CREDIT AUTHORIZATION AGREEMENT



         NBD Bank (the "Bank"), 611 Woodward Avenue, Detroit, Michigan 48226-
3947, has approved the credit facilities listed below (collectively, the
"Credit Facilities," and individually, as designated below) to Interface
Systems, Inc. (the "Borrower"), 5855 Interface Drive, Ann Arbor, Michigan 
48103 (Borrower's Address), subject to the terms and conditions set forth in
this agreement.

         1.0      Credit Facilities.  (Check and complete applicable sections)

         1.1      Uncommitted Credit Authorizations.  The Bank has approved
the uncommitted credit authorizations listed below (collectively, the
"Credit Authorizations," and individually, as designated below) subject to
the terms and conditions of this agreement and the Bank's continuing
satisfaction with the Borrower's financial status.  Disbursements under the
Credit Authorizations are solely at the Bank's discretion.  Any disbursement
on one or more occasions shall not commit the Bank to make any subsequent
disbursement.

         [ x ]    A.       Facility A.  The Bank has approved an uncommitted
Credit Authorization to the Borrower in the principal sum not to exceed
$3,500,000.00 in the aggregate at any one time outstanding ("Facility A"). 
Credit under Facility A shall be in the form of disbursements evidenced by
credits to the Borrower's account and shall be repayable as set forth in a
Master Demand Note executed concurrently (referred to in this agreement both
singularly and together with any other promissory notes referenced in this
Section 1 as the "Notes").  The proceeds of Facility A shall be used for the
following purpose:  Working capital.  Facility A shall expire on August 31,
1997 unless earlier withdrawn.

         [   ]    B.       Facility B (Including Letters of Credit).  The Bank
has approved an uncommitted Credit Authorization to the Borrower in the
principal sum not to exceed $                 
in the aggregate at any one time outstanding ("Facility B").  Facility B
shall include the issuance of [commercial/standby] letters of credit not
exceeding $                       in the aggregate at any one time
outstanding, expiring not later than                                  , 199  
   [which shall include time drafts expiring not later than                  
       , 199    ] (the "Letters of Credit").  (Strike bracketed words if
inapplicable.) Each Letter of Credit shall be in form acceptable to the Bank
and shall bear a fee of     % per year of the face amount of each standby
Letter of Credit plus an issuance fee of 
$                             upon issuance of each Letter of Credit.  (If
no fee is listed, the Letters of Credit shall bear a fee to be agreed upon
by the Bank and the Borrower).  Credit under Facility B shall be in the form
of disbursements evidenced by credits to the Borrower's account and shall be
repayable as set forth in a Master Demand Note executed concurrently
(referred to in this agreement both singularly and together with any other
promissory notes referenced in this Section 1 as the "Notes") or by issuance
of a Letter of Credit upon completion of an application acceptable to the
Bank.  The proceeds of Facility B shall be used for the following purpose:
                                                                          . 
Facility B shall expire on                        , 199      unless earlier
withdrawn.

         [x ]     C.       Facility C (Purchase Money Term Loans *and Leases). 
The Bank has approved an uncommitted credit authorization to the Borrower in
the principal sum not to exceed $200,000.00 in the aggregate at any one time
outstanding ("Facility C").  Facility C shall be in the form of loans
evidenced by the Borrower's notes on the Bank's form (referred to in this
agreement both singularly and together with any other promissory notes
referenced in this Section 1 as the "Notes"), the proceeds of which shall be
used to purchase the following equipment                                     
                                                            .  Interest on
each loan shall accrue at a rate to be agreed upon by the Bank and the
Borrower at the time the loan is made.  The maturity of each note shall not
exceed 60 months from the note date.  Notwithstanding the aggregate amount
of Facility C stated above, the original principal amount of each loan shall
not exceed the lesser of 80% of the cost of the equipment purchased with
loan proceeds or $200,000.00.  Facility C shall expire on August 31, 1997
unless earlier withdrawn. *Leases will not exceed 100%.

[   ]    1.2      Term Loans.  The Bank agrees to extend credit to the
Borrower in the form of term loan(s) (whether one or more, the "Term Loans")
in the principal sum(s) of $250,000.00 respectively, bearing interest and
payable as set forth in the Term Note(s) executed concurrently (referred to
in this agreement both singularly and together with any other promissory
notes referenced in this Section 1 as the "Notes").  The proceeds of the
Term Loans shall be used for the following purpose:                          
                   .

