Document:

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                                                                     EXHIBIT 4.3

                         TEXAS CAPITAL BANCSHARES, INC.

                           CERTIFICATE OF DESIGNATION
                                       OF
                    6.0% SERIES A CONVERTIBLE PREFERRED STOCK

         The undersigned certifies, on behalf of the Corporation, that on
December 18, 2001, pursuant to the authority contained in its Certificate of
Incorporation (the "Certificate of Incorporation"), the Board of Directors of
the Corporation hereby approves, consents to and adopts the following
resolution, and the actions therein authorized as the act of the Board of
Directors by written consent:

         RESOLVED, that pursuant to the authority expressly granted to the
Corporation's Board of Directors by the Certificate of Incorporation of the
Corporation, the directors hereby establish a series of the Corporation's
preferred stock, $0.01 par value per share, and hereby fix the designation, the
number of shares and the relative rights, preferences and limitations thereof as
follows:

         1.       Designation. The designation of the series of preferred stock
created by this resolution shall be 6.0% Series A Convertible Preferred Stock,
$0.01 par value per share (hereinafter referred to as the "Series A Preferred
Stock"), and the initial number of shares constituting such series shall be up
to a maximum of 1,100,000. Such number may be increased or decreased (but not
below the number of shares then outstanding) from time to time by the Board of
Directors. The Series A Preferred Stock shall rank senior to the common stock of
the Corporation, $0.01 par value (the "Common Stock"), with respect to the
payment of dividends and the distribution of assets.

         2.       Dividend Rights.

                  (a) The holders of shares of Series A Preferred Stock shall be
         entitled to receive, when, as and if declared by the Board of
         Directors, out of funds legally available therefor, compounding
         cumulative cash dividends, accruing from the date of issuance, at an
         annual rate of 6.0% per share (expressed as a percentage of the $17.50
         per share liquidation preference set forth in Section 3 hereof plus, as
         described below, the amount of arrearages in the payment of dividends),
         and no more, payable in arrears in quarterly installments mailed: (i)
         no later than forty-five (45) days after the end of the first fiscal
         quarter of each fiscal year of the Corporation; and (ii) no later than
         fifteen (15) days after the end of the second, third and fourth fiscal
         quarters of each fiscal year of the Corporation; provided, however,
         that the first date upon which holders of shares of Series A Preferred
         Stock shall be entitled to receive dividends shall be a date no later
         than forty-five (45) days after March 31, 2002. Dividends on the Series
         A Preferred Stock shall be compounding cumulative so that if, for any
         dividend accrual period, cash dividends at the rate specified herein
         are not declared and paid or set aside for payment, the amount of
         accrued but unpaid dividends shall accumulate and shall be added to the
         dividends payable for subsequent dividend accrual periods, and the
         amount of such arrearages shall, for purposes of calculating the amount
         of dividends accruing after such arrearage occurs, be added to the
         amount upon which dividends accrue. The rate at which dividends are
         paid shall be adjusted for any combinations or divisions or similar
         recapitalizations affecting the shares of Series A Preferred Stock. So
         long as any shares of Series A Preferred Stock are outstanding, (i) the
         amount of all dividends paid with respect to the shares of Series A
         Preferred Stock pursuant to this subparagraph shall be paid pro rata to
         the holders entitled thereto; and (ii) holders of shares of Series A
         Preferred Stock shall be entitled to receive the dividends provided for
         in this subparagraph in preference to and in priority over any
         dividends upon any Common Stock.

                  (b) Dividends on shares of Series A Preferred Stock shall be
         cumulative from the date of issuance whether or not there shall be
         funds available for the payment thereof under Delaware law or under the
         provisions hereof. Accumulations of dividends on the Series A Preferred
         Stock shall not bear interest. The Corporation shall not (i) declare,
         pay or set apart for payment any dividends or distributions on any
         stock ranking as to dividends junior to the Series A Preferred Stock
         (other than dividends paid in shares of such junior stock) or (ii) make
         any purchase or redemption of, or any sinking fund payment for the
         purchase or redemption of, any stock ranking as to dividends junior to
         the Series A Preferred Stock (other than a purchase or redemption made
         by issue or delivery of such junior stock) unless all dividends payable

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         on all outstanding shares of Series A Preferred Stock for all past
         dividend periods shall have been paid in full or declared and a
         sufficient sum set apart for payment thereof.

