Document:

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                                                                     EXHIBIT 4.2

------------                                                       -----------
   NUMBER                                                             SHARES
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    INCORPORATED UNDER THE LAWS                    COMMONWEALTH OF PENNSYLVANIA

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                        INTEGRATED CIRCUIT SYSTEMS, INC.

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                          SEE LEGENDS ON REVERSE SIDE

This Certifies that                              _______________ is the owner of
                                                    full paid and non-assessable

   Shares of the Class A Common Stock, $.01 par value per share, of Integrated
Circuit Systems, Inc., transferable on the books of the Corporation in person or
by duly authorized Attorney upon surrender of this Certificate properly
endorsed.

     In Witness Whereof, the said Corporation has caused this Certificate to be
signed by its duly authorized officers and sealed with the Seal of the
Corporation,

this_____________day                                of______________A.D._______

_____________________                               ___________________________
       SECRETARY                                                     PRESIDENT
<PAGE>

                   NOTICE: THE SIGNATURE TO THIS ASSIGNMENT
              MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE
             FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT
              ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER

For Value Received, _______ hereby sell, assign and transfer unto ___________
_____________________________________________________________________Shares
represented by the within Certificate, and do hereby irrevocably constitute and
appoint
       ________________________________________________________________Attorney
to transfer the said Shares on the books of the within named Corporation with
full power of substitution in the premises.

        Dated_________________________________

            In presence of
        _______________________________________________________________________

                         -----------------------------
                            THIS SPACE IS NOT TO BE
                              COVERED IN ANY WAY
                         -----------------------------<PAGE>

                                                                       EXHIBIT A

                              AMENDMENT NO. 1 TO
                            STOCKHOLDERS AGREEMENT

     This Amendment No. 1 to STOCKHOLDERS Agreement (the "Amendment") is made
and entered into as of December 29, 1999, by and among Integrated Circuit
Systems, Inc., a Pennsylvania corporation (the "Company"), each of the Persons
                                                -------
listed on Schedule I attached hereto (the "Bain Stockholders"), each of the
          ----------                       -----------------
Persons listed on Schedule II attached hereto (the "Bear Stearns Stockholders"),
                  -----------                       -------------------------
the Person listed on Schedule III hereto (the "First Boston Stockholder") and
                     ------------              ------------------------
the Person listed on Schedule IV hereto (the "Intel Stockholder").
                     -----------              -----------------

                                   RECITALS

     A.   The Bain Stockholders, the Bear Stearns Stockholder, the First Boston
Stockholder and the Company entered into that certain Stockholders Agreement
dated as of May 11, 1999 (the "Original Agreement") for the purposes, among
others, of (i) assuring continuity in the management and ownership of the
Company and (ii) limiting the manner and terms by which the Stockholders' Common
Stock may be transferred.

     B.   Pursuant to a Series A Cumulative Convertible Preferred Stock Purchase
Agreement dated December 28, 1999 between the Company and Intel Corporation (the
Purchase Agreement"), the Company has agreed to sell to Intel Corporation, and
------------------
Intel Corporation has agreed to purchase from the Company, certain shares of the
Company's Series A Cumulative Convertible Preferred Stock (the "Series A
                                                                --------
Preferred Stock").  Pursuant to the Purchase Agreement, the Company has agreed
---------------
to provide certain rights to the Intel Stockholder, as more particularly set
forth in this Amendment.

     C.   Terms not otherwise defined in this Amendment have the meanings given
to them in the Agreement.

                                   AGREEMENT

     The parties hereto, intending to be legally bound, hereby agree as follows:

     1.   This Amendment constitutes an amendment to the Original Agreement.
          The Original Agreement, as amended by this Amendment, is herein
          referred to as the "Agreement." Except as specifically amended
          pursuant to the terms of this Amendment, all of the terms of the
          Original Agreement shall continue in full force and effect. Unless
          otherwise provided in this Agreement, capitalized terms used herein
          shall have the meanings set forth in Section 11 of the Agreement.

