2900 Semiconductor Drive
Santa Clara, CA 95052-8090
408 721 5000 Tel




                                                                August __, 2002



Mr. Duane Oto
563 Dawn Drive
Sunnyvale, California 94087


Dear Mr. Oto:

     This addendum to your Employment Agreement ("Addendum") supplements certain
provisions of the Option and  Agreement  and Plan of Merger  entered into by and
among National Semiconductor Corporation  ("National"),  Nintai Acquisition Sub,
Inc. DigitalQuake,  Inc.  ("DigitalQuake"),  Paul A. Lessard and Michael G. Fung
dated as of February 8, 2002, as amended as of the date hereof,  and as same may
be  subsequently  amended from time to time (the "Merger  Agreement")  solely as
such provisions relate to National and each Principal Employee as an employee of
National.  Capitalized  terms used in this letter have the meanings  assigned to
them in the Merger Agreement.

     1.   Section 3.5 of the Merger Agreement provides that you will receive the
          second installment payment and the third installment payment due under
          the Merger  Agreement  with respect to your  DigitalQuake  Options and
          DigitalQuake  Common  Stock in cash.  This  Addendum  supplements  the
          Merger Agreement to give you the option to receive all or a portion of
          the  second  and third  installment  payments  in cash or in shares of
          National  Common  Stock  as set  forth  below.  As  used  herein,  the
          "National  Common  Stock" means the common  stock,  par value $.50 per
          share, of National.

          (a)  You may elect to receive all or a part of the second  installment
               payment in cash or shares of National  Common Stock by delivering
               notice of such election to National in the form  attached  hereto
               as Exhibit A and in the  manner set forth for  notices in Section
               14.3 of the Merger  Agreement  (an  "Election  Notice")  at least
               fifteen  (15) but no more than  thirty  (30) days prior to August
               24,  2003,  provided  you  have  been  continuously  employed  by
               National in its Displays  Group from the  Effective  Time through
               August 24,  2003.  Such notice  shall  specify the portion of the
               second  installment to be paid in cash and the portion to be paid
               in shares of NSC Common  Stock.  The number of shares of National
               Common Stock shall be  determined  in  accordance  with Section 3
               below; and


          (b)  You may elect to receive  all or a part of the third  installment
               payment in cash or shares of National  Common Stock by delivering
               notice of such  election to National an Election  Notice at least
               fifteen  (15) but no more than  thirty  (30) days prior to August
               29,  2004,  provided  you  have  been  continuously  employed  by
               National in its Displays  Group  through  August 29,  2004.  Such
               notice shall specify the portion of the third  installment  to be
               paid in cash and the  portion  to be paid in shares of NSC Common
               Stock.  The number of shares of  National  Common  Stock shall be
               determined in accordance with Section 3 below.

     2.   The form of the Election Notice is attached hereto as Exhibit A If you
          do not provide an Election  Notice under Section 1(a) or Section 1(b),
          you  will  be  deemed  to  have  elected  to  receive  the  applicable
          installment payment entirely in cash.

     3.   The number of shares of National Common Stock to be issued to you upon
          your  election  to  receive  all or a portion  of the  second or third
          installment payment in shares of National Common Stock shall equal the
          quotient  of (x)  the  dollar  amount  of the  applicable  installment
          payment  payable to you which you have  elected to receive in National
          Common  Stock on the  Election  Notice form divided by (y) the opening
          price of the  National  Common Stock as reported on the New York Stock
          Exchange  Composite  Tape on the Closing Date (or if there shall be no
          trading on such date, then on the first subsequent date on which there
          is  trading).  In the event  National  changes the number of shares of
          National  Common Stock issued and  outstanding  as a result of a stock
          split, stock dividend or similar recapitalization with respect to such
          stock and the record date  therefor (in the case of a stock  dividend)
          or the effective date thereof (in the case of a stock split or similar
          recapitalization  for which a record date is not established) shall be
          prior to August  29,  2004,  the number of shares of  National  Common
          Stock issuable pursuant to Section 1(a) or Section 1(b) above shall be
          proportionately adjusted. National shall file a registration statement
          with the U.S.  Securities and Exchange Commission on Form S-8 or other
          appropriate  form with respect to the shares of National  Common Stock
          issuable pursuant to this letter prior to August 24, 2003.

     4.   Your  right to  receive  the  second  installment  payment  and  third
          installment  payment in whole or in part in shares of National  Common
          Stock is contingent upon your being continuously  employed by National
          in its Display Group from the Effective  Time through  August 24, 2003
          and  through   August  29,  2004,   respectively.   Accordingly,   you
          acknowledge   that  your  right  to  receive   the  second  and  third
          installment  payment in whole or in part in shares of National  Common
          Stock,  with the number of shares to be  determined  by reference to a
          fixed  and  determined  price,  is a  benefit  to which  you would not
          otherwise  be  entitled  if you had not become an employee of National
          upon  the  completion  of  the  merger   contemplated  by  the  Merger
          Agreement.


     5.   All of the  shares of  National  Common  Stock  issuable  pursuant  to
          Section 1(a) or Section 1(b) above will be validly issued,  fully paid
          and nonassessable and free of and not subject to any preemptive rights
          or rights of first refusal created by statute or by National's  Second
          Restated  Certificate  of  Incorporation,  as amended,  or Amended and
          Restated Bylaws upon their issuance pursuant to this Addendum.

     6.   You  understand  that you may suffer adverse tax  consequences  in the
          event  you  elect  to  receive  all or part  of the  second  or  third
          installment payments in shares of National Common Stock. You represent
          that you have consulted with any tax consultants you deem advisable in
          connection with your option to exercise such election and that you are
          not relying on National for any tax advice.






Please sign below to confirm your agreement with the items set forth above.

                                            Very truly yours,

                                            NATIONAL SEMICONDUCTOR CORPORATION

                                            By:  //S// D A HANDORF

ACCEPTED AND AGREED TO AS OF
8/26/02:
- --------

//S// DUANE OTO
- ---------------
Duane Oto




                                    Exhibit A

       NOTICE OF ELECTION TO RECEIVE INSTALLMENT PAYMENT IN CASH OR STOCK


To:     National Semiconductor Corporation

From:   Duane Oto

Re:     Election to Receive Installment Payment in Cash or Stock


     Pursuant to the Option and Agreement and Plan of Merger entered into by and
among National Semiconductor Corporation  ("National"),  Nintai Acquisition Sub,
Inc. and  DigitalQuake,  Inc.  ("DigitalQuake"),  Paul A. Lessard and Michael G.
Fung dated as of February 8, 2002 as amended  (the "Merger  Agreement")  and the
Addendum to the Employment Agreement dated August ___, 2002 between National and
the  undersigned,  notice is hereby given that the undersigned  hereby elects to
receive the installment  payment set forth below  contemplated by Section 3.5 of
the Merger Agreement in the form set forth below:.

Check as applicable:

         _____  Second Installment Payment

         _____  Third Installment Payment

Form of Payment

         _____  All in cash, payable by check or wire transfer

         _____  All in shares of National Common Stock

         _____  A combination of cash and National Common Stock,  with $________
                to be paid in cash and  $_________  to be paid in shares  of
                National Common Stock



Dated: ______________

                                          ________________________________
                                          Duane Oto