<PAGE>   1
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.

                             CONFIDENTIAL TREATMENT
                        PDF SOLUTIONS, INC. HAS REQUESTED
                        THAT THE MARKED PORTIONS OF THIS
                        DOCUMENT BE ACCORDED CONFIDENTIAL
                      TREATMENT PURSUANT TO RULE 406 UNDER
                     THE SECURITIES ACT OF 1933, AS AMENDED.

                                                                   EXHIBIT 10.18


                               PDF SOLUTIONS, INC.

                         SOFTWARE SITE LICENSE AGREEMENT




      This SOFTWARE SITE LICENSE AGREEMENT is made as of ************* (this
"AGREEMENT") between PDF SOLUTIONS, INC., a corporation organized and existing
under the laws of the State of California ("LICENSOR"), whose address is 333
West San Carlos Street, Suite 700, San Jose, California, U.S.A. and TOSHIBA
CORPORATION, a corporation organized and existing under the laws of Japan (the
"CUSTOMER"), whose address is 1-1 Shibaura 1-chome, Minato-ku, Tokyo 105-01,
Japan.

                                    RECITALS:

      WHEREAS, Licensor has previously licensed to Customer certain of the
computer software packages identified on Schedule A hereto (the "SOFTWARE
PRODUCT") including end-user manuals and documentation, for use on a single
central processing unit pursuant to prior agreements between Licensor and
Customer.

      WHEREAS, Licensor and Customer wish to enter into a site or enterprise
license providing for a license of the Software Product by all employees of
Customer on Customer's central processing units, and to have all copies of
Software Product used by Customer covered under this Agreement.

      WHEREAS, this Agreement shall govern the relationship between both parties
with regard to any Software Product used by Customer.

      NOW, THEREFORE, in consideration of the mutual promises contained herein,
Licensor and Customer agree as follows:

1.    SOFTWARE PRODUCT LICENSE.

      (a)   GRANT.

            (i)   Licensor hereby grants to Customer a non-exclusive and
non-transferable license, without the right to sublicense, to use the Software
Product solely on the central processing units and other equipment owned or
operated by Customer on which the Software Product is designated to be used and
set forth in Schedule A (the "DESIGNATED EQUIPMENT"), and only for Customer's
own internal business use in the integrated circuit manufacturing and design
business. This Software Product License shall govern the license of all Software
Product licensed or used by Customer whether previously or hereafter provided or
licensed by Licensor to

                                                                             -1-

<PAGE>   2
Customer and shall replace any prior agreements entered into between Licensor
and Customer relating to licensing of copies the Software Product previously
delivered.

            (ii)  Subject to the provisions of Section 8, the term of the
Software Product License shall be for a period of three (3) years commencing on
January 1, 2001 after which period the Software Product License shall terminate
unless extended by mutual agreement between the parties.

            (iii) Customer shall not make the Software Product available to any
other party except (i) its subsidiaries in which Customer maintains a fifty
percent (50%) or greater ownership interest (but only for so long as Customer
retains such a percentage interest), by time-sharing or otherwise or (ii) others
who use the Software Product on Designated Equipment on Customer's premises for
the purposes specified in this Agreement and who agree in writing to maintain
the confidentiality of Licensor Information (as defined in Section 3(a).
Customer shall not use the Software Product to process any data other than its
own.

            (iv)  Customer shall not operate the Software Product on any central
processing unit other than the Designated Equipment, without the prior written
consent of Licensor.

            (v)   Customer acknowledges that it is receiving only a limited
license to use the Software Product and related documentation and that Licensor
retains all right, title and interest in and to the Software Product and related
documentation, including all patent, copyright, trade secret and other
intellectual property rights and any corrections, bug fixes, enhancements,
updates or other modifications, whether made by Licensor, Customer or any third
party.

            (vi)  Licensor shall grant to Customer, free of additional charge, a
license to use the interface and the related documentation therefor which is
developed by Licensor only for Customer. Such interface and documentation shall
constitute Software Product licensed under this Agreement.

      (b)   RISK OF LOSS. Licensor assumes the risk of loss or injury to
the Software Product until delivered to Customer. Thereafter, the risk of loss
and damage to the Software Product (except for replacement of defective items as
set forth in Section 5 hereof relating to warranties) shall be upon Customer.
Customer hereby assumes full responsibility for the selection, installation and,
subject to Section 4, maintenance of the Software Product.