     2.   The Intel Stockholder is hereby  added as a party to the Agreement,
          and the definition of "Stockholder" in the first paragraph of the
          Original Agreement shall be amended to include the Intel Stockholder.

     3.   Schedule IV shall be added to the Original Agreement, and the
          reference to "Schedule I, II or III" in Section 1 of the Original
          Agreement are hereby replaced with "Schedule I, II, III or IV."
<PAGE>

     4.   Section 2(a) of the Original Agreement is hereby amended to add ", the
          Intel Stockholder" after the words "the Bear Stearns Stockholders,"
          and before the words "or the First Boston Stockholder" in the first
          sentence thereof, and to replace the words "Public Offering" with the
          words "Qualified Initial Public Offering" in the first sentence
          thereof.

     5.   Section 2(b) of the Original Agreement is hereby amended to add the
          words "the Intel Stockholder," after the words "the Bear Stearns
          Stockholders," and before the words "the First Boston Stockholder" in
          part (iv) thereof.

     6.   Section 3(a) of the Original Agreement is hereby amended to add the
          words "(in connection with a Transfer by an Intel Stockholder only),
          3(d)," after the word "3(c)" and to add "the Intel Stockholder," after
          the word "Neither" and before the words " the First Boston
          Stockholder" in the first sentence thereof.

     7.   Section 3(b)(i) of the Original Agreement is hereby amended to add ",
          the Intel Stockholder," after the words "the Bear Stearns
          Stockholders" and before the words "and the First Boston Stockholder"
          in the first and last sentences thereof.

     8.   Section 3 of the Original Agreement is hereby amended by renumbering
          the existing paragraphs (c) and (d) thereof as paragraph (d) and (e),
          respectively, and by adding the following subsection as new paragraph
          (c):

               "(c)  Intel Right of First Offer. Other than
                     --------------------------
               pursuant to an Approved Sale or an Approved
               Bain Sale, the Intel Stockholder may not
               Transfer any Stockholder Shares, directly or
               indirectly, in one transaction or a series of
               related transactions, to a Person engaged in
               the business of designing, producing and
               marketing mixed signal integrated circuits (a
               "Competitor"). Prior to making any Transfer
                ----------
               of Intel Shares pursuant to this Section
               3(c), Intel shall deliver a written notice
               (the "Intel Offer Notice") to the Company.
                     ------------------
               The Intel Offer Notice shall disclose in
               reasonable detail the proposed number of its
               Stockholder Shares to be transferred (the
               "Offered Shares") and the proposed sale
                --------------
               price, terms and conditions of the Transfer.
               The Company may elect to purchase all, but
               not less than all, of the Offered Shares at
               the price and on the other terms specified in
               the Intel Offer Notice by delivering written
               notice of such election to Intel within 20
               days after receipt of the Intel Offer Notice
               by the Company. If the Company has elected to
               purchase the Offered Shares from Intel within
               the aforementioned 20-day period, the
               Transfer of such shares shall be consummated
               as soon as practical after the delivery of
               the election notice to Intel, but in any
               event within 45 days after receipt of the
               Intel Offer Notice by the Company (or such
               longer period of time as may be required
               pursuant to applicable law). If the Company
               does not elect

                                      -2-
<PAGE>

               within the aforementioned 20-day period to
               purchase the Offered Shares, Intel may,
               within 80 days after the Company's receipt of
               the Intel Offer Notice, transfer such Intel
               Shares to one or more Persons (other than a
               Competitor) at a price and on other terms no
               more favorable to the transferee(s) thereof
               than offered to the Company in the Intel
               Offer Notice. Any Intel Shares not
               transferred within such 45-day period shall
               be reoffered to the Company in accordance
               with this Section 3(c) prior to any
               subsequent Transfer."

