EXHIBIT A

                      AGREEMENT AND PLAN OF MERGER BETWEEN

                    PMC-SIERRA, INC., A DELAWARE CORPORATION

                                       AND

           SIERRA SEMICONDUCTOR CORPORATION, A CALIFORNIA CORPORATION


         THIS  AGREEMENT AND PLAN OF MERGER dated as of ________ __, 1997,  (the
"Agreement")   is   between   PMC-SIERRA,    INC.,   a   Delaware    corporation
("Sierra-Delaware")   and  SIERRA   SEMICONDUCTOR   CORPORATION,   a  California
corporation  ("Sierra-California").  Sierra-Delaware and  Sierra-California  are
sometimes referred to herein as the "Constituent Corporations."

                                 R E C I T A L S
                                 ---------------
         A. Sierra-Delaware  is a  corporation duly organized and existing under
the laws of the State of Delaware and has an  authorized  capital of  55,000,000
shares,  50,000,000 of which are designated  "Common  Stock," no par value,  and
5,000,000 of which are designated  "Preferred  Stock",  no par value.  As of the
date  of  this  Agreement,   1,000  shares  of  Common  Stock  were  issued  and
outstanding, all of which were held by Sierra-California. No shares of Preferred
Stock were issued and outstanding.

         B. Sierra-California is a corporation duly organized and existing under
the laws of the State of California and has an authorized  capital of 55,405,916
shares,  50,000,000  of which  are  designated  "Common  Stock",  no par  value,
5,000,000 of which are designated  "Preferred  Stock", no par value, and 405,916
of which are designated "Series D Preferred Stock," no par value. As of the date
of  this  Agreement,   ___________  shares  of  Common  Stock  were  issued  and
outstanding.  No  shares  of  Preferred  Stock or  Series D  Preferred  Stock or
undersigned preferred Stock were issued and outstanding.

         C. The Board of Directors of Sierra-California has determined that, for
the purpose of effecting the reincorporation of  Sierra-California  in the State
of Delaware, it is advisable and in the best interests of Sierra-California that
Sierra-California  merge  with  and into  Sierra-Delaware  upon  the  terms  and
conditions herein provided.

         D.  The  respective   Boards  of  Directors  of   Sierra-Delaware   and
Sierra-California  have  approved  this  Agreement  and have  directed that this
Agreement be submitted to a vote of their  respective  shareholders and executed
by the undersigned officers.

         NOW, THEREFORE, in consideration of the mutual agreements and covenants
set forth herein, Sierra-Delaware and Sierra-California hereby agree, subject to
the terms and conditions hereinafter set forth, as follows:

                                   I. MERGER

         1.1.  Merger. In accordance with the provisions of this Agreement,  the
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Delaware  General   Corporation  Law  and  the  California   Corporations  Code,
Sierra-California  shall be merged with and into Sierra-Delaware (the "Merger"),
the separate  existence  of  Sierra-California  shall cease and  Sierra-Delaware
shall be, and is herein sometimes referred as, the "Surviving Corporation",  and
the name of the Surviving Corporation shall be PMC-Sierra, Inc.

         1.2. Filing and Effectiveness.  The Merger shall become  effective when
              ------------------------
the following  actions shall have been completed:

                  (a)     This  Agreement and Merger shall have been adopted and
approved by the shareholders of each Constituent  Corporation in accordance with
the  requirements  of the Delaware  General  Corporation  Law and the California
General Corporation Law;

                  (b)     All of the conditions precedent  to the  consummation
of the Merger shall have been  satisfied or duly waived by the party entitled to
satisfaction thereof;

                  (c)     Executed  documents  evidencing the Merger and meeting
the  requirements  of the Delaware  General  Corporation  Law and the California
Corporations  Code,  shall have been filed  with the  Secretary  of State of the
State of Delaware and with the Secretary of State of the State of California.

         The date and time when the Merger shall become effective, as aforesaid,
is herein called the "Effective Date."

         1.3.  Effect of the  Merger.  Upon the  Effective  Date,  the  separate
               ---------------------
existence of Sierra-California shall cease and Sierra-Delaware, as the Surviving
Corporation, (i) shall continue to possess all of its assets, rights, powers and
property as constituted  immediately  prior to the Effective Date, (ii) shall be
subject to all actions previously taken by its and by Sierra-California's Boards
of Directors, (iii) shall succeed, without other transfer, to all of the assets,
rights,  powers and  property  of  Sierra-California  in the manner set forth in
Section 259 of the Delaware  General  Corporation Law, (iv) shall continue to be
subject  to  all  of its  debts,  liabilities  and  obligations  as  constituted
immediately  prior to the Effective  Date, and (v) shall succeed,  without other
transfer, to all of the debts,  liabilities and obligations of Sierra-California
in the same  manner as if  Sierra-Delaware  had  itself  incurred  them,  all as
provided under the applicable provisions of the Delaware General Corporation Law
and the California Corporations Code.


