Document:

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                                                                     EXHIBIT 4.6

                                 PROMISSORY NOTE

$25,000.00                                                      October 26, 2001

For value received, INTEGRATED SECURITY SYSTEMS, INC., a Delaware corporation
(hereinafter referred to as "Maker"), promises to pay to the order of FROST
NATIONAL BANK, CUSTODIAN, FBO RENAISSANCE US GROWTH & INCOME TRUST PLC, a public
limited company registered in England and Wales (hereinafter referred to as
"Payee"), the principal sum of Twenty-Five Thousand Dollars ($25,000.00). The
principal of and interest on this Note shall be due and payable in lawful money
of the United States of America, c/o Security Processing T-8, P. O. Box 2479,
San Antonio, Texas 78298. All correspondence and notices should be mailed to the
above address with a copy to the offices of Payee at 8080 N. Central Expressway,
Suite 210, Dallas, Texas 75206, or at such other place as the holder hereof may
from time to time designate by written notice to Maker.

         1. Interest. Interest shall accrue on the unpaid principal balance due
under this Note at an annual rate equal to eight percent (8%). Interest shall
accrue from and including the date of this Note until, but not including, the
day on which it is paid in full. In no event shall the interest charged
hereunder exceed the maximum rate of interest allowed from time to time by law.
Interest shall be due and payable monthly on the first (1st) day of each month,
commencing November 1, 2001.

         2. Payment of Note. The principal balance of, and all accrued unpaid
interest on, this Note shall be due and payable one hundred twenty (120) days
from the date hereof, except as otherwise provided herein. ("Maturity Date").

         3. Prepayment. This Note may be prepaid in whole or in part at any
time, at the option of Maker, without premium or penalty.

         4. Default, Enforcement. Upon default in payment of this Note, Payee
may pursue any and all rights and remedies to which Payee may be entitled under
applicable law.

         5. Limitation of Interest. All agreements between Maker and Payee,
whether now existing or hereafter arising and whether written or oral, are
expressly limited so that in no contingency or event whatsoever, whether by
reason of advancement of the proceeds hereof, acceleration of the maturity of
the unpaid principal balance hereof, or otherwise, shall the amount contracted
for, charged, received, paid or agreed to be paid to the holder hereof for the
use, forbearance, or detention of the money evidenced by this Note or for the
payment or performance of any covenant or obligation contained herein or in any
other document pertaining to the indebtedness evidenced by this Note exceed the
maximum amount permissible under applicable usury laws. If, from any
circumstance whatsoever, fulfillment of any provision hereof or of any other
agreement shall, at the time fulfillment of such provision be due, involve
transcending the limit of validity prescribed by law which a court of competent
jurisdiction may deem applicable hereto, then, ipso facto, the obligation to be
fulfilled shall be reduced to the limit of such validity; and if from any
circumstance the holder hereof shall ever receive as interest an amount which
would exceed the maximum lawful

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rate, any amount equal to any excessive interest shall (a) be applied to the
reduction of the unpaid principal balance due hereunder and not to the payment
of interest, or (b) if such excess interest exceeds the unpaid principal balance
of this Note, such excess shall be refunded to Maker. All sums contracted for,
charged or received hereunder for the use, forbearance or detention of the
indebtedness evidenced hereby shall, to the extent permitted by applicable law,
be amortized, prorated, allocated and spread throughout the full term of this
Note until payment in full so that the rate of interest on account of such
indebtedness is uniform throughout the term hereof. The terms and provisions of
this paragraph shall control and supersede every other provision of all
agreements between Maker and the holder hereof.

         6. Waiver. Except as otherwise expressly provided herein, Maker waives
demand, presentment for payment, notice of intent to accelerate, notice of
acceleration, notice of nonpayment or dishonor, grace, protest, notice of
protest, all other notices, and any and all diligence or delay in collection or
the filing of suit hereon.

         7. Governing Law and Venue. This Note shall be construed according to
and governed by the laws of the State of Texas. The obligations of Maker under
this Note are performable in Dallas County, Texas.

