Exhibit 10.28




                                 PROMISSORY NOTE

<TABLE>
<CAPTION>

    Principal        Loan Date       Maturity     Loan No.     Call      Collateral       Account         Officer      Initials
<S>                  <C>       <C>             <C>           <C>       <C>            <C>               <C>           <C>
  $1,000,000.00      11-17-1997     07-31-1998       NEW       LINE           U         921101700;01        LGW

</TABLE>

    References in the shaded area are for Lender's use only and do not limit the
applicability of this document to any particular loan or item.

Borrower: MicroFrame, Inc. (TIN: 22-2413505)   Lender:   UNITED NATIONAL BANK
          21 Meridian Road                               1130 ROUTE 22 EAST
          Edison, NJ  08820                              P.O. BOX 6000
                                                         BRIDGEWATER, NJ  08807

--------------------------------------------------------------------------------

Principal Amount: $1,000,000.00                Initial Rate: 9.000%  
Date of Note: November 17, 1997

PROMISE TO PAY. Microframe, Inc. ("Borrower") promises to pay to UNITED NATIONAL
BANK ("Lender"),  or order, in lawful money of the United States of America, the
principal amount of One Million & 00/100 Dollars  ($1,000,000.00)  or so much as
may be outstanding,  together with interest on the unpaid outstanding  principal
balance of each  advance.  Interest  shall be  calculated  from the date of each
advance until repayment of each advance.
Borrower also promises to pay all applicable fees and expenses.

PAYMENT.  Borrower will pay this loan on demand, or if no demand is made, in one
payment of all  outstanding  principal plus all accrued unpaid  interest on July
31, 1998.  In addition,  Borrower will pay regular  monthly  payments of accrued
unpaid  interest  beginning  December  17,  1997,  and all  subsequent  interest
payments are due on the same day of each month after that.  The annual  interest
rate for this Note is computed  on a 365/360  basis;  that is, by  applying  the
ratio of the annual  interest  rate over a year of 360 days,  multiplied  by the
outstanding  principal  balance,  multiplied  by the  actual  number of days the
principal  balance is outstanding.  Borrower will pay Lender at Lender's address
shown above or at such other place as Lender may  designate  in writing.  Unless
otherwise  agreed or required by applicable law,  payments will be applied first
to accrued unpaid interest,  then to principal,  and any remaining amount to any
unpaid collection costs and late charges.

VARIABLE INTEREST RATE. The interest rate on this Note is subject to change from
time to time based on changes in an independent index, which is the "Prime Rate"
with respect to any day means the rate of interest  adopted and made public from
time to time by the Chase Manhattan Bank, New York, N.Y.; or its successors,  as
its  Prime  Rate,  but does not  reflect  the rate of  interest  charged  to any
particular class of borrower.  In the event that there should be a change in the
announced  Prime Rate of Chase  Manhattan Bank which would result in a change in
the rate of interest  on this Note,  then,  in that event,  the rate of interest
herein shall change accordingly as of the date of the said change without notice
to the Borrower(s) or any Endorser,  Guarantor, or Surety. Any such change shall
not effect or alter any of the terms and  conditions of this Note,  all of which
shall  remain  in  full  force  and  effect  (the  "Index").  The  Index  is not
necessarily the lowest rate charged by Lender on its loans. If the Index becomes
unavailable  during the term of this loan,  Lender may  designate  a  substitute
index after notice to Borrower. Lender

                                                                                

<PAGE>

                                 PROMISSORY NOTE
                                   (Continued)

will tell  Borrower the current  Index rate upon  Borrower's  request.  Borrower
understands  that  Lender  may make  loans  based on  other  rates as well.  The
interest  rate  change  will not occur  more  often  than  each  DAY.  The Index
currently  is 8.500% per annum.  The  interest  rate to be applied to the unpaid
principal balance of this Note will be at a rate of 0.500 percentage points over
the Index,  resulting in an initial rate of 9.000% per annum.  NOTICE:  Under no
circumstances  will the interest rate on this Note be more than the maximum rate
allowed by applicable law.