         3.       Liquidation Preference.

                  (a) In the event of any liquidation, dissolution or winding up
         of the affairs of the Corporation, whether voluntary or involuntary,
         the holders of Series A Preferred Stock at that time shall be entitled
         to receive out of the assets of the Corporation available for
         distribution to shareholders an amount equal to $17.50 per share plus
         an amount equal to accrued and unpaid dividends thereon through and
         including the date of such distribution, and no more, before any
         distribution shall be made to the holders of any class of stock of the
         Corporation ranking junior to the Series A Preferred Stock as to the
         distribution of assets.

                  (b) If the assets of the Corporation available for
         distribution to shareholders upon any liquidation, dissolution or
         winding up of the affairs of the Corporation, whether voluntary or
         involuntary, are insufficient to pay in full the amounts payable with
         respect to the Series A Preferred Stock, the holders of Series A
         Preferred Stock at that time shall share ratably in any distribution of
         assets of the Corporation in proportion to the full respective
         preferential amounts to which they are entitled.

                  (c) The merger or consolidation of the Corporation into or
         with any other corporation, the merger or consolidation of any other
         corporation into or with the Corporation or the sale of the assets of
         the Corporation substantially as an entirety shall not be deemed a
         liquidation, dissolution or winding up of the affairs of the
         Corporation within the meaning of this paragraph.

         4.       Conversion Rights. The shares of Series A Preferred Stock
shall be convertible into shares of Common Stock on the following terms and
conditions:

                  (a) The Series A Preferred Stock will automatically convert
         into one (1) share of authorized but unissued Common Stock (the
         "Conversion Rate") upon the occurrence of any of the following: (i) any
         transaction, whether by merger, consolidation, asset sale, tender
         offer, reverse stock split, or otherwise, which results in the
         acquisition of beneficial ownership (as such term is defined under the
         rules and regulations promulgated under the Securities Exchange Act of
         1934, as amended) by any person or entity, or any group of persons or
         entities acting in concert, of 50% or more of the outstanding shares of
         Common Stock of the Corporation; (ii) the sale of all or substantially
         all of the assets of the Corporation; (iii) the Common Stock is
         authorized for trading on the New York Stock Exchange or the National
         Market tier of the Nasdaq Stock Market, Inc. and the market value per
         share of the Common Stock is $17.50 per share or greater as of the
         market close for thirty consecutive trading days; (iv) the Corporation
         consummates an underwritten public offering of any shares of Common
         Stock at a price of $17.50 per share or higher; or (v) the capital
         adequacy guidelines published by the Board of Governors of the United
         States Federal Reserve System are changed in any manner which results
         in the Series A Preferred Stock no longer qualifying as Tier I Capital
         under such guidelines.

                  (b) Each share of Series A Preferred Stock may be converted
         into shares of authorized but unissued Common Stock at the Conversion
         Rate at any time, at the option of the holder.

                  (c) Promptly upon the occurrence of any of the events set
         forth in Sections 4(a) or 4(b) above and the surrender of the
         certificate or certificates representing the share or shares of Series
         A Preferred Stock to be converted, the Corporation shall cause to be
         issued and delivered to said holder, registered in such name or names
         as such holder may direct, a certificate or certificates for the number
         of shares of Common Stock issuable upon the conversion of such share or
         shares. To the extent permitted by law, such conversion shall be deemed
         to have been effected as of the close of business on the date of
         conversion, at which time the rights of the holder of such share or
         shares as such holder shall cease, and the person or persons in whose
         name or names any certificate or certificates for shares of Common
         Stock shall be issuable upon such conversion shall be deemed to have
         become the holder or holders of record of the shares of Common Stock
         represented thereby.

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                  (d) No fractional shares of Common Stock shall be issued upon
         conversion of any shares of Series A Preferred Stock. The Corporation
         shall pay cash for any fractional shares which the Corporation
         otherwise would have been required to issue upon any conversion of such
         shares. The amount of such cash shall be determined in accordance with
         the market value of the Common Stock on the date of such conversion.

                  (e)      The market value of the Common Stock shall be
         determined as follows:

                           (i) If the Common Stock is listed on a national
                  securities exchange or admitted to unlisted trading privileges
                  on such exchange, or traded or listed for trading on the
                  Nasdaq Stock Market, Inc. or other nationally recognized
                  market, the market value shall be the last reported sale price
                  of the Common Stock on such exchange, system or market on any
                  applicable date (which, in the case of determining the market
                  value of fractional shares issuable upon conversion, shall be
                  the last business day prior to the date of conversion). If no
                  such sale is made on such day, the market value shall be the
                  average closing bid and asked prices for such day on such
                  exchange, system or market.

