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                                                                     Exhibit 4.2

               AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

     This Amended and Restated Registration Rights Agreement is made as of March
31, 2000 by and among Synplicity, Inc., a California corporation having its
principal executive offices at 935 Stewart Drive, Sunnyvale, California 94086
(the "Company"), the persons listed on Exhibit A (the "Existing Shareholders")
and the purchasers of the Company's Series C Preferred Stock (the "Purchasers").

     WHEREAS, the Company and the Existing Shareholders are parties to an
Amended and Restated Registration Rights Agreement dated March 9, 1999 (the
"Former Agreement").

     WHEREAS, the parties to the Former Agreement desire to amend and restate
the agreement to read as set forth below and to include the Purchasers as set
forth on Exhibit B hereto.

     WHEREAS, the Company and the Purchasers are entering into a Series C
Preferred Stock Purchase Agreement of even date herewith (the "Purchase
Agreement"), pursuant to which the Company shall sell, and the Purchasers shall
acquire, shares of the Company's Series C Preferred Stock.

     WHEREAS, in order to induce the Company to enter into the Purchase
Agreement and to induce the Purchasers to invest funds in the Company, the
parties desire that the Purchasers be granted registration rights and rights of
participation with respect to the Preferred Shares.

     NOW, THEREFORE, in consideration of the mutual promises and covenants
hereinafter set forth, the parties agree as follows:

                                  SECTION 1.

     1.1  Termination of Former Agreement.  Through their execution of this
          -------------------------------
Agreement, the Company and the Existing Shareholders agree to terminate the
Former Agreement and restate the terms thereof through this Agreement, with the
result that this Agreement shall constitute the sole agreement among the parties
hereto with respect to the registration of Registrable Securities.

     1.2  Certain Definitions. As used in this Agreement, the following terms
          -------------------
shall have the following respective meanings:

          "Commission" shall mean the Securities and Exchange Commission or any
           ----------
other federal agency at the time administering the Securities Act.

          "Conversion Stock" shall mean the Common Stock issued or issuable
           ----------------
pursuant to conversion of the Preferred Shares.

          "Holders" shall mean (i) any person who purchased the Company's
           -------
Preferred Shares or any person holding Registrable Securities to whom the rights
under this Section 1 have been transferred in accordance with Section 1.12
hereof and (ii) Alisa Yaffa and Kenneth McElvain as
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common shareholders (the "Founders").

          "Initiating Holders" shall mean the Holders or transferees of the
           ------------------
Holders under Section 1.12 hereof  who, in the aggregate, are Holders of at
least 51% of the Preferred Shares or at least 51% of the shares held by the
Founders.

          "Preferred Shares" shall mean the Series A Preferred Stock, Series B
           ----------------
Preferred Stock and Series C Preferred Stock of the Company.

          "Registrable Securities" means (i) the Conversion Stock, (ii) the
           ----------------------
Common Stock held by Alisa Yaffa and Kenneth McElvain on the date hereof (the
"Founders' Common Stock") and (iii) any Common Stock of the Company issued or
issuable in respect of the Conversion Stock or other securities issued or
issuable pursuant to the conversion of the Preferred Shares or upon any stock
split, stock dividend, recapitalization or similar event, or any Common Stock
otherwise issued or issuable with respect to the Founders' Common Stock or the
Preferred Shares, provided, however, that shares of Common Stock or other
securities shall no longer be treated as Registrable Securities if (A) they have
been sold to or through a broker or dealer or underwriter in a public
distribution or a public securities transaction, (B) they have been sold in a
transaction exempt from the registration and prospectus delivery requirements of
the Securities Act so that all transfer restrictions and restrictive legends
with respect thereto are removed upon consummation of such sale, (C) in the case
of a Holder who then holds less than one percent (1%) of the then outstanding
Common Stock (determined on the basis of assumed conversion of all securities
convertible into Common Stock), the shares are available for sale, in the
opinion of counsel to the Company, without compliance with the registration and
prospectus delivery requirements of the Securities Act so that all transfer
restrictions and restrictive legends with respect thereto may be removed upon
the consummation of such sale, or (D) they may be sold under Rule 144 (excluding
144A) of the Securities Act (as defined below) within a three month period.

          The terms "register," "registered" and "registration" refer to a
                     --------    ----------       ------------
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of the
effectiveness of such registration statement.