PREPAYMENT. Borrower may pay without penalty all or a portion of the amount owed
earlier than it is due. Early  payments will not,  unless agreed to by Lender in
writing,  relieve Borrower of Borrower's obligation to continue to make payments
of accrued unpaid interest. Rather, they will reduce the principal balance due.

LATE  CHARGE.  If a payment  is 10 days or more late,  Borrower  will be charged
5.000% of the  regularly  scheduled  payment.  This late charge shall be paid to
Lender by Borrower  for the  purpose of  defraying  the expense  incident to the
handling of the delinquent payment.

DEFAULT.  Borrower  will be in  default  if any of the  following  happens:  (a)
Borrower  fails to make any payment when due.  (b)  Borrower  breaks any promise
Borrower has made to Lender, or Borrower fails to comply with or to perform when
due any other term, obligation, covenant, or condition contained in this Note or
any agreement  related to this Note, or in any other  agreement or loan Borrower
has with Lender.  (c)  Borrower  defaults  under any loan,  extension of credit,
security  agreement,  purchase or sales agreement,  or any other  agreement,  in
favor of any  other  creditor  or  person  that  may  materially  affect  any of
Borrower's  property  or  Borrower's  ability  to  repay  this  Note or  perform
Borrower's obligations under this Note or any of the Related Documents.  (d) Any
representation  or  statement  made or  furnished  to Lender by  Borrower  or on
Borrower's  behalf is false or misleading in any material  respect either now or
at the time made or furnished.  (e) Borrower  becomes  insolvent,  a receiver is
appointed for any part of Borrower's property,  Borrower makes an assignment for
the benefit of creditors,  or any proceeding is commenced  either by Borrower or
against Borrower under any bankruptcy or insolvency laws. (f) Any creditor tries
to take any of Borrower's  property on or in which Lender has a lien or security
interest.  This includes a garnishment of or levy on any of Borrower's  accounts
with Lender. (g) Any guarantor dies or any of the other events described in this
default  section  occurs  with  respect to any  guarantor  of this  Note.  (h) A
material  adverse  change occurs in Borrower's  financial  condition,  or Lender
believes the prospect of payment or performance of the indebtedness is impaired.
(i) Lender in good faith deems itself insecure.

If any default,  other than a default in payment, is curable and if Borrower has
not been given a notice of a breach of the same  provision  of this Note  within
the preceding twelve (12) months,  it may be cured (and no event of default will
have occurred) if Borrower, after receiving written notice from Lender demanding
cure of such default:  (a) cures the default  within thirty (30) days; or (b) if
the cure requires more than thirty (30) days,  immediately initiates steps which
Lender deems in Lender's  sole  discretion  to be sufficient to cure the default
and  thereafter  continues  and  completes all  reasonable  and necessary  steps
sufficient to produce compliance as soon as reasonably practical.

LENDER'S  RIGHTS.  Upon default,  Lender may declare the entire unpaid principal
balance on this Note and all accrued unpaid interest  immediately  due,  without
notice, and then Borrower will pay that amount. Upon default,  including failure
to pay upon final maturity,  Lender, at its option, may also, if permitted under
applicable  law,  increase  the  variable  interest  rate on this  Note to 5.000
percentage  points over the Index. The interest rate will not exceed the maximum
rate  permitted by applicable  law.  Lender may hire or pay someone else to help
collect this Note if

                                                                                

<PAGE>

                                 PROMISSORY NOTE
                                   (Continued)

Borrower does not pay. Borrower also will pay Lender that amount. This includes,
subject  to any  limits  under  applicable  law,  Lender's  attorneys'  fees and
Lender's legal expenses whether or not there is a lawsuit,  including attorneys'
fees and legal expenses for bankruptcy  proceedings (including efforts to modify
or vacate  any  automatic  stay or  injunction),  appeals,  and any  anticipated
post-judgment collection services. If not prohibited by applicable law, Borrower
also will pay any court  costs,  in addition to all other sums  provided by law.
This Note has been  delivered  to Lender and  accepted by Lender in the State of
New Jersey.  If there is a lawsuit,  Borrower  agrees upon  Lender's  request to
submit to the  jurisdiction of the courts of SOMERSET  County,  the State of New
Jersey.  Lender  and  Borrower  hereby  waive the right to any jury trial in any
action, proceeding, or counterclaim brought by either Lender or Borrower against
the other.  This Note shall be governed by and construed in accordance  with the
laws of the State of New Jersey.