                           (ii) If the Common Stock is not so listed, traded or
                  admitted to unlisted trading privileges, the market value
                  shall be the average closing bid and asked prices reported by
                  the OTC Bulletin Board System of the Nasdaq Stock Market, Inc.
                  or the National Quotation Bureau, Inc. on any applicable date
                  (which, in the case of determining the market value of
                  fractional shares issuable upon conversion, shall be the last
                  business day prior to the date of conversion). If bid and
                  asked prices are not so reported, the market value shall be an
                  amount determined by the Corporation's independent certified
                  public accountants or other nationally recognized independent
                  certified public accountants or professional appraisal firm
                  specified by the Corporation.

                  (f)      The Conversion Rate in effect at any time shall be
         subject to adjustment as follows:

                           (i) The Conversion Rate shall be adjusted if the
                  Corporation (A) declares or makes a distribution or dividend
                  on its Common Stock in shares of its capital stock, (B)
                  subdivides its outstanding shares of Common Stock into a
                  greater number of shares, (C) combines its outstanding shares
                  of Common Stock into a smaller number of shares or (D) issues
                  by reclassification of its shares of Common Stock (including
                  any reclassification in connection with a consolidation or
                  merger in which the Corporation is the continuing corporation)
                  any shares of Common Stock. The Conversion Rate in effect at
                  the time of the record date for such dividend or distribution,
                  or the effective date of any subdivision, combination or
                  reclassification, shall be adjusted so that the holder of any
                  shares of Series A Preferred Stock after such time shall be
                  entitled to receive the number and kind of shares which it
                  would have owned or have been entitled to receive if such
                  shares had been converted immediately prior to such time.
                  Similar adjustments shall be made successively whenever any
                  event listed above shall occur.

                           (ii) In the event of any consolidation of the
                  Corporation with, or merger of the Corporation into, any other
                  corporation (other than a consolidation or merger in which the
                  Corporation is the continuing corporation), the holders of the
                  Series A Preferred Stock shall have the right thereafter to
                  convert such shares into the kind and amount of shares of
                  stock or other securities of property, including cash, or any
                  combination thereof, receivable upon such consolidation or
                  merger by a holder of the number of shares of Common Stock of
                  the Corporation into which such shares might have been
                  converted immediately prior to such consolidation or merger.
                  The provisions of this subparagraph shall similarly apply to
                  successive consolidations and mergers.

                  (g) The Corporation shall at all times reserve and keep
         available out of its authorized Common Stock, free from preemptive
         rights, such shares of Common Stock as shall be issuable upon
         conversion of the Series A Preferred Stock. All shares of Common Stock
         which shall be so issuable shall, when issued, be duly and validly
         issued shares of the Corporation's authorized Common Stock and shall be
         fully paid and nonassessable, free of all liens and charges and not
         subject to preemptive rights.

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         5.       Voting Rights.

                  (a) With respect to all matters submitted for a vote of the
         holders of Common Stock, shares of Series A Preferred Stock shall be
         entitled to vote with the outstanding shares of Common Stock as a
         single class. When voting as a class with the Common Stock, each share
         of Series A Preferred Stock shall be entitled to cast a number of votes
         equal to the number of shares of Common Stock into which a share of
         Series A Preferred Stock is then convertible under Section 4.

                  (b) The Corporation shall not, without the consent of the
         holders of at least a majority of the shares of the outstanding Series
         A Preferred Stock, adopt any amendment to the Certificate of
         Incorporation which would alter or change the powers, preferences or
         special rights of the Series A Preferred Stock so as to affect them
         adversely, provided, that no such consent shall be required with
         respect to: (i) any amendment that increases or decreases the number of
         shares of Series A Preferred Stock which the Corporation is authorized
         to issue so long as no such amendment shall reduce the number of
         authorized shares to below the number of shares of Series A Preferred
         Stock then outstanding, or (ii) the establishment or issuance of any
         other series of preferred stock or any other class of stock of the
         Corporation that has any powers, preferences, rights, qualifications,
         limitations and restrictions that are in any way different from,
         greater than, superior to or in preference to those of the Series A
         Preferred Stock.

