Exhibit 4.4
                                                                   -----------
A-OK Controls Engineering, Inc.
4375 Giddings Road
Auburn Hills, Michigan  48326
Attn:  Matthew S. Galvez, President and CEO

         Re:      Loans by LaSalle Business Credit, LLC
Dear Mr. Galvez:

Reference is made to that certain Loan and Security  Agreement  dated as of June
30, 2000, as heretofore and hereafter amended, amended and restated or otherwise
modified  from time to time (the  "Agreement"),  by and  between  A-OK  Controls
Engineering, Inc. ("Borrower") and LaSalle Business Credit, Inc., predecessor by
merger to LaSalle Business Credit,  LLC, a Delaware  limited  liability  company
("Lender").  Each term set out herein and not  otherwise  defined shall have the
meaning ascribed to such term in the Agreement.

By our letters to you dated  October 3, 2001 and February 18, 2002,  we notified
you that Borrower is and remains in default (collectively, the "Defaults") under
the  Agreement.  The  Defaults  have not been cured or waived.  The terms of the
Agreement  provide  that  Lender  may,  as a result  of any  Event  of  Default,
including  any  Default,  accelerate  the payment of all  Liabilities.  Borrower
acknowledges the existence of each Default.

Lender has requested that Borrower obtain  alternative  financing,  and Borrower
has agreed to use its best efforts to obtain such alternate financing.  However,
Borrower has not yet obtained such alternative financing. Borrower has therefore
requested that Lender not immediately accelerate the payment of the Liabilities,
and that Lender, for the moment,  allow both parties to the Agreement to proceed
under the terms of the  Agreement.  In the event Borrower and each guarantor set
forth herein executes this letter and returns same to Lender,  together with the
fee  described in paragraph (g) below,  on or before May 2, 2003,  Lender hereby
agrees to allow both  parties to proceed  under the terms of the  Agreement  (as
such terms are amended  herein)  until further  notice to Borrower,  provided as
follows:

(a)  That there occurs no additional Event of Default; and
(b)  That there occurs no material  adverse  change (as  determined by Lender in
     its sole discretion) in Borrower or in its business; and

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(c)  That Borrower shall use its continuing best efforts to refinance all of the
     Liabilities with another lender as soon as practicable; and
(d)  That Borrower  agrees that the first sentence of Section 2 of the Agreement
     is hereby amended and restated to read in its entirety as follows:
        Subject to the terms and conditions of this Agreement and the Other
        Agreements, during the Original Term and any Renewal Term, absent the
        existence and continuation of an Event of Default, LaSalle may, in its
        sole discretion, make such  revolving loans and advances (the "Loans")
        to Borrower as Borrower shall from time to time request, in accordance
        with the terms of this paragraph 2; and
(e)  That Borrower agrees that the definition of "Commitment" set forth in
     Section 1 of the Agreement is hereby amended and restated, effective as of
     the date of this letter, to read in its entirety as follows:

     "Loan Commitment" shall mean:

     (A) at all times prior to and including  May 15, 2003,  Eight Hundred Fifty
         Thousand and No/100 Dollars ($850,000.00); and

     (B) for the period from May 16, 2003 through and including June 15, 2003:

          (i)  Eight  Hundred  Fifty  Thousand  and  No/100  Dollars
          ($850,000.00)  in the event that (x) Borrower and Nematron  shall have
          delivered to LaSalle,  on or before May 15,  2003,  at least three (3)
          written  proposals  (or groups of  proposals)  from  other  lenders to
          refinance  all  Liabilities  at or before the last day of the Original
          Term (it being understood,  for the avoidance of doubt, that any group
          of proposals which would collectively  refinance all Liabilities shall
          constitute,  for these  purposes,  one (1)  proposal;  and (y) LaSalle
          shall have deemed at least three (3) of such  proposals  (or groups of
          proposals)  viable in LaSalle's sole discretion (the occurrence of the
          conditions  in  clauses  (x)  and (y) is  referenced  to  herein  as a
          "Timely Proposal Event"); or

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          ii)  Seven  Hundred   Seventy-Five   Thousand  and  No/100
          Dollars  ($775,000.00)  in the event a Timely  Proposal  Event has not
          occurred; and

     (C)  for the period  from June 16,  2003,  through  the end of the Original
          Term:

