<PAGE>


Exhibit 10.15       Bank Line of Credit Agreement between Registrant
                    and U.S. National Bank of Oregon dated June 24, 1997.








April 9, 1997
                             
C. Albert Koob
Chief Financial Officer
Art Fletcher                      
Treasurer and Director of Financial Planning
Summit Design, Inc.
9305 S.W. Gemini Drive
Beaverton, OR  97005-7158

Gentlemen:

I am pleased to advise you that United States National Bank of Oregon 
("Bank") has approved the request of Summit Design, Inc. ("Summit"), for the 
following credit facilities,  subject to the following terms and conditions:


                               OPERATING LINE OF CREDIT
                               ------------------------
                                       
BORROWER:           Summit Design, Inc.

PURPOSE:            General Corporate Purposes.

BORROWING LIMIT:    $1,000,000.00

GUARANTORS:         None

EXPIRY:             April 30, 1998.

RATE:               Pricing will be based on United States National Bank of 
                    Oregon's Prime (1), or Inter Bank Offering Rate ("IBOR"), 
                    at the Borrower's option.  Rate will be fully floating and
                    computed on a 360-day year.  The spread over the base rates
                    will be determined quarterly by the Borrower's Total
                    Liabilities/Tangible Net Worth ("D/TNW"), as expressed in 
                    the chart below.


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


(1)  The interest rate charged to Borrower is tied to the Prime Rate of United 
     States National Bank of Oregon, Borrower is advised that United States 
     National Bank's Prime Rate is the rate of interest which the Bank from
     time to time identifies and publicly announces as its Prime Rate, and is 
     not necessarily, for example the lowest rate of interest which the Bank 
     collects from any borrower or group of borrowers.



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Summit Design, Inc.
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                 DEBT TO TANGIBLE NET WORTH IS DEFINED AS (TOTAL LIABILITIES 
                 MINUS UNEARNED REVENUE) / (SHAREHOLDERS' EQUITY MINUS 
                 INTANGIBLES).

-------------------------------------------------------------------------
         DEBT/WORTH              PRIME PRICING         IBOR PRICING
       Greater than 0.50        Prime + 0.75%         IBOR + 300 bps
         .26 to .050            Prime + 0.50%*        IBOR + 275 bps
       Less than 0.26           Prime +   0%          IBOR + 225 bps
-------------------------------------------------------------------------

                          *  At 12/31/96 the D/TNW was 0.27:1.00.

                 IBOR Terms:
    
                 A) Minimum Amount of $500,000, increments of $100,000 
                    thereafter.
                 B) Maturity and availability: Up to three months; may not 
                    exceed Expiry.
                 C) Prepayment of IBOR Borrowings not permitted.
                 D) Notification: Two day notification prior to 12:00 noon on 
                    the day of notification.
                 E) Irrevocability:  Acceptance of a pricing commitment from 
                    the Bank will constitute an irrevocable agreement to 
                    borrow under the revolving line of credit.
                 F) Interest computed on the basis of a 360 day year and the 
                    number of days elapsed.

REPAYMENT TERMS: Interest shall be payable monthly on the 1st day of each month.
                 Principal shall be payable on the earlier of April 30, 1998, or
                 demand by the Bank.  Repayment of each advance received by 
                 Borrower under the line of credit is subject to the terms of 
                 the promissory note evidencing that advance, as well as all 
                 terms and conditions of this letter.  In the event of any 
                 conflict between the two, the terms and conditions of the 
                 promissory note shall control.


FEES:            UP-FRONT FEE:  Initial up-front fee of 1/8 of 1% of the amount
                 of the line of credit, due upon acceptance  ($1,250).


                 COMMITMENT FEE:  A 1/8 of 1% fee, annualized, on the unused 
                 portion of the line of credit, payable quarterly in arrears.


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Summit Design, Inc.
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COLLATERAL:      The revolving line of credit provides for a flexible collateral
                 position according to the following matrix.  The assets of the
                 Borrower which are referenced below include a first lien 
                 position in all accounts, contract rights, chattel paper, 
                 general intangibles and inventory.


QUICK RATIO*     COLLATERAL

GREATER THAN
1.75:1.00        Unsecured with negative pledge agreement.

LESS THAN OR
EQUAL TO
1.75:1.00        UNSECURED WITH NEGATIVE PLEDGE, IF NOT BORROWING. If borrowing
                 and the ratio falls in this category, the line of credit will 
                 be secured.

LESS THAN OR
EQUAL TO
1.25 : 1.00      UNSECURED WITH NEGATIVE PLEDGE, IF NOT BORROWING.  If 
                 borrowing, line is secured and advances are margined at 75% of
                 eligible A/R up to 120 days after date of invoice.  

                 *  QUICK RATIO IS DEFINED AS ((CASH + NET TRADE ACCOUNTS) / 
                    (CURRENT  LIABILITIES - CURRENT PORTION OF UNEARNED 
                    REVENUE)).
                   

