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                                                                EXHIBIT 4a


                       COMMERCIAL DEMAND PROMISSORY NOTE


$7,500,000.00                                           Hartford, Connecticut
                                                             November 7, 1995


FOR VALUE RECEIVED, the undersigned hereby promises to pay to THE BANK OF
BOSTON CONNECTICUT (together with its successors or assigns, the "Bank"), a
banking corporation with its Head Office at 31 Pratt Street, Hartford
Connecticut 06103, ON DEMAND the aggregate principal amount of all loans made
by the Bank to the undersigned pursuant to the letter agreement between the
Bank and the undersigned dated November 7, 1995, as shown in the schedule
attached hereto (the "Note Schedule"), together with interest on each loan from
the date such loan is made until the demand thereof at the applicable rate set
forth in the Note Schedule. The principal amount of each loan shall be payable
ON DEMAND or, if demand is not earlier made, on the last day of the applicable
interest period, if any, indicated in the Note Schedule. Interest on the
principal amount of each loan shall be payable in arrears on the same day as
the principal amount is due, provided that interest on each loan bearing
interest at the Base Rate shall be payable on the first day of each month,
beginning on the first of such dates occurring after the date of such loan and
when such loan is due. Loans which are bearing interest at the Base Rate shall
bear interest at a rate per annum equal to the rate of interest announced from
time to time by the Bank at its head office as its Base Rate plus the
applicable margin, if any. The applicable floating rate shall change as and
when the Base Rate changes, and changes in the Base Rate shall take effect on
the day announced unless otherwise specified in the announcement. Interest
shall be calculated on the basis of a 360-day year for the actual number of
days elapsed including holidays and days on which the Bank is not open for the
conduct of banking business.

SECTION 1.  PAYMENT TERMS

1.1  PAYMENTS; PREPAYMENTS.  All payments hereunder shall be made by the
undersigned to the Bank in United States currency at the Bank's address
specified above (or at such other address as the Bank may specify), in
immediately available funds, on or before 2:00 p.m. Hartford time on the due
date thereof. Payments received prior to the occurrence of an Event of Default
(as defined in Section 2) will be applied first to fees, expenses and other
amounts due hereunder (excluding principal and interest); second to accrued
interest; and third to outstanding principal; after the occurrence of an Event
of Default, payments will be applied to obligations under this Note as the Bank
determines in its sole discretion. Subject to Section 1.2, the undersigned may
pay all or a portion of the amount earlier than it is due without premium or
other charge.

1.2  PREPAYMENT CHARGE.  If any loan made under this Note bears interst at a
fixed rate and any prepayment of principal is made for any reason on any date
other than the date scheduled therefor, whether voluntary or as a result of
demand or otherwise, the undersigned shall reimburse the Bank for the loss, if
any, including any lost profits, resulting from such prepayment, as reasonably
determined by the Bank. The undersigned shall pay such loss, setting forth the
Bank's calculation thereof, which notice and calculation (including the method
of calculation) shall be deemed true and correct absent manifest error.

1.3  DEFAULT RATE.  To the extent permitted by applicable law, upon and after
the occurrence of an Event of Default (whether or not the Bank has demanded
payment of this Note), interest on all principal

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and overdue interest due and payable shall, at the option of the Bank, be
payable on demand at a rate per annum equal to 5% above the greater of the rate
of interest otherwise payable hereunder or the Base Rate.

1.4 LATE PAYMENT CHARGE. If a payment of principal or interest hereunder is not
made when due, the undersigned will pay on demand a late payment charge equal
to 3% of the amount of such payment. Nothing in the preceding sentence shall
effect the Bank's right to demand maturity of this Note.

1.5 DEPOSIT ACCOUNT. The undersigned shall maintain with the Bank a commercial
demand deposit account. The undersigned requests and authorizes the Bank to
debit such account for amounts due hereunder on each date such amounts become
due. The undersigned shall maintain sufficient collected balances in this
account to pay any such amounts as they become due.