                  II. CHARTER DOCUMENTS, DIRECTORS AND OFFICERS

         2.1.  Certificate  of  Incorporation  and Bylaws.  The  Certificate  of
               ------------------------------------------
Incorporation and Bylaws of  Sierra-Delaware  as in effect  immediately prior to
the Effective Date shall continue in full force and effect as the Certificate of
Incorporation  and Bylaws of the  Surviving  Corporation  until duly  amended in
accordance with the provisions thereof and applicable law.

         2.2.  Directors   and   Officers.   The   directors   and  officers  of
               --------------------------
Sierra-California immediately prior to the Effective Date shall be the directors
and officers of the Surviving Corporation until their successors shall have been
duly  elected  and  qualified  or as  otherwise  provided  by  law,  or  by  the
Certificate of Incorporation or Bylaws of the Surviving Corporation.


                        III. MANNER OF CONVERSION OF STOCK

         3.1.  Sierra-California  Common Stock Shares.  Upon the Effective Date,
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each  share  of  Sierra-California  Common  Stock,  no  par  value,  issued  and
outstanding  immediately prior thereto shall by virtue of the Merger and without
any action by the Constituent  Corporations,  by the holder of such shares or by
any other  person,  be  converted  into and  exchanged  for one  fully  paid and
nonassessable share of Common Stock, no par value, of the Surviving Corporation.
No fractional  share  interests of Surviving  Corporation  Common Stock shall be
issued. In lieu thereof,  any fractional share interests to which a holder would
otherwise be entitled shall be aggregated.

         3.2.  Sierra-California Options, Stock Purchase Rights  and Convertible
               -----------------------------------------------------------------
Securities.
- - -----------
                  (a) Upon the Effective Date, the Surviving  Corporation  shall
assume the  obligations of  Sierra-California  under,  and continue,  the option
plans  (including  without  limitation,  the 1987 Incentive Stock Plan, the 1991
Employee Stock  Purchase Plan, and the 1994 Incentive  Stock Plan) and all other
employee benefit plans of Sierra-California,  and the Exchange Agreement between
PMC-Sierra,   Inc.,   the  Canadian   subsidiary   of   Sierra-California,   and
Sierra-California,  as amended.  Each outstanding and unexercised option,  other
right to  purchase  (including  without  limitation,  the  rights of  holders of
special   shares   of   PMC-Sierra,    Inc.,   the   Canadian    subsidiary   of
Sierra-California,  and of options to  purchase  such  special  shares,  and the
rights of the holders of options of PMC-Sierra,  Inc.  (Portland)),  or security
convertible  into,  Sierra-California  Common  Stock (a "Right")  shall  become,
subject to the provisions in paragraph (c) hereof, an option,  right to purchase
or a security  convertible into the Surviving  Corporation's Common Stock on the
basis of one  share of the  Surviving  Corporation's  Common  Stock for each one
share of Sierra-California  Common Stock issuable pursuant to any such Right, on
the same terms and  conditions  and at an exercise  price equal to the  exercise
price applicable to any such Sierra-California Right at the Effective Date. This
paragraph  3.2(a) shall not apply to  Sierra-California  Common Stock,  which is
subject to paragraph 3.1.

                  (b) A number of shares of the Surviving  Corporation's  Common
Stock shall be  reserved  for  issuance  upon the  exercise  of  options,  stock
purchase  rights  and  convertible  securities  equal to the number of shares of
Sierra-California  Common Stock so reserved  immediately  prior to the Effective
Date.


                  (c) The assumed Rights shall not entitle any holder thereof to
a fractional  share upon exercise or  conversion.  In addition,  no  "additional
benefits"  (within the meaning of Section 424(a)(2) of the Internal Revenue Code
of 1986,  as  amended)  shall  be  accorded  to the  optionees  pursuant  to the
assumption of their options.

         3.3. Sierra-Delaware Common Stock Shares. Upon the Effective Date, each
share of Common  Stock of  Sierra-Delaware  issued and  outstanding  immediately
prior  thereto  shall,  by  virtue  of the  Merger  and  without  any  action by
Sierra-Delaware,  the holder of such shares or by any other person,  be canceled
and returned to the status of authorized but unissued shares.