      (c)   COPIES. In addition to such copies as are installed on Designated
Equipment, Customer may make one (1) copy of each item of the Software Product
for backup purposes only.

      (d)   REVERSE ENGINEERING. Customer agrees that only Licensor shall have
the right to maintain, enhance or otherwise modify the Software Product.
Customer shall not cause or permit the decompilation, disassembly, modification
or reverse engineering of all or any part of the Software Product and shall not
attempt to do so. Customer further acknowledges that the Product Software
incorporates certain tracking software (the "TRACKING SOFTWARE") designed to
track use of the Product Software and the fees payable hereunder. Customer shall
not amend or modify


                                                                             -2-
<PAGE>   3
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.



such tracking software or take any other action which might disable or alter
such tracking features or the results obtained therefrom.

2.    PAYMENTS TO BE MADE BY CUSTOMER.

      (a)   PAYMENTS. Customer shall pay the charges for the Software Product in
the amounts and at the times indicated in Schedule B hereto.
********************************************************************************
********************************************************************************
********************* Customer shall hold Licensor harmless from all claims and
liabilities arising from Customer's failure to report or pay any such taxes,
duties and assessments subject to the following conditions and procedures.
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
**********************************************. Licensor agrees that the
payment may be made by Toshiba America Incorporated on Customer's behalf
provided that such payment is made in accordance with the conditions required by
Customer under this Agreement.

      (b)   AUDITING. In furtherance of any and all of Licensor's rights under
this Agreement, Customer shall, upon forty-eight (48) regular business hours
prior notice and no more than once during any twelve (12) month period, provide
Licensor with sufficient access to the data generated by and results of the
Tracking Software and shall provide such materials, documentation, reports and
other information as Licensor shall request to support and prove the usage of
and number of copies made under this Agreement and Customer's compliance with
the other provisions of this Agreement. Following delivery of such data, results
and other materials, if Licensor is not reasonably satisfied with such proof and
should Licensor reasonably request, Customer shall permit an independent third
party mutually acceptable to Licensor and Customer to enter upon Customer's
premises to audit Customer's compliance with the terms of this Agreement at
Licensor's expense.

3.    CONFIDENTIALITY AND USE OF SOFTWARE PRODUCT.

      (a)   GENERAL. Customer acknowledges that it has no proprietary interest
in or right to use the Software Product except in accordance with the terms of
the Software Product License granted in this Agreement. Customer agrees that,
during the term of this Agreement and thereafter, it will hold the Software
Product, the terms of this Agreement and any other confidential information of
the Licensor that may come into Customer's possession ("LICENSOR INFORMATION")
in confidence, that it will not sell, license, sublicense, publish, display,
distribute, disclose or otherwise make the Licensor Information or any part
thereof available to any third party except employees of Customer within the
scope of their employment and to others under a duty of confidence to Customer
while on Customer's premises, and that it will take all reasonable steps and
precautions to maintain the confidentiality of the Licensor Information.


                                                                             -3-
<PAGE>   4

            Notwithstanding the foregoing, information received by Customer in
connection with this Agreement shall not be considered Licensor Information if:

            (i)   The information is known by written records to Customer at the
time of disclosure; or

            (ii)  The information is or becomes public knowledge other than
through the unauthorized disclosure by Customer; or

            (iii) The information is rightfully received from a third party who
has the right to disclose the information; or

            (iv)  The information is specifically excluded from Licensor
Information by Licensor's prior written approval; or

            (v)   The information is independently developed by Customer without
prior knowledge of the Licensor's information.

      (b)   SPECIFIC. Without limiting the foregoing, Customer further agrees as
follows:

            (i)   It will not use the Software Product or any part thereof on
any central processing unit other than Designated Equipment, or at any location
other than Customer's business addresses, except as indicated in Section 1(a) of
this Agreement.

            (ii)  It will not remove or permit to be removed from any item
included in the Software Product any notice placed thereon by Licensor
indicating the confidential or proprietary nature thereof.

