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                                                                    EXHIBIT 4.13

                   AMENDED AND RESTATED REVOLVING CREDIT NOTE


$6,000,000.00                                     Dated as of September 28, 1998
                                                             Ann Arbor, Michigan


         On October 31, 1998, for value received, the undersigned (herein called
the "Borrower") promises to pay to the order of KEYBANK NATIONAL ASSOCIATION, a
national banking association (herein called the "Bank"), at its main office, in
good and collected funds, the principal sum of Six Million and 00/100 Dollars
($6,000,000.00) with interest from the date of the Note until October 31, 1998,
at a floating rate per annum of one-quarter of one percent (.25%) in excess of
the Prime Rate of the Bank in effect from time to time, but not to exceed the
maximum rate permitted by law, payable October 1, 1998, and at maturity,
computed on the principal sum hereof remaining from time to time unpaid. In the
event of any change in the Prime Rate of Bank, the interest rate on this Amended
Note shall be immediately and correspondingly adjusted, but in no event shall
the interest rate on this Amended Note prior to maturity exceed the highest rate
permitted by law on the date of this Amended Note. The Prime Rate of Bank is
defined as that rate established from time to time by Bank as Bank's Prime Rate,
whether or not such rate is publicly announced; the Prime Rate may not be the
lowest interest rate charged by Bank for commercial or other extensions of
credit. After maturity or the occurrence of an Event of Default, the unpaid
principal and accrued interest on this Amended Note shall, until paid, bear
interest at a rate per annum equal to the greater of four percent (4%) in excess
of the Prime Rate, which rate shall be immediately and correspondingly adjusted
with each change in the Prime Rate, or sixteen percent (16%); but in no event
shall the interest rate on this Amended Note after maturity exceed the highest
rate permitted by law on the date of maturity.

         Prior to maturity, if any payment of principal or interest is not paid
when due, Borrower shall pay Bank a late fee equal to the greater of ten percent
(10%) of the amount of such payment or twenty five dollars ($25).

         Borrower may prepay this Amended Note, in whole or in part, without the
payment of any premium, but all such payments shall be applied to the principal
installments of this Amended Note in the inverse order of their maturity.

         This Amended Note is issued pursuant to a certain Repayment Agreement
executed on even date herewith by and between Borrower and Bank, among others
(said Repayment Agreement as it may be from time to time amended, restated or
otherwise modified being herein called the "Repayment Agreement") to which
reference is hereby made for a statement of the rights of Bank and the duties
and obligations of Borrower in relation thereto, but neither this reference to
the Repayment Agreement nor any provision thereof shall affect or impair the
absolute and unconditional obligation of Borrower to pay the principal of and
interest on this Amended Note when due. This Amended Note amends and restates in
its entirety the Revolving Credit Note dated February 12, 1997 in the principal
amount of $6,000,000.00, including any 

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amendments or modifications thereto, and referred to in the Repayment Agreement
and does not represent evidence of new indebtedness, or repayment of any
indebtedness. The notes which formerly evidenced the debt now evidenced by this
Amended Note shall remain in full force and effect only for the purpose of
evidencing any amounts due thereunder which for any reason, in fact or in law,
that do not become obligations of the Borrower under this Amended Note as
intended by the Borrower. Capitalized terms used herein and not defined shall
have the meaning given to them in the Repayment Agreement. The headings of
paragraphs of the Repayment Agreement and the titles of any and all documents
executed in conjunction therewith, including this Amended Note, are for the
convenience of reference only, and are not to be considered as limiting or
otherwise affecting any of the terms hereof or thereof.

         This Amended Note and every other obligation, indebtedness, and
liability of Borrower to Bank, whether joint or several, absolute or contingent,
due or to become due, and whether heretofore or hereafter contracted or existing
and in whatsoever manner acquired by or accruing to Bank, whether before or
after maturity and whether the same may have been or shall be participated, in
whole or in part to others, and including all amendments, extensions, and
renewals thereof (all herein called "Obligations"), are secured as set forth in
the Repayment Agreement.

         Borrower represents and warrants that it is a duly-organized and
existing corporation under the laws of the State of Michigan that the execution
and delivery hereof have been duly authorized by appropriate corporate action,
that there is no prohibition either in law, in its articles of incorporation,
by-laws, or regulations, or in any agreement to which it is a party which in any
way restricts or prevents the execution of this Amended Note and performance of
the Obligations herein in any respect, and that this Amended Note has been duly
executed and is a valid and binding Obligation of Borrower.

         Borrower shall be in default hereunder if there shall occur an Event of
Default as set forth in the Repayment Agreement. If there shall occur any Event
of Default, Bank, by notice given to Borrower (only if and to the extent such
notice is required by the Repayment Agreement), may declare the unpaid principal
of and accrued interest owing upon this Amended Note and all other Obligations
to be immediately due and payable and upon any such declaration such principal
and interest shall become and be forthwith due and payable without any further
notice, presentment, or demand of any kind, all of which are hereby expressly
waived by Borrower. Further as provided in the Repayment Agreement for specific
Events of Default, the unpaid principal and accrued interest owing upon this
Amended Note and all other Obligations shall become and be forthwith due and
payable without declaration, notice, presentment, or demand of any kind, all of
which are hereby expressly waived by Borrower.

