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                                                                  EXHIBIT 10.5.1

                               NASSDA CORPORATION

                        2001 EMPLOYEE STOCK PURCHASE PLAN

                         FORM OF SUBSCRIPTION AGREEMENT

_____ Original Application                          Enrollment Date: ___________
_____ Change in Payroll Deduction Rate
_____ Change of Beneficiary(ies)

1.       ____________________ hereby elects to participate in the NASSDA
         Corporation Employee Stock Purchase Plan (the "Employee Stock Purchase
         Plan") and subscribes to purchase shares of the Company's Common Stock
         in accordance with this Subscription Agreement and the Employee Stock
         Purchase Plan.

2.       I hereby authorize payroll deductions from each paycheck in the amount
         of ____% of my Compensation on each payday during the Offering Period
         in accordance with the Employee Stock Purchase Plan. (Please note that
         the percentage withholding must be between 1% and 15% and that no
         fractional percentages are permitted.)

3.       I understand that said payroll deductions shall be accumulated for the
         purchase of shares of Common Stock at the applicable Purchase Price
         determined in accordance with the Employee Stock Purchase Plan. I
         understand that if I do not withdraw from an Offering Period, any
         accumulated payroll deductions will be used to automatically exercise
         my option.

4.       I have received a copy of the complete Employee Stock Purchase Plan. I
         understand that my participation in the Employee Stock Purchase Plan is
         in all respects subject to the terms of the Plan. I understand that my
         ability to exercise the option under this Subscription Agreement is
         subject to stockholder approval of the Employee Stock Purchase Plan.

5.       Shares purchased for me under the Employee Stock Purchase Plan should
         be issued in the name(s) of (Employee or Employee and Spouse only):
         _____________________________.

6.       I understand that if I dispose of any shares received by me pursuant to
         the Plan within 2 years after the Enrollment Date (the first day of the
         Offering Period during which I purchased such shares) or one year after
         the Exercise Date, I will be treated for federal income tax purposes as
         having received ordinary income at the time of such disposition in an
         amount equal to the excess of the fair market value of the shares at
         the time such shares were purchased by me over the price which I paid
         for the shares. I hereby agree to notify the Company in writing within
                         ------------------------------------------------------
         30 days after the date of any disposition of my shares and I will make
         ----------------------------------------------------------------------
         adequate provision for Federal, state or other tax withholding
         --------------------------------------------------------------
         obligations, if any, which arise upon the
         -----------------------------------------

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         disposition of the Common Stock. The Company may, but will not be
         -------------------------------
         obligated to, withhold from my compensation the amount necessary to
         meet any applicable withholding obligation including any withholding
         necessary to make available to the Company any tax deductions or
         benefits attributable to sale or early disposition of Common Stock by
         me. If I dispose of such shares at any time after the expiration of the
         2-year and 1-year holding periods, I understand that I will be treated
         for federal income tax purposes as having received income only at the
         time of such disposition, and that such income will be taxed as
         ordinary income only to the extent of an amount equal to the lesser of
         (1) the excess of the fair market value of the shares at the time of
         such disposition over the purchase price which I paid for the shares,
         or (2) 15% of the fair market value of the shares on the first day of
         the Offering Period. The remainder of the gain, if any, recognized on
         such disposition will be taxed as capital gain.

7.       I hereby agree to be bound by the terms of the Employee Stock Purchase
         Plan. The effectiveness of this Subscription Agreement is dependent
         upon my eligibility to participate in the Employee Stock Purchase Plan.

8.       In the event of my death, I hereby designate the following as my
         beneficiary(ies) to receive all payments and shares due me under the
         Employee Stock Purchase Plan:

         NAME: (Please print)__________________________________________________
                                 (First)           (Middle)            (Last)

         _________________________     ________________________________________
         Relationship
                                       ________________________________________
                                       (Address)

         Employee's Social
         Security Number:              _______________________________
         Employee's Address:
                                       _______________________________

                                       _______________________________

                                       _______________________________

I UNDERSTAND THAT THIS SUBSCRIPTION AGREEMENT SHALL REMAIN IN EFFECT THROUGHOUT
SUCCESSIVE OFFERING PERIODS UNLESS TERMINATED BY ME.

