<PAGE>

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS 
AMENDED (THE "ACT") OR THE SECURITIES LAWS OF ANY STATE. THIS WARRANT MAY NOT 
BE SOLD, PLEDGED, TRANSFERRED, ASSIGNED OR OTHERWISE DISPOSED OF IN THE 
ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER PROVISIONS OF 
THE FEDERAL ACT AND ALL APPLICABLE STATE SECURITIES LAWS.

                                  Right to Purchase Shares of Common Stock 
                                  of Zycad Corporation
                                  February 13, 1997

                              ------------------------

                            Common Stock Purchase Warrant

    ZYCAD CORPORATION, a Delaware corporation (the "Company"), hereby 
certifies that for $10.00 and other good and valuable consideration, the 
receipt and sufficiency of which are hereby acknowledged, HERACLES FUND, 
having an address at c/o Bank of Bermuda (Cayman) Limited, P.O. Box 513, 
Third Floor, British American Tower, Dr. Roy's Drive, Georgetown, Grand 
Cayman, Cayman Islands, BWI ("Purchaser") or any other Warrant Holder is 
entitled, on the terms and conditions set forth below, to purchase from the 
Company at any time beginning after the date hereof and ending sixty (60) 
months after the date hereof Fifty Thousand (50,000) shares of fully paid and 
nonassessable shares of Common Stock, $.10 par value, of the Company (the 
"Common Stock"),  at a purchase price per share of Two Dollars and Twenty 
Five Cents (U.S. $2.25) per share of Common Stock (the "Purchase Price"), as 
the same may be adjusted pursuant to Section and 5 herein.

    1.   DEFINITIONS.

         (a) the term "Warrant Holder" shall mean the Purchaser or any 
         assignee of all or any portion of this Warrant at any given time 
         who, at the time of assignment, acquired the right to purchase at 
         least 2,000 Warrant Shares, (such number being subject to 
         adjustment after the date hereof pursuant to Section 5 herein.)

         (b) the term "Warrant Shares" shall mean the Shares of Common Stock 
         or other securities issuable upon exercise of this Warrant.

         (c) other terms used herein which are defined in the Convertible 
         Securities Subscription Agreement (the "Agreement") or the 
         Registration Rights Agreement (the "Registration Rights 
         Agreement"), both of even date and delivery between the Company and 
         the Purchaser, or in the Debentures 


<PAGE>

         issued by the Company to the Purchaser pursuant to the Agreement 
         (the "Debentures"), shall have the same meanings herein as therein.

    2.   EXERCISE OF WARRANT. This Warrant may be exercised by the Warrant 
Holder, in whole or in part, at any time and from time to time by surrender 
of this Warrant, together with the form of subscription at the end hereof 
duly executed by Warrant Holder, to the Company at its principal office.  In 
the event that the Warrant is not exercised in full, the number of Warrant 
Shares shall be reduced by the number of such Warrant Shares for which this 
Warrant is exercised, and the Company, at its expense, shall forthwith issue 
and deliver to or upon the order of Warrant Holder a new Warrant of like 
tenor in the name of Warrant Holder or as Warrant Holder (upon payment by 
Warrant Holder of any applicable transfer taxes) may request, reflecting such 
adjusted Warrant Shares. 

    If, despite the Company's obligations provided in Paragraphs 4(a) and 
4(d) hereof, the Company shall not have registered pursuant to a Registration 
Statement under the Act and/or available for issuance upon exercise of this 
Warrant sufficient shares of Common Stock for such issuance as such 
registered shares then, notwithstanding anything contained herein to the 
contrary and in addition to and not in lieu of any of the other rights and 
remedies to which the Warrant Holder may be entitled by reason of the 
Company's failure fully to meet its obligations under Paragraphs 4(a) and 
4(d) hereof, the Warrant Holder may, at its election exercised in its sole 
discretion, exercise this Warrant in whole or in part and, in lieu of making 
the cash payment otherwise contemplated to be made to the Company upon such 
exercise in payment of the Purchase Price, elect instead to receive upon such 
exercise the Net Number of shares of Common Stock determined according to the 
following formula:

    Net Number  =  (A X B)  -  (A X C)
                   -------------------
                            B

         For purposes of the foregoing formula:  

              A = the total number of shares with respect to which this
                    Warrant is then being exercised.

