<PAGE>   1
                                                                   EXHIBIT 10.24

                            SECURED PROMISSORY NOTE

$9,727.62                                                Santa Clara, California
                                                   Effective as of June 14, 2000


     FOR VALUE RECEIVED, the undersigned, _________________, an individual
("Borrower"), promises to pay to the order of SONICblue INCORPORATED (formerly
S3 Incorporated), a Delaware corporation (the "Corporation"), the principal sum
of nine thousand seven hundred twenty-seven dollars and sixty two cents
($9,727.62) payable on June 14, 2003, or such other later date as the parties
shall mutually agree (the "Maturity Date"). This Note shall bear interest from
the date hereof on the unpaid principal and accrued but unpaid interest at the
rate of six and fifty three-hundredths percent (6.53%) per annum, the aggregate
interest to be payable on the Maturity Date. From and after the Maturity Date,
or such earlier date of an Event of Default (as defined below), this Note shall
bear interest on the unpaid principal and accrued but unpaid interest at the
rate of six and fifty three-hundredths percent (6.53%) until paid in full.
Notwithstanding any provision of this Note, it is the intent and agreement of
the parties that in the event any interest specified herein is found to violate
any applicable law or regulation, this Note shall be construed or deemed amended
so that the interest is reduced to the extent necessary to comply with such
applicable law or regulation.

     The obligations hereunder shall be non-recourse to the Borrower and the
Corporation's sole recourse upon an Event of Default (as defined herein) shall
be to act on the 24,380 shares of Common Stock of RioPort, Inc., a Delaware
corporation ("RioPort"), pledged pursuant to a Security Agreement of even date
herewith which is on filed with the Secretary of the Corporation.

     The occurrence of any of the following shall constitute an "Event of
Default" under this Note: (i) Borrower shall fail to pay when due any principal
or other amounts payable under this Note; (ii) Borrower shall suffer or consent
to or apply for the appointment of a receiver, trustee, custodian or liquidator
of itself or any of its property; Borrower shall file a voluntary petition in
bankruptcy, or seeking reorganization, in order to effect a plan or other
arrangement with creditors or any other relief under the Bankruptcy Reform Act,
Title 11 of the United States Code, as amended or recodified from time to time
(the "Bankruptcy Code"), or under any state or federal law granting relief to
debtors, whether now or hereafter in effect; or any involuntary petition or
proceeding pursuant to the Bankruptcy Code or any other applicable state or
federal law relating to bankruptcy, reorganization or other relief for debtors
is filed or commenced against Borrower; or (iii) Borrower is no longer a member
of the Board of Directors of the Corporation. Upon the occurrence of any Event
of Default under this Note (and if such Event of Default shall not have been
cured, waived or postponed pursuant to a written agreement entered into between
Borrower and the Corporation within thirty (30) days after (x) written notice of
such Event of Default from either Borrower or the Corporation to the other party
with respect to an Event of Default pursuant to subsection (i) of this paragraph
or (y) the date of occurrence of an Event of Default pursuant to subsection (ii)
or (iii) of this paragraph), (a) all indebtedness of Borrower under this Note,
any term hereof to the contrary notwithstanding, shall at the Corporation's
option become immediately due and payable without presentment, demand,


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protest or notice of dishonor, all of which are expressly waived by Borrower and
(b) the Corporation shall have all rights, powers and remedies available under
each of the Note and the Security Agreement, or accorded by law, including,
without limitation, the right to resort to any or all security subject hereto
and to exercise any or all of the rights of a beneficiary or secured party
pursuant to applicable law; provided, however, that after such acceleration the
Corporation may rescind and annul such acceleration and its consequences if all
existing Events of Default, other than the nonpayment of accelerated principal
or premium, if any, that has become due solely because of the acceleration, have
been cured or waived. All rights, powers and remedies of the Corporation may be
exercised at any time by the Corporation and from time to time after the
occurrence of an Event of Default, are cumulative and not exclusive, and shall
be in addition to any other rights, powers or remedies provided by law or
equity.