1.6 CHANGE IN CIRCUMSTANCES. If any change in banking law or regulation or the
administration thereof (whether or not having the force of law) affects the
amount of capital required or expected to be maintained by the Bank or any
entity controlling it, and such amount is increased by reason of this Note, the
Bank may notify the undersigned thereof. The undersigned and the Bank shall
negotiate an adjustment payable to the Bank to compensate for such increase. If
no agreement is reached within 90 days, the Bank may increase the fees payable
hereunder by the amount determined by the Bank to be necessary to provide such
compensation.


SECTION 2.  DEFAULTS AND REMEDIES.

2.1 DEFAULT. The occurrence of any of the following events or conditions shall
constitute an "Event of Default":

(a)(i) default in the payment when due of the principal of or interest on this
Note or (ii) any other default in the payment or performance of this Note or of
any other Obligation or (iii) default in the payment or performance of any
obligation of any Obligor to others for borrowed money or in respect of any
extension of credit or accommodation or under any lease;

(b) failure of any representation or warranty herein or in any agreement,
instrument, document or financial statement delivered to the Bank in connection
herewith to be true and correct in any material respect;

(c) default or breach of any condition under any mortgage, security agreement,
assignment of lease, or other agreement securing, constituting or otherwise
relating to any collateral for the Obligations;

(d) failure to furnish the Bank promptly on request with financial information
about, or to permit inspection by the Bank of any books, records and properties
of any Obligor;

(e) merger, consolidation, sale of all or substantially all of the assets or
change in control of any Obligor, or

(f) any Obligor generally not paying its debts as they become due; the death,
dissolution, termination of existence or insolvency of any Obligor; the
appointment of a trustee, receiver, custodian, liquidator, or other similar
official of any Obligor or any substantial part of its property or the
assignment for the benefit of creditors by any Obligor; or the commencement of
any proceedings under any bankruptcy or insolvency laws by or against the 
Obligor.

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As used herein, "Obligation" means any obligation hereunder or otherwise of any
Obligor to the Bank or to any of its affiliates, whether direct or indirect,
absolute or contingent, due or to become due, now existing or hereafter
arising; and "Obligor" means the undersigned, any guarantor or any other person
primarily or secondarily liable hereunder or in respect hereof, including any
person or entity who has pledged or granted to the Bank a security interest in,
or lien on, property on behalf of the undersigned as collateral for the
Obligations. 

2.2 REMEDIES. Regardless of the undersigned's compliance with any covenant or
other term set forth herein, the Bank may at any time and upon any number of
occasions, in its sole and absolute discretion, make demand on the undersigned
for immediate payment of all amounts outstanding hereunder and under the other
loan documents. Upon an Event of Default described in section 2.1(f)
immediately and automatically, and upon or after the occurrence of any other
event of default at the option of the bank, all obligations of the undersigned
shall become immediately due and payable without notice or demand, and the Bank
shall then have in any jurisdiction where enforcement hereof is sought, the
rights and remedies under the Uniform Commercial Code of Connecticut. All
rights and remedies of the Bank are cumulative and are exclusive of any rights
or remedies provided by law or in equity or in any other agreement and may be
exercised separately or concurrently.

SECTION 3. MISCELLANEOUS

3.1 WAIVER; AMENDMENT. No delay or omission on the part of the Bank in
exercising any right hereunder shall operate as a waiver of such right or of
any other right under this Note. No waiver of any right shall be effective
unless in writing and signed by the Bank, nor shall a waiver on one occasion be
construed as a bar to or waiver of any such right on any future occasion.
Without limiting the generality of the foregoing, the acceptance of the Bank of
any late payment shall not be deemed to be a waiver of the Event of Default
arising as a consequence thereof. Each Obligor waives presentment, demand,
notice, protest, and all other demands and notices in connection with the
delivery, acceptance, performance, default or enforcement of this Note or of any
collateral for the Obligations, and assents to any extensions or postponements
of the time of payment and to any other indulgences under this Note or with
respect to any such collateral, to any substitutions, exchanges or releases of
any such collateral, and to any additions or releases of any other parties or
persons primarily or secondarily liable hereunder, that from time to time may
be granted by the Bank in connection herewith.

3.2 Intentionally left blank.

3.3 TAXES. The undersigned agrees to indemnify the Bank and hold it harmless
from and against any transfer taxes, documentary taxes, assessments or charges
made by any governmental authority by reason of the execution, delivery, and
performance of this Note or any collateral for the Obligations.