              B = the fair market value of a share of Common Stock at the
                    time of such calculation, as determined in accordance
                    with Paragraph 3(b) hereof.    

              C = the Purchase Price then in effect at the time of such
                    exercise.

    3.   DELIVERY OF STOCK CERTIFICATES.

         (a)  Subject to the terms and conditions of this Warrant, as soon as
practicable after the exercise of this Warrant in full or in part, and in any
event within five 


                                     -2-
<PAGE>


(5) days thereafter, the Company at its expense (including, without 
limitation, the payment by it of any applicable issue taxes) will cause to be 
issued in the name of and delivered to Warrant Holder, or as Warrant Holder 
(upon payment by Warrant Holder of any applicable transfer taxes) may 
lawfully direct, a certificate or certificates for the number of fully paid 
and non-assessable shares of Common Stock to which Warrant Holder shall be 
entitled on such exercise, together with any other stock or other securities 
or property (including cash, where applicable) to which Warrant Holder is 
entitled upon such exercise.

         (b)  This Warrant may not be exercised as to fractional shares of 
Common Stock.  In the event that the exercise of this Warrant, in full or in 
part, would result in the issuance of any fractional share of Common Stock, 
then in such event Warrant Holder shall be entitled to cash equal to the fair 
market value of such fractional share.  For purposes of this Warrant, fair 
market value shall equal the closing trading price of the Common Stock on the 
Nasdaq Stock Market, the American Stock Exchange or the New York Stock 
Exchange, whichever is the principal trading exchange or market for the 
Common Stock (the "Principal Market") on the date of determination or, if the 
Common Stock is not listed or admitted to trading on any national securities 
exchange or quoted in the Nasdaq Stock Market, the average of the closing bid 
and asked prices on the over-the-counter market as furnished by any New York 
Stock Exchange member firm reasonably selected from time to time by the 
Company for that purpose, or, if the Common Stock is not listed or admitted 
to trading on any national securities exchange or quoted on the Nasdaq Stock 
Market or traded over-the-counter and the average price cannot be determined 
a contemplated above, the fair market value of the Common Stock shall be as 
reasonably determined in good faith by the Company's Board of Directors.

    4.   COVENANTS OF THE COMPANY.

         (a)  The Company shall use its reasonable best efforts to insure 
that a Registration Statement under the Act covering the issuance of the 
Warrant Shares and the resale or other disposition thereof by Warrant Holder 
is effective as provided in its Registration Rights Agreement.

         (b)  The Company shall take all necessary action and proceedings as 
may be required and permitted by applicable law, rule and regulation, 
including, without limitation the notification of the Nasdaq Stock Market, 
for the legal and valid issuance of this Warrant and the Warrant Shares to 
the Warrant Holder under this Warrant.

         (c)  From the date hereof through the last date on which this 
Warrant is exercisable, the Company shall take all steps reasonably necessary 
and within its control to insure that the Common Stock remains listed on the 
Principal Market and shall not amend its Certificate of Incorporation or 
Bylaws so as to adversely affect any rights of the Warrant Holder under this 
Warrant.


                                     -3-
<PAGE>

         (d)  The Company shall at all times reserve and keep available, 
solely for issuance and delivery as Warrant Shares hereunder, such shares of 
Common Stock as shall from time to time be issuable.

         (e)  The Warrant Shares, when issued in accordance with the terms 
hereof, will be duly authorized and, when paid for or issued in accordance 
with the terms hereof, shall be validly issued, fully paid and 
non-assessable.  The Company has authorized and reserved for issuance to 
Warrant Holder the requisite number of shares of Common Stock to be issued 
pursuant to this Warrant.

