SCHEDULE 14A INFORMATION

                  Proxy Statement Pursuant to Section 14(a) of
                      the Securities Exchange Act of 1934

    Filed by the Registrant / /
    Filed by a Party other than the Registrant /X/

    Check the appropriate box:
    / /  Preliminary Proxy Statement
    / /  Confidential, for Use of the Commission Only (as permitted by Rule
         14a-6(e)(2))
    / /  Definitive Proxy Statement
    /X/  Definitive Additional Materials
    / /  Soliciting Material Pursuant to Section240.14a-11(c) or
         Section240.14a-12

                                QUICKTURN DESIGN SYSTEMS, INC.
- --------------------------------------------------------------------------------
                (Name of Registrant as Specified In Its Charter)

                                 MENTOR GRAPHICS CORPORATION
- --------------------------------------------------------------------------------
    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)
 
Payment of Filing Fee (Check the appropriate box):
 
/X/  No fee required.
/ /  Fee computed on table below per Exchange Act Rules 14a-6(i)(1)
     and 0-11.
     (1) Title of each class of securities to which transaction applies:
         -----------------------------------------------------------------------
     (2) Aggregate number of securities to which transaction applies:
         -----------------------------------------------------------------------
     (3) Per unit price or other underlying value of transaction computed
         pursuant to Exchange Act Rule 0-11 (set forth the amount on which the
         filing fee is calculated and state how it was determined):
         -----------------------------------------------------------------------
     (4) Proposed maximum aggregate value of transaction:
         -----------------------------------------------------------------------
     (5) Total fee paid:
         -----------------------------------------------------------------------
/ /  Fee paid previously with preliminary materials.
/ /  Check box if any part of the fee is offset as provided by Exchange Act Rule
     0-11(a)(2) and identify the filing for which the offsetting fee was paid
     previously. Identify the previous filing by registration statement number,
     or the Form or Schedule and the date of its filing.
     (1) Amount Previously Paid:
         -----------------------------------------------------------------------
     (2) Form, Schedule or Registration Statement No.:
         -----------------------------------------------------------------------
     (3) Filing Party:
         -----------------------------------------------------------------------
     (4) Date Filed:
         -----------------------------------------------------------------------


                  DELAWARE CHANCERY COURT ORDERS ADJOURNMENT UNTIL
                    DECEMBER 11 OF SPECIAL MEETING OF QUICKTURN
                           STOCKHOLDERS CALLED BY MENTOR

WILSONVILLE, OR, NOVEMBER 20, 1998 -- Mentor Graphics Corporation (Nasdaq: MENT)
announced today that the Delaware Chancery Court had ordered the adjournment
until December 11, 1998 of the special meeting of the stockholders of Quickturn
Design Systems (Nasdaq: QKTN), which had been called by Mentor for November 24,
1998.

The order to which both Mentor and Quickturn agreed arose from a letter from the
Delaware Chancery Court.  The letter stated that it was not certain that the
Court would be able to decide Mentor's challenge to the validity of Quickturn's
poison pill and bylaw amendments prior to November 24, the date previously set
for the special meeting called by Mentor.  The adjournment of the Quickturn
special meeting to December 11 is intended to provide time for the Court to
decide the case and for Mentor and Quickturn to communicate the ruling to
Quickturn's stockholders.

As previously announced, the principal purpose of the special meeting is to vote
on replacing the Quickturn Board of Directors with a slate of independent
directors nominated by Mentor.  If the nominees are elected, Mentor expects
that, subject to their fiduciary duties to all Quickturn stockholders, the new
directors will take the steps necessary to facilitate the stockholders' ability
to accept Mentor 's $12.125 per share all-cash offer.  Quickturn asserts that
the special meeting date has been conditionally set for January 8, 1999, citing
a bylaw purportedly adopted after Mentor commenced its offer, which bylaw is the
subject of the Delaware litigation.

Mentor's Offer to Purchase, proxy solicitation materials and related documents
are available on a Mentor World Wide Web site at http://www.mentorg.com/file.

The Dealer Manager for the Offer is Salomon Smith Barney.  The Information Agent
for the Offer is MacKenzie Partners, Inc., which can be reached toll-free at
800-322-2885 or by collect call at 212-929-5500.

CONTACT:       Anne M. Wagner                     Roy Winnick/Todd Fogarty
               Vice President, Marketing          Kekst and Company
               503/685-1462                       212/521-4800

                                       #  #  #