3.4 EXPENSES. The undersigned will pay on demand all expenses of the Bank in
connection with the preparation, administration, default, collection, waiver or
amendment of this Note and any other agreement, document, or instrument
evidencing any of the Obligations or in connection with the Bank's exercise,
preservation or enforcement of any of its rights, remedies or options
thereunder, including, without limitation, fees of outside legal counsel or the
allocation costs of in-house legal counsel, accounting, consulting, brokerage
or other similar professional fees or expenses, and any fees or expenses
associated with any travel or other costs relating to any appraisals or
examinations conducted  in connection with the Obligations or any collateral
therefor, and the amount of all such shall, until paid, bear interest at the
rate 


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applicable to principal hereunder (including any default rate) and be an
Obligation secured by any such collateral.

3.5 BANK RECORDS. The entries on the records of the Bank (including any
appearing on this Note) shall be prima facie evidence of the aggregate
principal amount outstanding under this Note and interest accrued thereon.

3.6 INFORMATION. The undersigned shall furnish to the Bank from time to time
with such financial statements and other information relating to any Obligor or
any collateral securing this Note as the Bank may require. All such information
shall be true and correct and fairly represent the financial condition and the
operating results of such Obligor as of the date and for the periods for which
the same are finished. The undersigned shall permit representatives of the Bank
to release and disclose to its affiliates, agents, and contractors, any
financial statements and other information relating to said Obligor provided to
or prepared by or for the Bank in connection with any Obligation. The
undersigned will notify the Bank promptly of the existence or upon the
occurrence of an Event of Default or event which, with the giving of notice or
the passage of time or both, would become an Event of Default.

3.7 GOVERNING LAW; CONSENT TO JURISDICTION. This Note shall be governed by and
construed in accordance with the laws of the State of Connecticut, without
regard to its conflict of law rules. The undersigned agrees that any suit for
the enforcement of this Note may be brought in the courts of such state or any
Federal Court sitting in such state and consents to the non-exclusive
jurisdiction of each such court and to service of process in any such suit
being made upon the undersigned by mail at the address specified below. The
undersigned hereby waives any objection that it may now or hereafter have to
the venue of any such court or that such suit was brought in an inconvenient
court.

3.8 SEVERABILITY; AUTHORIZATION TO COMPLETE; PARAGRAPH HEADINGS. If any portion
of this Note shall be invalid, illegal, or unenforceable, such provisions shall
not in any way be affected or impaired thereby. The Bank is hereby authorized,
without further notice, to fill in any blank spaces on this Note, and to date
this Note as of the date funds are first advanced hereunder. Paragraph headings
are for the convenience of reference only and are not part of this Note and
shall not affect its interpretations.

3.9 WAIVERS. THE BANK (BY ITS ACCEPTANCE OF THIS NOTE) AND THE UNDERSIGNED
AGREE THAT NEITHER OF THEM NOR ANY ASSIGNEE OR SUCCESSOR SHALL (A) SEEK A JURY
TRIAL IN ANY LAWSUIT, PROCEEDING, COUNTERCLAIM, OR ANY OTHER ACTION BASED UPON,
OR ARISING OUT OF, THIS NOTE, ANY RELATED INSTRUMENTS, ANY COLLATERAL OR THE
RELATIONSHIP BETWEEN OR AMONG ANY OF THEM, OR (B) SEEK TO CONSOLIDATE ANY SUCH
ACTION WITH ANY OTHER ACTION IN WHICH A JURY TRIAL CANNOT BE OR HAS NOT BEEN
WAIVED. THE PROVISIONS OF THIS PARAGRAPH SHALL BE SUBJECT TO NO EXCEPTIONS.
NEITHER THE BANK NOR THE UNDERSIGNED HAS AGREED WITH OR REPRESENTED TO THE
OTHER THAT THE PROVISIONS OF THIS PARAGRAPH WILL NOT BE FULLY ENFORCED IN ALL
INSTANCES.

