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                                                               EXHIBIT 10.12

                           UNCONDITIONAL GUARANTY
                                 (CORPORATE)

      For and in consideration of the loan accommodations by SILICON VALLEY 
BANK (individually and in its capacity as servicing agent) and BANK OF HAWAII 
(collectively, the "Banks") to Cymer Japan, Inc. ("Borrower"), which are made 
pursuant to the Loan Agreement of even date herewith between Borrower and 
Cymer, Inc., on one side, and the Banks, on the other side (the "Agreement"), 
the undersigned guarantor ("Guarantor") hereby unconditionally and 
irrevocably guarantees the prompt and complete payment of all amounts that 
Borrower owes to Banks and performance by Borrower of the Agreement and any 
other agreements between Borrower and Banks, as amended from time to time 
(collectively referred to as the "Agreements"), in strict accordance with 
their respective terms.

      1.  If Borrower does not perform its obligations in strict accordance 
with the Agreements, Guarantor shall immediately pay all amounts due 
thereunder (including, without limitation, all principal, interest, and fees) 
and otherwise to proceed to complete the same and satisfy all of Borrower's 
obligations under the Agreements.

      2.   The obligations hereunder are independent of the obligations of 
Borrower, and a separate action or actions may be brought and prosecuted 
against Guarantor whether action is brought against Borrower or whether 
Borrower be joined in any such action or actions.  Guarantor waives the 
benefit of any statute of limitations affecting its liability hereunder or 
the enforcement thereof, to the extent permitted by law.  Guarantor's 
liability under this Guaranty is not conditioned or contingent upon the 
genuineness, validity, regularity or enforceability of the Agreements.

      3.   Guarantor authorizes Banks, without notice or demand and without 
affecting its liability hereunder, from time to time to (a) renew, extend, or 
otherwise change the terms of the Agreements or any part thereof; (b) take 
and hold security for the payment of this Guaranty or the Agreements, and 
exchange, enforce, waive and release any such security; and (c) apply such 
security and direct the order or manner of sale thereof as Banks in their 
sole discretion may determine.

      4.   Guarantor waives any right to require Banks to (a) proceed against 
Borrower or any other person; (b) proceed against or exhaust any security 
held from Borrower; or (c) pursue any other remedy in Banks' power 
whatsoever.  Banks may, at its election, exercise or decline or fail to 
exercise any right or remedy it may have against Borrower or any security 
held by Banks, including without limitation the right to foreclose upon any 
such security by judicial or nonjudicial sale, without affecting or impairing 
in any way the liability of Guarantor hereunder.  Guarantor waives any 
defense arising by reason of any disability or other defense of Borrower or 
by reason of the cessation from any cause whatsoever of the liability of 
Borrower, other than the indefeasible prior and complete payment of the 
Obligations provided that such payment is not partially or fully disgorged or 
otherwise subject to disgorgement for any reason by the Banks in a 
bankruptcy, insolvency or any other proceeding.  Guarantor waives any setoff, 
defense or counterclaim that Borrower may have against Banks. Guarantor 
waives any defense arising out of the absence, impairment or loss of any 
right of reimbursement or subrogation or any other rights against Borrower. 
Until all of the amounts that Borrower owes to Banks have been paid in full, 
Guarantor shall have no right of subrogation or reimbursement for claims 
arising out of or in connection with this Guaranty, contribution or other 
rights against Borrower, and Guarantor waives any right to enforce any remedy 
that Banks now have or may hereafter have against Borrower.  Guarantor waives 
all rights to participate in any security now or hereafter held by Banks.  
Guarantor waives all presentments, demands for performance, notices of 
nonperformance, protests, notices of protest, notices of dishonor, and 
notices of acceptance of this Guaranty and of the existence, creation, or 
incurring of new or additional indebtedness.  


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Guarantor assumes the responsibility for being and keeping itself informed of 
the financial condition of Borrower and of all other circumstances bearing 
upon the risk of nonpayment of any indebtedness or nonperformance of any 
obligation of Borrower, warrants to Banks that it will keep so informed, and 
agrees that absent a request for particular information by Guarantor, Banks 
shall have no duty to advise Guarantor of information known to Banks 
regarding such condition or any such circumstances.  Guarantor waives the 
benefits of California Civil Code sections 2809, 2810, 2819, 2845, 2847, 
2848, 2849, 2850, 2899 and 3433.

      5.   Guarantor acknowledges that, to the extent Guarantor has or may have
certain rights of subrogation or reimbursement against Borrower for claims
arising out of this Guaranty, those rights may be impaired or destroyed if Banks
elect to proceed against any real property security of Borrower by non-judicial
foreclosure.  That impairment or destruction could, under certain judicial cases
and based on equitable principles of estoppel, give rise to a defense by
Guarantor against its obligations under this Guaranty.  Guarantor waives that
defense and any others arising from Banks' election to pursue non-judicial
foreclosure.  Without limiting the generality of the foregoing, Guarantor waives
any and all benefits and defenses under California Code of Civil Procedure
Sections 580a, 580b, 580d and 726, to the extent they are applicable.