            (iii) Other than copies installed pursuant to Section 1(a)(i) and
the backup copy permitted by Section 1(c), it will not copy or duplicate by any
means the Software Product or any part thereof without the prior written consent
of Licensor. Any copy made by Customer shall include all copyright or other
proprietary notices of Licensor included in or on the original Software Product
provided by Licensor. Customer shall keep a record of each copy made, where such
copy is located and in whose custody it is, and shall provide to Licensor a
monthly report specifying all additional central processing units on which the
Product Software is installed and designated to be used under Section 1(a).

            (iv)  It will restrict all use of the information provided hereunder
solely to the field of use defined and granted herein, and will not use any
information in tangible or intangible form which has been or may be delivered or
disclosed to Customer or Customer's employees by Licensor or Licensor's
employees for the purpose of creating or attempting to create, or permitting
others to create or attempt to create, any product similar to the Software
Product or any part thereof.

            (v)   It will limit access to the Software Product to only those
employees of Customers and others who who need access thereto for the purposes
specified in this Agreement

                                                                             -4-
<PAGE>   5

and who have agreed in writing to protect the confidentiality of the Licensor
Information in the manner set forth in this Section

            (vi)  It will not copy any source code received by it from Licensor,
and it will take all necessary steps to assure that no copies are made by
employees or third parties.

            (vii) To protect and maintain the confidentiality of the Licensor
Information, it will take precautions at least as stringent as it uses to
protect its own confidential information.

      (c)   DISCLOSURE. Licensor recognizes that under certain circumstances,
Customer may be required by judicial order, regulatory authority, or in order to
satisfy its auditors, to disclose certain information about the Software
Product, and Licensor hereby consents to such disclosure, provided that:

            (i)   If the disclosure is to be to a governmental authority or
pursuant to judicial order, Customer shall notify Licensor within forty-eight
(48) regular business hours after Customer receives such a notice, and

            (ii)  If such request is by Customer's auditors, then before any
disclosure is made, Customer shall obtain from such auditors a covenant and
agreement to respect the confidentiality required by this Section 3. Upon
request, Licensor shall provide forms for this purpose.

4.    UPDATES, SUPPORT AND MAINTENANCE. Customer shall receive modifications and
updates to the Software Product, including updates to user documentation, and
advice by telephone or mail and other support and maintenance services with
respect thereto in accordance with the terms of a separate Software Maintenance
Agreement executed simultaneously with the execution of this Agreement. Such
modifications, updates, support and maintenance will be provided without
additional charges beyond those set forth in this Agreement, except as
specifically provided in the Software Maintenance Agreement.

5.    EXPRESS WARRANTIES AND EXCLUSION OF IMPLIED WARRANTIES.

      (a)   AUTHORITY. Licensor warrants that it has the right to grant the
license of the Software Product granted in this Agreement.

      (b)   INFRINGEMENT ACTIONS. Licensor will defend at its expense any action
brought against Customer to the extent that it is based on a claim that the
Software Product constitutes infringement of any patent, copyright, or other
intellectual proprietary rights in the United States and Japan, and Licensor
will pay all damages and costs reasonably incurred by Customer in such action
which are attributable to such claims, provided that Licensor is informed in
writing and furnished a copy of each communication, notice or other action
relating to the alleged infringement and is given authority, information and
assistance (at Licensor's expense) necessary to defend or settle such claim.
Should the Software Product become, or in Licensor's opinion be likely to
become, the subject of a claim of infringement of any United States and/or
Japanese patent, copyright, or other intellectual proprietary rights, then
Licensor may at its option (i)

                                                                             -5-
<PAGE>   6

procure for Customer the right to use the Software Product free of any liability
for infringement or (ii) replace such Software Product with non-infringing
substitutes otherwise complying substantially with all of the requirements of
this contract. In the event that Licensor attempts in good faith but is unable
to resolve such infringement, Licensor may terminate this Agreement and shall
refund to Customer a prorated portion of the amount Customer has paid to
Licensor based upon the portion of the year that customer has had use of the
Software Product prior to such termination.

      Licensor will not be obligated to defend or be liable for costs and
damages if the infringement arises out of any software developed by Licensor in
compliance with the Customer's specifications or a modification of the Software
Product after delivery by Licensor.