     If payment is not made when due, and if action is instituted on this Note,
the undersigned agrees to pay reasonable attorneys' fees and costs of suit as
fixed by the court.

     The undersigned shall have the right to prepay all or any part of the
unpaid principal amount and accrued interest of this Note without premium at any
time prior to the maturity hereof.

     This Note shall be governed by and construed in accordance with the laws of
the State of California without regard to principles of conflict of laws.

     IN WITNESS WHEREOF, the undersigned has caused this note to be signed,
dated and delivered as of the day and year first above written.



                                       ------------------------------------
                                                 [Name of Director]


                                      -2-
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                               SECURITY AGREEMENT

     THIS SECURITY AGREEMENT (this "Agreement"), effective as of June 14, 2000,
by and between ___________________, an individual ("Purchaser"), and SONICblue
INCORPORATED (formerly S3 Incorporated), a Delaware corporation (the
"Corporation"),

                              W I T N E S S E T H:

     WHEREAS, on June 14, 2000, Purchaser and the Corporation entered into a
Stock Purchase Agreement by and between Purchaser and RioPort, Inc., a Delaware
corporation ("RioPort"), pursuant to which Purchaser agreed to purchase 24,380
shares of Common Stock of RioPort (the "Shares"), for an aggregate purchase
price of $9,752.00;

     WHEREAS, the Corporation has advanced to Purchaser the purchase price for
the Shares (less the par value thereof) and has paid to RioPort such purchase
price, and Purchaser has executed and delivered to the Corporation a Promissory
Note in the principal amount of $9,727.62 (the "Note") for the purchase price of
the Shares; and

     WHEREAS, Purchaser has agreed to pledge 24,380 shares of RioPort Common
Stock to the Corporation as security for the payment of the Note:

     NOW, THEREFORE, the parties agree as follows:

     1.   Purchaser hereby delivers to the Corporation a certificate for 24,380
shares of Common Stock of RioPort, together with two assignments separate from
certificate (the "Assignments") signed by Purchaser. Purchaser hereby pledges
said stock as security for the payment of the Note. In an Event of Default (as
defined in the Note), Purchaser hereby appoints the Corporation as Purchaser's
true and lawful attorney to take such action as may be necessary or appropriate
to cause said stock to be transferred into the name of the Corporation, or to
any purchaser thereof.

     2.   The Corporation agrees to hold said stock as security for the payment
of the Note thereon as therein provided, and the Corporation shall not at any
time dispose of said stock or encumber same, except as otherwise provided
herein.

     3.   At all times while the Corporation is holding said stock as security
hereunder, the Corporation shall (a) collect all dividends declared thereon and
shall credit the same against principal of the Note, as part payment thereon,
and (b) collect and hold any other securities and/or other property distributed
on account of such stock, all of which shall be pledged to the Corporation
hereunder.

     4.   While the Corporation holds said stock as security hereunder,
Purchaser shall have the right to vote the same at all meetings of the
shareholders of the Corporation, so long as Purchaser is not in default in the
performance of any of the terms of this Agreement, or in the payments due under
the Note.

                                      -1-
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     5.   Upon repayment of the balance of the Note and other charges due
thereon, the Corporation shall redeliver to Purchaser the certificates for said
stock, and the Assignments.

     6.   In the event Purchaser shall fail to perform any of the terms of this
Agreement, or there occurs an Event of Default under the Note, the Corporation
shall have all the rights and remedies of a creditor and secured party at law
and in equity, including the rights and remedies provided under the California
Uniform Commercial Code, and without limiting the foregoing, the Corporation
may, after fifteen days' prior written notice to Purchaser by certified mail at
Purchaser's residence or business address, sell any or all of the stock pledged
hereunder in such manner and for such price as the Corporation may determine,
and out of the proceeds of such sale the Corporation may retain an amount
sufficient to pay the principal then due on the Note, together with expenses of
the sale and reasonable attorneys' fees, and the Corporation shall pay the
balance of said proceeds, if any, to Purchaser. At any bona fide sale which
qualifies as a public sale under the California Uniform Commercial Code, the
Corporation may (if the Corporation is the highest bidder) purchase all or any
part of said stock at such price as the Corporation deems proper. Purchaser
shall be liable for any deficiency remaining following exercise by the
Corporation of its rights hereunder.