                  (c) Except as provided in this Section 5 or otherwise required
         by law, the holders of Series A Preferred Stock shall have no right or
         power to vote with respect to any matter.

         6.       Reacquired Shares. Shares of Series A Preferred Stock
converted, redeemed, or otherwise purchased or acquired by the Corporation shall
be restored to the status of authorized but unissued shares of the Corporation's
preferred stock without designation as to series.

         7.       No Sinking Fund. Shares of Series A Preferred Stock are not
subject to the operation of a sinking fund.

         8.       Tier 1 Capital. The Series A Preferred Stock shall at all
times constitute Tier 1 Capital of the Corporation within the meaning of all
regulations now in effect applicable to bank holding companies promulgated by
the Board of Governors of the Federal Reserve System and any other applicable
regulatory agency or authority. Accordingly, if any provision hereof would
result in the failure of the Series A Preferred Stock to constitute Tier 1
Capital within the meaning of any such regulations, such provision shall be void
and of no further force or effect.

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         IN WITNESS WHEREOF, the undersigned has executed this Certificate of
Designation as of December 19, 2001.

                                       /s/ LARRY A. MAKEL
                                       -----------------------------------
                                       Larry A. Makel, Secretary

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                                                                   EXHIBIT 10(l)

                             INTERPHASE CORPORATION

                     AMENDED AND RESTATED STOCK OPTION PLAN

         WHEREAS, on August 24, 1984, the Board of Directors (the "Board") of
Interphase Corporation adopted the Interphase Corporation Incentive Stock Option
Plan (the "Plan"); and

         WHEREAS, the Board subsequently amended the Plan from time to time to
increase the number of shares of common stock of the Company available under the
Plan from 200,000 shares to 1,350,000 shares and to make certain changes to the
Plan; and

         WHEREAS, the Board now desires to amend and restate the Plan, and in
connection therewith, add provisions to the Plan to allow the grant of
non-qualified stock options and to rename the Plan the Interphase Corporation
Amended and Restated Stock Option Plan;

         NOW, THEREFORE, in consideration of the foregoing, the Board hereby
adopts the Amended and Restated Stock Option Plan effective November 9,1994:

                  1. PURPOSE. The purpose of the Plan is to continue to provide
         selected employees with a proprietary interest in the Company through
         the granting of either incentive stock options or non-qualified stock
         options which will

                           (a) increase the interest of the selected employees
                  in the Company's welfare;

                           (b) furnish an incentive to the selected employees to
                  continue their services for the Company; and

                           (c) provide a means through which the Company may
                  attract able persons to enter its employ.

                  2. ADMINISTRATION. The Plan will be administered by the Board.

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                  3. PARTICIPANTS. The Board shall, from time to time, select
         the particular employees of the Company and its Subsidiaries to whom
         options are to be granted, and who will, upon such grant, become
         participants in the Plan.

                  4. STOCK OWNERSHIP LIMITATIONS. No Incentive Option may be
         granted to an employee who owns more than 10% of the voting power of
         all classes of stock of the Company or its Parent or Subsidiaries. This
         limitation will not apply if the option price is at least 110% of the
         fair market value of the stock at the time the Incentive Option is
         granted and the Incentive Option is not exercisable more than five
         years from the date it is granted.

                  5. SHARES SUBJECT TO PLAN. The Board may not grant options
         under the Plan for more than 1,350,000 shares of Common Stock of the
         Company, but this number may be adjusted to reflect, if deemed
         appropriate by the Board, any stock dividend, stock split, share
         combination, recapitalization or the like, of or by the Company. Shares
         to be optioned and sold may be made available from either authorized
         but unissued Common Stock or Common Stock held by the Company in its
         treasury. Shares that by reason of the expiration of an option or
         otherwise are no longer subject to purchase pursuant to an option
         granted under the Plan may be reoffered under the Plan.

                  6. LIMITATION ON AMOUNT. The aggregate fair market value
         (determined at the time of grant) of the shares of Common Stock which
         any employee is first eligible to purchase in any calendar year by
         exercise of Incentive Options granted under this Plan and all incentive
         stock option plans (within the meaning of Section 422 of the Internal
         Revenue Code) of the Company or its Parent or Subsidiaries shall not
         exceed $100,000. For this purpose, the fair market value (determined at
         the respective date of grant of each option) of the stock purchasable
         by exercise of an Incentive Option (or an installment thereof) shall

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         be counted against the $100,000 annual limitation for an employee only
         for the calendar year such stock is first purchasable under the terms
         of the Incentive Option.