DOCUMENTATION:   Execution of Notes, Loan Agreements, Security Agreements, UCC
                 Financing Statements and all other documentation required by 
                 the Bank in a form satisfactory to the Bank.


BORROWER WILL COMPLY WITH THE FOLLOWING QUARTERLY FINANCIAL COVENANTS:
      
                 1. TANGIBLE NET WORTH shall not be less then $10,000,000. 
                    TANGIBLE NET WORTH IS DEFINED AS (SHAREHOLDER'S EQUITY 
                    -INTANGIBLES).  NOTE: INTANGIBLES INCLUDE ALL CAPITALIZED
                    SOFTWARE.
         
                 2. TOTAL LIABILITIES TO TANGIBLE NET WORTH  shall not exceed 
                    .75 to 1.00.  TOTAL LIABILITIES TO TANGIBLE NET WORTH IS 
                    DEFINED AS (TOTAL LIABILITIES MINUS DEFERRED REVENUE)/
                    (TANGIBLE NET WORTH). 
    
                 Failure to maintain these covenants will be considered an event
                 of default under the loan documents.  
    
OTHER TERMS AND CONDITIONS:

                 1. Distribution in the form of dividends shall not exceed 25% 
                    of net income, measured annually as of December 31.
    

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Summit Design, Inc.
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REPORTING REQUIREMENTS: 

                   - Quarterly financial statements to be submitted within 45 
                     days of quarter end.
                   - Annual CPA audited financial statements to be submitted
                     within 90 days of fiscal year end.
                   - If the Quick Ratio falls to 1.25:1.00 or below:  A 
                     Borrower's Certificate will be submitted with each advance,
                     and a Borrower's Certificate will accompany the monthly AR
                     and AP agings.

              
ADVANCE STRUCTURE: Advances will be limited to the Borrowing Limit when the
                   Quick Ratio is greater than 1.25:1.00. When the quick ratio
                   is less than or equal to 1.25: 1.00, advances will be 
                   limited to 75% of eligible accounts receivable to 120 days 
                   after the date of invoice.

                   Disbursements under the line of credit shall terminate on the
                   earlier occurrence of the date indicated above as the Expiry 
                   Date or the date on which this Bank, in its sole discretion,
                   determines that there has been a material adverse change in 
                   the financial condition or management of the Borrower, or 
                   determines that there has been any non-compliance with any 
                   term or condition stated herein.  Non-compliance with the 
                   conditions and terms of this letter and all other loan 
                   documents will be considered as an event of default, 
                   entitling the Bank to all the default provisions as provided
                   for in documents evidencing this line of credit.


OTHER:             Under Oregon law, most agreements, promises and commitments
                   made by lenders after October 3, 1989, concerning loans and 
                   other credit extensions which are not for personal, family 
                   or household purposes or secured solely by the borrower's 
                   residence must be in writing, express consideration and be 
                   signed by the lender to be enforceable.


If the above terms and conditions to extend this credit facility to Summit 
Design, Inc. are acceptable to you, please sign and return the Acknowledgment 
Copy of this letter on or before June  30, 1997.


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Summit Design, Inc.
4/9/97
Page 5


We are pleased to provide you this borrowing accommodation and look forward 
to serving your banking needs in the future.

Sincerely,




Daniel J. Hempy
Senior Vice President


BY OREGON STATUTE (ORS 41.580), THE FOLLOWING DISCLOSURE IS REQUIRED: UNDER 
OREGON LAW MOST AGREEMENTS PROMISES AND COMMITMENTS MADE BY LENDERS AFTER 
OCTOBER 3, 1989 CONCERNING LOANS AND OTHER CREDIT EXTENSIONS WHICH ARE NOT 
FOR PERSONAL, FAMILY, OR HOUSEHOLD PURPOSE OR SECURED SOLELY BY THE 
BORROWER'S RESIDENCE MUST BE IN WRITING, EXPRESS CONSIDERATION AND BE SIGNED 
BY THE LENDER TO BE ENFORCEABLE.

THE UNDERSIGNED HEREBY ACKNOWLEDGES AND ACCEPTS THIS OFFER TO EXTEND CREDIT 
SUBJECT TO THE TERMS AND CONDITIONS STATED ABOVE.

SUMMIT DESIGN, INC.

BY: /s/ C. Albert Koob  Chief Financial Officer       6/18/97  
    -------------------------------------------       -------
                               Title                    Date

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Summit Design, Inc.
4/9/97
Page 6








June 24, 1997

C. Albert Koob
Chief  Financial Officer
Art Fletcher
Treasurer and Director of Financial Planning
Summit Design, Inc.
9305 S.W. Gemini Drive
Beaverton, OR 97005-7158

Gentlemen:

Please find enclosed the  " Alternative Rate Options Promissory Note" to
    complete the documentation necessary for Summit Design's Operating Line of
    Credit.  Please sign where indicated and return to me.

If you have any questions or comments please call me or Dan Hempy, at 275-5172
    or 275-5879, respectively.

We are pleased to provide you this borrowing accommodation and look forward to
    serving your banking needs in the future.