          "Registration Expenses" shall mean all expenses incurred by the
           ---------------------
Company in complying with Sections 1.3, 1.4 and 1.5 hereof, including, without
limitation, all registration, qualification and filing fees, printing expenses,
escrow fees, fees and disbursements of counsel for the Company and the
reasonable cost of one special legal counsel to represent all of the Holders
together in any such registration shall be borne by the Company, blue sky fees
and expenses, normal audit expenses (but not including the expense of any
special audits incident to or required by any such registration where the
Company is not registering any of its securities, excluding the compensation of
regular employees of the Company which shall be paid in any event by the
Company).

          "Restricted Securities" shall mean the securities of the Company
           ---------------------
required to bear the legend set forth in Section 8.2 of the Purchase Agreement.

          "Securities Act" shall mean the Securities Act of 1933, as amended, or
           --------------
any similar

                                                                             -2-
<PAGE>

federal statute and the rules and regulations of the Commission thereunder, all
as the same shall be in effect at the time.

          "Selling Expenses" shall mean all underwriting discounts, selling
           ----------------
commissions and stock transfer taxes applicable to the securities registered by
the Holders.

     1.3  Requested Registration.
          ----------------------
          (a)  Request for Registration.  In case the Company shall receive from
               ------------------------
Initiating Holders a written request that the Company effect any registration,
qualification or compliance with respect to not less than 20% of the shares of
Registrable Securities then held by such Initiating Holders (or any lesser
percentage if the reasonably anticipated aggregate price to the public of such
shares, net of underwriting discounts and commissions, would exceed $2,000,000),
the Company will:

               (i)  Promptly give written notice of the proposed registration,
qualification or compliance to all other Holders and

               (ii) as soon as practicable, but in any case within ninety (90)
days, use its best efforts to file a registration statement covering the
Registrable Securities to effect such registration, qualification or compliance
(including, without limitation, appropriate qualification under applicable blue
sky or other state securities laws and appropriate compliance with applicable
regulations issued under the Securities Act and any other governmental
requirements or regulations) as may be so requested and as would permit or
facilitate the sale and distribution of all or such portion of such Registrable
Securities as are specified in such request, together with all or such portion
of the Registrable Securities of any Holder or Holders joining in such request
as are specified in a written request received by the Company within 20 days
after receipt of such written notice from the Company.

     Provided, however, that the Company shall not be obligated to take any
action to effect any such registration, qualification or compliance pursuant to
this Section 1.3:

                    (A)  Prior to the earlier of February 19, 2002 or within six
months after the effective date of the Company's initial or other registration
statement relating to an underwritten public offering of the Company's
securities filed under the Securities Act;

                    (B)  After the Company has effected two such registrations
pursuant to this subparagraph 1.3(a), and such registrations have been declared
or ordered effective; or

                    (C)  If the Company shall furnish to such Holders a
certificate signed by the President of the Company stating that in the good
faith judgment of the Board of Directors it would be seriously detrimental to
the Company or its shareholders for a registration statement to be filed at such
time, then the Company's obligation to use its best efforts to register, qualify
or comply under this Section 1.3 shall be deferred for a period not to exceed
180 days from the date of receipt of written request from the Initiating
Holders; provided, however, that the Company shall not exercise such right more
than once in any twelve month period.

                                                                             -3-
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     Subject to the foregoing clauses (A) through (C), the Company shall file a
registration statement covering the Registrable Securities so requested to be
registered as soon as practicable but in any case within ninety (90) days after
receipt of the request or requests of the Initiating Holders.

          (b)  Underwriting.  If the Initiating Holders intend to distribute the
               ------------
Registrable Securities covered by their request by means of an underwriting,
they shall so advise the Company as part of their request made pursuant to
Section 1.3 hereof and the Company shall include such information in the written
notice referred to in Section 1.3(a)(i) above. In such event, the right of any
Holder to registration pursuant to Section 1.3 shall be conditioned upon such
Holder's participation in the underwriting arrangements required by this Section
1.3, and the inclusion of such Holder's Registrable Securities in the
underwriting to the extent requested shall be limited to the extent provided
herein.

     The Company shall (together with all Holders proposing to distribute their
securities through such underwriting) enter into an underwriting agreement in
customary form with the managing underwriter selected for such underwriting by a
majority in interest of the Initiating Holders, but subject to the Company's
reasonable approval. Notwithstanding any other provision of this Section 1.3, if
the managing underwriter advises the Initiating Holders in writing that
marketing factors require a limitation of the number of shares to be
underwritten, the managing underwriter may limit the Registrable Securities to
be included in such offering. The Company shall so advise all Holders of
Registrable Securities and the number of shares of Registrable Securities that
may be included in the registration and underwriting shall be allocated among
all Holders thereof in proportion, as nearly as practicable, to the respective
amounts of Registrable Securities held by such Holders at the time of filing the
registration statements. No Registrable Securities excluded from the
underwriting by reason of the underwriter's marketing limitation shall be
included in such registration. To facilitate the allocation of shares in
accordance with the above provisions, the Company or the underwriters may round
the number of shares allocated to any Holder to the nearest 100 shares.

