DEFA14A

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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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EX-99.(A)

                                                                Exhibit 99(a)


     MENTOR GRAPHICS REITERATES ITS COMMITMENT TO TRANSACTION IN RESPONDING TO
                  QUICKTURN'S REJECTION OF ITS $12.125 PER SHARE 
                                   ALL-CASH OFFER


WILSONVILLE, ORE., AUGUST 24, 1998 -- Dr. Walden C. Rhines, President and Chief
Executive Officer of Mentor Graphics Corporation (Nasdaq: MENT), said today that
the actions taken by the board of Quickturn Design Systems, Inc. (Nasdaq: QKTN)
in rejecting Mentor's all-cash, premium, fully financed offer are "deplorable
and not in the best interests of Quickturn stockholders."  Dr. Rhines reiterated
Mentor's commitment to completing the proposed transaction.

"We believe that Quickturn's rejection of our $12.125 per share all-cash offer
is unjustifiable in light of the 51.6 percent premium that offer represents over
Quickturn's closing share price the day before our offer was announced," Dr.
Rhines said.  "The $12.125 per share price is also approximately forty times
First Call consensus estimates for Quickturn in 1999.  Nevertheless, we are
fully committed to our offer, which we believe provides significant value to the
stockholders and customers of both companies. 

"The claim by Quickturn President and CEO Keith R. Lobo that Mentor's offer
comes at a 'moment of weakness' for Quickturn's stock price is hardly credible. 
The facts are that this so-called moment of weakness has lasted for six months. 
Quickturn's stock has languished since February of this year as Quickturn's
management has failed to develop and execute a value-enhancing business plan.  

"Moreover, if Mr. Lobo honestly believes this is only a 'moment of weakness,'
why did Quickturn reprice 1.546 million stock options in June of this year to
$7.44 per share?"It would appear, in short, that the actions of Quickturn in
response to our offer--including the rejection of that offer, and the amendments
to the Quickturn by-laws with regard to the company's special stockholders
meeting and 'poison pill'-- are unreasonable and serve to entrench management
rather than deliver value to Quickturn stockholders."

Dr. Rhines said: "The strategic fit of Mentor Graphics, with its primary focus
on the software side of electronic design automation (EDA), and Quickturn, the
market leader in system-level hardware emulation solutions, is compelling.  That
strategic fit, and the resulting ability to provide our respective semiconductor
and systems customers throughout the world with the industry's broadest range of
software and hardware solutions, is what this transaction is about.  This
transaction is NOT just about resolving the ongoing patent litigation between
the two companies.  We would pursue this strategic combination even if this
litigation didn't exist. 

                                       (more)





"For these reasons, we intend to take all actions necessary to remove the
obstacles to consideration of our offer so Quickturn stockholders can realize
the benefits of our offer as quickly as possible," Dr. Rhines concluded.
                                          
The tender offer is scheduled to expire at 12:00 midnight, New York City time,
on September 9, 1998, unless extended.  As previously indicated, the offer is
subject to terms and conditions including a majority of outstanding Quickturn
shares being validly tendered and not withdrawn; redemption or removal of
Quickturn's shareholder rights plan; the inapplicability of the Delaware
business combination statute; and the expiration or termination of the
Hart-Scott-Rodino waiting period.  The Offer to Purchase and ancillary documents
are available on a Mentor Graphics World Wide Web site at
http://www.mentorg.com/file.

This news release does not constitute an offer to purchase any securities, nor a
solicitation of a proxy, consent, authorization or agent designation with
respect to a meeting of the Quickturn stockholders.  The tender offer and the
agent designation solicitation are being made pursuant to separate materials in
compliance with the requirements of applicable federal and state law.

Mentor Graphics' financial advisor with regard to the transaction is Salomon
Smith Barney.  MacKenzie Partners, Inc. is acting as Information Agent for the
Offer and as solicitor for the agent designation solicitation, and can be
reached by collect call at 212-929-5500 or, toll-free, at 800-322-2885.  

               Contacts: Anne M. Wagner                     Gregory K. Hinckley
                         Vice President, Marketing          COO and CFO
                         503-685-1462                       503-685-4833

                         Dennis Weldon                      Roy Winnick
                         Treasurer                          Kekst and Company
                         503-685-1462                       212-521-4842