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                         PATRIOT SCIENTIFIC CORPORATION




                                  FORM 10Q-SB/A
                       Amendment No. 1 to Quarterly Report



                                EXHIBIT NO. 4.15


                          Registration Rights Agreement


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                          REGISTRATION RIGHTS AGREEMENT

      THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is entered into as of
February 24, 1999, by and among Patriot Scientific Corporation, a corporation
duly incorporated and existing under the laws of the State of Delaware (the
"Company") and the subscriber as named on the signature page hereto (hereinafter
referred to as "Subscriber").

                                    RECITALS:

      WHEREAS, pursuant to the Company's offering ("Offering") of up to Five
      Million Dollars ($5,000,000), excluding any funds paid upon exercise of
      the Warrants, of Common Stock of the Company pursuant to that certain
      Regulation D Common Stock Investment Agreement of even date herewith (the
      "Investment Agreement") between the Company and the Subscriber, the
      Company has agreed to sell and the Subscriber has agreed to purchase, from
      time to time as provided in the Investment Agreement, shares of the
      Company's Common Stock for a maximum aggregate offering amount of Five
      Million Dollars ($5,000,000);

      WHEREAS, pursuant to the terms of the Investment Agreement, the Company
      has agreed to issue to the Subscriber, from time to time, Purchase
      Warrants, as defined in the Investment Agreement, to purchase a number of
      shares of Common Stock, exercisable for five years from the date of
      issuance (collectively, the "Subscriber Warrants" or the "Warrants"); and

      WHEREAS, pursuant to the terms of the Investment Agreement, the Company
      has agreed to provide the Subscriber with certain registration rights with
      respect to the Common Stock to be issued in the Offering and the Common
      Stock issuable upon exercise of the Subscriber Warrants as set forth in
      this Registration Rights Agreement.

                                     TERMS:

      NOW, THEREFORE, in consideration of the mutual promises, representations,
warranties, covenants and conditions set forth in this Agreement and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

      1.    Certain Definitions. As used in this Agreement (including the
Recitals above), the following terms shall have the following meanings (such
meanings to be equally applicable to both singular and plural forms of the terms
defined):

            "1934 Act" shall mean the Securities Exchange Act of 1934, as
amended, together with the rules and regulations promulgated thereunder.

            "Additional Registration Statement" shall have the meaning set forth
in Section 3(b).

            "Agreement" shall have the meaning set forth in the preamble hereto.

            "Amended Registration Statement" shall have the meaning set forth in
Section 3(b).

            "Business Day" shall have the meaning set forth in the Investment
Agreement.


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            "Closing Bid Price" shall have the meaning set forth in the
Investment Agreement.

            "Common Stock" shall mean the common stock, par value $0.00001, of
the Company.

            "Company" shall have the meaning set forth in the preamble hereto.

            "Due Date" shall mean the date that is one hundred twenty (120) days
after the date of this Agreement.

            "Effective Date" shall have the meaning set forth in Section 2.4.

            "Filing Date" shall mean the date that is forty five (45) days after
the date of this Agreement.

            "Holder" shall mean Subscriber, and any other person or entity
owning or having the right to acquire Registrable Securities or any permitted
assignee thereof.

            "Investment Agreement" shall have the meaning set forth in the
Recitals hereto.

            "Offering" shall have the meaning set forth in the recitals hereto.

            "Put" shall have the meaning as set forth in the Investment
Agreement.

            "Register," "Registered," and "Registration" shall mean and refer to
a registration effected by preparing and filing a registration statement or
similar document in compliance with the Securities Act of 1933, as amended (the
"Act"), and pursuant to Rule 415 under the Act or any successor rule, and the
declaration or ordering of effectiveness of such registration statement or
document;

            "Registrable Securities" shall have the meaning set forth in Section
2.1.

            "Registration Period" shall have the meaning set forth in Section
2.7.

            "Registration Statement" shall have the meaning set forth in Section
2.2.

            "Rule 144" shall mean Rule 144, as amended, promulgated under the
Act.

            "SEC" shall have the meaning set forth in Section 3(a).

            "Subscriber" shall have the meaning set forth in the preamble to
this Agreement.

            "Subscriber Warrants" shall have the meaning set forth in the above
Recitals.

            "Supplemental Registration Statement" shall have the meaning set
forth in Section 3(b).