Sincerely,


Richard Glassman
Assistant Relationship Manager




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Page 7



THIS EXHIBIT IS ATTACHED TO AND MADE A PART OF THAT CERTAIN PROMISSORY NOTE FOR
    $1,000,000.00 DATED JUNE 23, 1997 FROM SUMMIT DESIGN, INC. TO US BANK.


                                           
                                     EXHIBIT "A"
                                PERFORMANCE PRICING:

Pricing to be based upon Borrower's ratio of debt to worth, at the
    Borrower's Option, as expressed in the following matrix.  The spread
    over the base rates will be determined quarterly beginning
    September 30, 1997.

DEBT/WORTH                        PRIME PRICING                 IBOR PRICING
----------                        -------------                 ------------
-Greater than or equal to-0.51        Prime + 75%                       3.00%
0.26 to .050                      Prime + .50%                  2.75%
-Less than or equal to-0.25           Prime + 0.00%
                              2.25%

The initial Prime option is Prime + 0.50%. ;  Current IBOR Pricing is +2.75%

Debt to Tangible Net Worth is defined as ( Total Liabilities - Unearned 
    Revenue)  /  (Shareholder's Equity - Intangibles).

Summit Design, Inc.


BY:  /s/ C. Albert Koob        
     ------------------
     Authorized Officer







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4/9/97
Page 8

                               ALTERNATIVE RATE OPTIONS
                                   PROMISSORY NOTE
                                 (PRIME RATE, LIBOR)
                                       
$1,000,000.00                                         Dated as of: 06-23-97
-----------------------------------------------------              --------
Summit Design, Inc.                                        ("Borrower")
-----------------------------------------------------
U.S. BANK                                                   ("Lender")

1.  TYPE OF CREDIT.  This note is given to evidence Borrower's obligation to 
    repay all sums which lender may from time to time advance to Borrower 
    ("Advances") under a:
    / / single disbursement loan.  Amounts loaned to Borrower hereunder will 
                be disbursed in a single Advance in the amount shown in 
                Section 2.
    /x/ revolving line of credit.  No Advances shall be made Which create a 
                maximum amount outstanding at any one time which exceeds the 
                maximum amount shown in Section 2.  However, Advances hereunder 
                may be borrowed , repaid and reborrowed, and the aggregate 
                Advances loaned hereunder from time to time may exceed such 
                maximum amount.
    / / non-revolving line of credit.  Each Advance made from time to time 
                hereunder shall reduce the maximum amount available shown in 
                Section 2. Advances loaned hereunder which are repaid may not 
                be reborrowed.

2.  PRINCIPAL BALANCE.  The unpaid Principal balance of all Advances 
    outstanding under this note ("Principal Balance") at one time shall not 
    exceed $ 1,000,000.00.
           ---------------

3.  PROMISE TO PAY.  For value received Borrower promises to pay Lender or    
    order at OR COMMERCIAL LOAN SERVICING, 555 SW OAK, PL-7 PORTLAND, OR     
    97204, the Principal Balance of this note, with interest thereon at the   
    rate(s) specified in Sections 4 and 11 below.

4.  INTEREST RATE.  The interest rate on the Principal Balance outstanding 
    may vary from time to time pursuant to the provisions of this note.  
    Subject to the provisions of this note, Borrower shall have the option 
    from time to time of choosing to pay interest at the rate or rates and 
    for the applicable periods of time based on the rate options provided 
    herein; PROVIDED, however, that once Borrower notifies Lender of the rate 
    option chosen in accordance with the provisions of this note, such notice 
    shall be irrevocable.  The rate options are the Prime Borrowing Rate and 
    the LIBOR Borrowing Rate, each as defined herein.
   
    (a)  DEFINITIONS.  The following terms shall have the following meanings:
         
                 "Business Day" means any other day than a Saturday, Sunday, 
or other day that commercial banks in Portland, Oregon or New York City are 
authorized or required by law to close; provided, however that when used in 
connection with a LIBOR Rate, LIBOR Amount,

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Summit Design, Inc.
4/9/97
Page 9

or LIBOR Interest Period such term shall also exclude any day on which dealings
in U.S. dollar deposits are not carried on in the London interbank market.
         
                 "LIBOR Amount" means each principal amount for which 
Borrower chooses to have the LIBOR Borrowing Rate apply for any specified 
LIBOR Interest Period.

                 "LIBOR Interest Period" means as to any LIBOR amount, a 
period of 1,2 OR 3 months commencing on the date the LIBOR Borrowing Rate 
becomes applicable thereto; PROVIDED, however, that: (I)  the first day of 
each LIBOR Interest Period must be a Business Day; (ii) no LIBOR Interest 
Period shall be selected which would extend beyond EXPIRY; (iii) no LIBOR 
Interest Period shall extend beyond the date of any principal payment 
required under section 6 of this note, unless the sum of the Prime Rate 
Amount, plus LIBOR Amounts with LIBOR Interest Periods ending on or before 
the scheduled date of such principal payment, plus principal amounts 
remaining unborrowed under a line of credit, equals or exceeds the amount of 
such principal payment; (iv) any LIBOR Interest Payment which would otherwise 
expire on a day which is not a Business Day, shall be extended to the next 
succeeding Business Day, unless the result of such extension would be to 
extend such LIBOR Interest Period into another calendar month, in which event 
the LIBOR Interest Period shall end on the immediately preceding Business 
Day; and (v) any LIBOR Interest Period that begins on the last Business Day 
of a calendar month (or on a day for which there is no numerically 
corresponding day in the calendar month at the end of such LIBOR Interest 
Period) shall end on the last Business Day of a calendar month. 

