<PAGE>

                   AMENDMENT TO LOAN AND SECURITY AGREEMENT
                   ----------------------------------------
                         DATED FEBRUARY 10, 2000 AMONG
                         -----------------------------
     DYNAMICS RESEARCH CORPORATION, DRC ENCODER, INC., DRC METRIGRAPHICS,
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                INC., DRC SOFTWARE, INC., AND DRC TELECOM, INC.
                -----------------------------------------------
                                      AND
                                      ---
        BROWN BROTHERS HARRIMAN & CO., AS ADMINISTRATIVE AGENT AND AS A
        ---------------------------------------------------------------
       LENDER, AND FAMILY BANK, FSB, AS COLLATERAL AGENT AND AS A LENDER
       -----------------------------------------------------------------

     This Amendment to Loan and Security Agreement (hereinafter, the
"Amendment") is made as of the 31st day of March, 2000 by and between Dynamics
Research Corporation, DRC Encoder, Inc., DRC Metrigraphics, Inc., DRC Software,
Inc., and DRC Telecom, Inc., Massachusetts corporations with their principal
executive offices at 60 Frontage Road, Andover, Massachusetts (hereinafter,
individually and collectively, jointly and severally, the "Borrowers") and Brown
Brothers Harriman & Co., as administrative agent and as a lender, and Family
Bank, FSB, as collateral agent and as a lender (hereinafter, individually and
collectively, the "Lenders"), in consideration of the mutual covenants contained
herein and the benefits to be derived herefrom. Unless otherwise specified
herein, all capitalized terms shall have the same meaning as set forth in the
Loan Agreement (as defined hereinbelow).

                             W I T N E S S E T H:
                             -------------------

     WHEREAS, the Borrowers executed and delivered to the Lenders a certain Loan
and Security Agreement dated February 10, 2000, (hereinbefore and hereinafter,
the "Loan Agreement") pursuant to which, among other things, the Lenders
extended in favor of the Borrowers a Revolving Credit in the original maximum
principal amount of $20,000,000.00; and

     WHEREAS, the Borrowers have requested that the Lenders correct the error in
Section 11-9 of the Loan Agreement; and

     WHEREAS, the Lenders have agreed to such correction to reflect the original
intent of the parties, BUT ONLY on the terms and conditions contained in this
                       --------
Amendment; and

     WHEREAS, all parties have determined that this Amendment is in their
respective best interests.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

     1.   The Borrowers hereby certify to the Lenders that, to the best of the
Borrowers' knowledge and belief after due inquiry, the representations and
warranties contained in the Loan Agreement, as corrected by this Amendment, are
true as of the date hereof and that no Event of Default under the Loan Agreement
or any document executed in connection therewith has occurred and is continuing.
<PAGE>

     2.   Section 11-9 of the Loan Agreement is hereby amended by deleting the
words "less than" used therein and substituting the words "greater than"
therefor.

     3.   This Amendment and all other documents, instruments or agreements
executed in connection herewith incorporate all discussions and negotiations
between the Borrowers and the Lenders, either expressed or implied, concerning
the matters included herein, any statute, custom, or usage to the contrary
notwithstanding. No such discussions or negotiations shall limit, modify or
otherwise affect the provisions hereof. No modification, amendment, or waiver of
any provision of this Amendment or the Loan Agreement or any provision under any
other agreement, document or instrument between the Borrowers and the Lenders
shall be effective unless executed in writing by the party to be charged with
such modification, amendment or waiver, and if such party be the Lenders, then
by a duly authorized officer of each Lender.

     4.   Except as specifically modified herein, the Loan Agreement shall
remain in full force and effect as originally written and the Borrowers hereby
ratify and confirm all terms and conditions contained therein and further ratify
and reaffirm all representations and warranties made therein as of the date
hereof.

     5.   This Amendment shall be construed in accordance with and governed by
the laws of the Commonwealth of Massachusetts and shall take effect as a sealed
instrument.

     IN WITNESS WHEREOF, the parties have hereunto set their hands and seals as
of the date first written above.


                                        DYNAMICS RESEARCH CORPORATION

                                        BY: /S/ David Keleher
                                            -----------------

                                        TITLE: V.P. of Finance, Chief Financial
                                               Officer


                                        DRC ENCODER, INC.

                                        BY: /S/ David Keleher
                                            -----------------

                                        TITLE: V.P. of Finance, Chief Financial
                                               Officer


                                        DRC METRIGRAPHICS, INC.

                                        BY: /S/ David Keleher
                                            -----------------

                                        TITLE: V.P. of Finance, Chief Financial
                                               Officer
<PAGE>

                                        DRC SOFTWARE, INC.

                                        BY: /S/ David Keleher
                                            -----------------

                                        TITLE: V.P. of Finance, Chief Financial
                                               Officer


                                        DRC TELECOM, INC.

                                        BY: /S/ David Keleher
                                            -----------------

                                        TITLE: V.P. of Finance, Chief Financial
                                               Officer


ACKNOWLEDGED AND AGREED:


BROWN BROTHERS HARRIMAN & CO.

By: /s/ Timothy J. Telman
-------------------------

Name:   Timothy J. Telman
-------------------------

Title:  Vice President


FAMILY BANK, FSB

By: /S/ C. Lee Willingham
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Name:   C. Lee Willingham
-------------------------

Title:  Vice President