                  7. ALLOTMENT OF SHARES. The Board shall determine the number
         of shares of Common Stock to be offered from time to time by grant of
         options to employees of the Company or its Subsidiaries. The grant of
         an option to an employee shall not be deemed either to entitle the
         employee to, or to disqualify the employee from, participation in any
         other grant of options under the Plan.

                  8. GRANT OF OPTIONS. The Board is authorized to grant
         Incentive Options and Nonqualified Options under the Plan. The grant of
         options shall be evidenced by stock option agreements containing such
         terms and provisions as are approved by the Board, but not inconsistent
         with the Plan, including provisions that may be necessary to assure
         that any option that is intended to be an Incentive Option will comply
         with Section 422 of the Internal Revenue Code. The Company shall
         execute stock option agreements upon instructions from the Board. The
         Plan shall be submitted to the Company's stockholders for approval. The
         Board may grant options under the Plan prior to the time of stockholder
         approval, which options will be effective when granted, but if for any
         reason the stockholders of the Company do not approve the Plan prior to
         one year from the date of adoption of the Plan by the Board, all
         options granted under the Plan will be terminated and of no effect, and
         no option may be exercised in whole or in part prior to such
         stockholder approval.

                  A stock option agreement may provide that the participant may
         request approval from the Board to exercise an option or a portion
         thereof by tendering shares of Common Stock at the fair market value
         per share on the date of exercise in lieu of cash payment of the
         exercise price.

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                  9. OPTION PRICE. The option price shall not be less than 100%
         of the fair market value per share of the Common Stock on the date the
         option is granted.

                  10. OPTION PERIOD. The Option Period will begin on the date
         the option is granted, which will be the date the Board authorizes the
         option unless the Board specifies a later date. No option may terminate
         later than 10 years from the date the option is granted. The Board may
         provide for the exercise of options in installments and upon such
         terms, conditions and restrictions as it may determine. The Board may
         provide for termination of the option in the case of termination of
         employment or any other reason.

                  11. RIGHTS IN THE EVENT OF DEATH OR DISABILITY. If a
         participant dies or becomes disabled [within the meaning of Section
         22(e)(3) of the Internal Revenue Code] while in the employ of the
         Company but prior to termination of his right to exercise an option in
         accordance with the provisions of his stock option agreement without
         having totally exercised the option, the option may be exercised, to
         the extent of the shares with respect to which the option could have
         been exercised by the participant on the date of the participant's
         death or disability, by (i) the participant's estate or by the person
         who acquired the right to exercise the option by bequest or inheritance
         or by reason of the death of the participant in the event of the
         participant's death, or (ii) the participant or his personal
         representative in the event of the participant's disability, provided
         the option is exercised prior to the date of its expiration or not more
         than one year date of the participant's death or disability whichever
         first occurs.

                  12. PAYMENT. Full payment for shares purchased upon exercising
         an option shall be made in cash or by check or, if permitted by the
         stock option agreement, by tendering shares of Common Stock at the fair
         market value per share at the time of exercise, or on such

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         other terms as are set forth in the applicable option agreement. No
         shares may be issued until full payment of the purchase price therefore
         has been made, and a participant will have none of the rights of a
         stockholder until shares are issued to him.

                  13. EXERCISE OF OPTION. Options granted under the Plan may be
         exercised during the Option Period, at such times, in such amounts, in
         accordance with such terms and subject to such restrictions as are set
         forth in the applicable stock option agreements. In no event may an
         option be exercised or shares be issued pursuant to an option if any
         requisite action, approval or consent of any governmental authority of
         any kind having jurisdiction over the exercise of options shall not
         have been taken or secured.