     If any Holder of Registrable Securities disapproves of the terms of the
underwriting, such person may elect to withdraw therefrom by written notice to
the Company, the managing underwriter and the Initiating Holders. The
Registrable Securities and/or other securities so withdrawn shall also be
withdrawn from registration, and such Registrable Securities shall not be
transferred in a public distribution prior to (i) 180 days after the effective
date of the initial registration of the Company's securities, (ii) 90 days after
the effective date of any subsequent registration, or (iii) such other shorter
period of time as the underwriters may reasonably require.

     If the underwriter has not limited the number of Registrable Securities to
be underwritten, the Company may include securities for its own account or the
account of others in such registration if the underwriter so agrees and the
number of Registrable Securities which would otherwise have been included in
such registration and underwriting will not thereby be limited.

     1.4  Company Registration.
          --------------------
          (a)  Notice of Registration. If at any time or from time to time the
               ----------------------
Company shall determine to register any of its securities, either for its own
account or the account of a security

                                                                             -4-
<PAGE>

holder or holders, other than (i) a registration relating solely to employee
benefit plans, and (ii) a registration relating solely to a Commission Rule 145
transaction:

               (i)  promptly give to each Holder written notice thereof, and

               (ii) include in such registration (and any related qualification
under blue sky laws or other compliance), and in any underwriting involved
therein, all the Registrable Securities specified in a written request or
requests, made within 20 days after receipt of such written notice from the
Company by any Holder.

          (b)  Underwriting. If the registration of which the Company gives
               ------------
notice is for a registered public offering involving an underwriting, the
Company shall so advise the Holders as a part of the written notice given
pursuant to Section 1.4(a)(i). In such event the right of any Holder to
registration pursuant to Section 1.4 shall be conditioned upon such Holder's
participation in such underwriting and the inclusion of Registrable Securities
in the underwriting to the extent provided herein.

     All Holders proposing to distribute their securities through such
underwriting shall (together with the Company and the other holders distributing
their securities through such underwriting) enter into an underwriting agreement
in customary form with the managing underwriter selected for such underwriting
by the Company. Notwithstanding any other provision of this Section 1.3, if the
managing underwriter determines that marketing factors require a limitation of
the number of shares to be underwritten, the managing underwriter may limit the
Registrable Securities to be included in such registration. In such event, the
managing underwriter shall first limit or exclude up to all of the securities of
holders (other than Holders) proposing to distribute their securities through
such underwriting to be included in such registration and may thereafter limit
or exclude up to all of the Registrable Securities to be included in such
registration. The foregoing sentence notwithstanding, following the first such
registration, the managing underwriter may limit the number of shares to be
underwritten to not less than thirty percent (30%) of the shares included in the
registration even if as a result the numbers of shares of securities offered by
the Company is reduced. The Company shall so advise all Holders and other
holders distributing their securities through such underwriting and the number
of shares of Registrable Securities that may be included in the registration and
underwriting shall be allocated first among all Holders and thereafter to other
holders, all such allocations being made in proportion, as nearly as
practicable, to the respective amounts of Registrable Securities and Common
Stock held by such Holders and other holders at the time of filing the
registration statement. To facilitate the allocation of shares in accordance
with the above provisions, the Company may round the number of shares allocated
to any Holder or holder to the nearest 100 shares.

     If any Holder or holder disapproves of the terms of any such underwriting,
he or she may elect to withdraw therefrom by written notice to the Company and
the managing underwriter. Any securities excluded or withdrawn from such
underwriting shall be withdrawn from such registration, and shall not be
transferred in a public distribution prior to (i) 180 days after the effective
date of the initial registration of the Company's securities, (ii) 90 days after
the effective date of any subsequent registration, or (iii) such other shorter
period of time as the underwriters may require.

                                                                             -5-
<PAGE>

          (c)  Right to Terminate Registration. The Company shall have the right
               -------------------------------
to terminate or withdraw any registration initiated by it under this Section 1.4
prior to the effectiveness of such registration whether or not any Holder has
elected to include securities in such registration.

