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                        Quickturn Design Systems, Inc.
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CONTACTS:
      QUICKTURN DESIGN SYSTEMS, INC.                 ABERNATHY MACGREGOR FRANK
      Ray Ostby                                      Pauline Yoshihashi
      (408) 914-6000                                 (213) 630-6550
                                                     Judith Wilkinson
                                                     (212) 371-5999


FOR IMMEDIATE RELEASE


         QUICKTURN BOARD REJECTS MENTOR'S REVISED UNSOLICITED PROPOSAL
                            TO ACQUIRE 14.9% STAKE


       REMAINS COMMITTED TO STRATEGIC MERGER WITH CADENCE DESIGN SYSTEMS

SAN JOSE, Calif., December 30, 1998 -- Quickturn Design Systems, Inc. 
(Nasdaq: QKTN) said today its Board of Directors unanimously recommended that 
Quickturn stockholders reject a revised unsolicited proposal by Mentor Graphics 
Corporation (Nasdaq: MENT) to acquire a 14.9% stake in Quickturn. The Board 
continues to recommend that stockholders not tender their shares to Mentor, and 
urges Quickturn stockholders who may have tendered to withdraw their shares.

In making its recommendation, the board considered, among other things, that
Mentor's revised bid is limited to an offer to purchase 2,100,000 of Quickturn's
shares, and the fact that Mentor's purported proposal for a second-step merger
is highly conditional. The board also believes that Mentor's proposal could
interfere with Quickturn's previously announced strategic combination with
Cadence, which the board has determined is in the best interests of Quickturn's
stockholders. On December 8, 1998, Quickturn's board unanimously approved a
definitive merger agreement with Cadence Design Systems, Inc. (NYSE:CDN) under
which Cadence will acquire Quickturn in a tax-free, stock-for-stock transaction
with an aggregate purchase price of $253 million for all outstanding shares.
Upon closing of the merger, each stockholder of Quickturn will receive Cadence
common stock with a value of $14 per share.

Keith R. Lobo, president and chief executive officer of Quickturn, said, 
"Quickturn's board has accepted an offer from Cadence that involves no 
financing issues, provides all Quickturn stockholders with an attractive, 
immediate premium for their shares, and allows them to participate in the 
long-term benefits from this strategic combination. In contrast, Mentor's most 
recent illusory proposal does not represent a real offer to purchase the entire 
company, and Mentor has not demonstrated that it has committed financing for 
such a proposal. Further, as Mentor is well aware, its proposal imposes 
conditions that would require Quickturn to violate its merger agreement with 
Cadence.



 
"We believe Mentor's actions are not designed to acquire Quickturn but to 
interfere with the company's pending transaction with Cadence, thereby denying 
the benefits of that transaction to Quickturn's stockholders," Mr. Lobo added. 
"Our board continues to believe a transaction with Cadence is the best way to 
generate value for all of Quickturn's stockholders. The board further believes 
that the Cadence transaction will be completed in a timely manner, and does not 
raise significant antitrust concerns."

Quickturn Design Systems, Inc. is the leading provider of verification products 
and time-to-market engineering (TtME(TM)) services for the design of complex ICs
and electronic systems. The company's products are used worldwide by developers 
of high-performance computing, multimedia, graphics and communications systems. 
Quickturn is headquartered at 55 W. Trimble Road, San Jose, CA 95131-1013; 
Telephone: 408/914-6000. For more information, visit the Quickturn Web site at 
www.quickturn.com or send e-mail to info@quickturn.com.

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