         8. Security Agreement. This Note is secured by the Security Agreement,
dated September 27, 2001, among Maker, B&B Electromatic, Inc. and Intelli-Site,
Inc., Payee and Renaissance Capital Growth & Income Fund III, Inc., and Payee is
entitled to the rights and benefits thereunder.

         9. Stock Pledge Agreement. This Note is secured by the Stock Pledge
Agreement dated as of September 27, 2001, among Maker, Payee, Renaissance
Capital Growth & Income Fund III, Inc., and Payee is entitled to the rights and
benefits thereunder.

         10. Successors and Assign. This Note shall bind Maker's successors and
assigns.

         11. Collection Costs. If this Note is collected by legal proceeding or
through a probate or bankruptcy court, or is placed in the hands of an attorney
for collection after default (whether or not suit is filed), Maker agrees to pay
all costs of collection and/or suit, including but not limited to reasonable
attorneys' fees and expenses incurred by Payee.

         12. Unenforceability. The invalidity, or unenforceability in particular
circumstances, of any provision of this Note shall not extend beyond such
provision or such circumstances, and no other provision of this Note shall be
affected thereby.

         13. Headings. The paragraph headings of the sections of this Note are
inserted for convenience of reference only and shall not affect the meaning or
interpretation of this Note.

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         IN WITNESS WHEREOF, Maker has duly executed this Note as of the day and
year first above written.

                                        INTEGRATED SECURITY SYSTEMS, INC.

                                        By: /s/ C.A. RUNDELL, JR.
                                            ---------------------
                                            C. A. Rundell, Jr.
                                            Chairman and Chief Executive Officer<PAGE>

                                                                     EXHIBIT 4.7

THIS WARRANT AND THE SECURITIES ISSUABLE UPON THE EXERCISE HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933. THEY MAY NOT BE SOLD, OFFERED FOR
SALE, PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, OR AN OPINION
OF COUNSEL SATISFACTORY TO THE COMPANY THAT REGISTRATION IS NOT REQUIRED UNDER
SUCH ACT OR UNLESS SOLD PURSUANT TO RULE 144 UNDER SUCH ACT.

                             STOCK PURCHASE WARRANT

This Stock Purchase Warrant (this "Warrant"), dated October 26, 2001, is issued
to FROST NATIONAL BANK, CUSTODIAN, FBO RENAISSANCE CAPITAL GROWTH & INCOME FUND
III, INC., a Texas corporation (the "Holder"), by INTEGRATED SECURITY SYSTEMS,
INC., a Delaware corporation (the "Company").

         1. Purchase of Shares. Subject to the terms and conditions hereinafter
set forth, the Holder is entitled, upon surrender of this Warrant at the
principal office of the Company (or at such other place as the Company shall
notify the holder hereof in writing), to purchase from the Company 125,000 fully
paid and non-assessable shares of Common Stock, no par value (the "Common
Stock"), of the Company (as adjusted pursuant to Section 6 hereof, the "Shares")
for the purchase price specified in Section 2 below.

         2. Purchase Price. The purchase price for the Shares is $0.20 per
share. Such price shall be subject to adjustment pursuant to Section 6 hereof
(such price, as adjusted from time to time, is herein referred to as the
"Warrant Price").

         3. Exercise Period. This Warrant is exercisable in whole or in part at
any time from the date hereof through October 26, 2006.

         4. Method of Exercise. While this Warrant remains outstanding and
exercisable in accordance with Section 3 above, the Holder may exercise, in
whole or in part, the purchase rights evidenced hereby. Such exercise shall be
effected by:

                  (a) surrender of this Warrant, together with a duly executed
copy of the form of Exercise Notice attached hereto, to the Secretary of the
Company at its principal offices, and the payment to the Company of an amount
equal to the aggregate purchase price for the number of Shares being purchased;
or

                  (b) if the Company's Common Stock is publicly traded as of
such date, the instruction to retain that number of Shares having a value equal
to the aggregate exercise price of the Shares as to which this Warrant is being
exercised and to issue to the Holder the remainder of such Shares computed using
the following formula:
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                  X = Y(A-B)/A

Where:            X = the number of shares of Common Stock to be issued to the
                      Holder.

                  Y = the number of shares of Common Stock as to which this
                      Warrant is being exercised.

