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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 OFFERS $14.00 CASH PER SHARE TO BRING
                       QUICKTURN SHARES OWNED TO 14.9%

                 --MENTOR SEEKS MERGER AGREEMENT TO ACQUIRE
                        REMAINING QUICKTURN SHARES--


WILSONVILLE, OREGON, DECEMBER 28, 1998 -- Mentor Graphics Corporation (Nasdaq: 
MENT) today increased the offering price in its tender offer for shares of 
Quickturn Design Systems, Inc. (Nasdaq: QKTN) to $14.00 cash per share from 
$12.125 cash per share, and changed the number of shares being sought to 
2,100,000 shares. Those shares, together with the 591,500 shares of Quickturn 
stock Mentor already owns, would result in Mentor owning a total of 14.9% of 
Quickturn's outstanding stock, the maximum amount that can be acquired without 
triggering Quickturn's poison pill.

Mentor said that if more than 2,100,000 shares are validly tendered, Mentor's 
purchases pursuant to the tender offer will be made as nearly as practicable 
on a pro rata basis.

Mentor plans to seek to negotiate a merger agreement with Quickturn to acquire 
the balance of the shares at the same cash price paid in the tender offer. The 
amended offer is scheduled to expire at 12:00 midnight, New York City time, on 
Monday, January 11, 1999, unless extended. Mentor said it intends to use 
available cash and working capital to consummate the offer; Mentor believes 
its financing commitments, which remain in place, would allow it to complete 
the proposed second-step merger with Quickturn.

Mentor President and Chief Executive Officer Dr. Walden C. Rhines said: "This 
offer will allow Mentor to increase its equity interest in Quickturn as the 
first step in completing a merger agreement or similar business combination 
between Mentor and Quickturn. Mentor's proposed transaction is more compelling 
than the proposed Cadence merger, and doesn't suffer from the Cadence deal's 
drawbacks.

"Our deal offers all cash, greater certainty as to timing and, importantly, no 
antitrust risk. We believe the electronics industry will object strongly to 
the proposed Cadence merger because of Cadence's already dominant share of the 
EDA market. Even though Mentor has already received antitrust clearance, when 
Mentor acquires Quickturn, Mentor currently expects to license the




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combined emulation intellectual property to the other participants in the 
sector. Cadence has given no indication that it will license the intellectual 
property."

On December 15, 1998, Mentor commenced a new lawsuit against Quickturn, the 
Quickturn directors and Cadence in the Delaware Court of Chancery. The suit 
alleges that the Quickturn directors again breached their fiduciary duties to 
Quickturn's stockholders and seeks to enjoin consummation of the proposed 
Cadence merger and to invalidate break-up fees payable to Cadence totaling 
$17,575,000.

In the event that Mentor is successful in invalidating all or any portion of 
the break-up fee and Mentor can negotiate a merger agreement with Quickturn, 
Mentor intends to pay all Quickturn stockholders whose shares are converted in 
the merger an amount per share which is equal to the tender offer price, which 
is currently $14.00, plus the lesser of (a) $.60 and (b) the quotient of (i) 
75% of any portion of the break-up fee which has been invalidated divided by 
(ii) the total number of shares outstanding on the date immediately preceding 
the date of the closing of the proposed merger.

Mentor said it stands ready to consider increasing its offer price and the 
price to be paid per share in a negotiated merger transaction if negotiation 
and due diligence demonstrate greater value of Quickturn to Mentor.

The Mentor offer will be subject to proration and satisfaction of certain 
conditions. The Mentor offer is not conditioned on the invalidation of any 
provision of the Cadence merger agreement. It also is not conditioned on "The 
Minimum Condition," "The Section 203 Condition," "The HSR Condition" or "The 
Rights Condition" of the original offer.

In order to acquire shares in a timely fashion and announce a proration 
number, if any, at the earliest practicable date following completion of the 
tender offer, guarantees of delivery of shares will no longer be accepted 
pursuant to the offer.

All stockholders who have previously tendered using guarantee of delivery 
procedures have either perfected their tender by delivering their shares and 
any other required documents or have withdrawn their tenders. Mentor 
understands that no shares that have been tendered and not withdrawn remain 
subject to guarantee of delivery procedures. As of the close of business on 
Thursday,




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December 24, 1998, 6,795,429 shares of Quickturn common stock had been validly 
tendered in the Offer, which, together with the 591,500 shares already owned 
by Mentor, represents approximately 41 percent of Quickturn's outstanding 
common stock (based upon 18,095,580 shares outstanding as of November 30, 
1998). The shares tendered represent 38 percent of the outstanding common 
stock.

Mentor said the special meeting of Quickturn's stockholders will be held on 
Friday, January 8, 1999 to consider Mentor's proposals relating to the removal 
of the current Quickturn Board and to replace the Quickturn directors with 
five new directors nominated by Mentor. If elected as directors of Quickturn, 
Mentor would encourage the nominees to, subject to their fiduciary duties as
directors under applicable law and in accordance with Quickturn's rights and 
obligations under the merger agreement with Cadence, seek to auction Quickturn 
to the highest bidder. Mentor would also encourage the nominees, subject to 
their fiduciary duties as directors of Quickturn under applicable law and in 
accordance with Quickturn's rights and obligations under the merger agreement 
with Cadence, to allow any bidder, including Mentor, promptly to conduct a due 
diligence review of Quickturn and seek to execute a merger agreement with the 
highest bidder. Mentor anticipates that any such merger agreement could be 
executed within 30 days of the nominees being elected as directors of 
Quickturn. The record date for stockholders to vote at the special meeting is 
November 10, 1998.

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.

Contacts:    Anne M. Wagner/Ry Schwark       Todd Fogarty/Jason Lynch
             Mentor Graphics Corporation     Kekst and Company
             503/685-1462                    212/521-4800


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