                  14. CAPITAL ADJUSTMENTS AND REORGANIZATIONS. The number of
         shares of Common Stock covered by each outstanding option granted under
         the Plan and the option price may be adjusted to reflect, as deemed
         appropriate by the Board, any stock dividend, stock split, share
         combination or the like of or by the Company. In the event of a merger,
         consolidation, share exchange, reorganization, liquidation,
         recapitalization, separation or the like of or by the Company, the
         Board may make such arrangements as it deems advisable with respect to
         outstanding options granted under the Plan, which arrangements shall be
         binding upon each employee that holds an outstanding option granted
         under the Plan, including, but not limited to, arrangements for the
         substitution of new options for any options then outstanding, the
         assumption of any such options, payment for the outstanding options and
         adjusting the number of shares covered by each outstanding option and
         the option price therefor. Any such arrangement relating to an
         Incentive Option shall comply with the requirements of Internal Revenue
         Code Section 422 and the regulations thereunder. If the Company becomes
         a party to an agreement providing for the merger,

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         consolidation or share exchange of or by the Company and pursuant to
         that agreement the holders of Common Stock would receive cash,
         securities or property from another person or entity and if the Board
         does not make arrangements for the substitution of new options for any
         options then outstanding, the assumption of such options, or payment
         for such options, the Plan shall terminate and any options outstanding
         hereunder shall terminate on the effective date of such transaction;
         provided, however, all outstanding options granted under the Plan shall
         become immediately exercisable during the five business days
         immediately preceding the effective date of such transaction. If the
         options will so terminate on the effective date of the transaction, the
         Company shall give each Option Holder at least 15 days' notice of such
         termination and an opportunity to exercise such options prior to such
         termination.

                  15. NON-ASSIGNABILITY. Options may not be transferred other
         than by will or by the laws of descent and distribution. During a
         participant's lifetime, options granted to a participant may be
         exercised only by the participant.

                  16. INTERPRETATION. The Board shall interpret the Plan and
         shall prescribe such rules and regulations in connection with the
         operation of the Plan as it determines to be advisable for the
         administration of the Plan. The Board may rescind and amend its rules
         and regulations.

                  17. AMENDMENT OR DISCONTINUANCE. The Plan may be amended or
         discontinued by the Board without the approval of the stockholders of
         the Company, except that any amendment that would (a) materially
         increase the benefits accruing to participants under the Plan, (b)
         materially increase the number of securities that may be issued under
         the

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         Plan, or (c) materially modify the requirements or eligibility for
         participation in the Plan must be approved by the stockholders of the
         Company.

                  18. EFFECT OF PLAN. Neither the adoption of the Plan nor any
         action of the Board shall be deemed to give any officer or employee any
         right to be granted an option to purchase Common Stock of the Company
         or any other rights except as may be evidenced by a stock option
         agreement, or any amendment thereto, duly authorized by the Board and
         executed on behalf of the Company and then only to the extent and on
         the terms and conditions expressly set forth therein.

                  19. TERM. Unless sooner terminated by action of the Board,
         this Plan will terminate on November 8, 2004. The Board may not grant
         options under the Plan after that date, but options granted before that
         date will continue to be effective in accordance with their terms.

                  20. DEFINITIONS. For the purpose of this Plan, unless the
         context requires otherwise, the following terms shall have the meanings
         indicated:

                           (a) "Plan" means this Amended and Restated Stock
                  Option Plan as amended from time to time.

                           (b) "Company" means Interphase Corporation, a Texas
                  corporation.

                           (c) "Board" means the board of directors of the
                  Company or a committee appointed by the board of directors to
                  administer the Plan or any portion of the Plan.

                           (d) "Common Stock" means the Common Stock which the
                  Company is currently authorized to issue or may in the future
                  be authorized to issue (as long as the common stock varies
                  from that currently authorized, if at all, only in amount of
                  par value).

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                           (e) "Subsidiary" means any corporation in an unbroken
                  chain of corporations beginning with the Company if, at the
                  time of the granting of the option, each of the corporations
                  other than the last corporation in the unbroken chain owns
                  stock possessing 50% or more of the total combined voting
                  power of all classes of stock in one of the other corporations
                  in the chain, and "Subsidiaries" means more than one of any
                  such corporations.

                           (f) "Parent" means any corporation in an unbroken
                  chain of corporations ending with the Company if, at the time
                  of granting of the option, each of the corporations other than
                  the Company owns stock possessing 50% or more of the total
                  combined voting power of all classes of stock in one of the
                  other corporations in the chain.

                           (g) "Option Period" means the period during which an
                  option may be exercised.

                           (h) "Incentive Option" means an option granted under
                  the Plan which meets the requirements of Section 422 of the
                  Internal Revenue Code.

                           (i) "Nonqualified Stock Option" means an option
                  granted under the Plan which is not intended to be an
                  Incentive Option.

