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                                                                   EXHIBIT 10.16

                              SILICON VALLEY BANK
                          AMENDMENT TO LOAN AGREEMENT

BORROWER:  QLOGIC CORPORATION
ADDRESS:   3545 HARBOR BOULEVARD, P.O. BOX 5001
           COSTA MESA, CALIFORNIA 92682

Dated as of: July 6, 2000

     THIS AMENDMENT TO LOAN AGREEMENT is entered into between SILICON VALLEY
BANK ("Silicon") and the borrower named above ("the borrower").

     The parties agree to amend the Loan and Security Agreement between them,
dated March 31, 1994, as amended by that Amendment to Loan and Security
Agreement dated July 10, 1995, as amended by that Amendment to Loan and Security
agreement dated July 5, 1996, and as amended by that Amendment to Loan Agreement
dated as of July 6, 1998, and as amended by that Amendment to Loan Agreement
dated as of July 6, 1999, (as so amended and as otherwise amended from time to
time, the "Loan Agreement"), as follows, effective as of the date hereof.
(capitalized terms used but not defined in this Amendment, shall have the
meanings set forth in the Loan Agreement.)

     1. Amended Maturity Date. The section of the Schedule to the Loan Agreement
        entitled "Maturity Date (Section 5.1)" is amended to read as follows:

        "Maturity Date
        (Section 5.1): JULY 5, 2001

     2. Facility Fee. Borrower shall pay to Silicon concurrently herewith a
        facility fee of $25,000, which shall be in addition to all interest and
        all other fees payable to silicon and shall be non-refundable.

     3. General Provisions. Borrower represents and warrants to Silicon that all
        representations and warranties set forth in the Loan Agreement, as
        amended hereby, are true and correct. This Amendment, the Loan
        Agreement, any prior written amendments to the Loan between silicon and
        the Borrower set forth in full all of the representations and agreements
        of the parties with respect to the subject matter hereof and supersede
        all prior discussions, representations, agreements and understandings
        between the parties with respect to the subject hereof. Except as herein
        expressly amended, all of the term and provisions of the Loan Agreement,
        and all other documents and agreements between silicon and the Borrower
        shall continue in full force and effect and the same are hereby ratified
        and confirmed.

                                                         
QLogic CORPORATION                                          SILICON VALLEY BANK

By              /s/  THOMAS R. ANDERSON                     By               /s/  MARLA JOHNSON
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President or Vice President

By                /s/  MICHAEL MANNING                      Title            Sr. Vice President
   --------------------------------------------------       -----------------------------------------------------
            Secretary or Ass't Secretary