     1.5  Registration on Form S-3.
          ------------------------

          (a)  If any Holder or Holders request that the Company file a
registration statement on Form S-3 (or any successor form to Form S-3) for a
public offering of shares of the Registrable Securities, the reasonably
anticipated aggregate price to the public of which would exceed $2,000,000, and
the Company is a registrant entitled to use Form S-3 to register the Registrable
Securities for such an offering, the Company shall use its best efforts to cause
such Registrable Securities to be registered for the offering on such form;
provided, however, that the Company shall not be required to effect more than
two registrations pursuant to this Section 1.5 in any 12-month period. The
Company will (i) promptly give written notice of the proposed registration to
all other Holders and (ii) as soon as practicable but in any event within ninety
(90) days, use its best efforts to file a registration statement with respect to
such Registrable Securities to effect such registration (including, without
limitation, the execution of an undertaking to file post-effective amendments,
appropriate qualification under applicable blue sky or other state securities
laws and appropriate compliance with applicable regulations issued under the
Securities Act and any other governmental requirements or regulations) as may be
so requested and as would permit or facilitate the sale and distribution of all
or such portion of such Registrable Securities as are specified in such request,
together with all or such portion of the Registrable Securities of any Holder of
Holders joining in such request as are specified in a written request received
by the Company within 20 days after receipt of such written notice from the
Company. The substantive provisions of Section 1.3(b) shall be applicable to
each registration initiated under this Section 1.5.

          (b)  Notwithstanding the foregoing, the Company shall not be obligated
to take any action pursuant to this Section 1.5 (i) if the Company, within ten
days of the receipt of the request of the Holders, gives notice of its bona fide
intention to effect the filing of a registration statement with the Commission
within 90 days of receipt of such request (other than with respect to a
registration statement relating to a Rule 145 transaction or an offering solely
to employees); (ii) within six months after the effective date of a registration
statement relating to an underwritten public offering of the Company's
securities filed under the Securities Act or (iii) if the Company shall furnish
to such Holder a certificate signed by the President of the Company stating that
in the good faith judgment of the Board of Directors it would be seriously
detrimental to the Company or its shareholders for registration statements to be
filed in the near future, then the Company's obligation to use its best efforts
to file a registration statement shall be deferred for a period not to exceed
180 days from the receipt of the request to file such registration by such
Holder; provided, however, that the Company will not exercise such right more
than once in any twelve month period.

     1.6  Limitations on Subsequent Registration Rights. From and after the
          ---------------------------------------------
Closing Date, the Company shall not enter into any agreement granting any holder
or prospective holder of any securities of the Company registration rights with
respect to such securities unless (i) such new registration rights, including
standoff obligations, are on a pari passu basis with those rights of the Holders
hereunder or (ii) such new registration rights, including standoff obligations,
are subordinate to the registration rights granted Holders hereunder.

                                                                             -6-
<PAGE>

     1.7  Expenses of Registration.
          ------------------------

          (a)  All Registration Expenses incurred in connection with all
registrations pursuant to Sections 1.3 and 1.4 and three registrations under
Section 1.5 shall be borne by the Company. Unless otherwise stated, all Selling
Expenses relating to securities registered on behalf of the Holders and all
other Registration Expenses shall be borne by the Holders of such securities pro
rata on the basis of the number of shares so registered.

          (b)  All Registration Expenses and Selling Expenses incurred in
connection with more than three registrations pursuant to Section 1.5 shall be
borne pro rata by the Holder or Holders requesting such additional registration
on Form S-3 according to the number of Registrable Securities included in such
registration.

          (c)  The Company shall not be required to pay for expenses of any
registration proceeding begun pursuant to Section 1.3, the request for which is
subsequently withdrawn by the Initiating Holders for reasons other than a
material adverse change in the business or financial condition of the Company
occurring prior to the effectiveness of such registration statement, in which
case, such expenses shall be borne by the Holders of Registrable Securities
requesting such withdrawal, pro rata on the basis of the number of shares of
Registrable Securities so included in the registration request unless the
Holders of a majority of Registrable Securities agree to forfeit their right to
one requested registration pursuant to Section 1.3 in which event such right
shall be forfeited by all Holders. Notwithstanding the foregoing, however, if at
the time of the withdrawal, the Holders have learned of a material adverse
change in the condition, business or prospects of the Company from that known to
the Holders at the time of their request, of which the Company had knowledge at
the time of the request, then the Holders shall not be required to pay any of
said Registration Expenses or to forfeit the right to one demand registration.

     1.8  Obligations of the Company.  Whenever required under this Section 1 to
          --------------------------
effect the registration of any Registrable Securities, the Company shall, as
expeditiously as reasonably possible:

          (a)  Prepare and file with the Commission a registration statement
with respect to such Registrable Securities and use its diligent best efforts to
cause such registration statement to become effective, and, upon the request of
the Holders of a majority of the Registrable Securities registered thereunder,
keep such registration statement effective for up to 90 days or until the Holder
or Holders have completed the distribution relating thereto.

