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                                                                    EXHIBIT 4.15

                     FIRST AMENDMENT TO REPAYMENT AGREEMENT
                     AND FOURTH AMENDMENT TO LOAN AGREEMENT

         This First Amendment to Repayment Agreement and Fourth Amendment to
Loan Agreement ("First Amendment") is made as of the 1st day of December, 1998,
by and among KeyBank National Association, f/k/a Society Bank, Michigan, a
national banking association located at 127 Public Square, Cleveland, Ohio 44114
("KeyBank" or "Bank"), Nematron Corporation, a Michigan corporation located at
5840 Interface Drive, Ann Arbor, Michigan 48103 ("Borrower") and NemaSoft, Inc.,
a Michigan corporation located at 5840 Interface Drive, Ann Arbor, Michigan
48103 ("Guarantor"; Borrower and Guarantor together referred to as "Interested
Parties").

                                    RECITALS

         WHEREAS, Bank and the Interested Parties executed a certain Repayment
Agreement dated as of September 28, 1998 ("Repayment Agreement"); and

         WHEREAS, capitalized terms not otherwise defined herein shall have the
meanings ascribed thereto in the Repayment Agreement; and

         WHEREAS, the Line of Credit terminated, and the Amended Notes matured
on October 31, 1998, and have not been repaid; and

         WHEREAS, the Interested Parties have asked that Bank reactivate
Borrower's Line of Credit on the terms described herein, to enable Borrower to
obtain subordinated debt or an equity infusion of not less than One Million
Dollars ($1,000,000.00), to which request Bank has acquiesced.


AGREEMENT

         NOW, THEREFORE, in consideration of the foregoing, and the agreements
and covenants herein, the parties agree as follows:

         1.       Recitals.  The Recitals are incorporated herein by reference.

         2.       Restructure  and Amendment of Loan  Documents.  Certain of the
                  Loan Documents shall be amended as follows:

                           i) Section 1 of the Repayment Agreement is amended by
         deleting the definitions of "Amended and Restated Line Note" and
         "Amended and Restated Term Note" and inserting the following in lieu
         thereof:

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                           "Second Line Note" shall mean the Second Amended and
                  Restated Revolving Credit Note referred to in subsection 3(a)
                  of this Repayment Agreement and attached hereto as Exhibit B.

                           "Second Term Note" shall mean the Second Amended and
                  Restated Term Note referred to in subsection 3(c) of this
                  Repayment Agreement and attached hereto as Exhibit C.

                           ii) The Repayment Agreement is amended by deeming all
         references to the Amended and Restated Line Note and the Amended and
         Restated Term Note to be references to the Second Line Note and the
         Second Term Note, respectively.

         iii)      The prefatory paragraph, and subsections (a), (b), (c) and 
         (e) of Section 3 of the Repayment Agreement are deleted, and the
         following inserted in lieu thereof:
        
                  "3.      Restructure and Amendment of Loan Documents. The
                           Obligations evidenced by the Original Notes, as same
                           may have been amended and/or amended and restated
                           from time to time, shall be restructured pursuant to
                           the terms of the Second Amended and Restated
                           Revolving Credit Note and the Second Amended and
                           Restated Term Note. The Amended Notes do not
                           constitute repayment or cancellation of all or any
                           portion of the Indebtedness evidenced by the Original
                           Notes. The Original Notes, and any amendment and/or
                           restatement thereof, shall remain in full force and
                           effect only for the purpose of evidencing any amounts
                           due in connection with the Original Notes and any of
                           the Loan Documents which for any reason in fact or in
                           law, do not become Obligations of Borrower under the
                           Amended Notes, as intended by the parties hereto. In
                           connection with the restructure of the Obligations,
                           the following amendments are hereby made to the Loan
                           Agreement:

                           a)      Subsection 1.1.1 of the Loan Agreement is 
                           deleted in its entirety, and the following inserted
                           in lieu thereof:

                                            `1.1.1 Upon the request of Borrower,
                                    made at any time or from time to time
                                    between September 28, 1998 and October 31,
                                    1998, inclusive, and between December 1,
                                    1998 and January 30, 1999, inclusive, and so
                                    long as no Event of Default under this
                                    Agreement has occurred or is continuing,
                                    Bank shall make cash advances to Borrower in
                                    an amount up to:

                                    (a)     eighty percent (80%) of the 
                                            aggregate  outstanding  amount of
                                            Eligible Domestic Accounts;

                                            PLUS

                                    (b)     at Borrower's option, eighty percent
                                            (80%) of the aggregate outstanding
                                            amount of Eligible Foreign Accounts;

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                                            PLUS