          (i)  Eight  Hundred  Fifty  Thousand  and  No/100  Dollars
          ($850,000.00)  in the event  that (x) a Timely  Proposal  Event  shall
          have  occurred  and (y) both (1)  Borrower  and  Nematron  shall  have
          delivered  to LaSalle,  on or before June 15,  2003,  at least one (1)
          written  commitment (or group of commitments)  from another lender (or
          lenders) to  refinance  all  Liabilities  at or before the last day of
          the Original  Term, and (2) LaSalle shall have deemed at least one (1)
          such  commitment  (or group of  commitments)  viable in LaSalle's sole
          discretion  (the  occurrence of the  conditions in clauses  (y)(1) and
          (2) is referred to herein as a "Timely Commitment Event"); or

          (ii) Seven  Hundred   Seventy-Five   Thousand  and  No/100
          Dollars  ($775,000.00)  in the event (x) a Timely  Proposal  Event has
          occurred  but a Timely  Commitment  Event has not  occurred,  or (y) a
          Timely  Commitment  Event has occurred but a Timely Proposal Event has
          not occurred; or

          (iii) Seven   Hundred    Thousand    Dollars   and   No/100
          ($700,000.00) in the event that neither a Timely  Commitment Event nor
          a Timely Proposal Event has occurred; and

(f)  That Borrower  agrees that Section 12(a) of the Agreement is hereby amended
     by deleting the date  "November  12, 2003" and by inserting  the date "July
     15, 2003" in lieu thereof; and

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(g)  That  Borrower  pays Lender a fee in the amount of One  Thousand and No/100
     Dollars ($1,000.00) in consideration of Lender's  willingness to enter into
     this  letter  agreement,  which fees  shall be  payable,  fully  earned and
     nonrefundable upon Borrower's acceptance of this letter; and
(h)  That  Borrower  and each  Guarantor  agree that all  references  to LaSalle
     Business Credit,  Inc.  contained in the Agreement and the Other Agreements
     are hereby deemed to read "LaSalle Business Credit, LLC".

Pursuant to Section 12(a) of the  Agreement,  notice is hereby given that Lender
elects to terminate the Agreement and the Nematron Loan  Agreement at the end of
the Original Term.

Borrower  hereby (a) ratifies and affirms its  obligations  under the Agreement;
(b) denies and waives the existence of any defenses  relating to its obligations
under the Agreement;  and (c) waives and releases any claims or causes or action
against  Lender which may now or hereafter be available to it arising out of (i)
the  administration  of  the  Agreement  or  the  Other  Agreements,   (ii)  the
negotiation and execution of this letter,  or (iii) any other matter  pertaining
to the Agreement or the Other Agreements.

Each  of  the  undersigned  guarantors  hereby  (a)  ratifies  and  affirms  its
individual and several obligations under its respective Continuing Unconditional
Guaranty  executed by each guarantor in favor of Lender;  (b)  acknowledges  and
confirms that each Continuing Unconditional Guaranty continues in full force and
effect  notwithstanding  this letter; (c) denies and waives the existence of any
defenses relating to any of such Continuing  Unconditional  Guaranties;  and (d)
waives and releases any claims or causes or action  against Lender which may now
or hereafter be available to any guarantor arising out of (i) the administration
of the Agreement or the Other Agreements, (ii) negotiation and execution of this
letter,  or (iii) any other  matter  pertaining  to the  Agreement  or the Other
Agreements; provided, however, that the failure of any guarantor to execute this
letter shall not release such guarantor or any other guarantor of its respective
obligations under any of the Continuing Unconditional Guaranties.

By this letter  Lender does not waive any Default,  nor any  previous  Events of
Default  about which you have been  notified.  This letter is being written with
Lender reserving all of its rights to exercise any and all of Lender's remedies,
as provided in the Agreement and in all the Other  Agreements,  at such time and
in such  manner as  provided  therein.  Nothing  herein  shall be  construed  or
interpreted as being a waiver of any of Lender's rights or remedies (as provided

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to Lender under the terms of the Other Agreements,  the Uniform  Commercial Code
or otherwise),  by virtue of its  forbearance to date (it being  understood that
Lender has no  obligation  to continue to forbear)  or  extension  with  respect
thereto.

                                         Very truly yours,

                                         LASALLE BUSINESS CREDIT, LLC

                                         By s/s Dale P. Grzenia
                                         ----------------------
                                         Dale P. Grzenia, First Vice President

Accepted and agreed to this
30th day of April, 2003.

A-OK CONTROLS ENGINEERING, INC.

By /s/ David P. Gienapp
-----------------------

Its Secretary


Consented and agreed to by
the following guarantors of
the obligations of A-OK Controls Engineering, Inc.
to LaSalle Business Credit, LLC

NEMATRON CORPORATION                        OPTIMATION, INC.

By /s/ Marrhew S. Galvez                  By /s/ David P. Gienapp
------------------------                  ------------------------

Its President                             Its Secretary

Date: April 30, 2003                      Date: April 30, 2003


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