WILSON SONSINI GOODRICH & ROSATI
                            PROFESSIONAL CORPORATION


                               650 PAGE MILL ROAD
                        PALO ALTO, CALIFORNIA 94304-1050
                  TELEPHONE 650-493-9300 FACSIMILE 650-493-6811


                                October 31, 2000

PMC-Sierra, Inc.
900 East Hamilton Avenue, Suite 250
Campbell, California 95008

   Re: Post Effective Amendment No. 2 to the Registration Statement on Form S-8

Ladies and Gentlemen:

         We  have  examined  Post  Effective  Amendment  No.  2 to  Registration
Statement  on  Form  S-8 to be  filed  by  PMC-Sierra,  Inc.  ("PMC")  with  the
Securities   and  Exchange   Commission  on  or  about  October  31,  2000  (the
"Registration   Statement")  in  connection  with  the  registration  under  the
Securities  Act of 1933,  as amended,  of 670,385  shares (the  "Shares") of PMC
common stock to be issued under PMC's assumed Malleable Technologies,  Inc. 1998
Stock Incentive Plan ("Malleable Plan").

         It is our opinion that, when shares of PMC are issued and sold pursuant
to options  granted in the manner  described in the Malleable Plan, and pursuant
to the agreements  which accompany each option grant, the Shares will be legally
and validly issued, fully paid and non-assessable.

         We consent to the use of this opinion as an exhibit to the Registration
Statement,  and further consent to the use of our name wherever appearing in the
Registration Statement.

                                            Very truly yours,

                                            /s/Wilson Sonsini Goodrich & Rosati

                                            WILSON SONSINI GOODRICH & ROSATI
                                            Professional Corporation