                                    (c)     thirty five percent (35%) of the
                                            aggregate sum (not to exceed
                                            $2,500,000) of (i) Eligible Raw
                                            Inventory (valued at the lower of
                                            Borrower's and NemaSoft's cost, or
                                            market) and (ii) Eligible Finished
                                            Inventory (valued at Borrower's and
                                            NemaSoft's cost of production):

                                            PLUS

                                    (d)     the Permitted Overadvance;

                                            LESS

                                    (e)     the aggregate outstanding amount of
                                            any issued and outstanding Letters 
                                            of Credit;

                                    PROVIDED, HOWEVER, that in no event shall
                                    the aggregate amount of outstanding cash
                                    advances made pursuant to this Section 1.1.1
                                    ("BORROWING FORMULA") be, at any time,
                                    greater than the sum of Five Million and
                                    00/100 Dollars ($5,000,000.00). The amount
                                    outstanding under the Line of Credit shall
                                    be evidenced by a Second Amended and
                                    Restated Revolving Credit Note dated as of
                                    December 1, 1998 ("Note"). The terms of the
                                    Note, and all renewals, modifications and
                                    amendments thereto, are hereby incorporated
                                    herein specifically by reference. Subject to
                                    the foregoing limitations Borrower may
                                    borrow, repay and reborrow under the Line of
                                    Credit. During the period between October
                                    31, 1998 and December 1, 1998, the Line of
                                    Credit shall be suspended, and all funds
                                    received by Bank through the mechanism
                                    established by the Cash Collateral Agreement
                                    executed in connection with the Repayment
                                    Agreement may be, at Bank's option, applied
                                    to reduce the indebtedness evidenced by the
                                    Note.'

                           b)       The Loan Agreement is amended by renumbering
                                    existing subsection 1.2.8 as subsection
                                    1.2.9, and adding new subsections 1.2.8 and
                                    1.2.10 as follows:

                                            `1.2.8 "Permitted Overadvance" means
                                    an amount of up to (i) Seven Hundred
                                    Fifty-Three Thousand Three Hundred
                                    Forty-Five Dollars ($753,345) during the
                                    period between September 28, 1998 and
                                    October 31, 1998, (ii) Zero Dollars ($0)
                                    during the period October 31, 1998 through
                                    November 30, 1998, and (iii) One Million One
                                    Hundred Thousand Dollars ($1,100,000) during
                                    the period between December 1, 1998 and
                                    January 31, 1999.

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                                    1.2.10 "Repayment Agreement" means an
                                    agreement, so called, among Borrower,
                                    NemaSoft and Bank dated September 28, 1998,
                                    as amended from time to time.'

                           c)       Subsection 1.7 of the Loan Agreement is
                                    deleted and the following inserted in lieu
                                    thereof:

                                            `1.7 Term Loan. Bank agrees to lend
                                    Borrower the sum of One Million One Hundred
                                    Seventy Thousand and 00/100 Dollars
                                    ($1,170,000.00) ("Term Loan"). The Term Loan
                                    shall be evidenced by a Second Amended and
                                    Restated Term Note dated as of December 1,
                                    1998 ("Term Note") maturing on January 31,
                                    1999, and containing other terms as set
                                    forth therein.'

                           e)       Article VI of the Loan Agreement is amended
                                    by adding new subsections 6.9, 6.10, 6.11,
                                    6.12 and 6.13 as follows:

                                    `6.9    An Event of Default shall occur
                                            under the Repayment Agreement, as
                                            amended from time to time.

                                    6.10    Borrower shall fail to obtain an
                                            infusion of cash in the form of
                                            convertible debt subordinated (in
                                            form and substance acceptable to
                                            Bank) to the repayment of all
                                            indebtedness of Borrower to Bank, or
                                            equity, of not less than One Million
                                            Dollars ($1,000,000) between
                                            November 26, 1998 and December
                                            1, 1998.

                                    6.11    Borrower shall fail to enter into an
                                            arrangement for financing a
                                            percentage of certain of Borrower's
                                            purchase orders with a third party
                                            on terms acceptable to Bank, and in
                                            connection therewith, Borrower shall
                                            have executed such amendments to the
                                            Loan Documents as Bank shall
                                            request, all by no later than
                                            December 15, 1998.

                                    6.12    Subsection 6.4 hereof
                                            notwithstanding, Borrower shall fail
                                            to comply in all respects with
                                            subsections 3.5.4 and/or 3.5.10
                                            hereof.

                                    6.13    There shall occur a material adverse
                                            change in Borrower's or NemaSoft's
                                            financial condition or prospects,
                                            from that disclosed in writing to
                                            Bank prior to December 1, 1998, all
                                            as determined by Bank in the
                                            exercise of its reasonable business
                                            judgment.'"

