PROXY CARD 
                        QUICKTURN DESIGN SYSTEMS, INC.
                        SPECIAL MEETING OF STOCKHOLDERS
                               CALLED BY MENTOR
                        
                        THIS PROXY IS SOLICITED BY 
           THE BOARD OF DIRECTORS OF QUICKTURN DESIGN SYSTEMS, INC.

  The undersigned hereby appoints Keith R. Lobo and Raymond K. Ostby, each of
them, with full power of substitution, the proxies of the undersigned to vote
all of the outstanding Common Shares, par value $1.00 per share ("Common
Shares"), of Quickturn Design Systems, Inc. (the "Company") that the
undersigned is entitled to vote at the Special Meeting of Stockholders of the
Company called by Mentor (the "Special Meeting"), currently scheduled for
January 8, 1999 or at any adjournment or postponement of the Special Meeting,
on the following matters which are described in the Proxy Statement of the
Board of Directors of the Company, dated September 21, 1998, and the Addendum
to Proxy Statement dated December 24, 1998 (collectively, the "Proxy
Statement"; all capitalized terms used herein without definition having the
meaning set forth therein) as follows: 
 
 THE BOARD OF DIRECTORS OF THE COMPANY RECOMMEND THAT YOU VOTE "AGAINST" EACH
                          OF ITEMS 1 THROUGH 4. 
ITEM
1:
To remove all members of the Board of Directors of the Company, other than the
Nominees (as defined below), if then directors.
 
 
ITEM
2:
To adopt an amendment to Section 3.2 of the Bylaws of the Company to reduce
the number of Company Directors from eight to five.
ORF
AGAINST
   ABSTAIN
 
 
ORF
AGAINST
   ABSTAIN
 
ITEM
3:
To elect Mentor's nominees to the Board of Directors of the Company: Gideon
Argov, Scott H. Brice, Harry L. Demorest, C. Scott Gibson, and Michael J.K.
Savage (collectively, the "Nominees")
 
(Instruction: To grant
authority to vote for
only one or more
nominees, mark "AGAINST"
above and print the
name(s) of the person(s)
with respect to whom you
wish to grant authority
to vote for in the space
provided below).
 
- ------------------------
ITEM
4:
To adopt a stockholder resolution repealing each provision of the Bylaws or
any amendment thereto adopted by the Board of Directors of the Company
subsequent to March 30, 1998 and prior to the effective date of the Mentor
proposals.
ORF
AGAINST
   ABSTAIN
 
 
ORF
AGAINST
   ABSTAIN
 
  The proxies of the undersigned named above are authorized to vote, in their
discretion, upon such other matters, procedural or substantive, as may
properly come before the Special Meeting and any adjournment or postponement
thereof.
                       
                       [PROXY CONTINUED ON REVERSE] 
 

 

  THIS PROXY WHEN PROPERLY EXECUTED WILL BE VOTED IN THE MANNER MARKED HEREIN
BY THE UNDERSIGNED. IF NO MARKING IS MADE AS TO ANY PROPOSAL OR ALL PROPOSALS,
THIS PROXY REVOCATION WILL BE VOTED "AGAINST" PROPOSALS 1 THROUGH 4 DESCRIBED
ABOVE. THE UNDERSIGNED HEREBY ACKNOWLEDGES RECEIPT OF THE PROXY STATEMENT OF
THE BOARD OF DIRECTORS OF THE COMPANY DATED SEPTEMBER 21, 1998, AND THE
ADDENDUM TO PROXY STATEMENT DATED DECEMBER 24, 1998, SOLICITING PROXIES FOR
THE SPECIAL MEETING. 
 
  All previous proxies given by the undersigned to vote at the Special Meeting
or at any adjournment or postponement thereof are hereby revoked.
                            
                            Please sign exactly as name appears on this Proxy:
                            
                            ---------------------------------------------------
                                                (Signature)
 
                            ---------------------------------------------------
                                       (Signature, if jointly held)
 
                            Title:
                              -------------------------------------------------
                            
                            Dated: _______________________________  , 199_ 
 
  When shares are held by joint tenants, both should sign. When signing as an
attorney, executor, administrator, trustee or guardian, give full title as
such. If a corporation, sign in full corporate name by President or other
authorized officer. If a partnership, sign in partnership name by authorized
person.
           
           PLEASE COMPLETE, SIGN, DATE AND MAIL THIS PROXY CARD 
                      PROMPTLY IN THE ENCLOSED ENVELOPE.