THE UNDERSIGNED ACKNOWLEDGES THAT THIS NOTE AND ALL RELATED DOCUMENTS EVIDENCE
A "COMMERCIAL TRANSACTION" AS SUCH IS DEFINED IN CHAPTER 903a OF THE
CONNECTICUT GENERAL STATUTES AS AMENDED FROM TIME TO TIME. THE UNDERSIGNED
HEREBY UNDERSTANDS AND AGREES THAT IN THE EVENT A HOLDER OF THIS NOTE DEEMS IT
NECESSARY, AT ANY TIME WHETHER UPON DEMAND OR PRIOR

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THERETO, TO EXERCISE ITS RIGHTS (WHETHER NOW EXISTING OR HEREAFTER ARISING, AND
WHETHER ACTING IN ITS CAPACITY AS CREDITOR, SECURED PARTY OR IN ANY OTHER
CAPACITY WHATSOEVER, AND SPECIFICALLY INCLUDING, BUT NOT LIMITED TO, THE
EXERCISE OF RIGHTS WHICH MAY DEPRIVE THE UNDERSIGNED OR AFFECT THE USE,
POSSESSION OR ENJOYMENT OF ITS PROPERTY PRIOR TO THE RENDITION OF A FINAL
JUDGMENT) TO OBTAIN A PREJUDGMENT REMEDY AGAINST THE UNDERSIGNED, AND IN THE
EVENT THE UNDERSIGNED WOULD BE ENTITLED TO NOTICE AND/OR HEARING UNDER
CONNECTICUT GENERAL STATUTES TITLE 52, SECTION 278A THROUGH 278N OR ANY OTHER
SIMILAR LAW, PRIOR TO THE EXERCISE BY A HOLDER OF THIS NOTE OF ANY SUCH
PREJUDGMENT REMEDY RIGHTS, THE UNDERSIGNED HEREBY EXPRESSLY WAIVES ANY SUCH
RIGHT TO NOTICE AND JUDICIAL HEARING. PRIOR COURT ORDER OR ANY AND ALL DUE
PROCESS RIGHTS, TO THE BROADEST EXTENT RECOGNIZABLE UNDER THE CONSTITUTIONS OF
THE UNITED STATES AND THE STATE OF CONNECTICUT IN CONNECTION WITH OBTAINING A
PREJUDGMENT REMEDY BY THE HOLDER OF THIS NOTE IN CONNECTION WITH ANY SUIT ON
THIS NOTE OR ANY EXTENSIONS OR RENEWALS OF THE SAME OR ANY DEFICIENCY THEREON.
THE UNDERSIGNED HEREBY EXPRESSLY WAIVES ANY SUCH RIGHT TO NOTICE, HEARING, THE
FURNISHING OF A BOND, OR ANY OTHER DUE PROCESS RIGHT GRANTED BY SUCH STATUTES
OR CONSTITUTIONS.

In witness whereof, the undersigned has caused this Note to be signed in its
corporate name by its duly authorized officer on the day and in the year just
above written.


ACMAT Corporation



       /s/ Henry W. Nozko Jr.
------------------------------------
By:        Henry W. Nozko Jr
Its:       EVP, COO & Treasurer
Dated:     November 30, 1995
233 Main Street
New Britain CT 06050


STATE OF CONNECTICUT)
                    ) ss. Hartford
COUNTY OF HARTFORD  )                                         November 30, 1995
                                                              -----------
Personally appeared Henry W. Nozko Jr, as aforesaid, signer of the foregoing
instrument, and acknowledged the same to be his/her free act and deed as such
EVP, COO & Treasurer, and the free act and deed of said corporation, before me.



       /s/ Natalie P. Sihpol
----------------------------------
Notary Public                   NATALIE P. SIHPOL
My Commission Expires:          NOTARY PUBLIC
                                MY COMMISSION EXPIRES SEP. 30, 1998

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                                    SCHEDULE

$7,500,000 Note dated November 7, 1995 of ACMAT Corporation, payable to the
order of Bank of Boston Connecticut.

<TABLE>
<CAPTION>
                                                                   Date &
                Principal                                        Amount of
                Amount of      Last Day of                        Payment     Notation Made
Date of Loan       Loan      Interest Period    Interest Rate     Received         by
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<S>             <C>          <C>                <C>              <C>          <C>
------------    ---------    ---------------    -------------    ---------    -------------

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</TABLE>


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