Document:

<PAGE>   1
                                                                    EXHIBIT 4.20

                           CONVERTIBLE PROMISSORY NOTE

$50,000.00                                                     November 17, 2000

         For value received, INTEGRATED SECURITY SYSTEMS, INC., a Delaware
corporation (hereinafter referred to as "Maker"), promises to pay to the order
of C.A. RUNDELL, JR. an individual (hereinafter referred to as "Payee"), the
principal sum of Fifty Thousand and No/100 Dollars ($50,000.00). The principal
of and interest on this Note shall be due and payable in lawful money of the
United States of America, at the offices of Payee at 2200 Ross Avenue, Suite
4660 West, Dallas, Texas 75201, 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 on interest allowed from time to time by law.
Interest shall be due and payable monthly on the first (1st) day of each month.

         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
after the date hereof, except as otherwise provided herein ("Maturity Date").

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

         4. Conversion. This Note shall be convertible, at the option of Payee
in its sole and absolute discretion, in whole or in part and at any time or from
time to time, into fully paid and nonassessable shares (the "Conversion Shares")
of Common Stock, $.01 par value (the "Common Stock"), of Integrated Security
Systems, Inc., a Delaware corporation (the "Company"), at the conversion price
of $.20 per share. If Payee elects to exercise its option, then the following
shall occur:

               (a) Payee shall deliver to Maker a notice of such election (the
               "Conversion Notice"), indicating the amount of principal of this
               Note to be converted (such amount to be converted referred to
               herein as the "Converted Amount").

               (b) Promptly upon receipt of the Conversion Notice, Maker shall
               deliver to the Company (i) a certificate or certificates of
               Maker's Common Stock representing at least the number of shares
               issuable to Payee upon conversion of the Converted Amount, duly
               endorsed in blank or accompanied by a stock transfer power
               executed in like manner, and (ii) a copy of the Conversion
               Notice.

               (c) Upon its receipt of Maker's endorsed Common Stock
               certificate(s) and the Conversion Notice, the Company shall
               immediately issue and deliver to Payee or its designated
               affiliates a certificate or certificates for the number of shares
               of Common Stock, registered in Payee's or its designated
               affiliates' name(s), to

<PAGE>   2

               which Payee shall be entitled upon such conversion, bearing such
               legends as may be required by applicable state and federal
               securities laws. The Company shall issue to Maker a certificate
               representing any shares surrendered by Maker in excess of the
               shares issued to Payee upon conversion.

               (d) If this Note is converted in whole, Payee shall deliver this
               Note to Maker marked "Canceled," and Maker shall immediately pay
               to Payee all accrued and unpaid interest then due and owing on
               the date of such conversion. If this Note is converted in part,
               Maker shall immediately pay to Payee all accrued and unpaid
               interest then due and owing on the date of such conversion, and
               Payee shall deliver to Maker a replacement Note for any
               outstanding principal amount not converted, dated the date of
               such conversion, with the same Maturity Date and provisions as
               contained in this Note.

               (e) No fractional shares will be issued on conversion of this
               Note.

         5. Adjustment for Issuance of Shares at Less Than the Conversion Price.
If and whenever any Additional Common Stock (herein defined) shall be issued by
Maker (the "Stock Issue Date") for a consideration per share less than the
Conversion Price, then in each such case the initial Conversion Price shall be
reduced to a new Conversion Price in an amount equal to the price per share of
the Additional Common Stock then issued, as determined in accordance with
general accepted accounting principles, if issued other than for cash, and the
number of shares issuable to Payee upon conversion shall be proportionately
increased; and, in the case of Additional Common Stock issued without
consideration, the initial Conversion Price shall be reduced in amount and the
number of shares issued upon conversion shall be increased in an amount so as to
maintain for the Payee the right to convert this Note into shares equal in
amount to the same percentage interest in the Common Stock of the Company as
existed for the Payee immediately preceding the Stock Issue Date.

        6. Sale of Shares. In case of the issuance of Additional Common Stock
for a consideration part or all of which shall be cashed, the amount of the cash
consideration therefore shall be deemed to be the gross amount of the cash paid
to Maker for such shares, before deducting any underwriting compensation or
discount in the sale, underwriting or purchase thereof by underwriters or
dealers or others performing similar services for any expenses incurred in
connection therewith. In case of the issuance of any shares of Additional Common
Stock for a consideration part or all of which shall be other than cash, the
amount of the consideration therefore, other than cash, shall be deemed to be
the then fair market value of the property received.

        7. Stock Dividends. Shares of Common Stock issued as a dividend or other
distribution on any class of capital stock of Maker shall be deemed to have been
issued without consideration.