                           iv)      Section 3 of the Repayment Agreement is 
         further amended by adding new subsections (f), (g) and (h) as follows:

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                           "f)      Subsection 3.5.4 of the Loan Agreement is 
                                    deleted, and the following inserted in lieu 
                                    thereof:

                                            ` 3.5.4 within fifteen (15) days 
                                    after the last day of each month between
                                    September 30, 1996 and November 30, 1998,
                                    and on a daily basis thereafter, a Borrowing
                                    Base Certificate, the form of which is
                                    acceptable in the sole and absolute
                                    discretion of the Bank, signed by an officer
                                    of Borrower and NemaSoft certifying to its
                                    correctness;'


                           g)       Subsection 3.5.10 of the Loan Agreement is
                                    renumbered as 3.5.11, and a new subsection
                                    3.5.10 is inserted as follows:



                           `3.5.10  by the second business day of each week, a
                                    rolling twelve week projection, acceptable
                                    to Bank in the exercise of its reasonable
                                    business judgment, of anticipated cash
                                    receipts and disbursements, and showing that
                                    Borrower will at all times be in compliance
                                    with the Borrowing Formula, as well as an
                                    actual statement of cash receipts and
                                    disbursements for the immediately preceding
                                    week.'

                           h)       The Loan Agreement is amended by deleting
                                    the monetary reference "$6,000,000" (whether
                                    such reference is expressed numerically or
                                    is written out) wherever it occurs, and
                                    inserting in lieu thereof a monetary
                                    reference of "$5,000,000"."


                                    v)      The Repayment Agreement is hereby 
         amended by deleting subsection 5(b) in its entirety and inserting the
         following in lieu thereof:

                           "b)      Amendment to Mortgage. On or before December
                                    1, 1998, Borrower shall execute and deliver
                                    to Bank a Second Amendment to Mortgage in
                                    the form of Exhibit D attached hereto."

                                    vi)     The Repayment Agreement is hereby 
         amended by adding a new subsection 5(i) as follows:


                           "i)      Subordination Agreements. On or before 12:00
                                    p.m. on December 2, 1998, J. Eric May, James
                                    A. Nichols, Globus Growth Group and Gregory
                                    J. Schwartz & Co. and shall execute and
                                    deliver to Bank Subordination Agreements in
                                    the form of Exhibits I-1 through I-4
                                    attached hereto."

                                    vii)    The Repayment Agreement is amended 
         by deleting the prefatory paragraph of Section 17, and inserting in
         lieu thereof the following:

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                         Notices.   Any notice, demand or communication required
                                    or permitted to be given by any provision of
                                    this Repayment Agreement will be in writing
                                    and will be deemed to have been given when
                                    delivered personally or by facsimile,
                                    receipt confirmed, to the party designated
                                    to receive such notice, or on the date
                                    following the day sent by overnight courier,
                                    or on the third (3rd) business day after the
                                    same is sent by certified mail, postage and
                                    charges prepaid, directed to the following
                                    addresses or to such other or additional
                                    addresses as any party might designate by
                                    written notice to the other party; provided,
                                    however, that in the event that Bank
                                    determines to cease making advances under
                                    Borrower's line of credit, Bank shall
                                    undertake to promptly so notify Borrower by
                                    both facsimile and overnight courier, though
                                    Bank's determination to cease providing
                                    advances shall be effective when made, and
                                    shall not be dependent upon Borrower's
                                    receipt of notice.

                           viii) The Repayment Agreement is amended by deleting
               Exhibits B, C and D, and replacing them with Exhibits B, C and D
               in the form of Annexes 1 through 3, respectively, attached
               hereto.
                           ix) The Repayment Agreement is amended by adding new
               Exhibits I-1 through I-4 in the form of Annex 4-A through 4-D
               attached hereto.

         3.    Effective Date. The provisions of this First Amendment shall be
effective on December 1, 1998 ("Effective Date"), provided that (i) a fully
executed copy of this First Amendment, the Second Amended and Restated Revolving
Credit Note, the Second Amended and Restated Term Note, the Second Amendment to
Mortgage, and the four (4) Subordination Agreements are delivered to Bank on or
before 12:00 p.m. on December 2, 1998, and (ii) that all accrued interest on the
Amended and Restated Term Note dated September 28, 1998, is paid on December 1,
1998.

         4.    Loan Documents. Any reference in any of the Loan Documents to the
Repayment Agreement shall, from and after the Effective Date, be deemed to refer
to the Repayment Agreement as modified by this First Amendment. Any and all
references to the Amended Notes in the Repayment Agreement, the Loan Documents
and this First Amendment shall hereafter refer to the Amended Notes in the forms
of the new Exhibits C and D, copies of which are attached hereto as Annexes 1
and 2.