                 "LIBOR Rate" means, for any LIBOR Interest Period, the rate 
          per annum (computed on the basis of a 360-day year and the actual 
          number of days elapsed and rounded upward to the nearest 1/16 of 
          1%) established by Lender as its LIBOR Rate, based on Lender's 
          determination, on the basis of such factors as Lender deems 
          relevant, of the rate of interest at which U.S. dollar deposits 
          would be offered to U.S. Bank in the London interbank market at 
          approximately 11 a.m. London time on the date which is two Business 
          Days prior to the first day of such LIBOR Interest Period for 
          delivery on the first day of such LIBOR Interest Period for the 
          number of months therein; provided, however, that the LIBOR Rate 
          shall be adjusted to take into account the maximum reserves 
          required to be maintained for Eurocurrency liabilities by banks 
          during each such LIBOR Interest Period as specified in Regulation D 
          of the Board of Governors of the Federal Reserve System or any 
          successor regulation.
        
"Prime Rate" means the rate of interest which Lender from time to time 
          establishes as its prime rate and is not, for example, the lowest 
          rate of interest which Lender collects from any borrower or class 
          of borrowers. When the Prime Rate is applicable under section 4 (b) 
          or 11 (b), the interest rate hereunder shall be adjusted without 
          notice effective on the day the Prime Rate changes, but in no event 
          shall the rate of interest be higher than allowed by law.

"Prime Rate Amount" means any portion of the Principal Balance bearing 
          interest at the Prime Borrowing Rate.

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    (b)  THE PRIME BORROWING RATE.

              (i)   The Prime Borrowing Rate is a per annum rate equal to the 
                    Prime Rate plus SEE ATTACHED EXHIBIT "A" % per annum.
             (ii)   Whenever Borrower desires to use the Prime Borrowing Rate 
                    option, Borrower shall give Lender notice orally or in 
                    writing in accordance with Section 15 of this note, which 
                    notice shall specify the requested effective date (which 
                    must be a Business Day) and principal amount of the 
                    Advance or increase in the Prime Rate Amount, and whether 
                    Borrower is requesting a new Advance under a line of 
                    credit or conversion of a LIBOR Amount to the Prime 
                    Borrowing Rate.
           (iii)    Subject to Section 11 of this note, interest shall accrue 
                    on the unpaid Principal Balance at the Prime Borrowing 
                    Rate unless and except to the extent that the LIBOR 
                    Borrowing Rate is in effect.

    (c)  THE LIBOR BORROWING RATE.
             (i)    The LIBOR Borrowing Rate is the LIBOR Rate plus SEE 
                    ATTACHED EXHIBIT "A" %  per annum.

            (ii)    Borrower may obtain LIBOR Borrowing Rate quotes from 
                    Lender between 8:00 a.m. and 10:00 a.m. ( Portland, 
                    Oregon time) on any Business Day. Borrower may request an 
                    Advance, conversion of any portion of the Prime Rate 
                    Amount to a LIBOR amount or a new LIBOR Interest Period 
                    for an existing LIBOR Amount, at such rate only by giving 
                    Lender notice in accordance with Section 4 ( c ) (iii) 
                    before 10:00 a.m. ( Portland, Oregon time) on  such day.

           (iii)    Whenever Borrower desires to use the LIBOR Borrowing Rate 
                    option, Borrower shall give Lender irrevocable notice ( 
                    either in writing or orally and promptly confirmed in 
                    writing) between 8:00a.m. and 10:00 a.m. (Portland, 
                    Oregon time) two (2) business days prior to the desired 
                    effective date of such rate. Any oral notice shall be 
                    given by, and any written notice or confirmation of an 
                    oral notice shall be signed by, the person (s) authorized 
                    in Section 15 of this note, and shall specify the 
                    requested effective date of the rate, LIBOR Interest 
                    Period and LIBOR Amount, and whether Borrower is 
                    requesting a new Advance at the LIBOR Borrowing Rate 
                    under a line of credit, conversion of all or any portion 
                    of the Prime Rate Amount to a LIBOR Amount, or a new 
                    LIBOR Interest Period for an outstanding LIBOR Amount.  
                    Notwithstanding any other term of this note, Borrower may 
                    elect the LIBOR Borrowing Rate in the minimum principal 
                    amount of $500,000.00 and in multiples of $100,000.00 
                    above such amount; PROVIDED, however, that no more than 
                    N/A separate LIBOR Interest Periods may be in effect at 
                    any one time.