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            "Warrants" shall have the meaning set forth in the above Recitals.


            "Warrant Shares" shall mean shares of Common Stock issuable upon
exercise of any Warrant.

      2.    Required Registration.

            2.1   Registrable Securities. "Registrable Securities" shall mean
those shares of the Common Stock of the Company together with any capital stock
issued in replacement of, in exchange for or otherwise in respect of such Common
Stock, that are: (i) issuable or issued to the Subscriber pursuant to the
Investment Agreement or in this Agreement, and (ii) issuable or issued upon
exercise of the Subscriber Warrants; provided, however, that notwithstanding the
above, the following shall not be considered Registrable Securities:

                  (a)   any Common Stock which would otherwise be deemed to be
Registrable Securities, if and to the extent that those shares of Common Stock
may be resold in a public transaction without volume limitations or other
material restrictions without registration under the Act, including without
limitation, pursuant to Rule 144 under the Act; and

                  (b)   any shares of Common Stock which have been sold in a
private transaction in which the transferor's rights under this Agreement are
not assigned.

            2.2   Filing of Initial Registration Statement. The Company shall,
by the Filing Date, file a registration statement ("Registration Statement") on
Form SB-2 (or other suitable form, at the Company's discretion, but subject to
the reasonable approval of Subscriber), covering the resale of a number of
shares of Common Stock as Registrable Securities equal to at least Twelve
Million (12,000,000) shares of Common Stock, and shall cover, to the extent
allowed by applicable law, such additional shares of Common Stock, if any, that
may become registrable pursuant to Rule 416 of the Act.

            2.3   [Intentionally Left Blank].

            2.4   Registration Effective Date. The Company shall use its best
efforts to have the Registration Statement declared effective by the SEC (the
date of such effectiveness is referred to herein as the "Effective Date") by the
Due Date.

            2.5   [Intentionally Left Blank].

            2.6   [Intentionally Left Blank].

            2.7   Shelf Registration. The Registration Statement shall be
prepared as a "shelf" registration statement under Rule 415, and shall be
maintained effective until the earlier of (i) the date that is one (1) year from
the Termination Date, as defined in the Investment Agreement (the "Registration
Period") or (ii) the date that all Registrable Securities are resold pursuant to
such 


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Registration Statement.

            2.8   Eligibility for Form SB-2. The Company understands that in
order to file the resale Registration Statement described herein on Form SB-2,
it must be eligible to file Form S-B2 for primary offerings. The Company
represents that it is presently eligible to effect the registration contemplated
hereby on Form SB-2 and will use its best efforts to continue to take such
actions as are necessary to maintain such eligibility. The Company covenants to
use its best efforts to use Form SB-2 (or other suitable form, at the Company's
discretion, but subject to the reasonable approval of the Holders) for the
registration required by this Section during all applicable times contemplated
by this Agreement.

            2.9   Supplemental Registration Statement. Anytime the Registration
Statement does not cover a sufficient number of shares of Common Stock to cover
all outstanding Registrable Securities, the Company shall promptly prepare and
file with the SEC such Supplemental Registration Statement and the prospectus
used in connection with such registration statement as may be necessary to
comply with the provisions of the Act with respect to the disposition of all
such Registrable Securities and shall use its best efforts to cause such
Supplemental Registration Statement to be declared effective as soon as
possible.

      3.    Obligations of the Company. Whenever required under this Agreement
to effect the registration of any Registrable Securities, the Company shall, as
expeditiously and reasonably possible:

                  (a)   Prepare and file with the Securities and Exchange
Commission ("SEC") a Registration Statement with respect to such Registrable
Securities and use its best efforts to cause such Registration Statement to
become effective and to remain effective during the Registration Period.

                  (b)   Prepare and file with the SEC such amendments and
supplements to such Registration Statement and the prospectus used in connection
with such Registration Statement ("Amended Registration Statement") or prepare
and file any additional registration statement ("Additional Registration
Statement," together with the Amended Registration Statement, "Supplemental
Registration Statements") as may be necessary to comply with the provisions of
the Act with respect to the disposition of all securities covered by such
Supplemental Registration Statements or such prior registration statement and to
cover the resale of all Registrable Securities.

                  (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.