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                                 AMENDMENT NO. 1
                                     TO THE
                             INTERPHASE CORPORATION
                     AMENDED AND RESTATED STOCK OPTION PLAN

         Pursuant to Section 17 of the Interphase Corporation Amended and
Restated Stock Option Plan (the "Plan"), the Plan is hereby amended as follows:

         1. Section 9 of the Plan is hereby amended to read in its entirety as
follows:

                  Section 9. Option Price. The option price for Incentive
         Options shall not be less than 100% of the fair market value per share
         of the Common Stock on the date the Incentive Option is granted. The
         option price for Nonqualified Options shall be, as determined by the
         Board, any price per share of the Common Stock that is greater than par
         value per share of the Common Stock.

         IN WITNESS WHEREOF, the undersigned has executed this Amendment
effective as of the 22nd day of March, 1995.

                                              INTERPHASE CORPORATION

                                              By: /s/ R. STEPHEN POLLEY
                                                  ---------------------

<PAGE>

                                 AMENDMENT NO. 2
                                     TO THE
                              INTERPHASE CORPORATION
                     AMENDED AND RESTATED STOCK OPTION PLAN

         Pursuant to Section 17 of the Interphase Corporation Amended and
Restated Stock Option Plan (the "Plan"), the Plan is hereby amended as follows:

         1. Section 5 of the Plan is hereby amended to read in its entirety as
follows:

                  5. SHARES SUBJECT TO PLAN. The Board may not grant options
         under the Plan for more than 2,350,000 shares of Common Stock of the
         Company, but this number may be adjusted to reflect, if deemed
         appropriate by the Board any stock dividend, stock split, share
         combination, recapitalization or the like, of or by the Company. Shares
         to be optioned and sold may be made available from either authorized
         but unissued Common Stock or Common Stock held by the Company in its
         treasury. Shares that by reason of the expiration of an option or
         otherwise are no longer subject to purchase pursuant to an option
         granted under the Plan may be reoffered under the Plan.

         IN WITNESS WHEREOF, the undersigned has executed this Amendment
effective as of the 25th day of June, 1996.

                                              INTERPHASE CORPORATION

                                              By: /s/ R. STEPHEN POLLEY
                                                  ---------------------

<PAGE>

                             AMENDMENT NO. 3 TO THE
                             INTERPHASE CORPORATION
                     AMENDED AND RESTATED STOCK OPTION PLAN

         Pursuant to Section 17 of the Interphase Corporation Amended and
Restated Stock Option Plan (the "Plan"), the first sentence of Section 5 of the
Plan is hereby amended to read as follows:

                  The Board may not grant options under the Plan for more than
         2,350,000 shares of Common Stock of the Company, but this number may be
         adjusted to reflect, if deemed appropriate by the Board, any stock
         dividend, stock split, share combination, recapitalization or the like,
         of or by the Company, and the total number of shares subject to option
         under the Plan represents the maximum number of shares for which
         options may be granted to any one participant in the Plan during the
         term of the Plan.

         IN WITNESS WHEREOF, the undersigned has executed this Amendment
effective as of the 21st day of April 1997.

                                              INTERPHASE CORPORATION

                                              By: /s/ R. STEPHEN POLLEY
                                                  ----------------------------
                                                  R. Stephen Polley, President

<PAGE>

                                 AMENDMENT NO.4
                                     TO THE
                             INTERPHASE CORPORATION
                     AMENDED AND RESTATED STOCK OPTION PLAN

         Pursuant to Section 17 of the Interphase Corporation Amended and
Restated Stock Option Plan (the "Plan"), the Plan is hereby amended as follows:

         1. Section 5 of the Plan is hereby amended to read in its entirety as
follows:

                  5. SHARES SUBJECT TO PLAN. The Board may not grant options
         under the Plan for more than 3,500,000 shares of Common Stock of the
         Company, but this number may be adjusted to reflect, if deemed
         appropriate by the Board, any stock dividend, stock split, share
         combination, recapitalization or the like, of or by the Company.
         Shares to be optioned and sold may be made available from either
         authorized but unissued Common Stock or Common Stock held by the
         Company in its treasury. Shares that by reason of the expiration of an
         option or otherwise are no longer subject to purchase pursuant to an
         option granted under the Plan may be reoffered under the Plan.

         IN WITNESS WHEREOF, the undersigned has executed this Amendment
effective as of the 19th day of January, 2000.

