Exhibit 10.28








                  THIRD   AMENDMENT,   dated  as  of  March   28,   1996   (this
"Amendment"),  to the Credit Agreement, dated as of January 13, 1995 (as amended
pursuant to the First Amendment thereto,  dated as of March 28, 1995, the Second
Amendment thereto, dated as of October 13, 1995, and this Amendment,  and as the
same may be further  amended,  supplemented  or otherwise  modified from time to
time,  the "Credit  Agreement"),  among  STANDARD  MICROSYSTEMS  CORPORATION,  a
Delaware  corporation (the "Borrower") and the several banks and other financial
institutions  from time to time parties  thereto  (collectively,  the "Lenders";
individually a "Lender").


                              W I T N E S S E T H :


                  WHEREAS,  the  Borrower  and the  Lenders  are  parties to the
Credit Agreement;

                  WHEREAS, the Borrower has requested that the Lenders amend the
Credit Agreement in the manner provided for herein; and

                  WHEREAS,  the Lenders  are  willing to agree to the  requested
amendments;

                  NOW,  THEREFORE,  in consideration  of the premises  contained
herein, the parties hereto agree as follows:

                  1. Defined Terms. Unless otherwise defined herein, terms which
are defined in the Credit Agreement and used herein as defined terms are so used
as so defined.

                  2.  Amendment to Subsection  1.1. (a) Subsection 1.1 is hereby
amended by  inserting  the word  "CSM"  before the  defined  term  "Subscription
Agreement"  and placing the defined  term "CSM  Subscription  Agreement"  in the
proper alphabetical order.

         (b) Subsection 1.1 of the Credit Agreement is hereby further amended by
inserting the following  definitions in the proper alphabetical order to read as
follows:

                  "DSNT":  Digital Secured Networks  Technology Inc., a Delaware
         corporation."

                  "DSNT Subscription Agreement": the Agreement dated as of March
         28, 1996, among DSNT and the Borrower

                  "Third  Amendment":  the Third  Amendment  to this  Agreement,
         dated as of April 28, 1996.

                  3. Amendment to Subsection  6.9.  Subsection 6.9 of the Credit
Agreement is hereby amended as follows:

                  (a) by deleting the word "and"  appearing at the end of clause
         (d) thereof;





                                                                   Exhibit 10.28

                  (b) by  deleting  the period at the end of clause (e)  thereof
         and substituting "; and" in lieu thereof; and

                  (c) by adding a new  clause at the end  thereof to read in its
         entirety as follows:

                           "(f)  the   acquisition   of  Series  A   Convertible
                  Preferred  Stock in DSNT by the Borrower  pursuant to the DSNT
                  Subscription  Agreement for an aggregate purchase price not to
                  exceed $250,000."

                  4.  Amendment to Schedule  3.15.  Schedule  3.15 of the Credit
Agreement  is hereby  amended by  deleting  such  Schedule in its  entirety  and
substituting in lieu thereof a new Schedule to read in its entirety as set forth
in Annex A hereto.

                  5.  Representations  and  Warranties.  On and  as of the  date
hereof, the Borrower hereby confirms, reaffirms and restates the representations
and warranties set forth in Section 3 of the Credit Agreement  mutatis mutandis,
except to the extent that such  representations and warranties  expressly relate
to a specific earlier date in which case the Borrower hereby confirms, reaffirms
and restates  such  representations  and  warranties  as of such  earlier  date,
provided that the references to the Credit Agreement in such representations and
warranties  shall be deemed to refer to the Credit Agreement as amended pursuant
to this Amendment.

                  6.  Conditions to  Effectiveness.  This Amendment shall become
effective as of the date first written above upon execution of this Amendment by
the Borrower and the Required  Lenders and upon execution of the  Acknowledgment
and Consent attached hereto by each Guarantor.