      (c)   PATENTS AND COPYRIGHTS. If any action is brought against Licensor,
based on a claim that any software developed by Licensor in compliance with
Customer's specifications and supplied to Customer directly infringes any duly
issued United States patent, copyright, or other proprietary right in the United
States, then the indemnity obligation herein stated with respect to Licensor
shall reciprocally apply with respect to Customer with respect to such claim of
infringement.

      (d)   CONFORMITY AND DOCUMENTATION. Licensor warrants that the Software
Product will, when delivered, conform to the documentation therefor provided by
Licensor. If, within 60 days after delivery of the Software Product, Customer
reports an alleged defect in the Software Product, Licensor's qualified
personnel will attempt to verify the defect and, within thirty (30) days
(determined in light of the nature and scope of the alleged defect), after
confirming the existence of a defect, Licensor shall correct the defect in the
Software Product or provide Customer with an avoidance procedure to correct the
defect.

      (e)   EXTENT OF LIABILITY.

            (i)   THE PROVISIONS OF SECTIONS 5(b) AND (c) STATE THE SOLE AND
EXCLUSIVE LIABILITY OF THE PARTIES HERETO FOR PATENT AND COPYRIGHT INFRINGEMENT
AND IS IN LIEU OF ALL CONDITIONS OR WARRANTIES EXPRESSED, IMPLIED, STATUTORY OR
OTHERWISE IN REGARD THERETO.

            (ii)  THE FOREGOING WARRANTIES DO NOT APPLY TO THE SOFTWARE PRODUCT
IF LOCATED OR USED IN A MANNER INCONSISTENT WITH ANY TERMS OR LIMITATIONS OF
THIS AGREEMENT. EXCEPT FOR THE EXPRESS WARRANTIES STATED IN THIS AGREEMENT,
LICENSOR DISCLAIMS ALL OTHER CONDITIONS AND WARRANTIES, WHETHER EXPRESSED,
IMPLIED OR STATUTORY INCLUDING ALL IMPLIED CONDITIONS OR WARRANTIES INCLUDING
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

6.    LIMITATION OF DAMAGES. In no event will Licensor be liable for any damages
arising from performance or non-performance of the Software Product or for any
lost profits, loss of use, loss of data, cost of procurement of substitute goods
or services, or other consequential,


                                                                             -6-
<PAGE>   7
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


incidental, special, indirect or exemplary damages, however caused and under any
theory of liability, even if Licensor has been advised of the possibility of
such damage, or for any claim against the Customer by any other party, except as
provided for in Section 5 with respect to infringement of the rights of others.
In no event shall Licensor's liability for any cause exceed the aggregate amount
paid by Customer to Licensor pursuant to this Agreement except for personal
injury or death resulting from Licensor's gross negligence or willful
misconduct. Customer acknowledges that the amounts payable hereunder are based
in part on these limitations and further agrees that these limitations shall
apply notwithstanding any failure of essential purpose of any limited remedy.

7.    NONTRANSFERABILITY. Customer shall not assign, sublicense, extend or
other-wise transfer in whole or in part this Agreement or any license granted
hereunder without written consent of Licensor to such transfer which consent
shall not be unreasonably withheld. Licensor will notify Customer in writing
prior to transferring or assigning this Agreement and Licensor will not be
released from its obligations hereunder without written consent of Customer to
such transfer or assignment. As used in the preceding sentence, "Customer" means
only the specific entity that has executed this Software License Agreement as
Customer.

8.    DEFAULT; EFFECT OF TERMINATION.

      (a)   DEFAULT; TERMINATION BY CUSTOMER. Customer shall be in default
hereunder upon the occurrence of any of the following events: (i) any sum of
money owed by Customer hereunder is not paid when due; (ii) Customer breaches
any provision of this Agreement relating to the non-disclosure or limited use of
confidential or proprietary information; or (iii) there occurs any material
violation of or failure to perform any other term of this Agreement to be
performed by Customer which is not remedied by Customer within thirty (30) days
after notice of such violation or failure has been given by Licensor to
Customer. Upon the occurrence of any such default, Licensor may terminate the
Software Product License granted in this Agreement and all sums of money owed by
Customer hereunder shall thereupon become due and payable to Licensor within
thirty (30) days. When the Software Product License granted in this Agreement
shall terminate due to violations of this Agreement without notice of
termination, such termination shall be effective as of the date upon which
Customer ceases to use the Software Product, and Licensor shall at all times
thereafter have the same rights and remedies as Licensor would have in the event
the Software Product License were terminated by virtue of a default by Customer
with notice having been given.

