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                                QUICKTURN DESIGN SYSTEMS, INC.
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                (Name of Registrant as Specified In Its Charter)
 
                                 MENTOR GRAPHICS CORPORATION
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    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)
 
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              MENTOR GRAPHICS SAYS INSTITUTIONAL SHAREHOLDER SERVICES 
                   RECOMMENDS VOTE FOR MENTOR'S DIRECTOR NOMINEES
                   AND PROPOSALS AT QUICKTURN STOCKHOLDER MEETING

WILSONVILLE, OR, OCTOBER 15, 1998 - Mentor Graphics Corporation (Nasdaq: MENT)
today said that Institutional Shareholder Services Inc. (ISS), one of the
nation's leading institutional shareholder advisory firms, has recommended to
its clients that they vote in favor of Mentor Graphics' director nominees and
related proposals at the Special Meeting of stockholders of Quickturn Design
Systems, Inc. (Nasdaq: QKTN).

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 Graphics.  If the nominees are elected, Mentor Graphics expects that,
subject to their fiduciary duties to all Quickturn stockholders, the nominees
will take the steps necessary to facilitate the stockholders' ability to accept
Mentor Graphics' $12.125 per share all-cash offer.

In its report, ISS states: "At best, ISS views the [Quickturn] board's actions
as an overzealous execution of its perceived fiduciary duty to shareholders.  At
worst, we must give weight to the self-preservation effects that the takeover
defenses produce on behalf of the board and management at the potential expense
of shareholders.  Fiduciary duty does not include eliminating or obstructing the
rights of shareholders to determine to accept any offer for their ownership in
the company."

The ISS report concludes: "The board's duty would have been more properly
executed by placing its argument squarely in opposition to the offer of [Mentor]
and allowing shareholders to exercise their right to vote democratically and
expeditiously on the matter."

Dr. Walden C. Rhines, President and CEO of Mentor Graphics, said, "We are very
pleased to have received the recommendation of ISS for our nominees and all our
proposals, and agree with this independent firm's criticism of the entrenchment
actions of Quickturn's Board and management.  It is time for Quickturn's Board
of Directors to listen to the wishes of its stockholders and 




allow them to decide for themselves the merits of Mentor Graphics' offer."

Mentor Graphics has called the Special Meeting of Quickturn stockholders for
October 29, 1998.  A trial on Mentor Graphics' challenge to Quickturn's
anti-takeover actions and Mentor Graphics' scheduling of the Special Meeting
will take place later this month in Delaware state court. 

Institutional Shareholder Services, based in Bethesda, Md., is a leading
independent advisor to several hundred institutional investors and provides
voting recommendations for proxy contests, corporate governance proposals and
other shareholder related issues.

The Dealer Manager for Mentor Graphics' tender 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.

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


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