If at any time the LIBOR Rate is unascertainable or unavailable to Lender or if
LIBOR Rate loans become unlawful, the option to select the LIBOR Borrowing Rate
shall terminate immediately.  If the LIBOR Borrowing Rate is in effect, (A) it
shall terminate automatically with respect to all LIBOR Amounts (i) on the last
day of each then applicable LIBOR Interest Period,

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Summit Design, Inc.
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Page 11



if  Lender may lawfully continue to maintain such loans, or (ii) immediately if
Lender may not lawfully continue to maintain such loans throuh such day, and
(B) subject to Section 11, the Prime Borrowing Rate automatically shall become
effective as to such amounts upon such termination.

       (iv)   If at any time after the date hereof  (A) any revision in or 
              adoption of any applicable law, rule, or regulation or in the 
              interpretation or administration thereof  (i)  shall subject 
              Lender or its Eurodollar lending office to any tax, duty, or 
              other charge, or change the basis of taxation of payments to 
              Lender with respect to any loans bearing interest based on the 
              LIBOR Rate, or (ii) shall impose or modify any reserve, 
              insurance, special deposit, or similar requirements against 
              assets of, deposits with or for the account of, or credit 
              extended by Lender or its Eurodollar lending office, or impose 
              on Lender or its Eurodollar lending office  any other 
              condition affecting any such loans, and (B) the result of any 
              of the forgoing is (i) to increase the cost to Lender of 
              making or maintaining any such loans or (ii) to reduce the 
              amount of any sum receivable under this note by Lender or its 
              Eurodollar lending office, Borrower shall pay Lender within 15 
              days after demand by Lender such additional amount as will 
              compensate Lender for such increased cost or reduction.  The 
              determination hereunder by Lender of such additional amount 
              shall be conclusive in the absence of manifest error.  If 
              Lender demands compensation under this Section 4  (c) (v), 
              Borrower may upon three (3) Business Days' notice to Lender 
              pay the accrued interest on all LIBOR Amounts, together with 
              any additional amounts payable under Section 4 (c)(vi). 
              Subject to Section 11, upon Borrower's paying such accrued 
              interest and additional costs, the Prime Borrowing Rate 
              immediately shall be effective with respect to the unpaid 
              principal balance of such LIBOR amounts.
    
       (v)    Borrower shall pay to Lender, on demand, such amount as Lender 
              reasonably determines (determined as though 100 % of the 
              applicable LIBOR Amount had been funded in the London 
              interbank market) is necessary to compensate Lender for any 
              direct or indirect losses, expenses, liabilities, costs, 
              expenses or reductions in yield to Lender, whether incurred in 
              connection with liquidation or re-employment of funds or 
              otherwise, incurred or sustained by Lender as a result of: (A) 
              Any payment or prepayment of a LIBOR Amount, termination of 
              the LIBOR Borrowing Rate or conversion of a LIBOR Amount to 
              the Prime Borrowing Rate on a day other than the last day of 
              the applicable LIBOR  Interest Period  (including  as a result 
              of acceleration or a notice persuant to Section 4 (c)(v)); or 
              (B) Any failure of Borrower to borrow, continue or prepay any 
              LIBOR Amount or to convert any portion of the Prime Rate 
              Amount to a LIBOR Amount after Borrower has given notice 
              thereof to Lender.
    
       (vi)   If Borrower chooses the LIBOR Borrowing Rate, Borrower shall pay 
              interest based on such rate, plus any other applicable taxes 
              or charges hereunder, even though Lender may have obtained the 
              funds loaned  to Borrower from sources other than the London 
              interbank market.  Lender's determination of the

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Summit Design, Inc.
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              LIBOR Borrowing Rate and any such taxes or charges shall be
              conclusive in the absence of manifest error.
    
       (vii)  Notwithstanding any other term of this note, Borrower may not 
              select the LIBOR Borrowing Rate if an event of default 
              hereunder has occurred and is continuing.
    
       (viii) Nothing contained in this note, including without limitation the
              determination of any LIBOR Interest Period or Lender's 
              quotation of any LIBOR Borrowing Rate, shall be construed to 
              prejudice Lender's right, if any, to decline to make any 
              requested Advance or to require payment on demand.

5.  COMPUTATION OF INTEREST .  All interest under Section 4 and Section 11 
    will e computed at the applicable rate based on a 360-day year and 
    applied to he actual number of days elapsed.

6.  PAYMENT SCHEDULE.
    (a)  PRINCIPAL. Principal shall be paid:
    /X/ on demand
    / / on demand. or if no demand, on______.
    / / on__________.
    / / subject to Section 8, in installments of
/ /____each, plus accrued interest, beginning on ____and on the same day of 
                       each ____ thereafter until ____ when the entire Principal
                       Balance plus interest thereon shall be due and payable.