      6.   If Borrower becomes insolvent or is adjudicated bankrupt or files 
a petition for reorganization, arrangement, composition or similar relief 
under any present or future provision of the United States Bankruptcy Code, 
or if such a petition is filed against Borrower, and in any such proceeding 
some or all of any indebtedness or obligations under the Agreements are 
terminated or rejected or any obligation of Borrower is modified or 
abrogated, or if Borrower's obligations are otherwise avoided for any reason, 
Guarantor agrees that Guarantor's liability hereunder shall not thereby be 
affected or modified and such liability shall continue in full force and 
effect as if no such action or proceeding had occurred.  This Guaranty shall 
continue to be effective or be reinstated, as the case may be, if any payment 
must be returned by Banks upon the insolvency, bankruptcy or reorganization 
of Borrower, Guarantor, any other guarantor, or otherwise, as though such 
payment had not been made.

      7.   Any indebtedness of Borrower now or hereafter held by Guarantor is 
hereby subordinated to any indebtedness of Borrower to Banks; and such 
indebtedness of Borrower to Guarantor shall be collected, enforced and 
received by Guarantor as trustee for Banks and be paid over to Banks on 
account of the indebtedness of Borrower to Banks but without reducing or 
affecting in any manner the liability of Guarantor under the other provisions 
of this Guaranty.

      8.   Guarantor agrees to pay a reasonable attorneys' fee and all other 
costs and expenses which may be incurred by Banks in the enforcement of this 
Guaranty.  No terms or provisions of this Guaranty may be changed, waived, 
revoked or amended without Banks' prior written consent.  Should any 
provision of this Guaranty be determined by a court of competent jurisdiction 
to be unenforceable, all of the other provisions shall remain effective.  
This Guaranty embodies the entire agreement among the parties hereto with 
respect to the matters set forth herein, and supersedes all prior agreements 
among the parties with respect to the matters set forth herein.  No course of 
prior dealing among the parties, no usage of trade, and no parol or extrinsic 
evidence of any nature shall be used to supplement, modify or vary any of the 
terms hereof.  There are no conditions to the full effectiveness of this 
Guaranty.  Banks may assign this Guaranty without in any way affecting 
Guarantor's liability under it.  This Guaranty shall inure to the benefit of 
Banks and their successors and assigns.  This Guaranty is in addition to the 
guaranties of any other guarantors and any and all other guaranties of 
Borrower's indebtedness or liabilities to Banks.

      9.   Guarantor represents and warrants to Banks that (i) Guarantor has 
taken all necessary and appropriate action to authorize the execution, 
delivery and performance of this Guaranty, (ii) execution, delivery and 
performance of this Guaranty do not conflict with or result 


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in a breach of or constitute a default under Guarantor's Articles of 
Incorporation or Bylaws or other organizational documents or agreements to 
which it is party or by which it is bound, and (iii) this Guaranty 
constitutes a valid and binding obligation, enforceable against Guarantor in 
accordance with its terms.

      10.  Guarantor covenants and agrees that Guarantor shall do all of the 
following:

           10.1  Guarantor shall maintain its corporate existence, remain in 
good standing in Delaware, and continue to qualify in each jurisdiction in 
which the failure to so qualify could have a material adverse effect on the 
financial condition, operations or business of Guarantor.  Guarantor shall 
maintain in force all licenses, approvals and agreements, the loss of which 
could have a material adverse effect on its financial condition, operations 
or business.

           10.2  Guarantor shall comply with all statutes, laws, ordinances, 
directives, orders, and government rules and regulations to which it is 
subject if non-compliance with such laws could adversely affect the financial 
condition, operations or business of Guarantor.

           10.3  At any time and from time to time Guarantor shall execute and 
deliver such further instruments and take such further action as may 
reasonably be requested by Bank to effect the purposes of this Agreement.

           11.  This Guaranty shall be governed by the laws of the State of 
California, without regard to conflicts of laws principles.  GUARANTOR WAIVES 
ANY RIGHT TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR 
ARISING OUT OF THIS GUARANTY OR ANY OF THE TRANSACTIONS CONTEMPLATED THEREIN, 
INCLUDING CONTRACT CLAIMS, TORT CLAIMS, BREACH OF DUTY CLAIMS, AND ALL OTHER 
COMMON LAW OR STATUTORY CLAIMS.  Guarantor submits to the exclusive 
jurisdiction of the state and federal courts located in San Diego County, 
California.

           IN WITNESS WHEREOF, the undersigned Guarantor has executed this 
Guaranty as of this 8th of December, 1997.

                              Cymer, Inc.

                              By:       /s/ William A. Angus, III
                                        --------------------------------------
                              Title:    Senior Vice President, Chief Financial
                                        Officer


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