RIGHT OF SETOFF.  Borrower  grants to Lender a contractual  possessory  security
interest in, and hereby assigns,  conveys,  delivers,  pledges, and transfers to
Lender all Borrower's right,  title and interest in and to, Borrower's  accounts
with  Lender  (whether  checking,  savings,  or some other  account),  including
without  limitation all accounts held jointly with someone else and all accounts
Borrower may open in the future,  excluding  however all IRA and Keogh accounts,
and all trust  accounts  for which the  grant of a  security  interest  would be
prohibited  by law.  Borrower  authorizes  Lender,  to the extent  permitted  by
applicable  law, to charge or setoff all sums owing on this Note against any and
all such accounts.

COLLATERAL.  This Note is  secured by a  Perfected  Security  Interest  by UCC-1
filings on business assets.

LINE OF CREDIT.  This Note evidences a revolving line of credit.  Advances under
this Note may be requested  orally by Borrower or as provided in this paragraph.
Lender  may,  but need not,  require  that all oral  requests  be  confirmed  in
writing.  All  communications,  instructions,  or  directions  by  telephone  or
otherwise  to Lender are to be directed  to Lender's  office  shown  above.  The
following  party or parties are  authorized  as provided  in this  paragraph  to
request advances under the line of credit until Lender receives from Borrower at
Lender's  address shown above written  notice of revocation of their  authority:
Stephen  B.  Gray,  President;  and  John F.  McTigue,  Vice  President  & Chief
Financial  Officer.  Advances under this line are at the sole  discretion of the
Bank and are in minimum amounts of One Thousand  ($1,000.00)  Dollars. To induce
the Bank to accept this Note and make advances under this Note, the  undersigned
waives any rights that it may have arising out of past or present  agreements or
representations that would obligate the Bank to make such advances. Requests for
such advances can be made by crediting the undersigned  account # 400-335-9 (the
Borrower's  account).  Borrower  agrees to be liable  for all sums  either:  (a)
advanced in accordance  with the  instructions  of an  authorized  person or (b)
credited to any of Borrower's accounts with Lender. The unpaid principal balance
owing on this Note at any time may be evidenced by  endorsements on this Note or
by Lender's internal records,  including daily computer print-outs.  Lender will
have no  obligation  to advance  funds  under this Note if: (a)  Borrower or any
guarantor  is in  default  under the terms of this  Note or any  agreement  that
Borrower or any  guarantor  has with Lender,  including  any  agreement  made in
connection  with the signing of this Note; (b) Borrower or any guarantor  ceases
doing  business or is insolvent;  (c) any guarantor  seeks,  claims or otherwise
attempts to limit,  modify or revoke such guarantor's  guarantee of this Note or
any other loan with Lender;  (d) Borrower has applied funds provided pursuant to
this Note for purposes other than those  authorized by Lender;  or (e) Lender in
good faith deems itself insecure under this Note or any other agreement  between
Lender and Borrower.


                                                                                

<PAGE>


                                 PROMISSORY NOTE
                                   (Continued)

ANNUAL RENEWAL. Not withstanding the foregoing,  the unpaid principal balance of
the Note shall be due and  payable,  if not called  earlier,  together  with all
accrued and unpaid interest, fees and charges from the date of this Note to July
31, 1998. The Lender will have the option to renew the Line of Credit created by
this Note and may terminate it at its absolute  discretion by giving thirty (30)
days written  notice to the Borrower at any time.  Should the Bank choose not to
renew the facility,  the Borrower(s)  shall pay the Bank the entire  outstanding
principal balance together with all accrued and unpaid interest, thereon and all
other unpaid fee, charges, and expenses.