     9.   Section 3(c) of the Original Agreement (renumbered as 3(d) pursuant to
          Section 8 hereof) is hereby amended to delete the second proviso which
          begins "and provided  further" and replace  the second proviso in its
                      -----------------
          entirety  with the following language: "and provided further that the
                                                      -------- -------
          transferees of such Stockholder Shares shall have agreed in writing to
          be bound by the provisions of this Agreement and, with respect to all
          Stockholders other than transferees of the Intel Stockholder, the
          Voting Agreement, in each case affecting the Stockholder Shares so
          transferred."

     10.  Section 4(a) of the Original Agreement is hereby amended to add the
          words ", subject to paragraph (d) of this Section 4" after the words
          "by executing definitive agreements with respect to the sale thereof"
          in the second sentence thereof and to add the words "and paragraph (d)
          of this Section 4" after the words "immediately preceding proviso" in
          the last sentence thereof.

     11.  Section 4 of the Original Agreement is hereby amended by renumbering
          the existing paragraph (d) as paragraph (e), and by adding the
          following subsection as new paragraph (d):

               "(d) Without the prior written consent of the
               Intel Stockholder, the Company shall not
               enter into any agreement in connection with
               an Approved Sale unless (i) with respect to
               the Intel Stockholder, the liability of the
               shareholders under the agreement for the
               Approved Sale is several, and not joint and
               several, (ii) the liability of the Intel
               Stockholder under the offer is limited to the
               Intel Stockholder's pro rata portion of any
               claim and the liability of the Intel
               Stockholder will not, in any event, exceed
               that portion of the purchase price received
               by the Intel Stockholder in the Approved
               Sale; and (iii) the Intel Stockholder shall
               not be restricted from engaging in any line
               of business or subject to any non-
               competition, non-solicitation or similar
               covenants."

     12.  Section 5(a) of the Original Agreement is hereby amended to add the
          words ", subject to paragraph (d) of this Section 5" after the words
          "by executing definitive

                                      -3-
<PAGE>

          agreements with respect to the sale thereof" in the second sentence
          thereof and again at the end of such Section.

     13.  Section 5 of the Original Agreement is hereby amended by renumbering
          the existing paragraph (d) as paragraph (e), and by adding the
          following subsection as new paragraph (d):

               "(d) out the prior written consent of the
               Intel Stockholder, the Company shall not
               enter into any agreement in connection with
               an Approved Bain Sale unless (i) with respect
               to the Intel Stockholder, the liability of
               the shareholders under the agreement for the
               Approved Bain Sale is several, and not joint
               and several, (ii) the liability of the Intel
               Stockholder under the offer is limited to the
               Intel Stockholder's pro rata portion of any
               claim and the liability of the Intel
               Stockholder will not, in any event, exceed
               that portion of the purchase price received
               by the Intel Stockholder in the Approved Bain
               Sale; and (iii) the Intel Stockholder shall
               not be restricted from engaging in any line
               of business or subject to any non-
               competition, non-solicitation or similar
               covenants."

     14.  Section 7 of the Original Agreement is hereby deleted and replaced in
          its entirety with the following section:

               "7.   Initial Public Offering. In the event
                     -----------------------
               that the Board approves an initial public
               offering and sale of Common Stock (a "Public
                                                     ------
               Offering") pursuant to an effective
               --------
               registration statement under the Securities
               Act of 1933, as amended, the holders of
               Common Stock shall take all necessary or
               desirable actions in connection with the
               consummation of the Public Offering. In the
               event that such Public Offering is an
               underwritten offering and the managing
               underwriters advise the Company in writing
               that in their opinion the Common Stock
               structure would adversely affect the
               marketability of the offering, each holder of
               Common Stock shall consent to and vote for a
               recapitalization, reorganization and/or
               exchange of the Common Stock into securities
               that the managing underwriters and the Board
               find acceptable and shall take all necessary
               or desirable actions in connection with the
               consummation of the recapitalization,
               reorganization and/or exchange; provided that
                                               --------
               (a) the resulting securities take into
               account the rights and preferences set forth
               in the Company's Amended and Restated
               Articles of Incorporation as in effect
               immediately prior to such Public Offering and
               (b) any securities issued in exchange for the
               Series A Preferred Stock shall have rights,
               preferences and

                                      -4-
<PAGE>

               privileges substantially similar to and no
               less favorable than the Series A Preferred
               Stock. Nothing in this Section 7 shall be
               deemed to constitute a consent or waiver by
               the holders of Series A Preferred Stock with
               respect to any action for which such consent
               is required under the Company's Amended and
               Restated Articles of Incorporation."

