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                                                                     EXHIBIT 4.2

                          [Form of Rights Certificate]


Certificate No. R-                                             __________ Rights


         NOT EXERCISABLE AFTER DECEMBER 6, 2010 OR EARLIER IF REDEEMED BY THE
         COMPANY. THE RIGHTS ARE SUBJECT TO REDEMPTION, AT THE OPTION OF THE
         COMPANY, AT $0.01 PER RIGHT ON THE TERMS SET FORTH IN THE RIGHTS
         AGREEMENT. UNDER CERTAIN CIRCUMSTANCES, RIGHTS BENEFICIALLY OWNED BY AN
         ACQUIRING PERSON (AS SUCH TERM IS DEFINED IN THE RIGHTS AGREEMENT) AND
         ANY SUBSEQUENT HOLDER OF SUCH RIGHTS MAY BECOME NULL AND VOID. [THE
         RIGHTS REPRESENTED BY THIS RIGHTS CERTIFICATE ARE OR WERE BENEFICIALLY
         OWNED BY A PERSON WHO WAS OR BECAME AN ACQUIRING PERSON OR AN AFFILIATE
         OR ASSOCIATE OF AN ACQUIRING PERSON (AS SUCH TERMS ARE DEFINED IN THE
         RIGHTS AGREEMENT). ACCORDINGLY, THIS RIGHTS CERTIFICATE AND THE RIGHTS
         REPRESENTED HEREBY MAY BECOME NULL AND VOID IN THE CIRCUMSTANCES
         SPECIFIED IN SECTION 7(e) OF SUCH AGREEMENT.](2)


                               Rights Certificate

                             INTERPHASE CORPORATION


         This certifies that                      , or registered assigns, is
the registered owner of the number of Rights set forth above, each of which
entitles the owner thereof, subject to the terms, provisions and conditions of
the Rights Agreement, dated as of December 7, 2000 (the "Rights Agreement"),
between Interphase Corporation, a Texas corporation (the "Company"), and
Computershare Investor Services, LLC, a limited liability company organized
under the laws of the State of Delaware (the "Rights Agent"), to purchase from
the Company at any time prior to 5:00 P.M. (New York City time) on December 6,
2010 at the office or offices of the Rights Agent designated for such purpose,
or its successors as Rights Agent, one fully paid, nonassessable share of Common
Stock (the "Common Stock") of the Company, at a purchase price of $93.00 per
share (the "Purchase Price"), upon presentation and surrender of this Rights
Certificate with the Form of Election to Purchase and related Certificate duly
executed. The


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         (2) The portion of the legend in brackets shall be inserted only if
applicable and shall replace the preceding sentence.


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Purchase Price shall be paid, at the election of the holder, in
cash or shares of Common Stock of the Company having an equivalent value. The
number of Rights evidenced by this Rights Certificate (and the number of shares
which may be purchased upon exercise thereof) set forth above, and the Purchase
Price per share set forth above, are the number and Purchase Price as of
December 7, 2000, based on the Common Stock as constituted at such date.

         Upon the occurrence of the Section 11(a)(ii) Event (as such term is
defined in the Rights Agreement), if the Rights evidenced by this Rights
Certificate are beneficially owned by (i) an Acquiring Person or an Affiliate or
Associate of any such Acquiring Person (as such terms are defined in the Rights
Agreement), (ii) a transferee of any such Acquiring Person, Associate or
Affiliate, or (iii) under certain circumstances specified in the Rights
Agreement, a transferee of a person who, after such transfer, became an
Acquiring Person, or an Affiliate or Associate of an Acquiring Person, such
Rights shall become null and void and no holder hereof shall have any right with
respect to such Rights from and after the occurrence of the Section 11(a)(ii)
Event.

         As provided in the Rights Agreement, the Purchase Price and the number
and kind of shares of Common Stock or other securities, which may be purchased
upon the exercise of the Rights evidenced by this Rights Certificate are subject
to modification and adjustment upon the happening of certain events, including
Triggering Events.

         This Rights Certificate is subject to all of the terms, provisions and
conditions of the Rights Agreement, which terms, provisions and conditions are
hereby incorporated herein by reference and made a part hereof and to which
Rights Agreement reference is hereby made for a full description of the rights,
limitations of rights, obligations, duties and immunities hereunder of the
Rights Agent, which limitations of rights include the temporary suspension of
the exercisability of such Rights under the specific circumstances set forth in
the Rights Agreement. Copies of the Rights Agreement are on file at the
above-mentioned office of the Rights Agent and are also available upon written
request to the Rights Agent.

         This Rights Certificate, with or without other Rights Certificates,
upon surrender at the principal office or offices of the Rights Agent designated
for such purpose, may be exchanged for another Rights Certificate or Rights
Certificates of like tenor and date evidencing Rights entitling the holder to
purchase a like aggregate number of Common Stock as the Rights evidenced by the
Rights Certificate or Rights Certificates surrendered shall have entitled such
holder to purchase. If this Rights Certificate shall be exercised in part, the
holder shall be entitled to receive upon surrender hereof another Rights
Certificate or Rights Certificates for the number of whole Rights not exercised.