         (f)  With a view to making available to Warrant Holder the benefits 
of Rule 144 promulgated under the Act and any other rule or regulation of the 
SEC that may at any time permit Warrant Holder to sell securities of the 
Company to the public without registration, the Company agrees to use its 
reasonable best efforts to:

         (i) make and keep public information available, as those terms are 
    understood and defined in Rule 144, at all times;

         (ii) file with the SEC in a timely manner all reports and other 
    documents required of the Company under the Act and the Exchange Act; and

         (iii) furnish to any Warrant Holder forthwith upon request a written
    statement by the Company that it has complied with the reporting 
    requirements of Rule 144 and of the Act and the Exchange Act, a copy of 
    the most recent annual or quarterly report of the Company, and such 
    other reports and documents so filed by the Company as may be reasonably 
    requested to permit any such Warrant Holder to take advantage of any 
    rule or regulation of the SEC permitting the selling of any such 
    securities without registration.

    5.   ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES.  The number of and
kind of securities purchasable upon exercise of this Warrant and the Purchase
Price shall be subject to adjustment from time to time as follows:

         (a)  SUBDIVISIONS, COMBINATIONS AND OTHER ISSUANCES.  If the Company 
shall at any time after the date hereof but prior to the expiration of this 
Warrant subdivide its outstanding securities as to which purchase rights 
under this Warrant exist, by split-up, spin-off, or otherwise, or combine its 
outstanding securities as to which purchase rights under this Warrant exist, 
the number of Warrant Shares as to which this Warrant is exercisable as of 
the date of such subdivision, split-up, spin-off or combination  shall 
forthwith be proportionately increased in the case of a subdivision, or 
proportionately decreased in the case of a combination.  Appropriate 
adjustments shall also be made to the purchase price payable per share, but 
the aggregate purchase price payable for the total number of Warrant Shares 
purchasable under this Warrant as of such date shall remain the same.


                                     -4-
<PAGE>

         (b)  STOCK DIVIDEND.  If at any time after the date hereof the 
Company declares a dividend or other distribution on Common Stock payable in 
Common Stock or other securities or rights convertible into Common Stock 
("Common Stock Equivalents") without payment of any consideration by holders 
of Common Stock for the additional shares of Common Stock or the Common Stock 
Equivalents (including the additional shares of Common Stock issuable upon 
exercise or conversion thereof), then the number of shares of Common Stock 
for which this Warrant may be exercised shall be increased as of the record 
date (or the date of such dividend distribution if no record date is set) for 
determining which holders of Common Stock shall be entitled to receive such 
dividends, in proportion to the increase in the number of outstanding shares 
(and shares of Common Stock issuable upon conversion of all such securities 
convertible into Common Stock) of Common Stock as a result of such dividend, 
and the Purchase Price shall be adjusted so that the aggregate amount payable 
for the purchase of all the Warrant Shares issuable hereunder immediately 
after the record date (or on the date of such distribution, if applicable), 
for such dividend shall equal the aggregate amount so payable immediately 
before such record date (or on the date of such distribution, if applicable).

         (c)  OTHER DISTRIBUTIONS.  If at any time after the date hereof the 
Company distributes to holders of its Common Stock, other than as part of its 
dissolution, liquidation or the winding up of its affairs, any shares of its 
capital stock, any evidence of indebtedness or any of its assets (other than 
cash, Common Stock or securities convertible into Common Stock), then the 
Company shall decrease the per share Purchase Price of this Warrant by an 
appropriate amount based upon the value distributed on each share of Common 
Stock as determined in good faith by the Company's Board of Directors.

         (d)  MERGER, ETC..  If at any time after the date hereof there shall 
be a merger or consolidation of the Company with or into or a transfer of all 
or substantially all of the assets of the Company to another entity, then the 
Warrant Holder shall be entitled to receive upon such transfer, merger or 
consolidation becoming effective, and upon payment of the aggregate Purchase 
Price then in effect, the number of shares or other securities or property of 
the Company or of the successor corporation resulting from such merger or 
consolidation, which would have been received by Warrant Holder for the 
shares of stock subject to this Warrant had this Warrant been exercised just 
prior to such transfer, merger or consolidation becoming effective or to the 
applicable record date thereof, as the case may be.