          (b)  Prepare and file with the Commission such amendments and
supplements to such registration statement as may be necessary to comply with
the provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement.

          (c)  Furnish to the Holders such numbers of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the
Securities Act, and such other documents as they may reasonably request in order
to facilitate the disposition of Registrable Securities owned by them.

                                                                             -7-
<PAGE>

          (d)  Use its best efforts to register and qualify the securities
covered by such registration statement under such other securities or blue sky
laws of such jurisdictions as shall be reasonably requested by the Holders,
provided that the Company shall not be required in connection therewith or as a
condition thereto to qualify to do business or to file a general consent to
service of process in any such states or jurisdictions.

          (e)  In the event of any underwritten public offering, enter into and
perform its obligations under an underwriting agreement, in usual and customary
form, with the managing underwriter of such offering. Each Holder participating
in such underwriting shall also enter into and perform its obligations under
such an agreement.

          (f)  Notify each Holder of Registrable Securities covered by such
registration statement at any time when a prospectus relating thereto is
required to be delivered under the Securities Act of the happening of any event
as a result of which the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing.

     1.9  Indemnification.
          ---------------

          (a)  To the extent permitted by law, the Company will indemnify each
Holder, each of its officers, directors, partners and affiliates, and each
person controlling such Holder, within the meaning of Section 15 of the
Securities Act, with respect to which registration, qualification or compliance
has been effected pursuant to this Agreement, and each underwriter, if any, and
each person who controls any underwriter within the meaning of Section 15 of the
Securities Act, against all expenses, claims, losses, damages or liabilities (or
actions in respect thereof), including any of the foregoing incurred in
settlement of any litigation, commenced or threatened, arising out of or based
on any untrue statement (or alleged untrue statement) of a material fact
contained in any registration statement, prospectus, offering circular or other
document, or any amendment or supplement thereto, incident to any such
registration, qualification or compliance, or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein, in light of the circumstances in which
they were made, not misleading, or any violation by the Company of any federal,
state or common law rule or regulation applicable to the Company in connection
with any such registration, qualification or compliance, and the Company will
reimburse each such Holder, each of its officers, directors and affiliates, and
each person controlling such Holder, each such underwriter and each person who
controls any such underwriter, for any legal and any other expenses reasonably
incurred in connection with investigating, preparing or defending any such
claim, loss, damage, liability or action, as such expenses are incurred,
provided that the Company will not be liable in any such case to the extent that
any such claim, loss, damage, liability or expense arises out of or is based on
any untrue statement or omission or alleged untrue statement or omission, made
in reliance upon and in conformity with written information furnished to the
Company by an instrument duly executed by such Holder, controlling person or
underwriter and stated to be specifically for use therein.

          (b)  To the extent permitted by law, each Holder will, if Registrable
Securities held by such Holder are included in the securities as to which such
registration, qualification or

                                                                             -8-
<PAGE>

compliance is being effected, indemnify the Company, each of its directors and
officers, each underwriter, if any, of the Company's securities covered by such
a registration statement, each person who controls the Company or such
underwriter within the meaning of Section 15 of the Securities Act, and each
other such Holder, each of its officers and directors and each person
controlling such Holder within the meaning of Section 15 of the Securities Act,
against all claims, losses, damages and liabilities (or actions in respect
thereof) arising out of or based on any untrue statement (or alleged untrue
statement) of a material fact contained in any such registration statement,
prospectus, offering circular or other document, or any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, and will reimburse the
Company, such Holders, such directors, officers, persons, underwriters or
control persons for any legal or any other expenses reasonably incurred in
connection with investigating or defending any such claim, loss, damage,
liability or action, as such expenses are incurred, in each case to the extent,
but only to the extent, that such untrue statement (or alleged untrue statement)
or omission (or alleged omission) is made in such registration statement,
prospectus, offering circular or other document in reliance upon and in
conformity with written information furnished to the Company by an instrument
duly executed by such Holder and stated to be specifically for use therein.
Notwithstanding the foregoing, the liability of each Holder under this
subsection (b) shall be limited in an amount equal to the public offering price
of the shares sold by such Holder.

          (c)  Each party entitled to indemnification under this Section 1.9
(the "Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom, provided that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or litigation, shall be
approved by the Indemnified Party (whose approval shall not unreasonably be
withheld), and the Indemnified Party may participate in such defense at such
party's expense, and provided further that the failure of any Indemnified Party
to give notice as provided herein shall not relieve the Indemnifying Party of
its obligations under this Section 1.9 unless the failure to give such notice is
materially prejudicial to an Indemnifying Party's ability to defend such action
and provided further, that the Indemnifying Party shall not assume the defense
for matters as to which there is a conflict of interest or separate and
different defenses. No Indemnifying Party, in the defense of any such claim or
litigation, shall, except with the consent of each Indemnified Party, consent to
entry of any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation. No Indemnified Party shall consent to entry of any judgment or enter
into any settlement without the consent of each Indemnifying Party, which
consent shall not be unreasonable withheld.