         8. Stock Splits, Subdivisions or Combinations. In the event of a stock
split or subdivision of shares of Common Stock into a greater number of shares,
the Conversion Price shall be proportionately decreased, and in the event of a
combination of shares of Common Stock into a smaller number of shares, the
Conversion Price shall be proportionately increased, such increase or decrease,
as the case may be, becoming effective at the record date.

<PAGE>   3

         9. Exceptions. The term "Additional Common Stock" herein shall mean all
shares of Common Stock hereafter issued by Maker (including Common Stock held in
the treasury of Maker), except for (A) Common Stock issued upon the conversion
of this Note; (B) Common Stock issued upon exercise of any outstanding warrants,
options or convertible debt instruments; and (C) Common Stock issued upon
exercise of outstanding employee stock options.

         10. Adjustment for Mergers, Sales and Consolidations. In the event of
any 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
consolidation, merger or sale, lawful provision shall be made, and duly executed
documents evidencing the same shall be delivered to the Payee, so that the Payee
shall have the right at any time prior to the maturity of this Note to purchase,
at a total price equal to the Conversion Price immediately prior to such event,
the kind and amount of cash, securities or other property receivable in
connection with such consolidation, merger or sale, by a holder of the same
number of shares of Common Stock as were exercisable by the Payee immediately
prior to such consolidation, merger or sale. In any such case, appropriate
provision shall be made with respect to the rights and interest of the Payee 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 Payee shall be entitled to receive distributions on
the date of such event on an equal basis with holders of Common Stock as if this
Note had been converted immediately prior to such event, less the Conversion
Price. Upon receipt of such payment, if any, the rights of the Payee shall
terminate and cease and this Note 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 Note, 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 Payee surrendering this
Note.

         11. Adequate Shares. Maker will at times reserve and keep available,
for the purpose of issuance upon conversion, a sufficient number of shares of
Common Stock owned by Maker deliverable upon Payee's exercise of its conversion
rights under this Note.

         12. Default, Enforcement. Upon default in payment of this Note, Payee
may pursue any and all remedies to which Payee may be entitled.

         13. 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 or 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

<PAGE>   4

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 limits of validity prescribed by
law which a court of competent jurisdiction may deem applicable hereto the 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 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.

         14. Waiver. Except as otherwise expressly provided herein, Maker waives
demand, 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.

         15. 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.

         16. Registration Rights. The shares of Common Stock issued upon
conversion of this Note shall be restricted from transfer by the Payee, unless
the shares are duly registered for sale pursuant to the Securities Act of 1933,
as amended, or the transfer is exempt from registration.

         17. Security Agreement. This Note is secured by the accounts receivable
of Intelli-Site, Inc.

         18. Successors and Assigns. This Note shall bind Maker's successors and
assigns.

         19. 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
attorney's fees incurred by Payee.

         20. 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.

         21. 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.

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

                                  INTEGRATED SECURITY SYSTEMS, INC.

                                  BY:
                                      ------------------------------------------
                                      Holly J. Burlage
                                      Executive Vice President and
                                      Chief Financial Officer<PAGE>   1
                                                                       EXHIBIT 2

                      REGULATION S STOCK PURCHASE AGREEMENT

<PAGE>   2

                      REGULATION S STOCK PURCHASE AGREEMENT

                             dated February 6, 2001

                                       for

                         TBX RESOURCES INC. COMMON STOCK

<PAGE>   3

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                 Page
                                                                                                                 ----

<S>                                                                                                              <C>
ARTICLE I.  PURCHASE, SALE AND TERMS OF SHARES....................................................................2
   1.1.    The Shares.............................................................................................2
   1.2.    Payment of Purchase Price; Closing.....................................................................2
   1.3.    Covenants of Best Efforts..............................................................................2
   1.4.    Representations by the Purchaser.......................................................................2

ARTICLE II.  REPRESENTATIONS AND WARRANTIES OF THE COMPANY........................................................6
   2.1.    Organization and Standing of the Company...............................................................6
   2.2.    Corporate Action.......................................................................................6
   2.3.    Governmental Approvals.................................................................................7
   2.4.    Litigation.............................................................................................7
   2.5.    Compliance with Other Instruments......................................................................7
   2.6.    Title to Assets; Intellectual Property Rights..........................................................8
   2.7.    Taxes..................................................................................................8
   2.8.    Disclosure.............................................................................................8
   2.9.    Brokers or Finders.....................................................................................9
   2.10.   Capitalization; Status of Capital Stock................................................................9
   2.11.   SEC Reports............................................................................................9
   2.12.   Books and Records......................................................................................9

