MASTER DEMAND BUSINESS LOAN NOTE


Due on Demand                                          $3,500,000.00    
                              
No.7243587-0100                              Date  February 19, 1997

Promise to Pay:  For value received, the undersigned (the "Borrower")
promises to pay On Demand to NBD Bank (the "Bank"), or order, at any office
of the Bank in the State of Michigan, the sum of Three Million Five Hundred
Thousand and no/100 DOLLARS ($3,500,000.00), or such lesser sum as is
indicated on Bank records, plus interest computed on the basis of the actual
number of days elapsed in a year of 360 days at the rate of:

                ------%     per annum until demand or maturity, whether by
                            acceleration or otherwise, (the "Note Rate") and
                            at the rate of 3% per annum above the Note Rate on
                            overdue principal from the date when due until
                            paid; or

                 1/2 %      per annum above the rate announced from time to
                            time by the Bank as its "prime" rate (the "Note
                            Rate"), which rate may not be the lowest rate
                            charged by the Bank to any of its customers, until
                            maturity, whether by demand, acceleration or
                            otherwise, and at the rate of 3% per annum above
                            the Note Rate on overdue principal from the date
                            when due until paid.  Each change in the "prime"
                            rate will immediately change the Note Rate.

In no event shall the interest rate exceed the maximum rate allowed by law;
any interest payment which would for any reason be deemed unlawful under
applicable law shall be applied to principal.

Interest will be computed on the unpaid principal balance from the date of
each borrowing.

The Borrower will pay this sum on demand.  Until demand, the Borrower will
pay consecutive Monthly (monthly/quarterly) installments of interest only
commencing  February 28, 1997.

Master Demand Note:  The Bank has authorized an uncommitted credit facility
to the Borrower in a principal amount not to exceed the face amount of this
note.  The credit facility is in the form of loans made from time to time by
the Bank to the Borrower at the Bank's sole discretion.  This note evidences
the Borrower's obligation to repay those loans.  The aggregate principal
amount of debt evidenced by this note shall be the amount reflected from
time to time in the records of the Bank but shall not exceed the face amount
of this note.  The Borrower acknowledges and agrees that no provision of
this note and no course of dealing by the Bank shall commit the Bank to make
loans to the Borrower and that notwithstanding any provision of this note or
any other instrument or document, all loans evidenced by this note are due
and payable on demand, which may be made by the Bank at any time, whether or
not any event of acceleration then exists.

Credit Agreement:  This note evidences a debt under the terms of a Credit
Authorization Agreement between the Bank and the Borrower dated February 19,
1997, and any amendments.

Security:  To secure the payment of this note and any other present or
future liability of the Borrower, whether several, joint, or joint and
several, the Borrower pledges and grants to the Bank a continuing security
interest in the following described property and all of its additions,
substitutions, increments, proceeds and products, whether now owned or later
acquired ("Collateral"):

1.              All securities and other property of the Borrower in the
                custody, possession or control of the Bank (other than
                property held by the Bank solely in a fiduciary capacity);

2.              All property or securities declared or acknowledged to
                constitute security for any past, present or future liability
                of the Borrower to the Bank;

3.              All balances of deposit accounts of the Borrower with the
                Bank;

4.              The following additional property: accounts receivable,
                inventory, machinery and equipment, general intangibles, and
                a mortgage(s) dated February 19, 1997 on property located at
                5855 Interface Drive and 7232 Jackson Road, Ann Arbor, MI 
                48103                                         .

Bank's Right to Setoff:  The Bank shall have the right at any time to apply
its own debt or liability to the Borrower or to any other party liable on
this note in whole or partial payment of this note or other present or
future liabilities, without any requirement of mutual maturity.

Representations by Borrower:  Each Borrower represents:  (a) that the
execution and delivery of this note and the performance of the obligations
it imposes do not violate any law, conflict with any agreement by which it
is bound, or require the consent or approval of any governmental authority
or any third party; (b) that this note is a valid and binding agreement,
enforceable according to its terms; and (c) that all balance sheets, profit
and loss statements, and other financial statements furnished to the Bank
are accurate and fairly reflect the financial condition of the organizations
and persons to which they apply on their effective dates, including
contingent liabilities of every type, which financial condition has not
changed materially and adversely since those dates.  Each Borrower, other
than a natural person, further represents:  (a) that it is duly organized,
existing and in good standing pursuant to the laws under which it is
organized; and (b) that the execution and delivery of this note and the
performance of the obligations it imposes (i) are within its powers and have
been duly authorized by all necessary action of its governing body; and (ii)
do not contravene the terms of its articles of incorporation or
organization, its by laws, or any partnership, operating or other agreement
governing its affairs.

WAIVER OF JURY TRIAL:  The Bank and the Borrower, after consulting or having
had the opportunity to consult with counsel, knowingly, voluntarily and
intentionally waive any right either of them may have to a trial by jury in
any litigation based upon or arising out of this note or any related
instrument or agreement or any of the transactions contemplated by this note
or any course of conduct, dealing, statements whether oral or written, or
actions of either of them.  Neither the Bank nor the Borrower shall seek to
consolidate, by counterclaim or otherwise, any action in which a jury trial
has been waived with any other action in which a jury trial cannot be or has
not been waived.  These provisions shall not be deemed to have been modified
in any respect or relinquished by either the Bank or the Borrower except by
a written instrument executed by both of them.

ADDRESS:                              BORROWER:
5855 Interface Drive                
Ann Arbor, MI  40103                Interface Systems, Inc.                  
       
                                    By: David O Schupp                       
                              
                                    Its:  Treasurer