any merger,
consolidation, sale of assets, reorganization or recapitalization of STB with
any party other than 3Dfx and its affiliates and against any liquidation or
winding up of STB.

     The attorneys and proxies named above may only exercise this proxy to vote
the Shares subject hereto at any time prior to termination of the Merger
Agreement at every annual, special or adjourned meeting of the shareholders of
STB and in every written consent in lieu of such meeting, in favor of approval
of the Merger and the Merger Agreement and any matter that could reasonably be
expected to facilitate the Merger, and against any merger, consolidation, sale
of assets, reorganization or recapitalization of STB with any party other than
3Dfx and its affiliates, and against any liquidation or winding up of STB, and
may not exercise this proxy on any other matter.  The undersigned Shareholder
may vote the Shares on all other matters.


<PAGE>

     Any obligation of the undersigned hereunder shall be binding upon the
successors and assigns of the undersigned.

     This proxy is irrevocable.


Dated: December __, 1998


     Signature of Shareholder:
                              ------------------------------
     Print Name of Shareholder:
                               -----------------------------
     Shares beneficially owned:

                             shares of Common Stock
     -----------------------


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