ARTICLE III.  MISCELLANEOUS......................................................................................10
   3.1.    No Waiver; Cumulative Remedies........................................................................10
   3.2.    Amendments; Waivers and Consents......................................................................10
   3.3.    Addresses for Notices.................................................................................10
   3.4.    Costs; Expenses and Taxes.............................................................................10
   3.5.    Effectiveness; Binding Effect; Assignment.............................................................11
   3.6.    Survival of Representations and Warranties............................................................11
   3.7.    Prior Agreements......................................................................................11
   3.8.    Severability..........................................................................................11
   3.9.    Governing Law;Venue...................................................................................11
   3.10.   Headings..............................................................................................12
   3.11.   Counterparts..........................................................................................12
   3.12.   Further Assurances....................................................................................12
</TABLE>

                                      -i-

<PAGE>   4

         Regulation S Stock Purchase Agreement, dated as of January 30,
2001between TBX Resources Inc., a Texas corporation having offices at 12300 Ford
Road, Suite 194, Dallas, Texas 75234 (the "Company"), and Citizen Asia Pacific
Limited, a Hong Kong company having offices at 13/F Silver Fortune Plaza, 1
Wellington Street, Central, Hong Kong (the "Purchaser").

                                   ARTICLE I.

                       PURCHASE, SALE AND TERMS OF SHARES

         1.1. The Shares. The Company agrees to issue and sell to the Purchaser
and, in consideration of and in express reliance upon the representations,
warranties, covenants, terms and conditions of this Agreement, the Purchaser
agrees to purchase from the Company up to 800,000 shares (the "Shares") of the
Company's Common Stock at a per share purchase price which shall be 30% of the
average of the closing prices of the Company's shares of Common Stock as quoted
on the OTC Bulletin Board (the "OTCBB") (or on such other United States stock
exchange or public trading market on which the shares of the Company trade if,
at the time of purchase, they are not trading on the OTCBB) for the ten (10)
consecutive trading days immediately preceding the date (the "Call Date") the
purchase order (the "Purchase Notice") is received by the Company (the "Purchase
Price"). The Purchaser understands and agrees that the Company in its sole
discretion reserves the right to accept or reject this subscription for the
Shares, in whole or in part, prior to receipt by the Company of the Purchase
Price, or any applicable portion thereof, as set forth in Section 1.3.

         1.2. Payment of Purchase Price; Closing. The Purchaser will pay the
purchase price by wire transfer of immediately available funds within ten (10)
business days of the Call Date to a non-interest bearing escrow account of
Gemini Financial Group Limited, for the benefit of Purchaser, along with written
instructions from Purchaser authorizing release of such funds to the Company
upon receipt by Gemini Financial Group Limited (or another party designated by
the Purchaser acceptable to Gemini Financial Group Limited ) of a series of
certificates representing the Shares.

         1.3 Covenant of Best Efforts. The Purchaser agrees to use its best
efforts to purchase the shares between February 7, 2001 and September 30, 2001.

         1.4. Representations by the Purchaser. The Purchaser makes the
following representations and warranties to the Company:

              (a) Access to Information. The Purchaser, in making the decision
to purchase the Shares, has relied solely upon independent investigations made
by it and/or its representatives, if any. The Purchaser and/or its
representatives during the course of this transaction, and prior to the purchase
of any Shares, has had the opportunity to ask questions of

<PAGE>   5

and receive answers from the management of the Company concerning the terms and
conditions of the offering of the Shares and to receive any additional
information, documents, records and books relative to its business, assets,
financial condition, results of operations and liabilities (contingent or
otherwise) of the Company.

              (b) Sophistication and Knowledge. The Purchaser and/or its
representatives has such knowledge and experience in financial and business
matters that it can represent itself and is capable of evaluating the merits and
risks of the purchase of the Shares. The Purchaser is not relying on the Company
with respect to the tax and other economic considerations of an investment in
the Shares, and the Purchaser has relied on the advice of, or has consulted
with, only the Purchaser's own advisor(s). The Purchaser represents that it has
not been organized for the purpose of acquiring the Shares.

              (c) Lack of Liquidity. The Purchaser acknowledges that the
purchase of the Shares involves a high degree of risk and further acknowledges
that it can bear the economic risk of the purchase of the Shares, including the
total loss of its investment. The Purchaser has no present need for liquidity in
connection with its purchase of the Shares.

              (d) No Public Solicitation. The Purchaser is not subscribing for
the Shares as a result of or subsequent to any advertisement, article, notice or
other communication published in any newspaper, magazine or similar media or
broadcast over television or radio, or presented at any seminar or meeting, or
any solicitation of a subscription by a person not previously known to the
Purchaser in connection with investments in securities generally.