         2.0      Conditions Precedent. 

         2.1      Conditions Precedent to Initial Extension of Credit.  Before
the first extension of credit under this agreement, whether by disbursement
of a loan, issuance of a letter of credit, or otherwise, the Borrower shall
deliver to the Bank, in form and substance satisfactory to the Bank: 

                  A.       Loan Documents.  The Notes; the letter of credit
applications required by Section 1.2; the security agreements, financing
statements, and mortgages required by Section 5.1; the guaranties required
by Section 6.0; the subordination agreements required by Section 7.0; and
any other loan documents which the Bank may reasonably require to give
effect to the transactions contemplated by this agreement;

                  B.       Evidence of Due Organization and Good Standing. 
Evidence satisfactory to the Bank of the due organization and good standing
of the Borrower and every other business entity that is a party to this
agreement or any other loan document required by this agreement; and

                  C.       Evidence of Authority to Enter into Loan Documents. 
Evidence satisfactory to the Bank that (i) each party to this agreement or
any other loan document required by this agreement is authorized to enter
into the transactions contemplated by this agreement and the other loan
documents, and (ii) the person signing on behalf of each such party is
authorized to do so. 

         2.2      Conditions Precedent to Each Extension of Credit.   Before
any extension of credit under this agreement, whether by disbursement of a
loan, issuance of a letter of credit, or otherwise, the following conditions
shall have been satisfied: 

                  A.       Representations.  The representations contained in
Section 10 shall be true on and as of the date of the extension of credit;

                  B.       No Event of Acceleration.  No event of acceleration
shall have occurred and be continuing or would result from the extension of
credit;

                  C.       Continued Satisfaction.  The Bank shall have
remained satisfied with the Borrower's managerial and financial status; 
 
                  D.       Additional Approvals, Opinions, and Documents.  The
Bank shall have received such other approvals, opinions and documents as it
may reasonably request; and

                  E.       Other Conditions.  

                  
         3.0      Borrowing Base/Annual Pay Down.

         3.1      Borrowing Base. (check and complete if applicable)
Notwithstanding any other provision of this agreement, the aggregate
principal amount outstanding at any one time under  (check applicable
clauses)

                  [ x ]    Facility A
                  [    ]   Facility B

shall not exceed the lesser of the Borrowing Base or $3,500,000.00 Borrowing
Base means: (Check and complete applicable clauses)

                  [x]      A.  75% of the Borrower's trade accounts receivable
in which the Bank has a perfected, first priority security interest,
excluding accounts more than 90 days past due from the date of invoice,
accounts subject to offset or defense, government, bonded, affiliate and
foreign accounts, accounts from trade debtors of which more than        % of
the aggregate amount owing from the trade debtor to the Borrower is more
than            days past due, and accounts otherwise unacceptable to the
Bank, plus

                  [x]      B.      Inventory of the Borrower in which the Bank
has a perfected first priority security interest, valued at the lower of
cost or market but not exceeding $    N/A           in the aggregate, as
follows:
                           [  ]    (1) N/A % of aggregate inventory; or

                           [X]     (1) 30% of purchased parts inventory; and

                           [X]     (2)   0% of work-in-process inventory and
service stock and demos; and 

                           [  ]    (3) 30% of finished goods inventory, plus

         [   ]    C.                 % of the                         value of
the Borrower's machinery and equipment in which the Bank has a perfected,
first priority security interest, but not exceeding 
$                                         , plus

         [   ]    D.       Additional Borrowing Base provisions are contained
in the attached addendum.

         3.2      Annual Pay Down. (complete if applicable) Notwithstanding
any other provision of this agreement, there shall be no debt outstanding
under                             for a period of                            
                           (Facility A, Facility B, etc.)   
consecutive months during each fiscal year of the Borrower.

         4.0      Fees and Expenses. (complete if applicable)

         4.1      Fees. Upon closing of a Facility C Loan, the Borrower shall
pay the Bank the following fees, all of which the Borrower acknowledges have
been earned by the Bank:  $25,000.00.

         4.2      Out-of-Pocket Expenses. In addition to any fee set forth in
Section 4.1 above, the Borrower shall reimburse the Bank for its out-of-
pocket expenses and reasonable attorney's fees (including the fees of in-
house counsel) allocated to the Credit Facilities.