Dated:_________________________        ________________________________________
                                       Signature of Employee

                                       ________________________________________
                                       Spouse's Signature (If beneficiary
                                       other than spouse)

                                      -2-

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                                    EXHIBIT B
                                    ---------

                               NASSDA CORPORATION

                        2001 EMPLOYEE STOCK PURCHASE PLAN

                              NOTICE OF WITHDRAWAL

         The undersigned participant in the Offering Period of the NASSDA
Corporation Employee Stock Purchase Plan which began on ____________, ______
(the "Enrollment Date") hereby notifies the Company that he or she hereby
withdraws from the Offering Period. He or she hereby directs the Company to pay
to the undersigned as promptly as practicable all the payroll deductions
credited to his or her account with respect to such Offering Period. The
undersigned understands and agrees that his or her option for such Offering
Period will be automatically terminated. The undersigned understands further
that no further payroll deductions will be made for the purchase of shares in
the current Offering Period and the undersigned shall be eligible to participate
in succeeding Offering Periods only by delivering to the Company a new
Subscription Agreement.

                                       Name and Address of Participant:

                                       ________________________________________

                                       ________________________________________

                                       ________________________________________

                                       Signature:

                                       ________________________________________

                                       Date:___________________________________<PAGE>

                                                                EXHIBIT 10.6

NASSDA

September 15, 2000

Shu-Hua Tammy Liu
[Address]

Dear Tammy:

     Nassda is very pleased to offer you a key contributor position to help grow
our business and bring forth our company's success. In accepting this offer, you
will assume the responsibilities as Nassda's Chief Financial Officer, reporting
directly to myself. With a close working relationship and support from the
entire Nassda's staff, we believe that you will be able to exert your best
effort to make Nassda's financial planning and financial operation/control as
well as financial analysis the first rated in EDA industry.

     More specifically, working as a team member along with John, An-Chang and
myself, you will be responsible for all financial related matters in Nassda,
including but not limited to budgeting, booking and revenue recognition, product
shipment, payment collection, payroll, accounting and financial reports,
auditing management, financial community relationship, legal document review,
international office installation and occasional financial analysis. You are
also expected to build and manage an efficient finance department, which will
serve the increasing needs as Nassda grows.

     Your compensation package will be comprised of a base annual salary of
$120,000. Our benefit package is relatively complete. Nassda provides a
comprehensive medical and dental coverage plan, life insurance and a 401K plan.

     As a key contributor, Nassda will offer you a stock option package of
165,000 shares of Nassda's common stock to be vested over a four-year period.
The first 25% of this option package will be vested upon your completion of
first year of service at Nassda. After the first year, the option shares will be
vested on a monthly basis. These option shares are subject to certain Security
Exchange Commission's restrictions and rules and the approval of Nassda's Board
of Directors. These option shares are purchasable upfront but any unvested
shares are subject to repurchasing by Nassda at cost if your employment with
Nassda is discontinued. In case of a change of control in Nassda due to a merger
or acquisition resulting in a loss of your CFO responsibilities, one of the
following dispositions of option vesting acceleration will be activated. If such
a change of control occurs before you fulfill your first two years service at
Nassda, then one year vesting acceleration will be automatically granted to you.
If you have served more than two years at Nassda at the time of such a change of
control, a full vesting acceleration of the four year option shares will be
granted.

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     Tammy, we firmly believe that you will be a solid member of Nassda's core
team and your contribution to Nassda's business success will be quite
significant.

     We warmly welcome you to join this family of very talented and productive
team of business professionals striving to create an excellent company with a
high degree of success in future years.

Sincerely,

/s/ Sang Wang
-----------------------
Sang Wang
Chief Executive Officer
Nassda Corporation

1, Shu-Hua Tammy Liu, accept this offer with the terms stated above on 9/18/2000
and commit to start working at Nassda on 9/18/00.

        /s/ Shu-Hua Tammy Liu
------------------------------------
Shu-Hua Tammy Liu

                                       -2-

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