         3.4. Exchange of Certificates. After the Effective Date, each holder of
an outstanding certificate representing shares of Sierra-California Common Stock
may be asked to surrender the same for  cancellation to Boston  EquiServe,  L.P.
(the  "Exchange  Agent"),  and each such holder  shall be entitled to receive in
exchange  therefor a  certificate  or  certificates  representing  the number of
shares of the Surviving  Corporation's  Common  Stock,  as the case may be, into
which  the  surrendered  shares  were  converted  as herein  provided.  Until so
surrendered,  each outstanding  certificate  theretofore  representing shares of
Sierra-California Common Stock shall be deemed for all purposes to represent the
number of shares of the Surviving Corporation's Common Stock, respectively, into
which such shares of  Sierra-California  Common Stock,  as the case may be, were
converted in the Merger.

         The  registered  owner  on the  books  and  records  of  the  Surviving
Corporation or the Exchange  Agent of any such  outstanding  certificate  shall,
until such certificate shall have been surrendered for transfer or conversion or
otherwise accounted for to the Surviving Corporation or the Exchange Agent, have
and be entitled to exercise  any voting and other  rights with respect to and to
receive dividends and other distributions upon the shares of Common Stock of the
Surviving  Corporation  represented by such outstanding  certificate as provided
above.

         Each certificate representing Common Stock of the Surviving Corporation
so issued in the Merger shall bear the same legends, if any, with respect to the
restrictions on  transferability  as the  certificates of  Sierra-California  so
converted and given in exchange  therefore,  unless otherwise  determined by the
Board of Directors of the Surviving  Corporation in compliance  with  applicable
laws.

         If any certificate for shares of the Surviving  Corporation's  stock is
to be issued in a name other than that in which the  certificate  surrendered in
exchange  therefor is  registered,  it shall be a condition of issuance  thereof
that the certificate so surrendered  shall be properly endorsed and otherwise in
proper form for transfer, that such transfer otherwise be proper and comply with
applicable  securities laws and that the person  requesting such transfer pay to
the Exchange  Agent any transfer or other taxes payable by reason of issuance of
such new  certificate in a name other than that of the registered  holder of the
certificate  surrendered  or  establish  to the  satisfaction  of the  Surviving
Corporation that such tax has been paid or is not payable.


                                   IV. GENERAL

         4.1.  Covenants  of  Sierra-Delaware.   Sierra-Delaware  covenants  and
               ------------------------------
agrees that it will, on or before the Effective Date:

                  (a)      Qualify  to  do business  as a foreign corporation in
the State of California and in connection therewith irrevocably appoint an agent
for service of process as required  under the  provisions of Section 2105 of the
California General Corporation Law.

                  (b)      File  any  and  all  documents  with  the  California
Franchise Tax Board  necessary for the assumption by  Sierra-Delaware  of all of
the franchise tax liabilities of Sierra-California.

                  (c)      Take  such   other actions as may be required  by the
California General Corporation Law.

         4.2.  Further  Assurances.  From time to time,  as and when required by
               -------------------
Sierra-Delaware  or by its  successors  or assigns,  there shall be executed and
delivered on behalf of Sierra-California  such deeds and other instruments,  and
there shall be taken or caused to be taken by it such further and other  actions
as shall be  appropriate  or necessary in order to vest or perfect in or conform
of record or otherwise by Sierra-Delaware the title to and possession of all the
property, interests, assets, rights, privileges,  immunities, powers, franchises
and  authority of  Sierra-California  and otherwise to carry out the purposes of
this  Agreement,  and the officers and  directors of  Sierra-Delaware  are fully
authorized in the name and on behalf of  Sierra-California  or otherwise to take
any and all such  action and to execute  and  deliver any and all such deeds and
other instruments.

         4.3.  Abandonment.   At  any  time  before  the  Effective  Date,  this
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Agreement may  be terminated  and the  Merger  may be  abandoned  for any reason
whatsoever  by  the  Board  of  Directors  of  either  Sierra-California  or  of
Sierra-Delaware,  or of both,  notwithstanding the approval of this Agreement by
the   shareholders  of   Sierra-California   or  by  the  sole   stockholder  of
Sierra-Delaware, or by both.

         4.4.  Amendment.The Boards of Directors of the Constituent Corporations
               ---------
may amend this  Agreement at any time prior to the filing of this  Agreement (or
certificate  in lieu  thereof)  with the  Secretary  of State of the  States  of
California  and  Delaware,  provided  that an amendment  made  subsequent to the
adoption of this Agreement by the shareholders of either Constituent Corporation
shall not: (1) alter or change the amount or kind of shares,  securities,  cash,
property and/or rights to be received in exchange for or on conversion of all or
any  of  the  shares  of  any  class  or  series  thereof  of  such  Constituent
Corporation, (2) alter or change any term of the Certificate of Incorporation of
the Surviving  Corporation to be effected by the Merger,  or (3) alter or change
any of the terms and conditions of this  Agreement if such  alteration or change
would  adversely  affect the holders of any class or series of capital  stock of
any Constituent Corporation.