         Subject to the provisions of the Rights Agreement, the Rights evidenced
by this Certificate may be redeemed by the Company at its option at a redemption
price of $0.01 per Right at any time prior to the earlier of the close of
business on (i) the tenth Business Day following the Stock Acquisition Date (as
such time period may be extended pursuant to the Rights Agreement), and (ii) the
Final Expiration Date.



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         The Company is not required to issue fractional shares of Common Stock
upon the exercise of any Right or Rights evidenced hereby (other than fractions
which are integral multiples of one share of Common Stock, which may, at the
election of the Company, be evidenced by depositary receipts), but in lieu
thereof a cash payment may be made, as provided in the Rights Agreement.

         No holder of this Rights Certificate shall be entitled to vote or
receive dividends or be deemed for any purpose the holder of shares of Common
Stock or of any other securities of the Company which may at any time be
issuable on the exercise hereof, nor shall anything contained in the Rights
Agreement or herein be construed to confer upon the holder hereof, as such, any
of the rights of a stockholder of the Company or any right to vote for the
election of directors or upon any matter submitted to stockholders at any
meeting thereof, or to give or withhold consent to any corporate action, or to
receive notice of meetings or other actions affecting stockholders (except as
provided in the Rights Agreement), or to receive dividends or subscription
rights, or otherwise, until the Right or Rights evidenced by this Rights
Certificate shall have been exercised as provided in the Rights Agreement.

         This Rights Certificate shall not be valid or obligatory for any
purpose until it shall have been countersigned by the Rights Agent.

         WITNESS the facsimile signature of the proper officers of the Company
and its corporate seal.


Dated as of                 ,
            ----------------  -----

Attest:                                INTERPHASE CORPORATION


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

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

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



Countersigned:

COMPUTERSHARE INVESTOR SERVICES, LLC


By:
   ----------------------------------
         Authorized Signature



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                  [Form of Reverse Side of Rights Certificate]



                               FORM OF ASSIGNMENT

                (To be executed by the registered holder if such
               holder desires to transfer the Rights Certificate.)


FOR VALUE RECEIVED _____________________________________________________________
hereby sells, assigns and transfers unto________________________________________

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                  (Please print name and address of transferee)

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this Rights Certificate, together with all right, title and interest therein,
and does hereby irrevocably constitute and appoint __________________ Attorney,
to transfer the within Rights Certificate on the books of the within-named
Company, with full power of substitution.


Date:                     ,
     ---------------------  ------


                                       -----------------------------------------
                                                       Signature


Signature Guaranteed:



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                                   CERTIFICATE


         The undersigned hereby certifies by checking the appropriate boxes
that:

                  (1) this Rights Certificate [ ] is [ ] is not being sold,
assigned and transferred by or on behalf of a Person who is or was an Acquiring
Person or an Affiliate or Associate of any such Acquiring Person (as such terms
are defined in the Rights Agreement); and

                  (2) after due inquiry and to the best knowledge of the
undersigned, it [ ] did [ ]did not acquire the Rights evidenced by this Rights
Certificate from any Person who is, was or subsequently became an Acquiring
Person or an Affiliate or Associate of an Acquiring Person.


Dated:               ,
      ---------------  ----                 -----------------------------
                                                      Signature

Signature Guaranteed:


                                     NOTICE


                  The signature to the foregoing Assignment and Certificate must
correspond to the name as written upon the face of this Rights Certificate in
every particular, without alteration or enlargement or any change whatsoever.



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                          FORM OF ELECTION TO PURCHASE

     (To be executed if holder desires to exercise Rights represented by the
                              Rights Certificate.)



To: INTERPHASE CORPORATION

         The undersigned hereby irrevocably elects to exercise ____________
Rights represented by this Rights Certificate to purchase the shares of Common
Stock issuable upon the exercise of the Rights (or such other securities of the
Company or of any other person which may be issuable upon the exercise of the
Rights) and requests that certificates for such shares be issued in the name of
and delivered to:

Please insert social security
or other identifying number
                           ----------------------------------

--------------------------------------------------------------------------------
                         (Please print name and address)

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


         If such number of Rights shall not be all the Rights evidenced by this
Rights Certificate, a new Rights Certificate for the balance of such Rights
shall be registered in the name of and delivered to:


Please insert social security
or other identifying number
                           ----------------------------


--------------------------------------------------------------------------------
                         (Please print name and address)

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

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

Dated:                     ,
      ---------------------  -----
                                       -----------------------------------------
                                                      Signature

Signature Guaranteed:



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                                   CERTIFICATE


         The undersigned hereby certifies by checking the appropriate boxes
that:

         (1) the Rights evidenced by this Rights Certificate [ ] are [ ] are not
being exercised by or on behalf of a Person who is or was an Acquiring Person or
an Affiliate or Associate of any such Acquiring Person (as such terms are
defined in the Rights Agreement); and

         (2) after due inquiry and to the best knowledge of the undersigned, it
[ ] did [ ] did not acquire the Rights evidenced by this Rights Certificate from
any Person who is, was or became an Acquiring Person or an Affiliate or
Associate of an Acquiring Person.


Dated:                ,
      ----------------  ----           -----------------------------------------
                                                      Signature


Signature Guaranteed:

                                     NOTICE

                  The signature to the foregoing Election to Purchase and
Certificate must correspond to the name as written upon the face of this Rights
Certificate in every particular, without alteration or enlargement or any change
whatsoever.



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