BORROWER'S FINANCIAL STATEMENTS. Borrower covenants and agrees with Lender that,
while this  Agreement is in effect,  Borrower shall furnish Lender with, as soon
as available,  but in no event later than ninety (90) days after the end of each
fiscal year,  Borrower's  balance sheet and income statement for the year ended,
audited by a certified public accountant  satisfactory to Lender.  All financial
reports  required  to be  provided  under this  Agreement  shall be  prepared in
accordance  with  generally  accepted  accounting   principles,   applied  on  a
consistent basis, and certified by Borrower(s) as being true and correct.

INTERIM  FINANCIAL  STATEMENTS.  Borrower  shall furnish Lender with, as soon as
available,  but in no event  later  than  sixty  (60) days after the end of each
fiscal  quarter,  Profit and Loss  Statements and Account  Receivables  list and
aging report. All financial reports required to be provided under this Agreement
shall be supplied by Borrower,  prepared on a consistent  basis and certified by
Borrower as being true and correct.

AUTOMATIC  PAYMENTS.  Borrower hereby authorizes Lender  automatically to deduct
from Borrower's  account numbered  400-335-9 the amount of any loan payment.  If
the funds are  insufficient to cover any payment,  Lender shall not be obligated
to advance funds to cover the payment. At any time and for any reason,  Borrower
or Lender may voluntarily terminate Automatic Payments.

BORROWING  BASE  REQUIREMENTS.  Borrower  covenants  and agrees with Lender that
while this Agreement is in effect: I) Maximum  borrowings shall be the lesser of
a) $1,000,000.00;  or b) 75.000% of aggregate amount of "Eligible Accounts." II)
Eligible  Accounts shall be Accounts  Receivable that are under ninety (90) days
evidenced  by  monthly  Borrowing  Base   Certificate.   III)  Monthly  Accounts
Receivable  aging  reports are to be submitted to Lender,  as soon as available,
but in no case later than ten (10) days after the end of each month.  IV) Lender
will  reserve  the  right to  conduct  an audit of  Accounts  Receivable,  twice
annually,  at the  Borrower's  expense  or at any  time and  frequency  should a
condition of default exist.

GENERAL  PROVISIONS.  This Note is payable on demand.  The inclusion of specific
default  provisions  or rights of Lender  shall not preclude  Lender's  right to
declare payment of this Note on its demand.  Lender may delay or forgo enforcing
any of its rights or remedies under this Note without losing them.  Borrower and
any other  person who signs,  guarantees  or endorses  this Note,  to the extent
allowed by law,  waive  presentment,  demand for payment,  protest and notice of
dishonor.  Upon any  change  in the terms of this  Note,  and  unless  otherwise
expressly  stated in  writing,  no party who signs this Note,  whether as maker,
guarantor,  accommodation  maker or endorser,  shall be released from liability.
All such parties agree that Lender may renew or extend  (repeatedly  and for any
length of time) this loan, or release any party or guarantor or  collateral;  or
impair,  fail to  realize  upon or perfect  Lender's  security  interest  in the
collateral;  and take any other action  deemed  necessary by Lender  without the
consent  of or notice to anyone.  All such  parties  also agree that  Lender may
modify this loan without the consent of or notice to anyone other than the party
with whom the modification is made.

                                                                                

<PAGE>


                                 PROMISSORY NOTE
                                   (Continued)

PRIOR TO SIGNING THIS NOTE,  BORROWER READ AND  UNDERSTOOD ALL THE PROVISIONS OF
THIS NOTE,  INCLUDING THE VARIABLE INTEREST RATE PROVISIONS.  BORROWER AGREES TO
THE TERMS OF THE NOTE AND ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THE NOTE.

BORROWER:

MicroFrame, Inc.


By:________________________________________
      John F. McTigue, Vice President

ATTEST:


____________________________________________                (Corporate Seal)