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                                                                   Exhibit 10.13

                              SEVERANCE AGREEMENT
                              -------------------

     This Severance Agreement is entered into as of this 8th day of July, 1998
by and between Aseco Corporation, a Delaware corporation (the "Company"), and
Mary R. Barletta (the "Employee").

                                   Recitals:
                                   --------

     WHEREAS, the Employee is an executive officer of the Company; and

     WHEREAS, the Company and the Employee wish to provide for the payment of
certain severance compensation by the Company to the Employee in the event the
Employee's employment by the Company is terminated.

     NOW, THEREFORE, in consideration of the Employee's continued service to the
Company and other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties agree as follows:

     1.  Definitions.
         -----------

     "Benefit Period" shall mean the twelve (12)-month period following the
Termination Date.

     "Cause" shall be deemed to exist if the Board of Directors of the Company
or its successor in good faith determines, after giving the Employee notice and
an opportunity to be heard, that the Employee has committed an act constituting
fraud, embezzlement, larceny or theft.

     "Change in Control" shall mean (i) the sale, lease, transfer or other
disposition by the Company of all or substantially all of its assets in a single
transaction or a series of related transactions; (ii) the merger or
consolidation of the Company with another entity in which the stockholders of
the Company immediately prior to such merger or consolidation hold less than 50%
of the outstanding voting stock of the surviving or resulting corporation
immediately following such transaction; or (iii) the sale or exchange (to or
with any person or entity other than the Company) by the stockholders of more
than 50% of the outstanding voting stock of the Company in a single transaction
or series of related transactions.

     "Good Reason" shall mean a material reduction in the duties and
responsibilities of the Employee or the assignment to the Employee of duties and
responsibilities that are inconsistent in a material and adverse respect with
his or her current position.

     "Ineligibility Period" shall mean that portion of the Benefit Period when
the Employee is ineligible for coverage under the Company's group life or group
health insurance policies.

     "Termination Date" shall mean the effective date of the termination of the
Employee's employment with the Company.
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     2.  Severance.
         ---------

     In the event the Employee's employment by the Company is terminated
(i) without Cause by the Company or any successor or (ii) for Good Reason by the
Employee, in either case within twelve (12) months following a Change in
Control, the Company or its successor shall (A) pay the Employee within five
days after the Termination Date a lump sum amount equal to twelve (12) times the
Employee's monthly base salary in effect at the time of such termination (less
applicable withholding taxes and FICA) and (B) continue to provide during the
Benefit Period life and health insurance coverage to the Employee, with benefits
substantially comparable to those provided to executive officers of the Company
generally immediately prior to such termination. Notwithstanding the foregoing,
the Company shall have the right, in lieu of providing such coverage during any
Ineligibility Period, to pay the Employee an amount equal to 200% of the amount
it would have cost the Company to provide such coverage during any Ineligibility
Period, assuming the Employee were eligible for coverage under the Company's
group insurance policies and assuming further no increase in premium costs under
such policies after the commencement of any Ineligibility Period.

     3.  Acceleration of Vesting; Extension of Exercise Period of Stock Options.
         ----------------------------------------------------------------------

     Upon a Change in Control, all options held by the Employee to purchase
common stock of the Company shall become fully vested and immediately
exercisable in full, notwithstanding any terms to the contrary contained in the
stock option agreements pursuant to which such options were granted.  In the
event the Employee's employment by the Company is terminated (i) without Cause
by the Company or any successor or (ii) for Good Reason by the Employee, in
either case, within twelve (12) months following a Change in Control, all
options held by the Employee to purchase common stock of the Company shall be
exercisable at any time prior to the earlier of (i) the first anniversary of the
date of termination of the Employee's employment with the Company and (ii) the
expiration date of the option, notwithstanding any terms to the contrary
contained in the stock option agreements pursuant to which such options were
granted.

     4.  Miscellaneous.
         -------------

         4.1  This Agreement constitutes the entire agreement between the
parties and supersedes all prior agreements and understandings, whether written
or oral, relating to the subject matter of this Agreement.

         4.2  This Agreement may be amended or modified only by a written
instrument executed by both the Company and the Employee.

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         4.3  This Agreement shall be construed, interpreted and enforced in
accordance with the laws of The Commonwealth of Massachusetts.

         4.4  This Agreement shall be binding upon and inure to the benefit of
both parties and their respective successors and assigns, including any
corporation with which or into which the Company may be merged or which may
succeed to its assets or business.

         4.5  The captions of the sections of this Agreement are for
convenience of reference only and in no way define, limit or affect the scope or
substance of any section of this Agreement.

         4.6  In case any provision of this Agreement shall be invalid, illegal
or otherwise unenforceable, the validity, legality and enforceability of the
remaining provisions shall in no way be affected or impaired thereby.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year set forth above.

                              ASECO CORPORATION


                              By: /s/ Sebastian J. Sicari
                                  ------------------------------

                              Title: President & COO
                                  ------------------------------



                              EMPLOYEE

                              /s/ Mary R. Barletta
                              ----------------------------------
                              Mary R. Barletta

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