<PAGE>

EXHIBIT 10 (b)                   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
                                         ------------------------------------

<PAGE>

                             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.


<PAGE>

          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


                                       2

<PAGE>

     exercise of an Incentive Option (or an installment thereof) shall 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.


                                       3

<PAGE>

               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.

          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 from the date of the participant's death or disability whichever
     first occurs.


                                       4

<PAGE>

          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 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


                                       5

<PAGE>

     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, 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


                                       6

<PAGE>

     Plan, (b) materially increase the number of securities that may be
     issued under the 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).


                                       7

<PAGE>

               (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.



                                       8