          (d)  If the indemnification provided for in this Section 1.9 is held
by a court of competent jurisdiction to be unavailable to an indemnified party
with respect to any loss, liability, claim, damage, or expense referred to
therein, then the indemnifying party, in lieu of indemnifying such indemnified
party hereunder, shall contribute to the amount paid or payable by such
indemnified party as a result of such loss, liability, claim, damage, or expense
in such proportion as is appropriate to reflect the relative fault of the
indemnifying party on the one hand and of the indemnified party on the other in
connection with the statements or omissions that resulted in such

                                                                             -9-
<PAGE>

loss, liability, claim, damage, or expense as well as any other relevant
equitable considerations. The relative fault of the indemnifying party and of
the indemnified party shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission or alleged to state a material fact relates to information supplied by
the indemnifying party or by the indemnified party and the parties' relative
intent, knowledge, access to information, and opportunity to correct or prevent
such statement or omission.

          (e)  Notwithstanding the foregoing, to the extent that the provisions
on indemnification and contribution contained in the underwriting agreement
entered into in connection with the underwritten public offering are in conflict
with the foregoing provisions, the provisions in the underwriting agreement
shall control.

     1.10  Information by Holder. The Holder or Holders of Registrable
           ---------------------
Securities included in any registration shall furnish to the Company such
information regarding such Holder or Holders, the Registrable Securities held by
them and the distribution proposed by such Holder or Holders as the Company may
reasonably request in writing and as shall be reasonably required in connection
with any registration, qualification or compliance referred to in this Section
1.

     1.11  Rule 144 Reporting.  With a view to making available the benefits of
           ------------------
certain rules and regulations of the Commission which may at any time permit the
sale of the Restricted Securities to the public without registration, after such
time as a public market exists for the Common Stock of the Company, the Company
agrees to use its best efforts to:

          (a)  Make and keep public information available, as those terms are
understood and defined in Rule 144 under the Securities Act, at all times after
the effective date that the Company becomes subject to the reporting
requirements of the Securities Act or the Securities Exchange Act of 1934, as
amended.

          (b)  File with the Commission in a timely manner all reports and other
documents required of the Company under the Securities Act and the Securities
Exchange Act of 1934, as amended (at any time after it has become subject to
such reporting requirements).

          (c)  So long as a Holder owns any Restricted Securities, to furnish to
the Holder forthwith upon request a written statement by the Company as to its
compliance with the reporting requirements of said Rule 144 (at any time after
90 days after the effective date of the first registration statement filed by
the Company for an offering of its securities to the general public), and of the
Securities Act and the Securities Exchange Act of 1934 (at any time after it has
become subject to such reporting requirements), a copy of the most recent annual
or quarterly report of the Company, and such other reports and documents of the
Company and other information in the possession of or reasonably obtainable by
the Company as a Holder may reasonably request in availing itself of any rule or
regulation of the Commission allowing a Holder to sell any such securities
without registration.

     1.12  Transfer of Registration Rights.  The rights to cause the Company to
           -------------------------------
register securities granted Holders under Sections 1.3, and 1.4 and 1.5 may be
assigned to a transferee or assignee reasonably acceptable to the Company in
connection with any transfer or assignment of

                                                                            -10-
<PAGE>

Registrable Securities by a Holder provided that: (i) such transfer may
otherwise be effected in accordance with applicable securities laws and (ii)
such assignee or transferee acquires at least 100,000 shares of Registrable
Securities (or if less, all of such shares held by such Holder) (appropriately
adjusted for stock splits, combinations, recapitalizations and the like).
Notwithstanding the foregoing, the rights to cause the Company to register
securities may be assigned to any constituent partner, or retired partner, or to
the estate of any of the partners or retired partners of a Holder identified as
a partnership herein without compliance with item (ii) above, provided written
notice thereof is promptly given to the Company.