              (e) Authority. The Purchaser has full right and power to enter
into and perform pursuant to this Agreement and make an investment in the
Company, and this Agreement constitutes the Purchaser's valid and legally
binding obligation, enforceable in accordance with its terms. The Purchaser is
authorized and otherwise duly qualified to purchase and hold the Shares and to
enter into this Agreement

              (f) Regulation S Exemption. The Purchaser understands that the
Shares are being offered and sold to it in reliance on an exemption from the
registration requirements of United States federal and state securities laws
under Regulation S promulgated under the Securities Act and that the Company is
relying upon the truth and accuracy of the representations, warranties,
agreements, acknowledgments and understandings of the Purchaser set forth herein
in order to determine the applicability of such exemptions and the suitability
of the Purchaser to acquire the Shares. In this regard, the Purchaser
represents, warrants and agrees that:

                   (i) The Purchaser is not a U.S. Person (as defined below) and
         is not an affiliate (as defined in Rule 501(b) under the Securities
         Act) of the Company. A U.S. Person means any one of the following:

<PAGE>   6

                      (A) any natural person resident in the United States of
                          America;

                      (B) any partnership or corporation organized or
                          incorporated under the laws of the United States of
                          America;

                      (C) any estate of which any executor or administrator is a
                          U.S. person;

                      (D) any trust of which any trustee is a U.S. person;

                      (E) any agency or branch of a foreign entity located in
                          the United States of America;

                      (F) any non-discretionary account or similar account
                          (other than an estate or trust) held by a dealer or
                          other fiduciary for the benefit or account of a U.S.
                          person;

                      (G) any discretionary account or similar account (other
                          than an estate or trust) held by a dealer or other
                          fiduciary organized, incorporated or (if an
                          individual) resident in the United States of America;
                          and (H) any partnership or corporation if:

                              (1) organized or incorporated under the laws of
                          any foreign jurisdiction; and

                              (2) formed by a U.S. person principally for the
                          purpose of investing in securities not registered
                          under the Securities Act, unless it is organized or
                          incorporated, and owned, by accredited investors (as
                          defined in Rule 501(a) under the Securities Act) who
                          are not natural persons, estates or trusts.

                   (ii) At the time of the origination of contact concerning
         this Agreement and the date of the execution and delivery of this
         Agreement, the Purchaser was outside of the United States.

                   (iii) The Purchaser will not, during the period commencing on
         the date of issuance of the Shares and ending on the first anniversary
         of such date, or such shorter period as may be permitted by Regulation
         S or other applicable securities law (the "Restricted Period"), offer,
         sell, pledge or otherwise transfer the shares in the United States, or
         to a U.S. Person for the account or benefit of a U.S. Person.

<PAGE>   7

                   (iv) The Purchaser will, after expiration of the Restricted
         Period, offer, sell, pledge or otherwise transfer the Shares only
         pursuant to registration under the Securities Act or an available
         exemption therefrom and, in accordance with all applicable state and
         foreign securities laws.

                   (v) The Purchaser has not in the United States, engaged in,
         and prior to the expiration of the Restricted Period will not engage
         in, any short selling of or any hedging transaction with respect to the
         Shares, including without limitation, any put, call or other option
         transaction, option writing or equity swap.

                   (vi) Neither the Purchaser nor or any person acting on its
         behalf has engaged, nor will engage, in any directed selling efforts to
         U.S. Citizens with respect to the Shares and the Purchaser and any
         person acting on its behalf have complied and will comply with the
         "offering restrictions" requirements of Regulation S under the
         Securities Act.

                   (vii) The transactions contemplated by this Agreement have
         not been pre-arranged with a buyer located in the United States or with
         a U.S. Person, and are not part of a plan or scheme to evade the
         registration requirements of the Securities Act.

                   (viii) Neither the Purchaser nor any person acting on its
         behalf has undertaken or carried out any activity for the purpose of,
         or that could reasonably be expected to have the effect of,
         conditioning the market in the United States, its territories or
         possessions, for any of the Shares. The Purchaser agrees not to cause
         any advertisement of the Shares to be published in any newspaper or
         periodical or posted in any public place and not to issue any circular
         relating to the Shares, except such advertisements that include the
         statements required by Regulation S under the Securities Act.