                  7. Continuing Effect; No Other Amendments. Except as expressly
amended hereby,  all of the terms and provisions of the Credit Agreement are and
shall remain in full force and effect.  The  amendments  provided for herein are
limited to the specific subsections of the Credit Agreement specified herein and
shall  not  constitute  an  amendment  of,  or an  indication  of  the  Lenders'
willingness to amend,  any other  provisions of the Credit Agreement or the same
subsections  for any  other  date or time  period  (whether  or not  such  other
provisions or compliance  with such  subsections for another date or time period
are affected by the circumstances addressed in this Amendment).

                  8.  Expenses.  The Borrower  agrees to pay and reimburse  each
Lender for all its  reasonable  costs and  out-of-pocket  expenses  incurred  in
connection  with the  preparation  and  delivery of this  Amendment,  including,
without  limitation,  the reasonable fees and  disbursements  of counsel to such
Lender.

                  9. Counterparts.  This Amendment may be executed in any number
of  counterparts  by the  parties  hereto,  each of which  counterparts  when so
executed  shall  be  an  original,  but  all  the  counterparts  shall  together
constitute one and the same instrument.





                                                                   Exhibit 10.28


                  10.  GOVERNING LAW. THIS  AMENDMENT  SHALL BE GOVERNED BY, AND
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.


                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Amendment  to be executed  and  delivered by their  respective  duly  authorized
officers as of the date first above written.


STANDARD MICROSYSTEMS CORPORATION


By:______________________________________
   Name:
   Title:


CHEMICAL BANK


By:______________________________________
   Name:
   Title:


NATIONAL WESTMINSTER BANK N.A.


By:______________________________________
   Name:
   Title:







                           ACKNOWLEDGEMENT AND CONSENT


                  Each of the undersigned corporations as a guarantor under that
certain Guarantee, dated as of January 13, 1995 (the "Guarantee"),  made by each
of such  corporations  in favor of the Lenders  confirms and agrees that,  after
giving effect to the Third Amendment to which this Acknowledgment and Consent is
attached,  the Guarantee is, and shall  continue to be, in full force and effect
and is hereby ratified and confirmed in all respects and the Guarantee does, and
shall continue to, secure the payment of all of the  Obligations  (as defined in
the  Guarantee)  pursuant to the terms of the Guarantee.  Capitalized  terms not
otherwise  defined herein shall have the meanings assigned to them in the Credit
Agreement  referred to in the Third Amendment to which this  Acknowledgment  and
Consent is attached.

STANDARD MICROSYSTEMS                  SMC FRANCE, INC.
CORPORATION (ASIA)


By                                     By
   -------------------------             -------------------------


Title                                  Title
      ----------------------                ----------------------





SMC AUSTRALIA, INC.                    SMC INTERNATIONAL, INC.


By                                     By
    ------------------------             ------------------------


Title                                  Title
      ----------------------                ----------------------








SMC MASSACHUSETTS INC.                 SMC NORTH AMERICA, INC. (formerly
                                         known as SMC SALES, INC.) 



By                                    By
    ------------------------              ------------------------


Title                                Title
      ----------------------                ----------------------








                                                                       Annex A

                                                                 Schedule 3.15

                        STANDARD MICROSYSTEMS CORPORATION

                            SCHEDULE OF SUBSIDIARIES


All subsidiaries are wholly-owned, except Toyo Microsystems Corporation.

Delaware corporations

Standard Microsystems Corporation (Asia)

SMC Australia, Inc.

SMC France, Inc.

SMC International, Inc.

SMC Massachusetts, Inc.

SMC North America, Inc. (formerly known as SMC Sales, Inc.)


Foreign corporations

Standard Microsystems Corporation (Canada)
         (incorporated in Ontario, Canada)

Standard Microsystems (Europe) Limited
         (incorporated in United Kingdom)

Standard Microsystems GmbH
         (incorporated in Germany)

Toyo Microsystems Corporation
         (incorporated in Japan)