     7.   Provided Purchaser has not failed to perform on a timely basis any of
Purchaser's obligations under the Note or this Agreement, the Corporation will
release the shares from the pledge hereunder upon payment in full of the Note.

     8.   This Agreement shall be governed by and construed in accordance with
the laws of the State of California without regard to principles of conflicts of
law.

     IN WITNESS WHEREOF, the parties have hereunto set their hands as of the day
and year first above written.


                                       ------------------------------------
                                                 [Name of Director]



                                       SONICBLUE INCORPORATED
                                       (formerly S3 Incorporated)



                                       By
                                          ----------------------------------

                                       Title
                                            --------------------------------


                                      -2-
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                      ASSIGNMENT SEPARATE FROM CERTIFICATE

     FOR VALUE RECEIVED, __________________ ("Stockholder") hereby sells,
assigns and transfers unto SONICblue Incorporated (formerly S3 Incorporated), a
Delaware corporation (the "Company"), ____________ (___) shares of Common Stock
of RioPort, Inc., a Delaware corporation ("RioPort"), represented by Certificate
No. _____ herewith and does hereby irrevocably constitute and appoint
________________ Attorney to transfer the said stock on the books of RioPort
with full power of substitution in the premises.

     Dated: __________, ____


                                       ------------------------------------
                                                 [Name of Director]


                                 SPOUSAL CONSENT

     ________________ (Purchaser's spouse) indicates by the execution of this
Assignment his or her consent to be bound by the terms herein as to his or her
interests, whether as community property or otherwise, if any, in the Shares.



                                       ------------------------------------
                                                    Signature


                                       ------------------------------------
                                                    Print Name

INSTRUCTIONS: PLEASE DO NOT FILL IN ANY BLANKS OTHER THAN THE SIGNATURE LINE.
THE PURPOSE OF THIS ASSIGNMENT IS TO ENABLE THE COMPANY TO EXERCISE ITS RIGHTS
SET FORTH IN THE SECURITY AGREEMENT WITHOUT REQUIRING ADDITIONAL SIGNATURES ON
THE PART OF PURCHASER.


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                      ASSIGNMENT SEPARATE FROM CERTIFICATE

     FOR VALUE RECEIVED, __________________ ("Stockholder") hereby sells,
assigns and transfers unto SONICblue Incorporated (formerly S3 Incorporated), a
Delaware corporation (the "Company"), ____________ (___) shares of Common Stock
of RioPort, Inc., a Delaware corporation ("RioPort"), represented by Certificate
No. _____ herewith and does hereby irrevocably constitute and appoint
________________ Attorney to transfer the said stock on the books of RioPort
with full power of substitution in the premises.

     Dated: __________, ____



                                       ------------------------------------
                                                 [Name of Director]



                                 SPOUSAL CONSENT

     ________________ (Purchaser's spouse) indicates by the execution of this
Assignment his or her consent to be bound by the terms herein as to his or her
interests, whether as community property or otherwise, if any, in the Shares.



                                       ------------------------------------
                                                    Signature


                                       ------------------------------------
                                                    Print Name



INSTRUCTIONS: PLEASE DO NOT FILL IN ANY BLANKS OTHER THAN THE SIGNATURE LINE.
THE PURPOSE OF THIS ASSIGNMENT IS TO ENABLE THE COMPANY TO EXERCISE ITS RIGHTS
SET FORTH IN THE SECURITY AGREEMENT WITHOUT REQUIRING ADDITIONAL SIGNATURES ON
THE PART OF PURCHASER.