     15.  Section 13 of the Original Agreement is hereby deleted and replaced in
          its entirety with the following section:

               "13.  Amendment and Waiver. Except as
                     --------------------
               otherwise provided herein, no modification,
               amendment or waiver of any provision of this
               Agreement shall be effective against the
               Company or the Stockholders unless such
               modification, amendment or waiver is approved
               in writing by the Company and the holders of
               a majority of each class of the Stockholder
               Shares; provided that in the event that such
                       --------
               modification, amendment, action or waiver (or
               any action with the effect of amending,
               modifying or waiving) would adversely affect
               the Intel Stockholder, the Bear Stearns
               Stockholders or the First Boston Stockholder
               in a manner different than the Bain
               Stockholders or otherwise reduce or diminish
               any rights that are applicable to the Intel
               Stockholder, the Bear Stearns Stockholders or
               the First Boston Stockholder unless the same
               rights applicable to the Bain Stockholders
               are reduced or diminished in the same manner,
               then such modification, amendment or waiver
               will require the consent of the Intel
               Stockholder, the Bear Stearns Stockholders or
               the First Boston Stockholder, as applicable.
               The failure of any party to enforce any of
               the provisions of this Agreement shall in no
               way be construed as a waiver of such
               provisions and shall not affect the right of
               such party thereafter to enforce each and
               every provision of this Agreement in
               accordance with its terms."

     16.  Section 18 of the Original Agreement is hereby deleted and replaced in
          its entirety with the following section:

               "18.  Remedies. The Company, the Bain
                     --------
               Stockholders, the Bear Stearns Stockholders,
               the Intel Stockholder and the First Boston
               Stockholder shall be entitled to enforce
               their rights under this Agreement
               specifically, to recover damages by reason of
               any breach of any provision of this Agreement
               and to exercise all other rights existing in
               their favor. The parties hereto agree and
               acknowledge that money damages would not be
               an adequate remedy for any breach of the
               provisions of this Agreement and that the

                                      -5-
<PAGE>

               Company, any of the Bain Stockholders, the
               Bear Stearns Stockholders, the Intel
               Stockholder or the First Boston Stockholder
               may in its sole discretion apply to any court
               of law or equity of competent jurisdiction
               for specific performance and/or injunctive
               relief (without posting a bond or other
               security) in order to enforce or prevent any
               violation of the provisions of this
               Agreement."

     17.  Section 23 of the Oiginal Agreement is hereby amended to add ", the
          Intel Stockholder" after the words "the Bear Stearns Stockholders" and
          before the words "and the First Boston Stockholder" in the first
          sentence thereof.

     18.  Section 25 of the Original Agreement is hereby deleted and replaced in
          its entirety with the following section:

               "25.  Rights Granted to the Bain
                     --------------------------
               Stockholders, the Bear Stearns Stockholders,
               -------------------------------------------
               the First Boston Stockholder, the Intel
                --------------------------------------
               Stockholder and their Affiliates. Any rights
               --------------------------------
               granted to the Bain Stockholders, the Bear
               Stearns Stockholders, the First Boston
               Stockholder, the Intel Stockholder or their
               Affiliates hereunder may also be exercised
               (in whole or in part) by its designees (which
               may be Affiliates)."