                  (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 the jurisdictions in which the Holders are located and of such
other jurisdictions as shall be reasonably requested by the Holders of the
Registrable Securities covered by such Registration Statement, provided that the
Company shall 


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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)   [Intentionally Omitted].

                  (f)   As promptly as practicable after becoming aware of such
event, notify each Holder of Registrable Securities of the happening of any
event of which the Company has knowledge, as a result of which the prospectus
included in the 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, in light of the
circumstances under which they were made, not misleading, use its best efforts
promptly to prepare a supplement or amendment to the Registration Statement to
correct such untrue statement or omission, and deliver a number of copies of
such supplement or amendment to each Holder as such Holder may reasonably
request.

                  (g) Provide Holders with notice of the date that a
Registration Statement or any Supplemental Registration Statement registering
the resale of the Registrable Securities is declared effective by the SEC, and
the date or dates when the Registration Statement is no longer effective.

                  (h) Provide Holders and their representatives the opportunity
and a reasonable amount of time, based upon reasonable notice delivered by the
Company, to conduct a reasonable due diligence inquiry of Company's pertinent
financial and other records and make available its officers and directors for
questions regarding such information as it relates to information contained in
the Registration Statement.

                  (i) Provide Holders and their representatives the opportunity
to review the Registration Statement and all amendments or supplements thereto
prior to their filing with the SEC by giving the Holder at least ten (10)
business days advance written prior to such filing.

                  (j) Provide each Holder with prompt notice of the issuance by
the SEC or any state securities commission or agency of any stop order
suspending the effectiveness of the Registration Statement or the initiation of
any proceeding for such purpose. The Company shall use its best efforts to
prevent the issuance of any stop order and, if any is issued, to obtain the
removal thereof at the earliest possible date.

                  (k) Use its best efforts to list the Registrable Securities
covered by the Registration Statement with all securities exchanges or markets
on which the Common Stock is then listed and prepare and file any required
filing with the NASD and any other exchange or market on which the Common Stock
is listed.

      4.    [Intentionally Left Blank].

      5.    [Intentionally Left Blank].

      6.    Dispute as to Registrable Securities. In the event the Company
believes that shares sought to be registered under Section 2 by Holders do not
constitute "Registrable Securities" by virtue of Section 2.1 of this Agreement,
and the status of those shares as Registrable Securities is 


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disputed, the Company shall provide, at its expense, an Opinion of Counsel,
reasonably acceptable to the Holders of the Securities at issue (and
satisfactory to the Company's transfer agent to permit the sale and transfer),
that those securities may be sold immediately, without volume limitation or
other material restrictions, without registration under the Act, by virtue of
Rule 144 or similar provisions.

      7.    Furnish Information. At the Company's request, each Holder shall
furnish to the Company such information regarding Holder, the Registrable
Securities held by it, and the intended method of disposition of such securities
to the extent required to effect the registration of its Registrable Securities
or to determine that registration is not required pursuant to Rule 144 or other
applicable provision of the Act. The Company shall include all information
provided by such Holder pursuant hereto in the Registration Statement,
substantially in the form supplied, except to the extent such information is not
permitted by law.

      8.    Expenses. All expenses, other than commissions and fees and expenses
of counsel to the selling Holders, incurred in connection with registrations,
filings or qualifications pursuant hereto, including (without limitation) all
registration, filing and qualification fees, printers' and accounting fees, and
fees and disbursements of counsel for the Company, shall be borne by the
Company.

      9.    Indemnification. In the event any Registrable Securities are
included in a Registration Statement under this Agreement:

            (a)   To the extent permitted by law, the Company will indemnify and
      hold harmless each Holder, the officers, directors, partners, legal
      counsel, and accountants of each Holder, any underwriter (as defined in
      the Act, or as deemed by the Securities Exchange Commission, or as
      indicated in a registration statement) for such Holder and each person, if
      any, who controls such Holder or underwriter within the meaning of Section
      15 of the Act the 1934 Act, against any losses, claims, damages, or
      liabilities (joint or several) to which they may become subject under the
      Act, the 1934 Act or other federal or state law, insofar as such losses,
      claims, damages, or liabilities (or actions in respect thereof) arise out
      of or are based upon any of the following statements or omissions: (i) any
      untrue statement or alleged untrue statement of a material fact contained
      in such registration statement, including any preliminary prospectus or
      final prospectus contained therein or any amendments or supplements
      thereto, or (ii) the 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 the Company will reimburse each
      such Holder, officer or director, underwriter or controlling person for
      any legal or other expenses reasonably incurred by them in connection with
      investigating or defending any such loss, claim, damage, liability, or
      action; provided, however, that the indemnity agreement contained in this
      subsection 9(a) shall not apply to amounts paid in settlement of any such
      loss, claim, damage, liability, or action if such settlement is effected
      without the consent of the Company (which consent shall not be
      unreasonably withheld), nor shall the Company be liable in any such case
      for any such loss, claim, damage, liability, or action to the extent that
      it arises out of or is based upon a violation which occurs in reliance
      upon and in conformity with written information furnished expressly for
      use in connection with such registration by any such Holder, officer,
      director, underwriter or controlling person; provided however, that the
      above shall not relieve the 


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      Company from any other liabilities which it might otherwise have.

            (b)   Promptly after receipt by an indemnified party under this
      Section 9 of notice of the commencement of any action (including any
      governmental action), such indemnified party will, if a claim in respect
      thereof is to be made against any indemnifying party under this Section 9,
      deliver to the indemnifying party a written notice of the commencement
      thereof and the indemnifying party shall have the right to participate in,
      and, to the extent the indemnifying party so desires, jointly with any
      other indemnifying party similarly noticed, to assume, the defense thereof
      with counsel mutually satisfactory to the parties; provided, however, that
      an indemnified party shall have the right to retain its own counsel, with
      the reasonably incurred fees and expenses of one such counsel to be paid
      by the indemnifying party, if representation of such indemnified party by
      the counsel retained by the indemnifying party would be inappropriate due
      to actual or potential conflicting interests between such indemnified
      party and any other party represented by such counsel in such proceeding.
      The failure to deliver written notice to the indemnifying party within a
      reasonable time of the commencement of any such action, if materially
      prejudicial to its ability to defend such action, shall relieve such
      indemnifying party of any liability to the indemnified party under this
      Section 9, but the omission so to deliver written notice to the
      indemnifying party will not relieve it of any liability that it may have
      to any indemnified party otherwise than under this Section 9.

            (c)   In the event that the indemnity provided in paragraph (a) of
      this Section 9 is unavailable to or insufficient to hold harmless an
      indemnified party for any reason, the Company and each Holder agree to
      contribute to the aggregate claims, losses, damages and liabilities
      (including legal or other expenses reasonably incurred in connection with
      investigating or defending same) (collectively "Losses") to which the
      Company and one or more of the Holders may be subject in such proportion
      as is appropriate to reflect the relative fault of the Company and the
      Holders in connection with the statements or omissions which resulted in
      such Losses. Relative fault shall be determined by reference to whether
      any alleged untrue statement or omission relates to information provided
      by the Company or by the Holders. The Company and the Holders agree that
      it would not be just and equitable if contribution were determined by pro
      rata allocation or any other method of allocation that does not take
      account of the equitable considerations referred to above. Notwithstanding
      the provisions of this paragraph (d), no person guilty of fraudulent
      misrepresentation (within the meaning of Section 10(f) of the Securities
      Act) shall be entitled to contribution from any person who was not guilty
      of such fraudulent misrepresentation. For purposes of this Section 9, each
      person who controls a Holder of Registrable Securities within the meaning
      of either the Securities Act or the Exchange Act and each director,
      officer, partner, employee and agent of a Holder shall have the same
      rights to contribution as such holder, and each person who controls the
      Company within the meaning of either the Act or the Exchange Act and each
      director and officer of the Company shall have the same rights to
      contribution as the Company, subject in each case to the applicable terms
      and conditions of this paragraph (c).

            (d)   The obligations of the Company and Holders under this Section
      9 shall survive the resale, if any, of the Common Stock, the completion of
      any offering of Registrable Securities in a Registration Statement under
      this Agreement, and otherwise.

      10.   Reports Under Securities Exchange Act of 1934. With a view to making
available to the Holders the benefits of Rule 144 promulgated under the Act and
any other rule or regulation of 


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the SEC that may at any time permit a Holder to sell securities of the Company
to the public without registration, the Company agrees to:

            (a)   make and keep public information available, as those terms are
understood and defined in Rule 144; and

            (b)   use its best efforts to file with the SEC in a timely manner
all reports and other documents required of the Company under the Act and the
1934 Act.