      (b)   NON-WAIVER. The exercise or non-exercise of any right granted to
Licensor or to Customer under the terms of this Section 8 or under any other
provision of this Agreement shall not operate as a waiver of any right which may
subsequently accrue to Licensor or Customer under any provision of this
Agreement and shall not preclude the exercise by Licensor or Customer of any
other rights or remedies which either Licensor or Customer may have in law or
equity or under the terms of this Agreement.

      (c)   SURVIVAL. The provisions of this Agreement relating to
confidentiality shall survive for a period of *********** after the termination
of the Software Product License. The


                                                                             -7-
<PAGE>   8
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


provisions of this Agreement relating to payments due, extent of liability,
limitation of damages, governing law and arbitration as well as this Section 8
shall survive the termination of the Software Product License.

      (d)   DISPOSITION OF SOFTWARE AND LICENSOR INFORMATION. Upon the
termination of the Software Product License, Customer agrees to return to
Licensor all copies of tangible portions of the Software Product and any
material containing or pertaining to the Licensor Information delivered or
disclosed to Customer by Licensor pursuant to the terms of this Agreement, or
otherwise, as well as any copies made by Customer. Title to the Software Product
and any changes, modifications or improvements made or developed with regard to
the Software Product, whether or not made or developed at Customer's request,
shall remain the property of Licensor and shall be deemed to have been part of
the Software Product, as of the date of this Agreement.

9.    ACCEPTANCE BY LICENSOR; ENTIRE AGREEMENT; AMENDMENTS. This Agreement shall
not be effective until accepted in writing by Licensor at its office set forth
in this Agreement. This Agreement constitutes the entire agreement and
understanding between Licensor and Customer concerning the subject matter
hereof, and cancels, terminates and supersedes all prior written and oral
understandings, agreements, proposals, promises and representations of the
parties respecting any and all subject matter contained herein. No
representation or promise hereafter made by a party, nor any modification or
amendment of this Agreement, shall be binding upon either party unless in
writing and signed by Customer and accepted in writing by an authorized agent of
Licensor at its office set forth in this Agreement.

10.   NOTICES. Any notices required or permitted to be given under the terms of
this Agreement shall be deemed given upon personal delivery or five days after
the day of postmark thereof if sent by mail, postage prepaid, registered or
certified mail, return receipt requested, and addressed to the other party at
the address as shown below or at such address as such party from time to time
may indicate by written notice given to the other party hereto.

If to Licensor:      PDF Solutions, Inc.
                     333 West San Carlos Street
                     Suite 700
                     San Jose, California 95110
                     U.S.A.
                     Attention:     President
                     Fax:           (408) 280-7915
                     Phone:         (408)280-7900



If to Customer:      Toshiba Corporation
                     *************************
                     *************************
                     Japan
                     Attention:   *************
                                  *************************
                     Fax:         *************



                                                                             -8-
<PAGE>   9
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


                     Phone:       *************

11.   GOVERNING LAW. This Agreement is entered into in, and shall be governed by
and construed in accordance with the laws of, the State of California without
reference to conflicts of law provisions.

12.   SEVERABILITY. The invalidity of unenforceability of any particular
provisions of this Agreement shall not affect the other provisions hereof, and
this Agreement shall be construed in all respects as if such invalid or
unenforceable provisions had been omitted.

13.   HEADINGS AND CAPTIONS. The headings and captions used in this Agreement
are for convenience of the parties only and shall in no way define, limit,
expand or otherwise affect the meaning of construction of any provision of this
Agreement.

14.   BINDING EFFECT. Subject to all of the terms and conditions hereof, this
Agreement inures to the benefit of and is binding upon the parties hereto and
their successors and assigns.