         5.0      Security.

         5.1      Payment of the borrowings under the Credit Facilities shall
be secured by a first security interest and/or real estate mortgage, as the
case may be, covering the following property and all its additions,
substitutions, increments, proceeds and products, whether now owned or later
acquired ("Collateral"):   (check and complete applicable clauses)

         [x]      A.       Accounts Receivable. All of the Borrower's
accounts, chattel paper, general intangibles, instruments, and documents (as
those terms are defined in the Michigan Uniform Commercial Code), rights to
refunds of taxes paid at any time to any governmental entity, and any
letters of credit and drafts under them given in support of the foregoing,
wherever located. The Borrower shall deliver to the Bank executed security
agreements and financing statements in form and substance satisfactory to
the Bank.

         [x]      B.       Inventory. All of the Borrower's inventory,
wherever located. The Borrower shall deliver to the Bank executed security
agreements and financing statements in form and substance satisfactory to
the Bank.

         [x]      C.       Equipment. All of the Borrower's equipment,
wherever located. The Borrower shall deliver to the Bank executed security
agreements and financing statements in form and substance satisfactory to
the Bank. 

         [x]      D.       Real Estate. The real property, including
improvements, located at 5855 Interface Drive, Ann Arbor, Michigan and 7232
Jackson Road, Ann Arbor, MI.  The Borrower shall deliver to the Bank an
executed mortgage, ALTA mortgage title insurance policy without exceptions,
mortgage survey certified to the Bank and, where applicable, an assignment
of rents, subordinations of leases, and/or collateral assignments of land
contracts, all in form and substance satisfactory to the Bank.

         [    ]   E.       Pledge of 65.6% or 1,400,000 shares of Interface
Systems International, Ltd.

         5.2      No forbearance or extension of time granted any subsequent
owner of the Collateral shall release the Borrower from liability.

         5.3      Additional Collateral/Setoff. To further secure payment of
the borrowings under the Credit Facilities and all of the Borrower's other
liabilities to the Bank, the Borrower grants to the Bank a continuing
security interest in: (i) 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) and (ii) all balances of deposit
accounts of the Borrower with the Bank. 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 for payment of the borrowings under the Credit Facilities, in
whole or partial payment of such borrowings or other present or future
liabilities, without any requirement of mutual maturity.

         5.4      Cross Lien. Any of the Borrower's other property in which
the Bank has a security interest to secure payment of any other debt,
whether absolute, contingent, direct or indirect, including the Borrower's
guaranties of the debts of others, shall also secure payment of and be part
of the Collateral for the Credit Facilities.

[    ]   6.0      Guaranties. (check and complete if applicable) Payment of
the Borrower's liabilities under the Credit Facilities shall be guaranteed
by I.G.K. Industries, Inc., by execution of the Bank's form of guaranty
agreement. The liability of the guarantors, if more than one, shall be joint
and several.

[    ]   7.0      Subordination. (check and complete if applicable)
         The Credit Facilities shall be supported by the subordination of all
debt owing from the Borrower to                                              
              , including without limitation debt currently owing in the
amount of $                                             , in manner and by
agreement satisfactory to the Bank.

         8.0      Affirmative Covenants. So long as any debt remains
outstanding under the Credit Facilities, the Borrower, and each of its
subsidiaries, if any, shall:

         8.1      Insurance. Maintain insurance with financially sound and
reputable insurers covering its properties and business against those
casualties and contingencies and in the types and amounts as shall be in
accordance with sound business and industry practices.

         8.2      Existence. Maintain its existence and business operations as
presently in effect in accordance with all applicable laws and regulations,
pay its debts and obligations when due under normal terms, and pay on or
before their due date, all taxes, assessments, fees and other governmental
monetary obligations, except as they may be contested in good faith if they
have been properly reflected on its books and, at the Bank's request,
adequate funds or security has been pledged to insure payment.

         8.3      Financial Records. Maintain proper books and records of
account, in accordance with generally accepted accounting principles where
applicable, and consistent with financial statements previously submitted to
the Bank.

         8.4      Notice. Give prompt notice to the Bank of the occurrence of
(i) any event of acceleration, and (ii) any other development, financial or
otherwise, which would affect the Borrower's business, properties or affairs
in a materially adverse manner.

         8.5      Collateral Audits. (complete if applicable) Permit the Bank
or its agents to perform 
                                                                      audits
of the Collateral. The Borrower shall compensate the Bank for such audits in
(monthly, annual, etc.) accordance with the Bank's schedule of fees as may
be amended from time to time. Whether or not this section has been
completed, the Bank shall retain the right to inspect the Collateral and
business records related to it at such times and at such intervals as the
Bank may reasonably require.

