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                                                                    EXHIBIT 10.6
                                IRREVOCABLE PROXY


                  The undersigned Stockholder of AverStar, Inc., a Delaware
corporation (the "COMPANY"), hereby irrevocably (to the fullest extent
permitted by law) appoints and constitutes The Titan Corporation, a Delaware
corporation ("ACQUIROR") and V T Acquisition Corp., a Delaware corporation
and wholly-owned subsidiary of Acquiror ("MERGER SUB"), and each of them, the
attorneys and proxies of the undersigned, with full power of substitution and
resubstitution, to the full extent of the undersigned's voting rights with
respect to (a) the outstanding shares of common stock, $.001 par value, of
the Company (the "COMPANY COMMON STOCK") or any other capital stock of the
Company (collectively with the Company Common Stock, the "CAPITAL STOCK")
owned of record by the undersigned as of the date of this proxy, which shares
are specified on the final page of this proxy, and (b) any and all other
shares of Capital Stock of the Company which the undersigned may acquire on
or after the date hereof. Upon the execution hereof, all prior proxies given
by the undersigned with respect to any of the Capital Stock are hereby
revoked, and the undersigned agrees that no subsequent proxy will be given
with respect to any of the Capital Stock.

                  This proxy is (i) irrevocable, (ii) coupled with an
interest, (iii) granted in connection with the execution and delivery of the
Voting Agreement dated as of the date hereof among Acquiror, the undersigned
and certain other stockholders of the Company (the "VOTING AGREEMENT"), and
(iv) granted in consideration of Acquiror and Merger Sub entering into the
Agreement and Plan of Merger dated as of the date hereof among Acquiror,
Merger Sub and the Company (the "MERGER AGREEMENT").

                  The proxy named above (and its successors) will, prior to
the Termination Date (as defined in the Voting Agreement), be empowered, and
may exercise this proxy, to vote the Capital Stock at any meeting of the
stockholders of the Company, however called, or in connection with any
solicitation of written consents from stockholders of the Company, for the
purpose of voting on the Merger Agreement and the transaction contemplated
thereby in favor of the approval and adoption of the Merger Agreement and the
approval of the merger contemplated thereby, and in favor of each of the
other actions contemplated by the Merger Agreement. The undersigned may vote
the Capital Stock on all other matters.

                  This proxy shall be binding upon the representatives,
successors and assigns of the undersigned (including any transferee of any of
the Capital Stock).

                  If any provision of this proxy or any part of any such
provision is held under any circumstances to be invalid or unenforceable in
any jurisdiction, then (a) such provision or part thereof shall, with respect
to such circumstances and in such jurisdiction, be deemed amended to conform
to applicable laws so as to be valid


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and enforceable to the fullest possible extent, (b) the invalidity or
unenforceability of such provision or part thereof under such circumstances
and in such jurisdiction shall not affect the validity or enforceability of
such provision or part thereof under any other circumstances or in any other
jurisdiction, and (c) the invalidity or unenforceability of such provision or
part thereof shall not affect the validity or enforceability of the remainder
of such provision or the validity or enforceability of any other provision of
this proxy. Each provision of this proxy is separable from every other
provision of this proxy, and each part of each provision of this proxy is
separable from every other part of such provision.

                  This proxy shall terminate upon the valid termination of
the Voting Agreement.

Date: March 24, 2000



                                                 /s/ John C. Rennie
                                                 ------------------------------
                                                 Stockholder's Name

                                                 Number of shares of common
                                                 stock of the Company owned
                                                 of record as of the date of
                                                 this proxy:



                                                   293,438 Shares of Class F
                                                 ------------------------------


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