                            / /____each, including accrued interest, beginning 
                       on____and on the same day of each____ thereafter until 
                       ____ when the entire Principal Balance plus interest 
                       thereon shall be due and payable.
/ /_________.
    (b)  INTEREST.
             (i)  Interest on the Prime Rate Amount shall be paid:
             /X/  on the first day of FEBRUARY, 1997 and on the same day of each
                  MONTH. thereafter prior to maturity and at maturity.
             / /  at maturity.
                            / / at the time each principal installment is due 
                                and at maturity.
                            / /______.
            (ii)  Interest on all LIBOR Amount shall be paid:

/X/  on the last day of the applicable LIBOR Interest Period, and if such LIBOR
                  Interest period is longer than three months, on the last day 
                  of each three month period occuring during such LIBOR 
                  Interest Period, and at maturity.
/X/  on the ____ day of _____ and on the same day of each ______ thereafter 
                  prior to maturity and at maturity. 
/ /  at maturity.
/ /  at the time each principal installment is due and at maturity.
/ /  ______.

7.  PREPAYMENT.
        (a)  Prepayments of all or any part of the Prime Rate Amount may be 
             made at any time without penalty.

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Summit Design, Inc.
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    (b)  Except as otherwise specifically set forth herein, Borrower may not
         prepay all or any part of any LIBOR Amount , or terminate any LIBOR
         Borrowing Rate except on the last day of the applicable LIBOR Interest
         Period.
    (c)  Principal prepayments will not postpone the date of or change the
         amount of any regularly scheduled payment.  At the time of any
         principal prepayment, all accrued interest, fees, costs, and expenses
         shall also be paid.
8.  CHANGE IN PAYMENT AMOUNT.  Each time the interest rate on this note changes
    the holder of this note may, from time to time, in holder's sole
    discretion, increase or decrease the amount of each of the installments
    remaining unpaid at the time of such change in rate to an amount holder in
    its sole discretion deems necessary to continue amortizing the Principal
    Balance at the same rate established by the installment amounts specified
    in Section 6(a), whether or not a "balloon" payment may also be due upon
    maturity of this note.  Holder shall notify the undersigned of each such
    change in writing.  Whether or not the installment amount is increased
    under this Section 8, Borrower understands that, as a result of increases
    in the rate of interest the final payment due, whether or not a "balloon" 
    payment, shall include the entire Principal Balance and interest thereon
    then outstanding,  and may be substantially more than the installment
    specified in Section 6.
9.  ALTERNATE PAYMENT DATE.  Notwithstanding any other term of this note, if in
    any month there is no day on which a scheduled payment would otherwise be
    due (e.g. February 31), such payment shall be paid on the last banking day
    of that month.
10. PAYMENT BY AUTOMATIC DEBIT.
/ / Borrower hereby authorizes Lender to automatically deduct the amount of all
                     principal and interest payments from account number _____ 
                     at _____.  If there are insufficient funds in the account
                     to pay the automatic deduction in full, Lender may allow
                     the account to become overdrawn, or Lender may reverse the
                     automatic deduction.  Borrower will pay all the fees on
                     the account which result from the automatic deductions,
                     including any overdraft and non-sufficient funds charges.
                     If for any reason Lender does not charge the account for
                     a payment, or if an automatic payment is reversed, the
                     payment is still due according to this note.  If the
                     account is a Money Market Account, the number of
                     withdrawals from that account is limited as set out in
                     the account agreement.  Lender may cancel the automatic
                     deduction at any time in its discretion.

Provided, however, if no account number is entered above, Borrower does not want
                     to make payments by automatic debit.

11. DEFAULT.
(a) Without prejudice to any right of Lender to require payment on demand or to
    decline to make any requested Advance, each of the following shall be an
    event of default: ( i )Borrower fails to make any payment when due. (ii)
    Borrower fails to perform or comply with any term, covenant or obligation
    in this note or any agreement related to this note, or in any other
    agreement or loan Borrower has with Lender. (iii) Borrower defaults under
    any loan, extension of credit, security agreement, purchase or sales
    agreement, or any other agreement,

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    in favor of any other creditor or person that may materially affect any of
    Borrower's property or Borrower's ability to repay this note or perform 
    Borrower's obligations under this note or any related documents. (iv) Any 
    representation or statement made or furnished to Lender by Borrower or on 
    Borrower's behalf is false or misleading in any material respect either 
    now or at the time made or furnished. (v) Borrower dies, becomes 
    insolvent, liquidates or dissolves, a receiver is appointed for any part 
    of Borrower's property, Borrower makes an assignment for the benefit of 
    creditors, or any proceeding is commenced either by Borrower or against 
    Borrower under any bankruptcy or insolvency laws. (vi) Any creditor tries 
    to take any of Borrower's property on or in which Lender has a lien or 
    security interest. This includes a garnishment of any of Borrower's 
    accounts with Lender. (vii)  Any of the events described in this default 
    section occurs with respect to any general partner in Borrower or any 
    guarantor of this note, or any guaranty of Borrower's indebtedness to 
    Lender ceases to be, or is asserted not to be, in full force and effect. 
    (viii) There is any material adverse change in the financial condition or 
    management of Borrower or Lender in good faith deems itself insecure with 
    respect to the payment or performance of Borrower's obligations to 
    Lender. If this note is payable on demand, the inclusion of specific 
    events of default shall not prejudice Lender's right to require payment 
    on demand or to decline to make any requested Advance.