     1.13  Standoff Agreement. Each Holder agrees in connection with the initial
           ------------------
registration of the Company's securities that, upon request of the Company or
the underwriters managing any underwritten initial public offering of the
Company's securities, not to sell, make any short sale of, loan, grant any
option for the purchase of, or otherwise dispose of any Registrable Securities
(other than those included in the registration) without the prior written
consent of the Company or such underwriters, as the case may be, for such period
of time (not to exceed 180 days) from the effective date of such registration as
may be reasonably requested by the underwriters, provided that the officers and
directors of the Company who own securities of the Company also agree to such
restrictions. Each Holder further agrees that in connection with any subsequent
registrations of the Company's securities that follow the initial registration,
upon request of the Company, or the underwriters managing such underwritten
public offerings of the Company's securities, not to sell, make any short sale
of, loan, grant any option for the purchase of, or otherwise dispose of any,
Registrable Securities (other than those included in the registration) without
the prior written consent of the Company or such underwriters, as the case may
be, for such period of time (not to exceed 90 days) from the effective date of
such registrations as may be reasonably requested by the underwriters, provided
that the officers and directors of the Company who own securities of the
Company, also agree to such restrictions. The shares held by all constituent
partners of any entity holding registration rights hereunder shall be bound by
this standoff agreement.

     1.14  Holders Who May Sell.  The rights to cause the Company to register
           --------------------
securities granted to Holders under Sections 1.3, 1.4 and 1.5 shall terminate
with regard to any Holders who can sell all of their shares under Rule 144
(excluding 144A) within a three month period.

                                  SECTION 2.

                                 Miscellaneous

     2.1   Governing Law. This Agreement shall be governed in all respects by
           -------------
the internal laws of the State of California.


     2.2   Successors and Assigns.  Except as otherwise provided herein, the
           ----------------------
provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, heirs, executors and administrators of the parties hereto.

     2.3   Entire Agreement; Amendment. This Agreement and the Purchase
           ---------------------------
Agreement constitute the full and entire understanding and agreement between the
parties with regard to the subjects hereof and thereof, and no party shall be
liable or bound to any other party in any manner by

                                                                            -11-
<PAGE>

any warranties, representations or covenants except as specifically set forth
herein or therein. Except as expressly provided herein, neither this Agreement
nor any term hereof may be amended, waived, discharged or terminated other than
by a written instrument signed by the party against whom enforcement of any such
amendment, waiver, discharge or termination is sought; provided, however, that
holders of a majority of the Preferred Shares and the holders of a majority of
the shares held by the Founders may, with the Company's prior written consent,
waive, modify or amend on behalf of all holders, any provisions hereof.

     2.4  Effect of Amendment or Waiver. The Purchasers and their successors and
          -----------------------------
assigns acknowledge that by the operation of Section 2.3 of this Agreement and
the holders of a majority of the outstanding Preferred Shares and the holders of
a majority of the outstanding shares held by the Founders, acting in conjunction
with the Company, will have the right and power to diminish or eliminate any or
all rights or increase any or all obligations pursuant to this Agreement.

     2.5  Rights of Holders. Each holder of Registrable Securities shall have
          -----------------
the absolute right to exercise or refrain from exercising any right or rights
that such holder may have by reason of this Agreement, including, without
limitation the right to consent to the waiver or modification of any obligation
under this Agreement, and such holder shall not incur any liability to any other
holder of any securities of the Company as a result of exercising or refraining
from exercising any such right or rights.

     2.6  Delays or Omissions. No delay or omission to exercise any right, power
          -------------------
or remedy accruing to any party to this Agreement, upon any breach or default of
the other party, shall impair any such right, power or remedy of such non-
breaching party nor shall it be construed to be a waiver of any such breach or
default, or an acquiescence therein, or of or is any similar breach as default
thereafter accruing; nor shall any waiver of any single breach or default be
deemed a waiver of any other breach or default theretofore or thereafter
occurring. Any waiver, permit, consent or approval of any kind as character on
the part of any party of any breach or default under this Agreement, or any
waiver on the part of any party of any provisions or conditions of this
Agreement, must be made in writing and shall be effective only to the extent
specifically set forth in such writing. All remedies, either under this
Agreement, or by law or otherwise afforded to any holder, shall be cumulative
and not alternative.

     2.7  Notices, etc. All notices and other communications required or
          ------------
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, or otherwise delivered by hand or by messenger,
addressed (a) if to any holder of any Registrable Securities, at such address as
such holder shall have furnished the Company in writing, or, until any such
holder so furnishes an address to the Company, then to and at the address of the
last holder of such shares who has so furnished an address to the Company or (b)
if to the Company, one copy should be sent to its address set forth above and
addressed to the attention of the Corporate Secretary, or at such other address
as the Company shall have furnished to the holders.

     Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when delivered if
delivered personally or by messenger, or, if sent by mail, at the earlier of its
receipt or 72 hours after the same has been deposited in a regularly maintained
receptacle for the deposit of the United States mail, addressed and mailed as
aforesaid.