     19.  Miscellaneous.
          -------------

          (a)  Severability.  Whenever possible, each provision of this
               ------------
               Amendment shall be interpreted in such manner as to be effective
               and valid under applicable law, but if any provision of this
               Amendment is held to be invalid, illegal or unenforceable in any
               respect under any applicable law or rule in any jurisdiction,
               such invalidity, illegality or unenforceability shall not affect
               the validity, legality or enforceability of any other provision
               of this Amendment in such jurisdiction or affect the validity,
               legality or enforceability of any provision in any other
               jurisdiction, but this Amendment shall be reformed, construed and
               enforced in such jurisdiction as if such invalid, illegal or
               unenforceable provision had never been contained herein.

          (b)  Entire Agreement. Except as otherwise expressly set forth herein,
               ----------------
               this Amendment embodies the complete agreement and understanding
               among the parties hereto with respect to the subject matter
               hereof and supersedes and preempts any prior understandings,
               agreements or representations by or among the parties, written or
               oral, which may have related to the subject matter hereof in any
               way.

          (c)  Successors and Assigns. Except as otherwise provided herein, this
               ----------------------
               Amendment shall bind and inure to the benefit of and be
               enforceable by the Company and its successors and assigns and the
               Stockholders and any

                                      -6-
<PAGE>

               subsequent holders of Stockholder Shares and the respective
               successors and assigns of each of them, so long as they hold
               Stockholder Shares.

          (d)  Counterparts.  This Amendment may be executed in multiple
               ------------
               counterparts, each of which shall be an original and all of which
               taken together shall constitute one and the same agreement.

          (e)  Governing Law.  The corporate law of the Commonwealth of
               -------------
               Pennsylvania shall govern all issues and questions concerning the
               relative rights of the Company and its stockholders. All other
               issues and questions concerning the construction, validity,
               interpretation and enforceability of this Amendment and the
               exhibits and schedules hereto shall be governed by, and construed
               in accordance with, the laws of the Commonwealth of Pennsylvania,
               without giving effect to any choice of law or conflict of law
               rules or provisions (whether of the Commonwealth of Pennsylvania
               or any other jurisdiction) that would cause the application of
               the laws of any jurisdiction other than the Commonwealth of
               Pennsylvania.

                                      -7-
<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Amendment as of the day
and year first above written.

                              INTEGRATED CIRCUIT SYSTEMS, INC.

                              By: /s/ Hock E. Tan
                                 ----------------------------------------
                              Name: Hock E. Tan
                              Its:  President and Chief Executive Officer

                              INTEL CORPORATION

                              By: /s/ Arvind Sodhni
                                 ----------------------------------------
                              Name: Arvind Sodhni
                              Its: Vice President and Tresurer

                                      -8-
<PAGE>

BAIN STOCKHOLDERS:
-----------------

BAIN CAPITAL FUND VI, L.P.

By:  Bain Capital Partners VI, L.P.
Its: General Partner

By:  Bain Capital Investors VI, Inc.
Its: General Partner

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

BCIP TRUST ASSOCIATES II

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

BCIP TRUST ASSOCIATES II-B

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

BCIP ASSOCIATES II

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

BCIP ASSOCIATES II-B

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

BCIP ASSOCIATES II-C

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

PEP INVESTMENTS PTY LTD.

By: /s/ Michael Krupka
   ------------------------
Name: Michael Krupka
Its:  Managing Director

RANDOLPH STREET PARTNERS II

By:_______________________________
Name:
Its:

RANDOLPH STREET PARTNERS 1998
DIF, L.L.C.

By:_______________________________
Name:
Its:

                                      -9-
<PAGE>

                                        BEAR STEARNS STOCKHOLDERS:
                                        -------------------------

                                        ICST ACQUISITION CORP.

                                        By: /s/ Bodil Arlander
                                           ----------------------
                                        Name: Bodil Arlander
                                        Its:  Vice President

                                      -10-
<PAGE>

                                  SCHEDULE IV
                                  -----------

Name and Address                    Number of Stockholder Shares
----------------                    ----------------------------

Intel Corporation                   3,366,670 shares of Series A Cumulative
                                    Convertible Preferred Stock

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