         5.    Conflicting Terms; No Other Modification. To the extent that any 
of the terms and conditions of this First Amendment are inconsistent with the
terms of the Repayment Agreement, the conditions of this First Amendment shall
prevail. Otherwise, unless expressly modified or superseded herein, all of the
terms and conditions of the Repayment Agreement are ratified and confirmed and
shall remain unaffected and in full force and effect.

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         6.    Course of Dealing. The parties hereto recognize that Borrower has
not fully complied with the terms of the Loan Documents. No course of dealing
between the parties is established by virtue of Borrower's non-compliance
therewith and Bank's failure exercise its legal rights responsive thereto.
Interested Parties understand that the Loan Documents will be strictly enforced
going forward, and that Bank's failure to insist on strict performance to date
shall not be interposed as a defense to Bank's exercise of its legal rights, nor
shall it constitute a waiver of any thereof.

         7.    Release. Effective as of the date of the delivery of a fully
executed copy or original of this First Amendment, the Interested Parties
jointly and severally agree to release and hereby do release and discharge,
Bank, its shareholders, agents, servants, employees, directors, officers,
attorneys, affiliates, subsidiaries, successors and assigns and all persons,
firms, corporations, and organizations acting on their behalf ("Bank Parties")
of and from all damages, losses, claims, demands, liabilities, obligations,
actions and causes of action whatsoever that each Interested Party has or claims
to have against any Bank Party as of the date hereof and whether known or
unknown at the time of this release, and of every nature and extent whatsoever
on account of or in any way, directly or indirectly, touching, concerning,
arising out of or founded upon the Loan Documents, or the relationship
respecting any agreement between any Interested Party and any Bank Party.

         8.    Third-Party Beneficiaries/Entire Agreement. All the conditions 
and obligations hereunder are imposed solely and exclusively for the benefit of
the parties hereto and their successors and assigns. No other person or entity
shall obtain any interest herein or require satisfaction of such conditions in
accordance with the terms hereof or be entitled to assume that any of the
parties hereto will enforce such conditions and obligations and no other person
shall, under any circumstances, be a beneficiary of such conditions. This First
Amendment embodies the entire agreement and understanding between the parties
hereto with respect to the subject matter of this First Amendment and supersedes
all prior and contemporaneous negotiations, agreements and understandings
relative to such subject matter.

         9.    Binding Effect; Governing Law. This First Amendment shall bind 
and inure to the benefit of the parties hereto and their respective successors
and assigns and shall be governed by and construed in accordance with the laws
of the State of Michigan without regard to principles of conflict of laws.

         10.   Counterparts. This First Amendment may be executed in any number
of counterparts, each of which, when so executed and delivered, shall be an
original and all of which counterparts together shall constitute one and the
same fully executed instrument.

         11.   Consent and Reaffirmation of Guaranty. Guarantor, being guarantor
of the Obligations of Borrower pursuant to a Continuing Guaranty dated October
6, 1995, joins in and consents to the within First Amendment and agrees that the
provisions of such guaranty are ratified and confirmed and that the guaranty
remains in full force and effect.

         12.   Corporate Authority. Borrower and Guarantor hereby represent and
warrant to Bank that (a) Borrower and Guarantor have the legal power and
authority to execute and deliver this First Amendment; (b) the officials
executing this First Amendment have been duly authorized to execute and deliver
the same and bind Borrower and Guarantor with respect to the 

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provisions hereof; (c) the execution and delivery hereof by Borrower and
Guarantor and the performance and observance by Borrower and Guarantor of the
provisions hereof do not violate or conflict with the organizational agreements
of Borrower or Guarantor or any law applicable to Borrower or Guarantor or
result in a breach of any provision of or constitute a default under any other
agreement, instrument or document binding upon or enforceable against Borrower
or Guarantor; (d) this First Amendment constitutes a valid and binding
obligation of Borrower and Guarantor in every respect, enforceable in accordance
with its terms.

         IN WITNESS WHEREOF, Interested Parties and Bank have caused this First
Amendment to be executed by their duly authorized officers as of the date first
written above.

Address:                                        NEMATRON CORPORATION
5840 Interface Drive                            By: /s/ Matthew S. Galvez
Ann Arbor, Michigan  48103                          ----------------------------
                                                Its:President
                                                    ----------------------------
Address:                                        NEMASOFT, INC., Guarantor

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


Address:                                        KEYBANK NATIONAL ASSOCIATION

202 S. Michigan Street                          By: /s/ Nancy Terrill
P.O. Box 6                                          ----------------------------
South Bend, Indiana  46601                      Its: Senior vice President
                                                    ----------------------------



                                    EXHIBITS

EXHIBIT B  SECOND AMENDED AND RESTATED REVOLVING CREDIT NOTE

EXHIBIT C  SECOND AMENDED AND RESTATED TERM NOTE

EXHIBIT D  SECOND AMENDMENT TO MORTGAGE

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