         (e)  RECLASSIFICATION, ETC.  If at any time after the date hereof 
there shall be a reorganization or reclassification of the securities as to 
which purchase rights under this Warrant exist into the same or a different 
number of securities of any other class or classes, then the Warrant Holder 
shall thereafter be entitled to receive upon exercise of this Warrant, during 
the period specified herein and upon payment of the Purchase Price then in 
effect, the number of shares or other securities or property resulting from 
such reorganization or reclassification, which would have been received by 
the Warrant Holder 


                                     -5-
<PAGE>

for the shares of stock subject to this Warrant had this Warrant at such time 
been exercised.

         (f)  PURCHASE PRICE ADJUSTMENT.  In the event that the Company 
issues or sells any Common Stock or securities which are convertible into or 
exchangeable for its Common Stock or any convertible securities, or any 
warrants or other rights to subscribe for or to purchase or any options for 
the purchase of its Common Stock or any such convertible securities (other 
than shares or options issued or which may be issued pursuant to the 
Company's employee or director option plans or shares issued upon exercise of 
options, warrants or rights outstanding on the date of the Agreement and 
listed in the Exchange Act Reports) at an effective purchase price per share 
which is less than the Purchase Price then in effect or the fair market value 
(as hereinabove defined) of the Common Stock on the trading day next 
preceding such issue or sale, then in each such case, the Purchase Price in 
effect immediately prior to such issue or sale shall be reduced effective 
concurrently with such issue or sale to an amount determined by multiplying 
the Purchase Price then in effect by a fraction, (x) the numerator of which 
shall be the sum of (1) the number of shares of Common Stock outstanding 
immediately prior to such issue or sale, including, without duplication, 
those deemed to have been issued under any provision of the Debentures and 
the Warrants plus (2) the number of shares of Common Stock which the 
aggregate consideration received by the Company for such additional shares 
would purchase at such fair market value or Purchase Price, as the case may 
be, then in effect; and (y) the denominator of which shall be the number of 
shares of Common Stock of the Company outstanding immediately after such 
issue or sale including, without duplication, those deemed to have been 
issued under any provision of the Debentures and Warrants.  For purposes of 
the foregoing fraction, Common Stock outstanding shall include, without 
limitation, any Equity Offerings (as defined in the Debentures) then 
outstanding, whether or not they are exercisable or convertible when such 
fraction is to be determined.

    In the event of any such issuance for a consideration which is less than 
such fair market value and also less than the Purchase Price then in effect, 
then there shall be only one such adjustment by reason of such issuance, such 
adjustment to be that which results in the greatest reduction of the Purchase 
Price computed as aforesaid.  The number of shares which may be purchased 
hereunder shall be increased proportionately to any reduction in Purchase 
Price pursuant to this paragraph 5(f), so that after such adjustments the 
aggregate Purchase Price payable hereunder for the increased number of shares 
shall be the same as the aggregate Purchase Price in effect just prior to 
such adjustments.

    6.   NO IMPAIRMENT.  The Company will not, by amendment of its 
Certificate of Incorporation or through any reorganization, transfer of 
assets, consolidation, merger, dissolution, issue or sale of securities or 
any other voluntary action, avoid or seek to avoid the observance or 
performance of any of the terms of this Warrant, but will at all times in 
good faith assist in the carrying out of all such terms and in the taking of 
all such action as may be necessary or appropriate in order to protect the 
rights of the Warrant Holder against impairment.  Without limiting the 
generality of the foregoing, the 


                                     -6-
<PAGE>

Company (a) will not increase the par value of any Warrant Shares above the 
amount payable therefor on such exercise, and (b) will take all such action 
as may be reasonably necessary or appropriate in order that the Company may 
validly and legally issue fully paid and nonassessable Warrant Shares on the 
exercise of this Warrant.  

    7.   NOTICE OF ADJUSTMENTS; NOTICES.  Whenever the Purchase Price or 
number of Shares purchasable hereunder shall be adjusted pursuant to Section 
5 hereof, the Company shall execute and deliver to the Warrant Holder a 
certificate setting forth, in reasonable detail, the event requiring the 
adjustment, the amount of the adjustment, the method by which such adjustment 
was calculated and the Purchase Price and number of shares purchasable 
hereunder after giving effect to such adjustment, and shall cause a copy of 
such certificate to be mailed (by first class mail, postage prepaid) to the 
Warrant Holder.