                  A = the fair market value of one share of Common Stock.

                  B = the Warrant Price.

         As used herein, the "fair market value of one share of Common Stock"
shall mean:

                  (1) Except in the circumstances described in clause (2) or (3)
hereof, the closing price of the Company's Common Stock, as reported in the Wall
Street Journal, on the trading day immediately prior to the date of exercise;

                  (2) If such exercise is in conjunction with a merger,
acquisition or other consolidation pursuant to which the Company is not the
surviving entity, the value received by the holders of the Common Stock pursuant
to such transaction for each share; or

                  (3) If such exercise is in conjunction with the initial public
offering of the Company, the price at which the Common Stock is sold to the
public in such offering.

         5. Certificates for Shares. Upon the exercise of the purchase rights
evidenced by this Warrant, one or more certificates for the number of Shares so
purchased shall be issued as soon as practicable thereafter, and in any event
within thirty (30) days of the delivery of the subscription notice.

         6.Reservation of Shares. The Company covenants that it will at all
times keep available such number of authorized shares of its Common Stock, free
from all preemptive rights with respect thereto, which will be sufficient to
permit the exercise of this Warrant for the full number of Shares specified
herein. The Company further covenants that such Shares, when issued pursuant to
the exercise of this Warrant, will be duly and validly issued, fully paid and
non-assessable and free from all taxes, liens and charges with respect to the
issuance thereof.

         7. Adjustment of Warrant Price and Number of Shares. The number and
kind of securities purchasable upon exercise of this Warrant and the Warrant
Price shall be subject to adjustment from time to time as follows:

                  a. Stock Dividends, Subdivisions, Combinations and Other
Issuances. If the Company shall at any time prior to the expiration of this
Warrant subdivide its Common Stock, by stock split or otherwise, combine its
Common Stock or issue additional shares of its Common Stock as a dividend with
respect to any shares of its Common Stock, the number of Shares issuable on the
exercise of this Warrant shall forthwith be proportionately increased in the
case of a subdivision or stock dividend and proportionately decreased in the
case of a combination. Appropriate adjustments

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shall also be made to the purchase price payable per share, but the aggregate
purchase price payable for the total number of Shares purchasable under this
Warrant (as adjusted) shall remain the same. Any adjustment under this Section
7(a) shall become effective at the close of business on the date the subdivision
or combination becomes effective or as of the record date of such dividend, or,
in the event that no record date is fixed, upon the making of such dividend

                  b. Reclassification, Reorganization, Merger, Sale or
Consolidation. In the event of any reclassification, capital reorganization or
other change in the Common Stock of the Company (other than as a result of a
subdivision, combination or stock dividend provided for in Section 7(a) above)
or in the event of a consolidation or merger of the Company with or into, or the
sale of all or substantially all of the properties and assets of the Company, to
any person, and in connection therewith consideration is payable to holders of
Common Stock in cash, securities or other property, then as a condition of such
reclassification, reorganization or change, consolidation, merger or sale,
lawful provision shall be made, and duly executed documents evidencing the same
shall be delivered to the Holder, so that the Holder shall have the right at any
time prior to the expiration of this Warrant to purchase, at a total price equal
to that payable upon the exercise of this Warrant immediately prior to such
event, the kind and amount of cash, securities or other property receivable in
connection with such reclassification, reorganization or change, consolidation,
merger or sale, by a holder of the same number of shares of Common Stock as were
exercisable by the Holder immediately prior to such reclassification,
reorganization or change, consolidation, merger or sale. In any such case,
appropriate provisions shall be made with respect to the rights and interest of
the Holder so that the provisions hereof shall thereafter be applicable with
respect to any cash, securities or property deliverable upon exercise hereof.
Notwithstanding the foregoing, (i) if the Company merges or consolidates with,
or sells all or substantially all of its property and assets to, any other
person, and consideration is payable to holders of Common Stock in exchange for
their Common Stock in connection with such merger, consolidation or sale which
consists solely of cash, or (ii) in the event of the dissolution, liquidation or
winding up of the Company, then the Holder shall be entitled to receive
distributions on the date of such event on an equal basis with holders of Common
Stock as if this Warrant had been exercised immediately prior to such event,
less the Warrant Price. Upon receipt of such payment, if any, the rights of the
Holder shall terminate and cease, and this Warrant shall expire. In case of any
such merger, consolidation or sale of assets, the surviving or acquiring person
and, in the event of any dissolution, liquidation or winding up of the Company,
the Company shall promptly, after receipt of this surrendered Warrant, make
payment by delivering a check in such amount as is appropriate (or, in the case
of consideration other than cash, such other consideration as is appropriate) to
such person as it may be directed in writing by the Holder surrendering this
Warrant.

