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                                                                    EXHIBIT 10.2


                            FIRST UNION NATIONAL BANK
                              Portfolio Management
                                     PA 1310
                             123 South Broad Street
                      Philadelphia, Pennsylvania 19109-1199
                                Fax 215-985-3143


                                December 19, 1997


Relland Winand
Chief Financial Officer
ECC International Corp.
175 Strafford Ave.
Wayne, PA  19087-3377

Dear Rell:

Reference is made to that certain:

1. Term Loan and Revolving Credit Agreement, dated as of September 20, 1994
(together with all amendments and modifications thereto), by and between ECC
International Corp. ("ECC"), and First Fidelity Bank, National Association, (the
"Bank", now named First Union National Bank) and all of the documents,
instruments and agreements executed in connection therewith (collectively, the
"ECC Loan Documents").

2. Revolving Credit Agreement, dated as of September 20, 1994 (together with all
amendments and modifications thereto), by and between ECC Simulation Limited
("Simulation", and, together with ECC, the "Borrowers"), and the Bank and all of
the documents, instruments and agreements executed in connection therewith
(collectively, the "Simulation Loan Documents" and, together with the ECC Loan
Documents, the "Loan Documents").

Terms capitalized but not defined herein shall have the meanings ascribed
thereto in the Loan Documents.

The Borrowers have requested that the Bank agree to modify Section P.1 of the
Term Loan and Revolving Credit Agreement to substitute $3,000,000.00 for
$2,000,000.00 where it appears therein (representing the maximum amount ECC may
lend to Simulation) for the period from the date hereof through January 31, 1998
(the 



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"Temporary Modification") and the Bank has agreed to do so pursuant to the
terms hereof.

The Borrowers hereby affirm, as of the date hereof, the representations and
warranties set forth in the Loan Documents exactly as if they were made on and
as of the date hereof, except where disclosed to the Bank in writing prior to
the date hereof or where immaterial. The Borrowers represent and warrant that
there is no breach of any term, covenant or provision of the Loan Documents and
that no Event of Default or other event which, with the passage of time, the
giving of notice, or both, would become an Event of Default has occurred and is
continuing. The Borrowers agree that the Loan Documents are binding and
enforceable against the Borrowers pursuant to the terms thereof and the
Borrowers have no defenses, set-offs, or counterclaims to their obligations
thereunder.

In reliance upon the Borrowers' reaffirmation and representations and warranties
stated above, the Bank agrees to the Temporary Modification.

All other terms, covenants and conditions of the Loan Documents are hereby
reaffirmed, ratified and confirmed in all respects and shall remain in full
force and effect. Nothing contained herein is intended to be or shall be
construed as a waiver of any default, Event of Default, or any of the Bank's
rights and remedies under the Loan Documents and applicable law, all of which
are expressly reserved and preserved.

Please acknowledge your receipt and acceptance of this letter by signing below
(and having the guarantors identified below also sign where indicated) and
returning a copy to the Bank. Upon the Bank's receipt of an executed copy of
this letter, this letter will become effective.

                                          Sincerely yours,

                                          First Union National Bank

                                          By:    /S/ SUZANNE S. STORM
                                             -----------------------------------
                                          Name:  Suzanne S. Storm
                                          Title: Senior Vice President




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THE UNDERSIGNED ACKNOWLEDGE, CONSENT AND AGREE TO THE FOREGOING TERMS, COVENANTS
AND CONDITIONS AND AGREE TO BE BOUND THEREBY.

DATE:    12/19/97
---------------------------------

                                             BORROWER
Attest:                                      ECC International Corp.

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: V.P., Finance                         Title: President

                                             GUARANTOR
Attest:                                      ECC Simulation Limited


By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary                             Title: President


                                             GUARANTOR
Attest:                                      Educational Computer Corporation

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary/Treasurer                   Title: President


                                             GUARANTOR
Attest:                                      ECC International, Inc.

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary/Treasurer                   Title: President


                                             BORROWER
Attest:                                      ECC Simulation Limited

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary                             Title: President




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                                             GUARANTOR
Attest:                                      Educational Computer Corporation

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary/Treasurer                   Title: President


                                             GUARANTOR
Attest:                                      ECC International, Inc.

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Secretary/Treasurer                   Title: President


                                             GUARANTOR
Attest:                                      ECC International Corp.

By:    /S/ RELLAND WINAND                    By:    /S/ GEORGE W. MURPHY
   ------------------------------               --------------------------------
Name:  Relland Winand                        Name:  George W. Murphy
Title: Vice President, Finance               Title: President