ASSUMPTION AGREEMENT

         THIS ASSUMPTION AGREEMENT ("Assumption Agreement") is entered into the
18th day of October, by and between Insys Technology, Inc., a Delaware
corporation ("Purchaser"), ATC InSys Technology Inc., a Delaware corporation,
("Seller") and ATC Group Services Inc., Seller's parent corporation and sole
shareholder ("ATC").

                                    RECITALS

         A.  Concurrent herewith, Purchaser and Seller and ATC Group Services
Inc. have entered into an Agreement For Sale and Purchase of Business Assets
dated October 5, 2000 ("Sale Agreement") in which Seller has agreed to sell
certain of its assets to Purchaser.

         B.  As a material inducement to Seller and ATC Group Services Inc. to
enter into the Sale Agreement, Purchaser has agreed to assume certain of
Seller's liabilities and obligations in connection with the business and/or
assets.

NOW, THEREFORE, in consideration of the above promises and other good and
valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, Purchaser, Seller and ATC Group Services Inc. do hereby agree as
follows:

         1.       Assumption of Obligations by Purchaser. Purchaser assumes and
agrees to pay and discharge, effective from and after the date hereof, the
specifically identified debts, obligations and liabilities listed on Schedule
"A" hereto (collectively referred to as the "Assumed Liabilities"). In case of a
conflict between this Assumption Agreement and the Sale Agreement, the Sale
Agreement shall control.

         2.       Substitution and Release of Seller.Purchaser agrees to use its
commercially reasonable best efforts to obtain a substitution of itself as the
obligated party under, and a release by the other party of the Seller from, all
liability under such Assumed Liabilities. Because the Purchaser can not compel
third party action, however, Purchaser shall incur no liability to Seller for
not accomplishing any such substitution, novation, and consent to substitute or
release of Seller from the Assumed Liabilities provided Purchaser has complied
with its obligations set forth in the prior sentence in this Section 2 and
elsewhere in this Assumption Agreement.

         3.       Indemnity by Purchaser. Purchaser agrees to indemnify and
defend Seller in accordance with the Indemnity provisions of Section 1.04 of
the Sale Agreement from and against any and all debts, costs or expenses,
including without limitation, reasonable attorney's fees, resulting or arising
from or incurred in connection with Purchaser's failure to perform and discharge
the Assumed Liabilities or its other obligations hereunder.

<PAGE>


         4.       Meaning of Terms. All terms in this Agreement shall have the
meaning ascribed to them in the Sale Agreement unless defined herein or unless
the context plainly requires otherwise.

         5.       Further Instruments. The parties hereto agree that they will
execute any and all other documents or legal instruments that may be necessary
or required to carry out and effectuate all of the provisions hereof.

         6.       Governing Law. This Agreement, and all matters relating
hereto, including any matter or dispute arising out of the Agreement, shall be
interpreted, governed, and enforced according to the Laws of the State of New
York, and the parties hereto consent to the jurisdiction of any appropriate
court in the State of New York.

         7.       Incorporation of Recitals and Schedule. The above recitals and
the schedule attached hereto are incorporated herein by reference and expressly
made a part of this Agreement.


         IN WITNESS WHEREOF, the parties have hereunto set their hands on the
date hereof.


ATC InSys Technology Inc.                       Insys Technology, Inc.



By: /s/ Paul J. Grillo                          By /s/ William O'Donnell
    ----------------------------------             -----------------------------
    Paul J. Grillo                                 William O'Donnell
    Chief Financial Officer                        Vice-President

Date:  October 18, 2000                         Date:  October 18, 2000
       -------------------------------                 -------------------------



ATC Group Services Inc.



By: /s/ Paul J. Grillo
    ----------------------------------
    Paul J. Grillo
    Chief Financial Officer

Date:  October 18, 2000
       -------------------------------



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