(b) Without prejudice to any right of Lender to require payment on demand, upon
    the occurance of an event of default, Lender may declare the entire unpaid
    Principal Balance on this note and all accrued unpaid interest immediately
    due and payable, without notice.  Upon default, including failure to pay
    upon final maturity, Lender at its option, may also,  if permitted under
    applicable law, increase the interest rate on this note to a rate equal to
    the Prime Borrowing Rate plus 5%.  The interest rate will not exceed the
    maximum rate permitted by applicable law.  In addition, if any payment of
    principal or interest is 19 or more days past due, Borrower will be charged
    a late charge of 5% of the delinquent payment.

12. EVIDENCE OF PRICIPAL BALANCE; PAYMENT ON DEMAND.  Holder's records shall,
    at any time, be conclusive evidence of the unpaid Principal Balance and
    interest owing on this note.  Notwithstanding any other provisions of this
    note, in the event holder makes Advances hereunder which result in an
    unpaid Principal Balance on this note which at any time exceeds the maximum
    amount specified in Section 2, Borrower agrees that all such Advances, with
    interest, shall be payable on demand.

13. LINE OF CREDIT PROVISIONS.  If the type of credit indicated in Section 1 is
    a revolving line of credit or a non-revolving line of credit, Borrower
    agrees that Lender is under no obligation and has not committed to make any
    Advances hereunder.  Each Advance hereunder shall be made at the sole
    option of Lender.

14. DEMAND NOTE.  If this note is payable on demand, Borrower acknowledges and
    agrees that (a) Lender is entitled to demand Borrower's immediate payment
    in full of all amounts owing hereunder and (b) neither anything to the
    contrary contained herein or in any other loan documents (including but not
    limited to, provisions relating to defaults, rights of cure, default rate
    of interest, installment payments, late charges, periodic review of
    Borrower's financial condition, and covenants) nor any act of Lender
    pursuant to any such provisions shall limit or

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    impair Lender's right or ability to require Borrower's payment in full of
    all amounts owing hereunder immediately upon Lender's demand.

15. REQUESTS FOR ADVANCES
    (a)  Any Advance may be made or interest rate option selected upon the
         request of Borrower (if an individual), any of the undersigned (if
         Borrower consists of more than one individual), any person or persons
         authorized in subsection (b) of this Section 15, and any person or
         persons otherwise authorized to execute and deliver promissory notes
         to Lender on behalf of Borrower.
    (b)  Borrower hereby authorizes any ____ of the following individuals to
         request Advances and to select interest rate options:______unless
         Lender is otherwise instructed in writing.
    (c)  All Advances shall be disbursed by deposit directly to Borrower's
         account number ____at ____ brance of Lender, or by cashier's check
         issued to Borrower.
    (d)  Borrower agrees that Lender shall have no obligation to verify the
         identity of any person making any request pursuant to this Section 15,
         and Borrower assumes all risks of the validiy and authorization of
         such requests.  In consideration of Lender agreeing, at its sole
         discretion, to make Advances upon such requests, Borrower promises to
         pay holder, in accordance with the provisions of this note, the
         Principal Balanc together with interest thereon and other sums due
         hereunder, although any Advances may have been requested by a person
         or persons not authorized to do so.

16. PERIODIC REVIEW.  Lender will review Borrower's credit accomodations
    periodically.  At the time of the review, Borrower will furnish Lender with
    any additional information regarding Borrower's financial condition and
    business operations that Lender requests.  This information may include but
    is not limited to, financial statements, tax returns, lists of assets and
    liabilities, agings of receivables and payables, inventory schedules,
    budgets and forecasts.  If upon review, Lender, in its sole discretion,
    determines that there has been a material adverse change in Borrower's
    financial condition, Borrower will be in default.  Upon default, lender
    shall have all rights specified herein.

17. NOTICES.   Any notice hereunder may be given by ordinary mail, postage paid
    and addressed to Borrower at the last known address of Borrower as shown on
    holder's records.  If Borrower consists of more than one person,
    notification of any said persons shall be complete notification of all.

18. ATTORNEY FEES.  Whether or not litigation or arbitration is commenced,
    Borrower promises to pay all costs of collecting overdue amounts.  Without
    limiting the foregoing , in the event that holder consults an attorney
    regarding the enforcement of any of its rights under this note or any
    ocument securing the same, or if this note is placed in the hands of an
    attorney for collection or if suit or litigation is brought to enforse this
    note or any document securing the same, Borrower promises to pay all costs
    thereof including such additional sums as the court or arbitrator(s) may
    adjudge reasonable as attorney fees, including without limitation, costs
    and attorney fees incurred in any appellate court, in any proceeding under
    the

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    bankruptcy code, or in any receivership and post-judgement attorney
    fees incurred in enforcing any judgement.