                  c. Certain Distributions. In case the Company shall fix a
record date for the making of a dividend or distribution of cash, securities or
property to all holders of Common Stock (excluding any dividends or
distributions referred to in Sections or 7(a) above, the number of Shares
purchasable upon an exercise of this Warrant after such record date shall be
adjusted to equal the product obtained by multiplying the number of Shares
purchasable upon an exercise of this Warrant immediately prior to such record
date by a fraction, the numerator of which shall be the Warrant Price
immediately prior to such distribution, and the denominator of which shall be
the Warrant Price immediately prior to such distribution, less the fair market
value per Share, as determined by the Holder, of the cash, securities or
property so distributed. Such adjustment shall

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be made successively whenever any such distribution is made and shall become
effective on the effective date of distribution.

         8. Pre-Exercise Rights. Prior to exercise of this Warrant, the Holder
shall not be entitled to any rights of a shareholder with respect to the Shares,
including without limitation, the right to vote such Shares, receive preemptive
rights or be notified of shareholder meetings, and the Holder shall not be
entitled to any notice or other communication concerning the business or affairs
of the Company.

         9. Restricted Securities. The Holder understands that this Warrant and
the Shares purchasable hereunder constitute "restricted securities" under the
federal securities laws inasmuch as they are being, or will be, acquired from
the Company in transactions not involving a public offering and accordingly may
not, under such laws and applicable regulations, be resold or transferred
without registration under the Securities Act of 1933, as amended, or an
applicable exemption from registration. In this connection, the Holder
acknowledges that Rule 144 of the Securities and Exchange Commission is not now,
and may not in the future be, available for resales of the Shares purchased
hereunder. The Holder further acknowledges that the Shares and any other
securities issued upon exercise of this Warrant shall bear a legend
substantially in the form of the legend appearing on the face hereof.

         10. Certification of Investment Purpose. Unless a current registration
statement under the Securities Act of 1933, as amended, shall be in effect with
respect to the securities to be issued upon exercise of this Warrant, the Holder
hereof, by accepting this Warrant, covenants and agrees that, at the time of
exercise hereof, the Holder will deliver to the Company a written certification
that the securities acquired by the Holder are acquired for investments purposes
only and that such securities are not acquired with a view to, or for sale in
connection with, any distribution thereof.

         11. Registration Rights. This Warrant and the Shares shall be subject
to the registration rights set forth in the Registration Rights Agreement of
even date herewith by and among the Holder and the Company, and the Holder shall
be entitled to all rights and benefits thereof.

         12. Successors and Assigns. The terms and provisions of this Warrant
shall inure to the benefit of, and be binding upon, the Company and the Holder
and their respective successors and assigns.

         13. Governing Law. This Warrant shall be governed by the laws of the
State of Texas, excluding the conflicts of laws provisions thereof.

                                       INTEGRATED SECURITY SYSTEMS, INC.

                                       By: /s/ C.A. RUNDELL, JR.
                                           ---------------------
                                           C. A. Rundell, Jr.
                                           Chairman and Chief Executive Officer

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                                 EXERCISE NOTICE

                                                           Dated _________, ____

         The undersigned hereby irrevocably elects to exercise the Stock
Purchase Warrant, dated October 26, 2001, issued by INTEGRATED SECURITY SYSTEMS,
INC., a Delaware corporation (the "Company") to the undersigned to the extent of
purchasing ___________ shares of Common Stock and hereby makes payment of
$_________ in payment of the aggregate Warrant Price of such Shares.

                                       RENAISSANCE CAPITAL GROWTH & INCOME
                                       FUND III, INC.

                                       By:
                                          --------------------------------------

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