15.   ARBITRATION. Any dispute arising in connection with this Agreement shall
be amicably settled. Should both parties fail to do so within *********** from
the date in which one party sends to the other party a letter describing the
dispute, such dispute shall be finally settled by arbitration in accordance of
the rules of the International Chamber of Commerce (ICC). Licensor and Customer
shall appoint one arbitrator each and the third arbitrator shall be appointed by
the other two arbitrators or, failing the agreement between them, by the
president of the International Chamber of Commerce within the time limits
provided for by the then existing rules of the International Chamber of
Commerce. The arbitration shall take place in Honolulu, Hawaii and the
arbitrator shall decide all disputes in accordance with equity and good
commercial practice and shall not be bound by the law of any jurisdiction of
process. The decision of the arbitrators shall be final and unappealable and may
be enforced in any country having jurisdiction over the parties or their assets.

16.   ESCROW.

      (a)   ESCROW AGENT. Immediately upon execution of this Agreement, Licensor
shall deposit with an escrow agent selected by Licensor ("ESCROW AGENT"), the
source code language of the Software Product, as well as source code
enhancements and modification to the Software Product (together referred to as
"SOURCE CODE") within ten (10) days after the same becomes available. Escrow
Agent shall act as custodian of the Source Code as long as this Agreement shall
be in effect

      Within one (1) month from the date of execution of this Agreement,
Licensor shall provide Customer with the evidence of the deposit of Source Code
and the copy of the escrow agreement between Licensor and Escrow Agent which
specifies the contingent events and procedure effecting disclosure of the
deposit to Customer.

      (b)   INSOLVENCY. Upon the occurrence of any one of the following events:


                                                                             -9-



<PAGE>   10

            (i)   Liquidation of Licensor or discontinuation of business by
Licensor without proper provisions for support to be provided by a third party
appointed by Licensor; or

            (ii)  Licensor's inability or failure to reasonably support all or
any portion of the Software Product within ninety (90) days after receiving
written notification of such failure;

Escrow Agent is hereby authorized to provide to Customer, upon Customer's
written request, a copy of the portion of the Source Code not so supported.

      (c)   USE OF SOURCE CODE. Upon provision by Escrow Agent of a copy of all
or any portion of the Source Code to Customer pursuant to Section 16(b),
Customer shall only have the right to use the Source Code for the purpose of
maintaining the Software Product and for support thereof but only for such
purpose and only for the term of this Agreement and for so long as the condition
set forth in such Section 16(b) is satisfied. The Source Code shall be deemed to
be confidential information as provided in Section 3 hereof with Customer
subject to all of the obligations set forth therein with regard to such Source
Code.


                                                                            -10-
<PAGE>   11
      (d)   AVAILABILITY OF SOURCE PRODUCT AND DIGITAL CONNECTION. Customer
shall have the right to continue to purchase the Software Product from Escrow
Agent or receiver per term's and conditions of this Agreement.

      IN WITNESS WHEREOF, the parties hereto executed this Agreement on the day
and year first written above.



LICENSOR:                              CUSTOMER:

PDF SOLUTIONS, INC.                    TOSHIBA CORPORATION

By:  /s/ P. Steven Melman              By:  /s/ Y. Morimoto
     -----------------------------          ---------------

Name:  P.S. Melman                     Name: Y. Morimoto
       ---------------------------           -----------

Title:  CFO                            Title: CEO Toshiba Semiconductor Company
        --------------------------            ---------------------------------



                                                                            -11-

<PAGE>   12
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.

                                   SCHEDULE A



                                SOFTWARE PRODUCT



*************

*************

*************

*************

*************

*************

*************

*************

*************





                              DESIGNATED EQUIPMENT





1)    *************************

2)    *************************

3)    *************************

4)    *************************



                                                                             -1-
<PAGE>   13
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.

                                   SCHEDULE B

                                  LICENSE FEES

      Pursuant to Section 2 of that certain Software Site License Agreement
dated as of ************* between PDF Solutions, Inc. and Toshiba Corporation,
Toshiba agrees to pay the fees set forth herein for use of the Software Product
licensed under the License Agreement:

      1.    DEFINITIONS. All defined terms used in this Schedule B shall have
the meanings ascribed to them in the Agreement; provided that for purposes of
this Schedule B, the following terms shall have the following respective
meanings:

            "AVERAGE ANNUAL PEAK USAGE" means the average of the Peak Monthly
Usage for the twelve (12) calendar months in any Usage Year.

