HALIFAX CORPORATION AMENDMENT TO 8% PROMISSORY NOTES

Exhibit 4.11

HALIFAX CORPORATION

AMENDMENT TO 8% PROMISSORY NOTES

     THIS AGREEMENT is made and entered into, effective for all purposes and in all respects as of the 29th day of June 2005 by and between (i) HALIFAX CORPORATION, a Virginia corporation (the “Company”) and (ii) the ARCH ▇. ▇▇▇▇▇▇▇▇ CHILDREN’S TRUST, dated December 9, 2003 (the “Trust”).

WITNESSETH

     WHEREAS, the Company is indebted to the Trust (pursuant to the Assignment of Promissory Notes dated as of October 18, 2004 by and between the Arch ▇. ▇▇▇▇▇▇▇▇ Trust, dated June 13, 1997 and made irrevocable on December 9, 2002 and the ▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇ Trust, dated December 9, 2002 and the Trust) in the aggregate principal amount of One Million Dollars ($1,000,000), with interest thereon pursuant to the 8% Promissory Notes dated October 8, 1998, October 13, 1998, November 2, 1998 and November 5, 1998 (the “Notes”);

     WHEREAS, the Subordination Agreement, dated March 6, 2002, by and among the Company, Research Industries and Provident Bank (successor by merger to Southern Financial Bank) (the “Subordination Agreement”) subordinates the Notes to the Senior Loan Facility (as defined below) and prohibits repayment of principal of the Notes while the Senior Loan Facility is outstanding without prior approval from the Company’s lender under the Senior Loan Facility;

     WHEREAS, in order to correct the inherent inconsistencies between the Notes and the Subordination Agreement, the Company and the Trust wish to extend the maturity date of the Notes to July 1, 2007, which date is the next day immediately succeeding the expiration of the Amended and Restated Loan and Security Agreement, dated as of November 8, 2004, by and between the Company, Halifax Engineering, Inc., a Virginia corporation, Microserv LLC, a Delaware limited liability company and Halifax AlphaNational Acquisition, Inc., a Delaware corporation, and Provident Bank, a Maryland banking corporation, of Baltimore, Maryland, and the successor by merger to Southern Financial Bank which Amended and Restated Loan and Security Agreement combines, amends and replaces the Security Agreement dated as of March 6, 2002, Change in Terms Agreements dated as of March 12, 2002 and April 3, 2003 and ARTS Security and Finance Agreement dated as of September 9, 2003, each executed by the Company and Bank, as amended, as may be amended and further extended from time to time (the “Senior Loan Facility”);

     WHEREAS, the Trust wishes to waive any rights it has regarding the acceleration of the Notes and the Company’s requirement that the Company provide the Trust with notice of events of default under the Notes which may have arisen or occurred prior to the date of this Agreement, it being understood that the Trust is not waiving its rights regarding the acceleration of the Notes as a result of, or notice of, any events of default under the Notes arising on or after the date hereof;

     NOW, THEREFORE, in consideration of the mutual covenants made herein and other good and valuable consideration, receipt of which is hereby acknowledged, the Company and the Trust hereby agree as follows:

     A. Recitals; Defined Terms. The foregoing recitals are hereby incorporated by this reference and made a substantive part hereof.

     B. Extension of the Maturity Date of the Notes. The Company and the Trust hereby agree that the maturity date of the Notes shall be July 1, 2007, which date is the next day immediately succeeding the expiration of the Senior Loan Facility.

     C. Waiver of Prior Events of Default. The Trust hereby waives any rights it has regarding the acceleration of the Notes and the Company’s requirement that the Company provide the Trust with notice of events of default under the Notes which may have arisen or occurred prior to the date of this Agreement, it being understood that the Trust is not waiving its rights regarding the acceleration of the Notes as a result of, or notice of, any events of default under the Notes arising on or after the date hereof.

     D. Representation and Warranties.

     1. The Company hereby represents and warrants as follows (with the effectiveness of this Agreement being further conditioned upon all such representations and warranties being true and correct in all material respects on the date of this Agreement):

     2. The Trust hereby represents and warrants as follows (with the effectiveness of this Agreement being further conditioned upon all such representations and warranties being true and correct in all material respects on the date of this Agreement):

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     E. Effect on the Agreement. Except as specifically amended or agreed to hereby, the Notes shall continue to be in full force and effect and are hereby in all respects ratified and confirmed. This Agreement shall be binding upon, and shall inure to the benefit of, the parties hereto and their respective successors and assigns.

     F. Execution in Counterparts. This Agreement may be executed in any number of counterparts and by different parties hereto in separate counterparts, each of which when so executed and delivered shall be deemed to be an original and all of which taken together shall constitute but one and the same agreement. Delivery of an executed counterpart of a signature page to this Agreement by telecopier or facsimile shall be effective as delivery of a manually executed counterpart of this Agreement.

[Signature Page Follows]

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     IN WITNESS WHEREOF, the parties have caused this Agreement to be duly executed on their behalf in their respective corporate names by their duly authorized officers all as of the date first above written.

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