    8.   RIGHTS AS STOCKHOLDER.  Prior to exercise of this Warrant, the 
Warrant Holder shall not be entitled to any rights as a stockholder of the 
Company with respect to the Warrant Shares, including (without limitation) 
the right to vote such shares, receive dividends or other distributions 
thereon or be notified of stockholder meetings.  However, in the event of any 
taking by the Company of a record of the holders of any class of securities 
for the purpose of determining the holders thereof who are entitled to 
receive any dividend (other than a cash dividend) or other distribution, any 
right to subscribe for, purchase or otherwise acquire any shares of stock of 
any class or any other securities or property, or to receive any other right, 
the Company shall mail to each Warrant Holder, at least 10 days prior to the 
date specified therein, a notice specifying the date on which any such record 
is to be taken for the purpose of such dividend, distribution or right, and 
the amount and character of such dividend, distribution or right.

    9.   REPLACEMENT OF WARRANT.  On receipt of evidence reasonably 
satisfactory to the Company of the loss, theft, destruction or mutilation of 
the Warrant and, in the case of any such loss, theft or destruction of the 
Warrant, on delivery of an indemnity agreement or security reasonably 
satisfactory in form and amount to the Company or, in the case of any such 
mutilation, on surrender and cancellation of such Warrant, the Company at its 
expense will execute and deliver, in lieu thereof, a new Warrant of like 
tenor.

    10.  SPECIFIC ENFORCEMENT; CONSENT TO JURISDICTION.

              (a)  The Company and the Warrant Holder acknowledge and agree 
that irreparable damage would occur in the event that any of the provisions 
of this Warrant were not performed in accordance with their specific terms or 
were otherwise breached.  It is accordingly agreed that the parties shall be 
entitled to an injunction or injunctions to prevent or cure breaches of the 
provisions of this Warrant and to enforce specifically the terms and 
provisions hereof, this being in addition to any other remedy to which either 
of them may be entitled by law or equity.


                                     -7-
<PAGE>


              (b)  Each of the Company and the Warrant Holder (i) hereby 
irrevocably submits to the exclusive jurisdiction of the United States 
District Court for the Southern District of New York for the purposes of any 
suit, action or proceeding arising out of or relating to this Warrant and 
(ii) hereby waives, and agrees not to assert in any such suit, action or 
proceeding, any claim that it is not personally subject to the jurisdiction 
of such court, that the suit, action or proceeding is brought in an 
inconvenient forum or that the venue of the suit, action or proceeding is 
improper.  Each of the Company and the Warrant Holder consents to process 
being served in any such suit, action or proceeding by mailing a copy thereof 
to such party at the address in effect for notices to it under this Warrant 
and agrees that such service shall constitute good and sufficient service of 
process and notice thereof.  Nothing in this paragraph shall affect or limit 
any right to serve process in any other manner permitted by law.

    11.  ENTIRE AGREEMENT; AMENDMENTS.  This Warrant, the Exhibits hereto and 
the provisions contained in the Agreement, the Registration Rights Agreement 
or the Debentures and incorporated into this Warrant and the Warrant Shares 
contain the entire understanding of the parties with respect to the matters 
covered hereby and thereby and, except as specifically set forth herein and 
therein, neither the Company nor the Warrant Holder makes any representation, 
warranty, covenant or undertaking with respect to such matters.  No provision 
of this Agreement may be waived or amended other than by a written instrument 
signed by the party against whom enforcement of any such amendment or waiver 
is sought.

    12.  RESTRICTED SECURITIES.  Sections 4.5, 5.1, 5.2 and 5.3 of the
Agreement are incorporated herein by reference and hereby made a part hereof.