         8.6      Management. (complete if applicable) Maintain Interface
Systems, Inc. as Shareholder.

         8.7      Financial Reports. Furnish to the Bank whatever information,
books, and records the Bank may reasonably request, including at a minimum:
(Check and complete applicable clauses. If the Borrower has subsidiaries,
all financial statements required will be provided on a consolidated and on
a separate basis.)

         [x]      A.       Within 30 days after each monthly period, a
consolidating balance sheet as of the end of that period and statements of
income, cash flows, and retained earnings from the beginning of that fiscal
year to the end of that period, certified as correct by one of its
authorized agents.

         [ x ]    B.       Within 90 days after, and as of the end of, each of
its fiscal years, a detailed audit including a balance sheet and statements
of income, retained earnings, and cash flows certified by an independent
certified public accountant of recognized standing.

         [x]      C.       Within 30 days after and as of the end of each
calendar month*, the following lists, each certified as correct by one of
its authorized agents: (check applicable clauses) *when borrowing

                  [x]      (1)     a list of accounts receivable, aged from
date of invoice;
                  [x]      (2)     a list of accounts payable, aged from date
of receipt;
                  [x]      (3)     a list of inventory, valued at the lower of
cost or market.

         [   ]    D.       Within ________________ days after and as of the
end of each calendar year, the signed personal financial statement of .
                                                                             
          (Borrower/Guarantor/other)

         [    ]   E.       Within five (5) days after filing, a signed copy of
the annual tax return, with exhibits, of .
                            (Borrower/Guarantor/other)

         [    ]   F.       An Environmental Certificate on the Bank's form on
and as of the date of this agreement and thereafter as required by the
Environmental Certificate.

         [ x ]    G.       Quarterly 10-Q's

         [ x ]    H.       Within 30 days after each month end, a borrowing
base exhibit indicating compliance with Section 3.1 herein, when borrowing.
         
         9.0      Negative Covenants

         9.1      Definitions. As used in this agreement, the following terms
shall have the following respective meanings:

                  A.       "Subordinated Debt" means debt subordinated to the
Bank in manner and by agreement satisfactory to the Bank.

                  B.       "Tangible Net Worth" means total assets less
intangible assets and total liabilities. Intangible assets include goodwill,
patents, copyrights, mailing lists, catalogs, trademarks, bond discount and
underwriting expenses, organization expenses, and all other intangibles.

         9.2      Unless otherwise noted, the financial requirements set forth
in this section shall be computed in accordance with generally accepted
accounting principles applied on a basis consistent with financial
statements previously submitted  by the Borrower to the Bank.

         9.3      Without the written consent of the Bank, so long as any debt
remains outstanding under the Credit Facilities, the Borrower shall not:
(where appropriate, covenants apply on a consolidated basis - clauses H-O
apply only if completed).

                  A.       Dividends.  Acquire or retire any of its shares of
capital stock, or declare or pay dividends or make any other distributions
upon any of its shares of capital stock, except dividends payable in its
capital stock and dividends payable to "Subchapter S" corporation
shareholders in amounts sufficient in amount to pay the shareholders' income
tax obligations related to the Borrower's taxable income.

                  B.       Sale of Shares. Issue, sell or otherwise dispose of
any shares of its capital stock or other securities, or rights, warrants or
options to purchase or acquire any such shares or securities.

                  C.       Debt. Incur, or permit to remain outstanding, debt
for borrowed money or installment obligations, except debt reflected in the
latest financial statement of the Borrower furnished to the Bank prior to
execution of this agreement and not to be paid with proceeds of borrowings
under the Credit Facilities. For purposes of this covenant, the sale of any
accounts receivable shall be deemed the incurring of debt for borrowed
money.

                  D.       Guaranties. Guarantee or otherwise become or remain
secondarily liable on the undertaking of another, except for endorsement of
drafts for deposit and collection in the ordinary course of business.

                  E.       Liens. Create or permit to exist any lien on any of
its property, real or personal, except: existing liens known to the Bank;
liens to the Bank; liens incurred in the ordinary course of business
securing current nondelinquent liabilities for taxes, worker's compensation,
unemployment insurance, social security and pension liabilities; and liens
for taxes being contested in good faith.