      11.   Amendment of Registration Rights. Any provision of this Agreement
may be amended and the observance thereof may be waived (either generally or in
a particular instance and either retroactively or prospectively), only with the
written consent of the Company and the written consent of each Holder affected
thereby. Any amendment or waiver effected in accordance with this paragraph
shall be binding upon each Holder, each future Holder, and the Company.

      12.   Notices. All notices required or permitted under this Agreement
shall be made in writing signed by the party making the same, shall specify the
section under this Agreement pursuant to which it is given, and shall be
addressed if to (i) the Company at: Patriot Scientific Corporation, 10989 Via
Frontera, San Diego, CA 92127, Telephone No. (619) 674-5000, Facsimile No. (619)
674-5005 (or at such other location as directed by the Company in writing) and
(ii) the Holders at their respective last address as the party as shown on the
records of the Company. Any notice, except as otherwise provided in this
Agreement, shall be made by fax and shall be deemed given at the time of
transmission of the fax.

      13.   Termination. This Agreement shall terminate on the date all
Registrable Securities cease to exist (as that term is defined in Section 2.1
hereof); but without prejudice to (i) the parties' rights and obligations
arising from breaches of this Agreement occurring prior to such termination (ii)
other indemnification obligations under this Agreement.

      14.   Assignment. No assignment, transfer or delegation, whether by
operation of law or otherwise, of any rights or obligations under this Agreement
by the Company or any Holder, respectively, shall be made without the prior
written consent of the majority in interest of the Holders or the Company,
respectively; provided that the rights of a Holder may be transferred to a
subsequent holder of the Holder's Registrable Securities (provided such
transferee shall provide to the Company, together with or prior to such
transferee's request to have such Registrable Securities included in a
Registration, a writing executed by such transferee agreeing to be bound as a
Holder by the terms of this Agreement), and the Company hereby agrees to file an
amended or supplemented registration statement including such transferee as a
selling security holder thereunder; and provided further that the Company may
transfer its rights and obligations under this Agreement to a purchaser of all
or a substantial portion of its business if the obligations of the Company under
this Agreement are assumed in connection with such transfer, either by merger or
other operation of law (which may include without limitation a transaction
whereby the Registrable Securities are converted into securities of the
successor in interest) or by specific assumption executed by the transferee.

      15.   Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware applicable to agreements made
in and wholly to be performed 


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in that jurisdiction, except for matters arising under the Act or the Securities
Exchange Act of 1934, which matters shall be construed and interpreted in
accordance with such laws.

      16.   Execution in Counterparts Permitted. This Agreement may be executed
in any number of counterparts, each of which shall be enforceable against the
parties actually executing such counterparts, and all of which together shall
constitute one (1) instrument.

      17.   Specific Performance. The Holder shall be entitled to the remedy of
specific performance in the event of the Company's breach of this Agreement, the
parties agreeing that a remedy at law would be inadequate.

      18.   Indemnity. Each party shall indemnify each other party against any
and all claims, damages (including reasonable attorney's fees), and expenses
arising out of the first party's breach of any of the terms of this Agreement.

      19.   Entire Agreement; Written Amendments Required. This Agreement,
including the Exhibits attached hereto, the Investment Agreement, the Common
Stock certificates, and the other documents delivered pursuant hereto 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 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.

        IN WITNESS WHEREOF, the undersigned have executed this Agreement as of
this 24th day of February, 1999

                                PATRIOT SCIENTIFIC CORPORATION


                                By: /S/ LOWELL W. GIFFHORN
                                    --------------------------------------------
                                    Lowell W. Giffhorn, Chief Financial Officer


                                Address:  Patriot Scientific Corporation
                                          10989 Via Frontera
                                          San Diego, CA 92127

                                          Telephone No. (619) 674-5000 
                                          Facsimile No. (619) 674-5005


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                                SUBSCRIBER:
                                SWARTZ PRIVATE EQUITY, LLC.



                                By: ____________________________________________
                                    Eric S. Swartz, Manager


                                Address:  1080 Holcomb Bridge Road
                                          Bldg. 200, Suite 285
                                          Roswell, GA 30076
                                          Telephone: (770) 640-8130
                                          Facsimile: (770) 640-7150


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