                                                                            -12-
<PAGE>

     2.8  Counterparts.  This Agreement may be executed in any number of
          ------------
counterparts, each of which may be executed by less than all parties to this
Agreement, each of which shall be enforceable against the parties actually
executing such counterparts, and all of which together shall constitute one
instrument.

     2.9  Severability. In the event that any provision of this Agreement
          ------------
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision.

     2.10 Titles and Subtitles. The titles and subtitles used in this Agreement
          --------------------
are used for convenience only and are not considered in construing or
interpreting this Agreement.

                                                                            -13-
<PAGE>

     The foregoing agreement is hereby executed as of the date first above
written.

                                    "COMPANY"

                                    Synplicity, Inc.,
                                    a California corporation

                                    By: /s/ Bernard Aronson
                                       ----------------------------------------

                                    Title: President
                                          -------------------------------------

"EXISTING SHAREHOLDERS"             /s/ Andreas Bechtolsheim
                                    -------------------------------------------
                                    Andreas Bechtolsheim

                                    /s/ Prahbu Goel
                                    -------------------------------------------
                                    The Goel Family Partnership

                                    /s/ Prahbu Goel
                                    -------------------------------------------
                                    Prabhu Goel as custodian of Pooneet Goel

                                    /s/ Prahbu Goel
                                    -------------------------------------------
                                    Prabhu Goel as custodian for Priyanka Goel

                                    /s/ Kenneth McElvain
                                    -------------------------------------------
                                    Kenneth McElvain

                                    /s/ Alisa Yaffa
                                    -------------------------------------------
                                    Alisa Yaffa

                                    /s/ Kevin Hall
                                    -------------------------------------------
                                    Norwest Venture Partners VII, L.L.P.
                                    ____________, as General Partner

                                    /s/ Kevin Hall
                                    -------------------------------------------
                                    Kevin G. Hall, Trustee of Kevin G. Hall
                                    Revocable Trust - 1998


<PAGE>

                                    /s/ Sam Baker
                                    -------------------------------------------
                                    Pilgrim Baxter Hybrid Partners I, L.P.
                                    ____________, as General Partner

                                    /s/ Markus von Bechtolsheim
                                    -------------------------------------------
                                    Markus von Bechtolsheim

                                        /s/ Andreas Bechtolsheim
"PURCHASERS"                        By:----------------------------------------
                                       Andreas Bechtolsheim

                                        /s/ Bruce R. Katz
                                    By:----------------------------------------
                                       Bruce R. Katz


                                    XILINX, INC.

                                        /s/ [ILLEGIBLE]
                                    By:----------------------------------------

                                            Chief Financial Officer
                                    Title:-------------------------------------

                                    COMDISCO, INC.

                                        /s/ [ILLEGIBLE]
                                    By:----------------------------------------

                                           Senior Vice President
                                    Title:-------------------------------------

                                    NORWEST VENTURE PARTNERS VII, L.L.P.

                                    By:  Itasca VC Partners VII, L.L.P.
                                         Its General Partner

                                         /s/ Kevin Hall
                                    By:________________________________________
                                         General Partner

                                      -2-

<PAGE>

                                    KEVIN HALL FAMILY PARTNERS, A CALIFORNIA
                                    LIMITED PARTNERSHIP


                                         /s/ Kevin G. Hall
                                    By:----------------------------------------
                                         Kevin G. Hall

                                    THE GOEL FAMILY PARTNERSHIP

                                         /s/ Prahbu Goel
                                    By:----------------------------------------
                                         General Partner

                                    PILGRIM BAXTER HYBRID PARTNERS I, L.P.

                                         /s/ Sam Baker
                                    By:----------------------------------------
                                         General Partner

                                                                             -3-
<PAGE>

                                    EXHIBIT A

                             EXISTING SHAREHOLDERS


     Andreas Bechtolsheim
     The Goel Family Partnership
     Prabhu Goel as custodian for Pooneet Goel
     Prabhu Goel as custodian for Priyanka Goel
     Kenneth McElvain
     Alisa Yaffa
     Norwest Venture Partners VII, L.L.P
     Kevin G. Hall Revocable Trust - 1998
     Pilgrim Baxter Hybrid Partners I, L.P.
     Markus von Bechtolsheim


<PAGE>

                                   EXHIBIT B

                                  PURCHASERS

     Andreas Bechtolsheim
     Bruce R. Katz
     Xilinx, Inc.
     Comdisco, Inc.
     Norwest Venture Partners VII, L.L.P
     Kevin Hall Family Partners, a California limited partnership
     The Goel Family Partnership
     Pilgrim Baxter Hybrid Partners I, L.P.