                                              INTERPHASE CORPORATION

                                              By: /s/ GREGORY B. KALUSH
                                                  ----------------------------
                                                  Gregory B. Kalush, President

<PAGE>

         INTERPHASE CORPORATION AMENDED AND RESTATED STOCK OPTION PLAN

                                 STOCK OPTIONS

                                    ADDENDUM

                                     FRANCE

The additional terms and conditions detailed below are to be read in conjunction
with the rules of the Interphase Corporation Amended and Restated Stock Option
Plan (hereinafter referred to as "the Plan") of Interphase Corporation
(hereinafter referred to as "the Company"). Defined terms are to have the same
meaning as that stated in the rules of the Plan. These additional terms and
conditions are specific to employees and certain non-employee directors,
described below, of Synaptel SARL, French subsidiary of Interphase Corporation,
only and do not affect the rights afforded to employees of other Group companies
who are granted Options under the Plan.

Options may be granted under this addendum to Participants who are, at present,
based in France as follows:

   1.    Options hereunder may only be granted to individuals having an
         employment contract with Synaptel SARL and/or to non-employee
         directors having a management function with Synaptel SARL
         [the president-directeur general," the "directeur-general," the
         "members of the directoire" (executive board of certain "societes
         anonymes") specified under July 24, 1966 corporate law.

   2.    Options granted to any Participants hold shares representing 10% or
         more of the Company's share capital will not be deemed to have been
         granted pursuant to this Addendum.

   3.    Any option to be allocated to beneficiaries whose "Option Price" at the
         time of the grant of the option is less than the higher of (i) the
         Option Price as defined under the Plan, (ii) 95% of the average stock
         exchange price during the 20 days preceding the related grant, or (iii)
         95% of the average repurchase price of its own shares held by
         Interphase Corporation shall be deemed not to have been granted under
         this Addendum.

   4.    Options granted within a 20-trading day period following a distribution
         of dividends or a capital increase shall be deemed not to have been
         granted under this Addendum.

   5.    Except as otherwise decided at the sole discretion of the [Board or
         Option Committee], the options granted under this addendum shall be
         exercisable (i) 75%

ATTACHMENT III
INTERPHASE CORPORATION AMENDED AND RESTATED STOCK OPTION PLAN
STOCK OPTIONS
ADDENDUM
FRANCE                                                                   PAGE 1

<PAGE>

         after the expiration of a TWO (2)-year period from the date of grant
         and (ii) 25% after the expiration of a THREE (3)-year period from the
         date of the grant. Except in the events provided under Section 91 ter
         of Annex II of the French tax code when all the conditions provided by
         this section are fulfilled and except as otherwise decided at the sole
         discretion of the [Board or Option Committee], the underlying shares
         cannot be sold or otherwise disposed of for an additional period of (i)
         THREE (3) years starting from the date the options can be exercised for
         the options which become exercisable after the expiration of a TWO-YEAR
         period from the date of grant or (ii) TWO (2) years starting from the
         date the options can be exercised for the options which become
         exercisable after the expiration of a THREE-YEAR period from the date
         of grant, i.e., the FIVE (5)-year period requirement (from the date of
         grant through the date of the sale) shall be in all cases fulfilled.
         The share certificate being established upon exercise of the options
         will include a provision stating that the share cannot be sold until
         before the fifth anniversary of the grant.

         Should any modifications of the French legal provisions arise that
         would concern the conditions to qualify for the tax and social security
         preferential treatment, the [Board or Option Committee] would be
         entitled to modify accordingly and for this sole purpose the dates of
         exercise of the options as well as the holding conditions of the
         shares. These changes should however remain in line with the vesting
         periods provided by the Plan.

   6.    The Option Price shall remain unchanged. The Option Price shall be
         adjusted only upon the occurrence of the events specified under July
         24, 1966 corporate law (Section 208-5) in accordance with French law.

   7.    In the event of the Participant's death and to the extent the option is
         exercisable under the Plan, the period during which the legal heirs are
         entitled to exercise the options is six months following the
         Participant's death.

   8.    The total number of options granted and remaining unexercised
         (outstanding options) under the Plan will never cover a number of
         shares exceeding one-third of Interphase Corporation's capital.

ATTACHMENT III
INTERPHASE CORPORATION AMENDED AND RESTATED STOCK OPTION PLAN
STOCK OPTIONS
ADDENDUM
FRANCE                                                                   PAGE 2

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