         Wherever used in this Amended Note, the term "Bank" shall include any
holder or assignee of this Amended Note. Except for notice expressly required by
the Repayment Agreement, if any, Borrower and each endorser, guarantor, and
surety hereof waives presentment, demand for payment, protest, notice of
protest, and notice of nonpayment, and further agrees and consents that, without
notice and without affecting their liability hereon, the holder hereof at any
time or times is authorized to: (a) correct patent errors and fill blanks
herein; (b) cause or permit the signature of one or more additional makers,
co-makers, sureties, guarantors and/or endorsers to be added hereto; (c) extend
the time of payment of this Amended Note in whole or in part; (d) sell,
exchange, surrender, substitute or otherwise deal with any 

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collateral now or hereafter securing this Amended Note; (e) add or release any
other person primarily or secondarily liable on this Amended Note; and (f)
modify, waive, supplement or otherwise change the terms of any security
agreement pertaining to this Amended Note.

         Borrower understands and agrees that this Amended Note is subject to
and shall be construed according to the laws of the State of Ohio, without
regard to principles of conflict of laws. Bank's rights, remedies, and powers
that are expressly specified in this Amended Note are in addition to Bank's
rights, remedies, and powers under any other instrument or agreement or under
applicable law.

         Any deposits or sums at any time credited by or due from Bank to
Borrower and any securities or other personal property of Borrower in the
possession of Bank may at all times be held and treated as additional security
for the payment of the Obligations. After the occurrence of any Event of
Default, Bank may apply or set off such deposits or other sums against the
Obligations at any time and without further notice.

         Any waiver of Bank's rights hereunder must be in writing and signed by
Bank. A waiver on any one or more occasions shall not be construed as a bar to
or waiver of any such right or remedy on a future occasion, nor as the
establishment of a course of dealing with respect to such waiver(s) or any other
action or inaction of Bank referred to in this paragraph. Delay or failure by
Bank to exercise its powers, rights, or remedies, in whole or in part, shall not
be deemed a waiver of any such power, right, or remedy; no single or partial
exercise of any right, power, or remedy hereunder shall preclude the exercise of
any other right, power, or remedy. All agreements, representations, and
warranties made herein will survive the making of the loan evidenced by this
Amended Note and will bind and inure to the benefit of Borrower and its
successors and assigns and Bank and its successors and assigns.

         Any notice required or authorized to be given to Borrower pursuant to
the provisions of this Amended Note shall be sufficiently given when such notice
is either delivered, sent by telegram, or mailed (deposited for delivery,
postage prepaid, by U.S. mail) to Borrower either at the address set forth below
(as modified by any change therein which Borrower has supplied in writing to
Bank) or at any other address at which Bank customarily communicates with
Borrower.

         If any provision of this Amended Note, or any covenant, stipulation,
obligation, agreement, act, or action, or part thereof made, assumed, entered
into, or taken hereunder or any application thereof, is for any reason held to
be illegal or invalid, such illegality or invalidity shall not affect any other
provision or any other covenant, stipulation, obligation, agreement, act, or
action or part thereof, made, assumed, entered into, or taken, each of which
shall be construed and enforced as if such illegal or invalid portion were not
contained herein. Such illegality or invalidity of any application of any
provision hereof shall not affect any legal and valid application thereof, and
each such provision, covenant, stipulation, obligation, agreement, act, or
action, or part shall be deemed to be effective, operative, made, entered into,
or taken in the manner and to the full extent permitted by law.

         The relationship between Borrower and Bank with respect to this Amended
Note and any writing executed or delivered in connection herewith is and shall
be solely that of debtor and 

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creditor, respectively, and Bank has no fiduciary obligation toward Borrower
with respect to any such document or the transactions contemplated thereby.

         This Amended Note and any agreement, document or instrument referred to
herein or executed between Bank and Borrower on or as of the date hereof
integrate all of the terms and conditions mentioned herein or incidental hereto
and supersede all oral representations and negotiations and prior writings with
respect to the subject matter hereof.

         Borrower agrees to promptly reimburse Bank for all costs and expenses,
including attorney's fees of Bank's in-house or outside counsel incurred by Bank
in connection with any restructurings of this Amended Note or any documents
executed and delivered in connection herewith and in connection with any
collection proceedings as a result of nonpayment of this Amended Note, as and
when due and payable.

         Borrower has received consideration which is the reasonable equivalent
value of the obligations and liabilities that Borrower has incurred to Bank.
Borrower is not insolvent as defined in any applicable state or federal statute,
nor will Borrower be rendered insolvent by the execution and delivery of this
Amended Note to Bank. Borrower is not engaged or about to engage in any business
or transaction for which the assets retained by it shall be an unreasonably
small capital, taking into consideration the obligations to Bank incurred
hereunder. Borrower does not intend to, nor does it believe that it will, incur
debts beyond its ability to pay them as they mature.

         Borrower, to the extent permitted by law, waives any right to have a
jury participate in resolving any dispute, whether sounding in contract, tort,
or otherwise, between Bank and Borrower arising out of, in connection with,
related to, or incidental to the relationship established between Borrower and
Bank in connection with this Amended Note or any other agreement, instrument or
document executed or delivered in connection therewith or the transactions
related thereto. This waiver shall not in any way affect, waive, limit, amend or
modify Bank's ability to pursue remedies pursuant to any confession of judgment
or cognovit provision contained in this Amended Note, or any other agreement,
instrument or document related thereto.

Address:                      NEMATRON CORPORATION

5840 Interface Drive          By:   /s/ David P. Gienapp
Ann Arbor, Michigan 48103        -----------------------------------------------

                              Title: Vice President - Finance and Administration
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