19. WAIVERS; CONSENT.  Each party hereto, whether maker, co-maker, guarantor or
    otherwise, waives diligence, demand, presentment for payment, notice of
    non-payment, protest and notice of protest and waives all defenses based on
    suretyship or impairment of collateral.  Without notice to Borrower and
    without diminishing or affecting Lender's rights or Borrower's obligations
    hereunder, Lender may deal in any manner with any person who at any time is
    liable for, or provides any real or personal property collateral for, any
    indebtedness of Borrower to Lender, including the indebtedness evidenced by
    this note.  Without limiting the foregoing, Lender may, in its sole
    discretion: (a) make secured or unsecured loans to Borrower and agree to
    any number of waivers, modifications, extensions and renewals of any length
    of such loans, including the loan evidenced by this note; (b) impair,
    release (with or without substitution of new collateral), fail to perfect a
    security interest in, fail to preserve the value of, fail to dispose of in
    accordance with applicable law, any collateral provided by any person; (c) 
    sue, fail to sue, agree not to sue, release, and settle or compromise with,
    any person.

20. JOINT AND SEVERAL LIABILITY.  All undertakings of the undersigned Borrowers
    are joint and several and are binding upon any marital community of which
    any of the undersigned are members.  Holder's rights and remedies under
    this note shall be cumulative.

21. SEVERABILITY.  If any term or provision of this note is declared by a court
    of competent jurisdiction to be illegal, invalid or unenforceable for any
    reason whatsoever, such illegality, invalidity or unenforceability shall
    not affect the balance of the terms and provisions hereof, which terms and
    provisions shall remain binding and enforceable, and this note shall be
    construed as if such illegal, invalid or unenforcable provision had not
    been contained herein.

22. ARBITRATION.
    (a)  Either Lender or Borrower may require that all disputes, claims,
         counterclaims and defenses, including those based on or arising from
         any alleged tort ("Claims") relating in any way to this note or any
         transaction of which this note is a part ( the "Loan"), be settled by
         binding arbitration in accordance with the Commercial Arbitration
         Rules of the American Arbitration Association and Title 9 of the U.S.
         Code.  All claims will be subject to the statutes of limitation
         applicable if they were litigated.  This provision is void if the
         Loan, at the time of the proposed submission to arbitration, is
         secured by real property located outside of Oregon or Washington, or
         if the effect of the arbitration procedure ( as opposed to any Claims
         of Borrower) would be to materially impair Lender's ability to realize
         on any collateral securing the Loan.
    (b)  If arbitration occurs and each party's claim is less than $100,000,
         one neutral arbitrator will decide all issues; if any party's claim is
         $100,000 or more,three neutral arbitrators will decide all issues. 
         All arbitrators will be active Oregon State Bar members in good
         standing.  All arbitration hearings will be held in Portland, Oregon. 
         In addition to all other powers, the arbitrator(s) shall have the
         exclusive right to

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         determine all issues of arbitrability.  Judgment on
         any arbitration award may be entered in any court with jurisdiction.
    (c)  If either party institutes any judicial proceeding relating to the
         Loan, such action shall not be a waiver of the right to submit any
         Claim to arbitration.  In addition, each has the right before, during
         and after any arbitration to exercise any number of the following
         remedies, in any order or concurrently: (i) Setoff; (ii) self-help
         repossession; (iii) judicial or non-judicial foreclosure against real
         or personal property collateral;and (iv) provisional remedies,
         including injunction,  appointment of receiver, attachement, claim and
         delivery and replevin.
23. GOVERNING LAW.  This note shall be governed by and construed and enforced
    in accordance with the laws of the State of Oregon without regard to
    conflicts of law principles; PROVIDED, however, that to the extent that
    Lender has greater rights or remedies under Federal law, this provision
    shall not be deemed to deprive Lender of such rights and remedies as may be
    available under Federal law. 

24. DISCLOSURE.

UNDER OREGON LAW, MOST AGREEMENTS, PROMISES AND COMMITMENTS MADE BY LENDERS
                  AFTER OCTOBER 3, 1989 CONCERNING LOANS AND OTHER CREDIT
                  EXTENSIONS WHICH ARE NOT FOR PERSONAL, FAMILY OR HOUSEHOLD
                  PURPOSES OR SECURED SOLELY BY THE BORROWER'S RESIDENCE MUCT
                  BE IN WRITING, EXPRESS CONSIDERATION AND BE SIGNED BY THE
                  LENDER TO BE ENFORCEABLE.

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EACH OF THE UNDERSIGNED HEREBY ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THIS
            DOCUMENT.

SUMMIT DESIGN, INC.
--------------------------------               --------------------------------
Borrower Name                                  Signature of Individual Borrower


 /s/  C. Albert Koob, Chief Financial Officer  --------------------------------
By                                    Title             Signature of Individual
                      Borrower


--------------------------------               --------------------------------
By                                    Title             Signature of Individual
                      Borrower



For valuable consideration, Lender agrees to the terms of the arbitration
                      provision set forth in this note.

                                                   Lender
                      Name:__________________________
                             By:_________________________________
                             Title:______________________________
                                          Date