October 16, 1996

                              FIRST AMENDMENT TO LEASE 


    This FIRST AMENDMENT TO LEASE ("First Amendment") is made on the 16th day
of October, 1996 between CMD REALTY INVESTMENT FUND, L.P., an Illinois limited
partnership ("Landlord"), and DATAMETRICS SYSTEMS CORPORATION, a Delaware
corporation ("Tenant").

    A.   Upland Industries Corporation, a Nebraska corporation and Collin
Equities, Inc., a Texas corporation, as tenants in common collectively,
("Original Landlord") and Tenant previously entered into that certain Office
Building Lease, dated July 31, 1992 ("Lease"), regarding the lease of certain
premises commonly known as Suite 300 ("Original Premises") in the building
("Building") commonly known as One Monument Place, 12150 Monument Drive,
Fairfax, Virginia 22033-4051.  Landlord is successor to Original Landlord.

    B.   Pursuant to the terms and conditions of Section 5 of Addendum I to the
Lease, Tenant desires to exercise its Right of First Offer contained therein,
and Landlord and Tenant desire to expand the Original Premises and make certain
other modifications to the terms and conditions of the Lease, all pursuant to
the terms and conditions hereof.

    Landlord and Tenant agree as follows:

         1.   DEFINITIONS.  All of the terms used in this First Amendment shall
have tile same meanings as set forth in the Lease except to the extent expressly
set forth herein.

              (a)  EXPANSION SPACE.  The term "EXPANSION SPACE" means those
certain premises known as Suite 301 designated on Exhibit A attached hereto and
made a part hereof.  It is hereby stipulated that Suite 301 is 5,224 rentable
square feet.

              (b)  EXPANSION SPACE COMMENCEMENT DATE.  The term "EXPANSION
SPACE COMMENCEMENT DATE" means the date Landlord notifies Tenant in writing that
the Expansion Space is ready for occupancy as defined in Section 3.03 of the
Lease.

         2.   IMPROVEMENTS TO BE CONSTRUCTED.  Landlord will make or construct
certain improvements in the Premises ("Tenant Improvements") substantially in
accordance with the Working Drawings and Specifications (as hereinafter defined)
and subject and according to the terms and conditions set forth herein.

              (a)  PREMISES WORKING DRAWINGS AND SPECIFICATIONS.  Landlord
shall cause to be prepared and delivered to Tenant working drawings and
specifications for the Tenant Improvements ("Working Drawings and
Specifications").  Tenant shall have the right to approve or disapprove the
Working Drawings and Specifications by written notice to Landlord within 5 days
after receipt thereof, which approval may not be unreasonably withheld.  If
Tenant fails to deliver a written notice of approval or disapproval within such
5 day period, the Working Drawings and Specifications shall be deemed approved. 
If Tenant delivers to Landlord within


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such 5 day period a written notice of disapproval of the Working Drawings and
Specifications, then Landlord shall revise the Working Drawings and
Specifications to remove the reasons for Tenant's disapproval within 10 days of
Landlord's receipt of such disapproval notice.  Landlord's preparation of the
Working Drawings and Specifications shall not constitute assumption of any
liability on the part of Landlord for the accuracy of their conformity with the
requirements of any building code or the municipal governmental regulation or
ordinance.

                     (i)     PREMISES CONSTRUCTION DOCUMENTS.  Promptly after
Tenant's approval or deemed approval of the Working Drawings and Specifications,
Landlord shall deliver to Tenant a copy of a written contract covering the
construction of the Premises Improvements ("Construction Contract"), setting
forth the total cost of completion of the Premises Improvements in accordance
with the Working Drawings and Specifications ("Contract Amount").  The Contract
Amount, plus Landlord's construction management fee (which shall equal five
percent (5%) of the Contract Amount) and the cost of preparing the Working
Drawings and Specifications are collectively referred to herein as the
"Construction Cost".

                    (ii)     PREMISES IMPROVEMENTS ALLOWANCE.

                             (a)  PREMISES IMPROVEMENTS ALLOWANCE.  The term
"Improvements Allowance" means, for the purpose of this Lease, an amount equal
to the lesser of (A) the Construction Cost, and (B) the Maximum Improvements
Allowance (as hereinafter defined).

                             (b)  MAXIMUM IMPROVEMENTS ALLOWANCE.  The term
"Maximum Improvements Allowance" shall be determined by the product of (x)
$20.00 multiplied by the number of square feet of the Rentable Area contained in
the Expansion Space and (y) the percentage obtained by dividing the number of
months remaining under the Term from and after the Expansion Space Commencement
Date by 60 (60 being the total number of months in the Term).

                   (iii)     PREMISES CONSTRUCTION ESCROW.  Landlord shall,
prior to the commencement of construction of the Premises Improvements,
establish an escrow ("Construction Escrow") with itself or a title company
satisfactory to Landlord ("Escrow Agent").  Landlord shall deposit in the
Construction Escrow as and when required amounts ("Landlord Deposits") which in
the aggregate do not exceed the Improvements Allowance.  If the Construction
Cost is greater than the Maximum Improvements Allowance, then Tenant shall
deposit in the Construction Escrow within seven (7) business days after the
establishment of the Construction Escrow an amount ("Tenant Deposit") equal to
the difference between (i) the Construction Cost and (ii) the Maximum
Improvements Allowance.  All amounts of the Construction Cost shall be paid by
the Escrow Agent.  All amounts payable to the Escrow Agent with respect to the
creation, maintenance and disbursement of the Construction Escrow shall be the
sole responsibility of Tenant.