         4.5   Registered  Office.  The  registered  office  of the  Surviving
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Corporation in the State of Delaware is 1209 Orange Street,  Wilmington,  County
of New Castle,  DE 19801,  and The  Corporation  Trust Company is the registered
agent of the Surviving Corporation at such address.

         4.6.  Agreement.  Executed  copies of this Agreement will be on file at
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the principal place of business of the Surviving Corporation at 2222 Qume Drive,
San  Jose,  California  95131  and  copies  thereof  will  be  furnished  to any
stockholder of either Constituent Corporation, upon request and without cost.

         4.7.  Governing Law. This Agreement shall in all respects be construed,
               -------------
interpreted  and  enforced in  accordance  with and  governed by the laws of the
State of  Delaware  and,  so far as  applicable,  the merger  provisions  of the
California General Corporation Law.

         4.8.  FIRPTA Notification. (a) On the Effective Date, Sierra-California
               -------------------
shall   deliver  to   Sierra-Delaware,   as  agent  for  the   shareholders   of
Sierra-California, a properly executed statement (the "Statement") substantially
in the form attached  hereto as Attachment A.  Sierra-Delaware  shall retain the
Statement  for a period of not less than seven  years and shall,  upon  request,
provide a copy thereof to any person that was a shareholder of Sierra-California
immediately prior to the Merger. In consequence of the approval of the Merger by
the shareholders of Sierra-California, (i) such shareholders shall be considered
to have  requested that the Statement be delivered to  Sierra-Delaware  as their
agent and (ii)  Sierra-Delaware  shall be  considered to have received a copy of
the Statement at the request of the Sierra-California  shareholders for purposes
of satisfying  Sierra-Delaware's  obligations under Treasury  Regulation Section
1.1445-2(c)(3).

         (b)   Sierra-California shall deliver to the Internal Revenue Service a
notice  regarding the Statement in accordance with the  requirements of Treasury
Regulation Section 1.897-2(h)(2).

         4.9.  Counterparts.   This Agreement  may  be executed in any number of
               ------------
counterparts,  each of which shall be deemed to be an original  and all of which
together shall constitute one and the same instrument.



         IN WITNESS  WHEREOF,  this Agreement  having first been approved by the
resolutions of the Boards of Directors of Sierra-Delaware and Sierra-California,
is hereby  executed on behalf of each of such two  corporations  and attested by
their respective officers thereunto duly authorized.

                                       SIERRA SEMICONDUCTOR CORPORATION
                                       a California corporation


                                   By:  
                                      ---------------------------------------
                                       James V. Diller, Chairman of the Board of
                                       Directors and Chief Executive Officer

ATTEST:



Neil J. Wolff, Assistant Secretary



                             
                                       PMC-SIERRA, INC.
                                       a Delaware corporation



                                   By:
                                      ------------------------------------------
                                       James V. Diller, Chairman of the Board of
                                       Directors and Chief Executive Officer



ATTEST:



Neil J. Wolff, Secretary




                                  ATTACHMENT A
                                  ------------

                                                       ------------------, 1997


TO THE SHAREHOLDERS OF SIERRA SEMICONDUCTOR CORPORATION:

         In connection with the  reincorporation  (the  "Reincorporation")  into
Delaware of Sierra  Semiconductor  Corporation,  a California  corporation  (the
"Company"), pursuant to the Agreement and Plan of Merger (the "Agreement") dated
as of__________  ___, 1997 between the Company and PMC-Sierra,  Inc., a Delaware
corporation and wholly-owned subsidiary of the Company ("Sierra-Delaware"), your
shares of the  Company's  stock will be replaced by shares of  Sierra-Delaware's
stock.

         In order to  establish  that (i) you will not be  subject  to tax under
Section 897 of the Internal  Revenue Code of 1986, as amended (the  "Code"),  in
consequence of the Reincorporation and (ii) Sierra-Delaware will not be required
under Section 1445 of the Code to withhold taxes from the Sierra-Delaware  stock
that you will receive in connection therewith,  the Company hereby represents to
you  that,  as of the  date of this  letter,  shares  of  Company  stock  do not
constitute  a "United  States  real  property  interest"  within the  meaning of
Section 897(c) of the Code and the regulations issued thereunder.

         A copy of this letter will be delivered to Sierra-Delaware  pursuant to
Section 4.8 of the Agreement.

         Under  penalties  of perjury,  the  undersigned  officer of the Company
hereby declares that, to the best knowledge and belief of the  undersigned,  the
facts set forth herein are true and correct.

                                   Sincerely,

                                    SIERRA SEMICONDUCTOR CORPORATION


                                    -----------------------------------------
                                By: James V. Diller, Chairman of the Board of
                                    Directors and Chief Executive Officer