            "PEAK MONTHLY USAGE" means the highest number of Usage Units
determined on any day during a specified Usage Month.

            "PRODUCT USES" with respect to any individual Software Product on
any day, shall mean the number of times on such day all users are using or
running such individual Software Product. For the purpose of this definition, a
time being used shall occur if on a particular day a particular user is using or
running a particular Software Product; provided that if at any given time on
that day such user is concurrently using or running such Software Product on
more than one central processing unit, then each such concurrent use shall count
as a separate time being used by such user; provided further that if on a day
such user is using or running a Software Product on more than one central
processing unit but such uses are at no time concurrent, then all such
nonconcurrent uses on such day by such user shall count as one time being used.
For example, if user A uses or has running ****** on two central processing
units and such uses are concurrent at any time during such day, user B uses or
has running ******** on three central processing units during such day but on
not more than two central processing units at any given time during such day,
and user C uses or has running ****** on two central processing units during
such day but such uses are not at any time concurrent, and there are no other
users of ********on such day then the number of ******** Product Uses on such
day is five (calculated as two times being used for user A, two times being used
for user B and one time being used for user C). As other examples, (a) the use
by user X of ****** on three separate occasions on the same central processing
unit on one day shall count as one time being used and (b) the nonconcurrent use
by user Y of ****** on three central processing units shall count as one time
being used. Uses of such Software Product shall include all copies of such
Software Product being used by Customer, including copies thereof delivered to
Customer prior to the execution of this Agreement.

            "USAGE DAY" shall mean the 24 hour period commencing at midnight and
ending at the following midnight, *************, Japan time.

            "USAGE MONTH" shall mean any calendar month during any
Usage Year.



<PAGE>   14
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


            "USAGE UNITS" accruing on any specific day shall mean a number equal
to (a) *********** of **** Product Uses for such day ****** (b) ***** multiplied
by ************************* Product Uses for such day ******* (c) ****
multiplied by ************* Product Uses for such day ***** (d) ***** multiplied
by ************************************* Product Uses ******* (e) *****
multiplied by ************************* Product Uses for such day ****** (f)
******* multiplied by ************************************* Product Uses for
such day **** (g) ****** multiplied by ************************* Product Uses
for such day ****** (h) ****************** Product Uses for such day (i)
************* ************************* Product uses for such day.

            "USAGE YEAR" shall mean the 12 month period commencing on any Usage
Year Commencement Date during the term of this Agreement and ending on the last
day of such twelfth month.

            "USAGE YEAR COMMENCEMENT DATE" shall mean January 1, 2001 (the
"FIRST USAGE YEAR COMMENCEMENT DATE") and each one year anniversary of such date
during the term of this Agreement.

           2. INITIAL LICENSE FEE; ADDITIONAL LICENSE FEE. Within 30 days of
each Usage Year Commencement Date during the term of this Agreement Toshiba
shall pay PDF the following initial license fee (the "INITIAL LICENSE FEE"): (a)
on the First Usage Year Commencement Date, an amount equal to equal to
$*************; and (b) on each subsequent Usage Year Commencement Date, an
amount equal to $*************. Within 30 days following the end of each Usage
Year, Toshiba shall pay, in addition to the Initial License Fee, the following
additional license fee (the "ADDITIONAL LICENSE FEE") for such just completed
Usage Year corresponding to the Average Annual Peak Usage for such Usage Year:

            AVERAGE ANNUAL
         PEAK USAGE FOR THE                               ADDITIONAL
              USAGE YEAR                                 LICENSE FEE
         ------------------                              -----------

     Greater than *** Usage Units but                   $*************
     less than or equal to *** Usage
     Units

     Greater than *** Usage Units but                   $*************
     less than or equal to **** Usage
     Units

     Greater than *** Usage Units but                   $*************
     less than or equal to **** Usage
     Units



<PAGE>   15
                             CONFIDENTIAL MATERIAL
                       OMITTED AND FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


     Greater than *** Usage Units                       $*************

3.    U.S. DOLLARS. All Dollar ($) amounts shall refer to United States Dollars.
All payments shall be made by wire transfer of immediately available funds to an
account specified by Licensor.