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                                                                     EXHIBIT 4.3

                             REVOLVING CREDIT NOTE
                           (Equipment Line of Credit)


LOANS UP TO:
Amount $500,000.00                      No.
                                        ------------------------

Due Date:  July 31, 1997                Date:  February 12, 1997


PROMISE TO PAY - The undersigned, NEMATRON CORPORATION, a Michigan corporation,
for value received, promises to pay to KeyBank National Association, or its
assigns (hereinafter "Bank") or order after the above date of execution, the
sum of Five Hundred Thousand and No/100 Dollars ($500,000.00) to the extent
such sum has been advanced to the undersigned by the Bank and remains due and
unpaid, as indicated on the books and records of the Bank, plus interest as set
forth herein on July 31, 1997.

INTEREST RATE - The outstanding principal balance shall earn interest at a rate
per annum equal to the Bank's Prime Rate, ("Effective Rate").  The Effective
Rate will change on the date of each announced change of the Prime Rate.
Interest is calculated upon the actual number of days elapsed over a year
assumed to have 360 days.   The Bank's Prime Rate may not be the lowest rate
charged by the Bank to any of its customers. In no event will the interest rate
under this Note exceed the maximum rate of interest allowed by law.  Interest
will be computed on the unpaid principal balance from the date of each advance
under this Note. Interest shall be payable monthly beginning March 1, 1997, and
on the first day of each month thereafter until maturity of this note.

DEFAULT RATE - Bank reserves the right to increase the interest rate after
default, whether by acceleration or otherwise, to a rate equal to the Effective
Rate plus three percent (3.00%) per annum, but no more than the maximum rate
allowed by law.

PRINCIPAL PAYMENTS - Except as set forth in Article VI of a Loan
Agreement dated September 30, 1996, as amended by a First Amendment of
even date ("Loan Agreement"), the undersigned shall pay the entire
unpaid principal and interest outstanding under this Note on  July 31,
1997.

APPLICATION OF PAYMENTS - Each payment will be applied first to interest, then
to costs, and the balance to principal.


FEES - Bank may charge a fee to cover additional administrative costs incurred
for any payment received by Bank six (6) business days or more after the due
date; such fee will be equal to two percent (2%) of the required 


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principal payment or $200.00, whichever is less.  No payments will be accepted
without payment of this fee.  In addition, Bank may charge a fee to cover
administrative costs incurred in origination and/or renewal of this Note, which
shall be payable upon execution of the Note.
        
SECURITY - To secure the payment of this Note and any or all other liabilities
of the undersigned to the Bank, howsoever arising or evidenced, whether direct
or indirect, absolute or contingent, due or to become due, now existing or
hereafter arising, several or joint, including any renewals, extensions,
modifications, etc., the undersigned hereby pledges to Bank and grants to Bank
a continuing security interest in the following described property, whether
real or personal, and in all additions, substitutions, and proceeds thereof:

      (i)   All property described in Security Agreements, Mortgages,
            Assignments and Documents listed in Section 3.11 of the Loan
            Agreement.

      (ii)  All securities and other property of the undersigned now or
            hereafter in the possession or custody of the Bank, together with
            substitutions, increments and proceeds;

      (iii) Any other property declared or acknowledged to constitute security
            for the indebtedness of the undersigned to the Bank, together with
            substitutions, increments and proceeds thereof, and

      (iv)  All balances of deposit accounts of the undersigned  now or
            at any time hereafter with the Bank.

The Bank shall have the right at any time to apply its own indebtedness or
liability to the undersigned or to any endorser or other party liable hereon in
whole or partial payment of this Note, either before or after its maturity, or
in whole or partial payment of any other liability due or to become due from
the undersigned to the Bank.

EVENTS OF DEFAULT - Any one of the following events shall be deemed a default
under the terms of this Note, triggering the Bank's remedies as provided under
statutory or contract law:  (a) failure to pay any payment required under the
terms herein; (b) any default in the performance of any of the terms and
conditions of any document evidencing this loan transaction including the Loan
Agreement, this Note, any security agreement, mortgage or other instrument; (c)
any default in any terms and conditions of any other loan agreement between
Bank and the undersigned; (d) the death, 

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dissolution, or insolvency of the undersigned, or the appointment of a trustee
or receiver for the undersigned, or the making of any assignment for the
benefit of creditors or the commencement of any bankruptcy proceeding by or
against the undersigned; (e) the placement or issuance of any lien, levy, writ
of garnishment or execution or similar process against the undersigned or any
property of the undersigned; (f) the death of any guarantor of this Note.
        
REMEDIES ON DEFAULT - Upon the occurrence of any one or more of the above
events of default, unless the Bank shall otherwise elect, the full amount of
the indebtedness evidenced hereby and all other liabilities of the undersigned
to the Bank shall become immediately due and payable, without notice or demand.
Thereafter, Bank shall have all the rights and remedies provided by law,
whether common, statutory or otherwise, including all the remedies granted to
Bank under the Uniform Commercial Code, the right to offset any deposit
accounts held by Bank, the right to repossess and dispose of any collateral
pledged for this or any other loan agreement between Bank and the undersigned,
the right to foreclose any mortgage by advertisement as provided under Michigan
law, etc.  The undersigned shall be liable for any deficiency remaining after
disposition of any property in which the Bank has a security interest to secure
payment of the indebtedness evidenced hereby, and the computation of such
deficiency or of the amount required to redeem such property shall include
actual attorneys' fees, legal expenses and any other costs incurred.

WAIVER - Each endorser hereof and any other party liable for the indebtedness
evidenced hereby severally waives demand, presentment, notice of dishonor and
protest of this Note and consents to any extension or postponement of time of
its payment without limit as to the number or period thereof, to any
substitution, exchange or release of all or any part of the collateral securing
this Note, to the addition of any party hereto, and to the release or discharge
of or suspension of any rights and remedies against any person who may be
liable hereon for the payment of the indebtedness evidenced hereby.

MISCELLANEOUS - No delay on the part of the Bank in the exercise of any right
or remedy shall operate as a waiver thereof, no single or partial exercise by
the Bank of any right or remedy shall preclude any other future exercise
thereof or the exercise of any other right or remedy, and 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, any such right on any future occasion.  The undersigned, if
more than one, shall be jointly and severally liable hereunder and the term
"undersigned" 

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shall mean any one or more of them.  Any reference to KeyBank National
Association or Bank herein shall be deemed to include any subsequent holder of
this Note.
        

                                NEMATRON CORPORATION


5840 Interface Drive

Ann Arbor, MI 48103             By:  /s/ David P. Gienapp
                                    ---------------------
                                     David P. Gienapp 
                                Its: Vice President of Finance
                                     and Administration and
                                     Treasurer









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