    13.  NOTICES.  Any notice or other communication required or permitted to 
be given hereunder shall be in writing and shall be effective (a) upon hand 
delivery or delivery by telex (with correct answer back received), telecopy 
or facsimile at the address or number designated below (if delivered on a 
business day during normal business hours where such notice is to be 
received), or the first business day following such delivery (if delivered 
other than on a business day during normal business hours where such notice 
is to be received) or (b) on the second business day following the date of 
mailing by express courier service, fully prepaid, addressed to such address, 
or upon actual receipt of such mailing, whichever shall first occur.  The 
addresses for such communications shall be:

         to the Company:

                      Zycad Corporation
                      47100 Bayside Parkway
                      Fremont, California 94538

                      Attn: Doug Klint   
                      Fax:  (510) 623-4575


                                     -8-
<PAGE>

         with copies to:

                      Wilson, Sonsini, Goodrich & Rosati
                      650 Page Mill Road
                      Palo Alto, California 94304-1050

                      Attn:  
                      Fax:  
    
         to the Warrant Holder:

                      Joseph A. Umbach
                      c/o Joseph Victori Wines
                      2525 Palmer Avenue
                      New Rochelle, New York, New York  10801

Copies of all notices to the Company or to the Warrant Holder shall also be
provided to:

                      Promethean Investment Group, L.L.C.
                      40 West 57th Street, Suite 1520
         `            New York, NY  10019

                      Attn: James F. O'Brien, Jr.
                      Fax:  (212) 698-0505

                      GOULSTON & STORRS
                      400 Atlantic Avenue
                      Boston, MA  02110-3333

                      Attn: Richard Langerman, Esq.
                      Fax: (617) 574-4112

Either party hereto may from time to time change its address for notices 
under this Section 13 by giving at least 10 days prior written notice of such 
changed address to the other party hereto.

    14.  MISCELLANEOUS.  This Warrant and any term hereof may be changed, 
waived, discharged or terminated only by an instrument in writing signed by 
the party against which enforcement of such change, waiver, discharge or 
termination is sought.  This Warrant shall be construed and enforced in 
accordance with and governed by the laws of the State of New York.  The 
headings in this Warrant are for purposes of reference only, and shall not 
limit or otherwise affect any of the terms hereof.  The invalidity or 
unenforceability of any provision hereof shall in no way affect the validity 
or enforceability of any other provision.


                                     -9-
<PAGE>

    15.  EXPIRATION.  The right to exercise this Warrant shall expire sixty
(60) months after the date hereof.


                          [Signatures on next page.]


                                     -10-
<PAGE>

Dated as of: February 13, 1997         ZYCAD CORPORATION


                                   By: /s/ Phillips W. Smith
                                      -------------------------------

                                   Title: President and Chief Executive Officer


[CORPORATE SEAL]


Attest:

/s/ Douglas E. Klint
-----------------------------

Its: Corporate Secretary

                                           Joseph A. Umbach

                                       By:  Promethean Investment Group, L.L.C.
                                       Its: Investment Advisor


                                       By: /s/ James F. O'Brien
                                          ----------------------------------
                                          Name: James F. O'Brien
                                          Title: President


                                     -11-
<PAGE>


                            FORM OF WARRANT EXERCISE
                  (TO BE SIGNED ONLY ON EXERCISE OF WARRANT)

TO _____________________

    The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise this Warrant for, and to purchase thereunder, _________
shares of Common Stock of ZYCAD CORPORATION, a Delaware corporation (the
"Company"), and herewith makes payment of $__________ therefor, and requests
that the certificates for such shares be issued in the name of, and delivered to
_________________, whose address is __________________.

Dated:                               _________________________________________
                                     (Signature must conform to name of holder
                                     as specified on the face of the Warrant)

                                     _________________________________________
                                                   (Address)

                                     Tax Identification Number:_______________


                                _____________________


                                 FORM OF ASSIGNMENT
                     (TO BE SIGNED ONLY ON TRANSFER OF WARRANT)

For value received, the undersigned hereby sells, assigns, and transfers unto
_________________ the right represented by the within Warrant to purchase
_____________ shares of Common stock of ZYCAD CORPORATION, a Delaware
corporation, to which the within Warrant relates, and appoints ________________
Attorney to transfer such right on the books of ZYCAD CORPORATION, a Delaware
corporation, with full power of substitution the premises.

Dated:                               _________________________________________
                                     (Signature must conform to name of holder
                                     as specified on the face of the Warrant)

                                     _________________________________________
                                                   (Address)

Signed in the presence of:

______________________________


                                     -12-