                  F.       Advances and Investments. Purchase or acquire any
securities of, or make any loans or advances to, or investments in, any
person, firm or corporation, except obligations of the United States
Government, open market commercial paper rated one of the top two ratings by
a rating agency of recognized standing, or certificates of deposit in
insured financial institutions.

                  G.       Use of Proceeds.  Use, or permit any proceeds of
the Credit Facilities to be used, directly or indirectly, for the purpose of
"purchasing or carrying any margin stock" within the meaning of Federal
Reserve Board Regulation U.  At the Bank's request, the Borrower shall
furnish to the Bank a completed Federal Reserve Board Form U-1.

                  H.       Working Capital. Permit the difference between its
current assets [less all sums owing from stockholders, member or partners,
as the case may be, and officers, managers and directors] and current
liabilities [plus all sums (other than Subordinated Debt) owing to
stockholders, members or partners, as the case may be, and officers,
managers and directors] to be less than 
$                                       . (Strike bracketed words if not
applicable.)

                  I.        Net Worth. Permit its Worth to be less than
$19,000,000 at 12-31-96 and increasing by 75% of monthly net income thereafter.

                  J.       Current Rates.  Permit the ratio of its current
assets to current liabilities to be less than        to 1.00.

                  K.  Leverage Ratio.  Permit the ratio of its total
liabilities  to its Tangible Net Worth to exceed 1.50 to 1.00.

                  L.  Fixed Assets.  Expend for, contract for, lease, rent, or
otherwise acquire fixed assets, if the expense to the Borrower, and its
subsidiaries, if any shall exceed $           in the aggregate.

                  M.  Leases.  Contract for or assume in any manner, lease
obligations if the aggregate of all payments shall exceed $    in any one
fiscal year.

         N.  Compensation.  Pay or award compensation of any kind, in any one
fiscal year to                exceeding $             .

         O.       Maintain Debt Service Coverage (defined as EBITDA divided by
principal plus interest payments of not less than 1.50 to 1.0.

         10.0   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.

         11.0 Acceleration

         11.1 Events of Acceleration:  If any of the following events occur,
the Credit Facilities shall terminate and all borrowings under them shall
become due immediately, without notice at the Bank's option, whether or not
the Bank has made demand:

A.       The Borrower or guarantor of any of the Credit Facilities (the
"Guarantor")  fails to pay when due any amount payable under the Credit
Facilities or under any agreement or instrument evidencing debt to any
creditor.

B.       The Borrower or Guarantor  (i) fails to observe or perform any term
of this agreement or the notes; (ii) makes any materially incorrect or
misleading representation, warranty, or certificate to the Bank (iii) makes
any materially incorrect or misleading representation in any financial
statement or other information delivered to the Bank; or (iv) defaults under
the terms of any agreement or instrument relating to any debt for borrowed
money (other than borrowings under the Credit Facilities), including any
capitalized lease obligation, such that the creditor declares the debt due
before its maturity.

C.       There is a default under the terms of any loan agreement, mortgage,
security agreement, or any other document executed as part of the Credit
Facilities or any guaranty of the liabilities under the Credit Facilities
becomes unenforceable in whole or in part, or any guarantor fails to
promptly perform under its guaranty.

D.       A "reportable event" (as defined in the Employee Retirement Income
Security Act of 1974 as amended) occurs that would permit the Pension
Benefit Guaranty Corporation to terminate any employee benefit plan of any
Guarantor or Borrower or any affiliate of any Guarantor or Borrower, or if
any of them becomes subject to any multi-employer plan.

E.       The Borrower or any Guarantor  becomes insolvent or unable to pay
its debts as they become due.

F.       The Borrower or any Guarantor (i) makes an assignment for the
benefit of creditors; (ii) consents to the appointment of a custodian,
receiver, or trustee for itself or for a substantial part of its assets; or
(iii) commences any proceeding under any bankruptcy, reorganization,
liquidation, insolvency or similar laws of any jurisdiction.

G.       A custodian, receiver or trustee is appointed for any Guarantor or
Borrower or for a substantial part of its assets without its consent, and is
not removed within 60 days after the appointment.

H.       Proceedings are commenced against any Borrower or Guarantor under
any bankruptcy, reorganization, liquidation, insolvency or similar laws of
any jurisdiction, and they remain dismissed for 60 days after commencement;
or any Guarantor or Borrower consents to the commencement of those
proceedings.