         3.   ADDITIONAL PREMISES.  From and after the Expansion Space
Commencement Date, Landlord does hereby lease to Tenant and Tenant does hereby
take and rent from Landlord the Expansion Space in "As Is" condition and upon
all of the terms and


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conditions of this First Amendment and the Lease except to the extent expressly
set forth herein.  From and after the Expansion Space Commencement Date, the
term "Premises" under the Lease shall be deemed to include the Expansion Space,
and Landlord and Tenant agree that from and after the Expansion Space
Commencement Date, the rentable area contained in the Premises shall be 18,874
square feet.

         4.   BASE RENT.  Notwithstanding anything contained in the Lease to
the contrary, commencing on the Expansion Premises Commencement Date, Tenant
shall pay to Landlord in the manner described in the Lease, Base Rent in equal
monthly installments as follows:

                                                 MONTHLY INSTALLMENT
              PERIOD                             OF BASE RENT

              Expansion Space Commencement            $25,705.99
              Date - 10/31/97

         5.   TENANT'S SHARE.  Notwithstanding anything contained in the Lease
to the contrary, Tenant's proportionate share, as defined in Section 1.01 of 
the Lease, as amended, shall be, from and after the Additional Premises 
Commencement Date, equal to 8.5855 %.

         6.   ADDENDUM I OF THE LEASE.  Sections 2, 3, 4, 5, and 9 of Addendum
I of the Original Lease are no longer applicable and are hereby deleted in their
entirety.

         7.   BROKERAGE.  Tenant represents and warrants to Landlord that, no
broker, agent, commission salesperson, or other person has represented Tenant
other than The Bank Companies, Inc.  ("Broker") in the negotiations for this
First Amendment, and that no commissions and/or fees of any kind are due and
payable in connection with this transaction other than that agreed to between
Landlord and Broker.  Tenant agrees to indemnify and hold Landlord harmless from
all loss, cost, and damage suffered or incurred by Landlord as a result of a
breach by Tenant of the representation and warranty contained herein, whether or
not disclosed.

         8.   PAYMENTS DUE LANDLORD.  Notwithstanding anything to the contrary
in the Lease, all rent and other payments required to be made by Tenant to
Landlord under the Lease, as amended from time to time, shall be payable to
Landlord at CMD Realty Investment Fund, L.P., c/o The First National Bank of
Chicago, P.O.  Box 70485, Chicago, Illinois 60673-0485, or at such other address
as Landlord may specify from time to time by written notice delivered in
accordance herewith.

         9.   NOTICES.  The address for notice or documents delivered to
Landlord set forth in the Lease is hereby deleted, and the following is
substituted in its place:


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         CMD Realty Investment Fund, L.P.
         c/o CMD Realty Investors, Inc.  
         12150 Monument Drive, Suite 215 
         Fairfax, Virginia 22033-4051 
         Attention: Senior Property Manager

with copies to:

         CMD Realty Investment Fund, L.P.  
         c/o CMD Realty Investors, Inc.  
         2500 Meridian Parkway, Suite 135 
         Durham, NC 27713
         Attention: Asset Manager

         CMD Realty Investment Fund, L.P.
         c/o CMD Realty Investors, Inc.
         227 West Monroe Street, Suite 3900
         Chicago, Illinois 60606
         Attention: General Counsel

         10.  AMENDMENT.  This First Amendment is an amendment to the Lease,
and not a lease for the Expansion Space separate and apart from the lease of the
premises under the Lease.  Notwithstanding the foregoing, any default by Tenant
under this First Amendment shall be a default, and Landlord may thereupon
exercise any and all rights available for default, under the Lease.

         11.  FULL FORCE AND EFFECT.  All of the terms and conditions set forth
in the Lease shall remain in full force and effect, except to the extent
otherwise expressly set forth in this First Amendment.

         12.  CONFLICTS.  In the event that any of the provisions of the Lease
conflict with any of the terms and provisions of this First Amendment, the terms
and conditions of this First Amendment shall prevail.

         13.  EXCULPATION.  Neither the partners, if Landlord is a partnership,
or if Landlord is a trustee of a trust, the beneficiaries of such trust, nor the
shareholders (nor any of the partners comprising same), directors or officers of
any of the foregoing (collectively, the "Parties") shall be liable for the
performance of Landlord's obligations under this First Amendment and the Lease. 
Tenant shall look solely to Landlord to enforce Landlord's obligations hereunder
and shall not seek any damages against the rest of the Parties.  The liability
of Landlord for Landlord's obligations under this First Amendment and the Lease
shall not exceed and shall be limited to the value of Landlord's interest in the
Building and Tenant shall not look to the property or assets of any of the
Parties in seeking either to enforce Landlord's obligations under this First
Amendment or the Lease or to satisfy a judgment against Landlord.


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         14.  TIME OF ESSENCE.  Time is of the essence of each and every term
of this First Amendment.

                             LANDLORD:

                             CMD REALTY INVESTMENT FUND, L.P., 
                             an Illinois limited partnership

                                  By:  CMD REIM, INC., an Illinois corporation,
                                  General Partner


                                  /s/ James R. Higley
                                  --------------------------------------------

                                  By:    James R. Higley

                                         Its:   Vice President 

                             TENANT:

                             DATAMETRICS SYSTEMS CORPORATION, a Delaware 
                             corporation


                             /s/ John N. Dripps
                             -------------------------------------------------

                             By:    John Dripps
                             Its:   Vice President, Finance & Admin.