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                                                                   EXHIBIT 10.66

         ALL SECTIONS MARKED WITH TWO ASTERISKS ("**") REFLECT PORTIONS WHICH
HAVE BEEN REDACTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
COMMISSION BY ROSS TECHNOLOGY, INC., AS PART OF A REQUEST FOR CONFIDENTIAL
TREATMENT.

                            VIPER AMENDMENT AGREEMENT

         This agreement ("Agreement"), dated as of March 30, 1998, is entered
into by and between FUJITSU LIMITED, a Japanese Corporation ("Fujitsu"), and
ROSS TECHNOLOGY, INC., a Delaware corporation (the "Company").

                                    RECITALS

         A. Fujitsu and the Company are parties to a Development Agreement,
dated as of June 25, 1997, as amended by agreements dated September 29, 1997
(the "First Amendment") and December 26, 1997 (the "Second Amendment") (as so
amended, the "Development Agreement"), pursuant to which the Company has agreed
to develop a microprocessor known as the Viper (the "Viper"). Defined terms used
herein without definition have the respective meanings set forth in the
Development Agreement.

         B. Pursuant to the Development Agreement, the Company has agreed to
deliver to Fujitsu certain Deliverables on the schedule attached to the
Development Agreement as Exhibit A, including, without limitation, to deliver to
Fujitsu Schematics in conformity with Milestone #4 of Exhibit B of the
Development Agreement (the "Subject Deliverable") on December 15, 1997.

         C. The Company has delivered to Fujitsu the Subject Deliverable but the
Subject Deliverable is not in full conformity with Milestone #4 (as amended and
restated as Appendix 2 of the Second Amendment). Nonetheless, Fujitsu is willing
to accept the non-conforming deliverable attached hereto as Appendix 1 (the
"Alternate Deliverable"), provided that the Company agrees that (1) Milestone #4
of Exhibit B (Schematics) of the Development Agreement shall be amended and
restated as Appendix 2 hereto and, as restated, will provide for a separate
Milestone #4-1 and Milestone #4-2, (2) the acceptance of the Alternate
Deliverable shall satisfy the Company's obligations only as to Milestone #4-1
(and shall not affect the Company's obligations as to Milestone #4-2) and (3)
the acceptance of the Alternate Deliverable shall not affect the Company's
continuing obligations to develop Viper in accordance with the Specifications,
and otherwise on the terms and conditions, set forth in the Development
Agreement.
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         NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, the parties hereto hereby agree as follows:

                                    AGREEMENT

         1. Amendment of Milestone #4 (SCHEMATICS). Milestone #4 of Exhibit B to
the Development Agreement (pages 7/22, 8/22 and 9/22) is hereby amended and
restated in its entirety as Appendix 2. Exhibit A of the Development Agreement
is hereby amended to provide that the payment of $4,500,000 with respect to
Milestone #4 shall, pursuant to this Agreement, be due $3,000,000 upon
acceptance of Milestone #4-1 and $1,500,000 upon acceptance of Milestone #4-2.

         2. Delivery and Acceptance of Alternate Deliverable. The Company hereby
delivers the Alternate Deliverable to Fujitsu for acceptance. Subject to and
upon the terms and conditions of this Agreement, Fujitsu hereby accepts the
Alternate Deliverable, effective as of March 19, 1998, in full satisfaction of
the Company's obligations with respect to Milestone #4-1 of Exhibit B of the
Development Agreement, as restated hereby.

         3. Limited Nature of Acceptance. The acceptance of the Alternate
Deliverable by Fujitsu shall not be deemed to modify in any respect the
performance specifications set forth in the Development Agreement (without
limitation, SPECint95 = 42 and SPECfp95 = 50) or the obligations of the Company
under the Development Agreement.

         4. Payment Terms. Fujitsu will make payment to the Company of
$3,000,000 for the Alternate Deliverable, as provided in Section 4.1(a) of the
Development Agreement, by April 20, 1998. The Company confirms that no other
amounts are due or payable by Fujitsu to the Company at the present time under
the Agreement. Fujitsu agrees that such payment shall be deemed fully earned
upon the effectiveness of this Agreement and shall be non-refundable; provided,
however, that the Company agrees that nothing herein, or in the First Amendment
or Second Amendment, shall limit the accrual of late delivery penalties through
the date of Fujitsu's acceptance as provided in Section 6.2 of the Development
Agreement, and for such purposes the parties agree that Milestone #4-1
Deliverable was delivered 94 days late.

         5. Representations and Warranties. Each party hereby represents and
warrants to the other that the execution and delivery by such party of this
Agreement have been duly authorized by all necessary corporate and other action
and do not and will not require any consent or approval of, notice to or action
by, any person (including any governmental agency) in order to be effective and
enforceable. The Development Agreement, as amended by this Agreement,


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constitutes the legal, valid and binding obligation of such party, enforceable
against it in accordance with its terms, without defense or counterclaim.

         6.       Reservation of Rights. The Company acknowledges and agrees
that neither Fujitsu's forbearance in exercising its rights in connection with
the delivery of the Alternate Deliverable nor the execution by Fujitsu of this
Agreement shall be deemed (i) to create a course of dealing or otherwise
obligate Fujitsu to forbear or execute a similar agreement under the same or
similar circumstances in the future, or (ii) to waive, relinquish or impair any
right of Fujitsu to future performance by the Company of the Development
Agreement strictly in accordance with its terms.

         7.       Miscellaneous.

                  (a) This Agreement contains the entire and exclusive agreement
and understanding between the parties with respect to its subject matter. Except
as herein expressly amended, all terms and conditions of the Development
Agreement are and shall remain in full force and effect. All references to the
Development Agreement shall henceforth refer to the Development Agreement as
amended hereby. There are no oral or other agreements of any kind or nature with
respect to the obligations of the parties under the Development Agreement, which
remains the sole and complete embodiment of the parties' understandings.

                  (b) This Agreement shall be binding upon and inure to the
benefit of the parties and their respective successors and assigns. No third
party beneficiaries are intended in connection with this Agreement.

                  (c) This Agreement shall be governed by and construed in
accordance with the law of the State of California (without regard to principles
of conflicts of laws).

                  (d) This Agreement may be executed in counterparts, each of
which shall be deemed an original, but all such counterparts together shall
constitute but one and the same instrument.

         IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Agreement as of the date first above written.

                                ROSS TECHNOLOGY, INC.


                                By: /s/ Trevor S. Smith
                                   ------------------------------------------
                                Title: V.P. of Engineering
                                      ---------------------------------------


                                FUJITSU LIMITED


                                Hatsuo Murano for
                                By: /s/ Yoshiro Yoshioka
                                   ------------------------------------------
                                Title: Group President, Computer System Group
                                      ---------------------------------------

**