I.       Any judgment is entered against Borrower or  any Guarantor, or any
attachment, levy, or garnishment is issued against any property of any
Guarantor or Borrower.

J.       The Borrower or any Guarantor dies.

K.       The Borrower or any Guarantor, without the Bank's written consent,
(i) is dissolved, (ii) merges or consolidates with any third party, (iii)
leases, sells or otherwise conveys a material part of its assets or business
outside the ordinary course of business, (iv) leases, purchases or otherwise
acquires a material part of the assets of any other corporation or business
entity except in the ordinary course of such business, or (v) agrees to do
any of the foregoing.

L.       The loan-to-value ratio of any pledged securities at any time
exceeds N/A % and that excess continues for five (5) days after notice from
the Bank to the Borrower.

M.       There is a substantial change in the existing or prospective
financial condition of the Borrower or any Guarantor which the Bank in good
faith determines to be materially adverse.

N.       The Bank in good faith deems itself insecure.

         11.2 Remedies:  If the amounts owning under the Credit Facilities
are not paid at maturity, whether by demand, acceleration or otherwise, the
Bank shall have all of the rights and remedies provided for by law or under
any agreement.  Any requirement of reasonable notice shall be met if the
Bank sends notice at least seven (7) days prior to the date of sale,
disposition or other event which requires notice.  The Bank is authorized to
cause all or any part of the Collateral to be transferred to or registered
in its name or in the name of any other person, firm or corporation, with 
or without designating the capacity of that nominee.  The Borrower shall be
liable for any deficiency remaining after disposition of any Collateral. 
The Borrowere is liable to the Bank for all reasonable costs and expenses of
every kind incurred in the making or collection of the Credit Facilitites,
including, without limitation, reasonable attorneys' fees and court costs
whether attributable to the Bank's in-house or outside counsel.  These costs
and expenses shall include, without limitation, any costs or expenses
incurred by the Bank in any bankruptcy, reorganization, insolvency or other
similar proceeding. 

         12.0 Miscellaneous.

         12.1 Notice from one party to another relating to this agreement
shall be deemed effective if made in writing (including telecommunications)
and delivered to the recipient's address, telex number or telecopier number
set forth under its name by any of the following means:  (a) hand delivery,
(b) registered or certified mail, postage prepaid, with return receipt
requested, (c) first class or express mail, postage prepaid, (d) Federal
Express, Purolator Courier or like overnight courier service or (e)
telecopy, telex or other wire transmission with request for assurance of
receipt in a manner typical with respect to communications of that type. 
Notice made in accordance with this section shall be deemed delivered on
receipt if delivered by hand or wire transmission, on the third business day
after mailing if mailed by first class. registered or certified mail, or on
the next business day after mailing or deposit with an overnight courier
service if delivered by express mail or overnight courier.

         12.2  No delay on the part of the Bank in the exercise of any right
or remedy shall operate as a waiver.  No single or partial exercise by the
Bank of any right or remedy shall preclude any other future exercise of it
or the exercise of any other right or remedy.  No waiver or indulgence by
the Bank of any default 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 that right on any future occasion.

         12.3  This agreement, the Notes and any related loan documents 
embody the entire agreement and understanding between the Borrower and the
Bank and supersede all prior agreements and understanding  relating to 
their subject matter.  If any one or more of the obligations of the Borrower
under this agreement or the Notes shall be invalid, illegal or unenforceable
in any jurisdiction, the validity, illegality, unenforceability in one
jurisdiction shall not affect the validity, legality or enforceability of
the obligations of the Borrowere under this agreement or the Notes in any
other jurisdiction.  

         12.4  The Borrower, if more than one, shall be jointly and severally
liable.

            12.5  This agreement is delivered in the state of Michigan and
governed by Michigan law.

            12.6  Sections headings are for convenience of reference only and
shall not affect the interpretation of this agreement.
 .
              13.0 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.

Executed by the parties on February 19, 1997.

"Bank"                                   "Borrower"

NBD BANK                                  INTERFACE SYSTEMS, INC.


By:  Michael K. Kelly                     By:  David O. Schupp
     First Vice President                      Treasurer

Address for Notices:                      Address for Notices:
125 S. Main Street                        5855 Interface Drive
Ann Arbor, MI  48102                      Ann Arbor, MI  48103
Fax/Telex No. (313) 995-8000              Fax/Telex No. (313) 769-1047