                   (ix) Each certificate representing the Shares shall be
         endorsed with the following legends:

                        (A) "THE SHARES ARE BEING OFFERED TO INVESTORS WHO ARE
              NOT U.S. PERSONS (AS DEFINED IN REGULATION S UNDER THE SECURITIES
              ACT OF 1933, AS AMENDED ("THE SECURITIES ACT")) AND WITHOUT
              REGISTRATION WITH THE UNITED STATES SECURITIES AND EXCHANGE
              COMMISSION UNDER THE SECURITIES ACT IN RELIANCE UPON REGULATION S
              PROMULGATED UNDER THE SECURITIES ACT."

                        (B) "INVESTORS UNDER REGULATION S ARE ALSO ADVISED THAT
              DURING THE ONE-YEAR RESTRICTED PERIOD PROVIDED FOR IN RULE 903 OF
              REGULATION S, NO OFFERS OR SALES

<PAGE>   8

              OF THE SHARES OFFERED HEREBY MAY BE MADE IN THE UNITED STATES
              OR TO U.S. PERSONS.

                        (C) Any other legend required to be placed thereon by
              applicable federal or state securities laws.

                   (x) The Purchaser consents to the Company making a notation
         on its records or giving instructions to any transfer agent of the
         Company in order to implement the restrictions on transfer of the
         Shares set forth in this Section 1.4.

                                   ARTICLE II

                  REPRESENTATIONS AND WARRANTIES OF THE COMPANY

         The Company represents and warrants as follows:

         2.1. Organization and Standing of the Company. The Company is a duly
organized and validly existing corporation in good standing under the laws of
the State of Texas and has all requisite corporate power and authority for the
ownership and operation of its properties and for the carrying on of its
business as now conducted and as now proposed to be conducted and to execute and
deliver this Agreement and other instruments, agreements and documents
contemplated herein (together with this Agreement, the "Transaction Documents"),
to issue, sell and deliver the Shares and to perform its other obligations
pursuant hereto. The Company is duly licensed or qualified and in good standing
as a foreign corporation authorized to do business in all jurisdictions wherein
the character of the property owned or leased or the nature of the activities
conducted by it makes such licensing or qualification necessary, except where
the failure to be so licensed or qualified would not have a material adverse
effect on the business, operations or financial condition of the Company.

         2.2. Corporate Action. The Transaction Documents have been duly
authorized, executed and delivered by the Company and constitute the legal,
valid and binding obligations of the Company, enforceable against the Company in
accordance with their respective terms. The Shares have been duly authorized.
The issuance, sale and delivery of the Shares have been duly authorized by all
required corporate action on the part of the Company. The Shares, when issued
and paid for in accordance with the Transaction Documents, will be validly
issued, fully paid and nonassessable, with no personal liability attaching to
the ownership thereof and will be free and clear of all liens, charges,
restrictions, claims and encumbrances imposed by or through the Company, except
as expressly set forth in the Transaction Documents.

         2.3. Governmental Approvals. No authorization, consent, approval,
license, exemption of or filing or registration with any court or governmental
department, commission, board, bureau, agency or instrumentality, domestic or
foreign, is or will be necessary for, or in

<PAGE>   9

connection with, the execution and delivery by the Company of this Agreement,
for the offer, issue, sale, execution or delivery of the Shares, or for the
performance by the Company of its obligations under the Transaction Documents
except for any filings required by applicable securities laws.

         2.4. Litigation. Except as set forth on Schedule 2.4, there is no
litigation or governmental proceeding or investigation pending or, to the
knowledge of the Company, threatened against the Company affecting any of its
properties or assets, nor, to the best knowledge of the Company, has there
occurred any event or does there exist any condition on the basis of which any
litigation, proceeding or investigation might properly be instituted. The
Company is not in default with respect to any order, writ, injunction, decree,
ruling or decision of any court, commission, board or other government agency,
which such default might have a material adverse effect on the business, assets,
liabilities, operations, Intellectual Property Rights, (as defined hereinafter)
management or financial condition of the Company. There are no actions or
proceedings pending or, to the Company's knowledge, threatened (or any basis
therefor known to the Company) against the Company which might result, either in
any case or in the aggregate, in any material adverse change in the business,
operations, Intellectual Property Rights, affairs or financial condition of the
Company or in any of its properties or assets, or which might call into question
the validity of any of the Transaction Documents, any of the Shares, or any
action taken or to be taken pursuant hereto or thereto.

         2.5. Compliance with Other Instruments. The Company is in compliance in
all respects with its Certificate of Incorporation and Bylaws, each as amended
and/or restated to date, and in all respects with the material terms and
provisions of all mortgages, indentures, leases, agreements and other
instruments by which it is bound or to which it or any of its properties or
assets are subject. The Company is in compliance in all material respects with
all judgments, decrees, governmental orders, laws, statutes, rules or
regulations by which it is bound or to which it or any of its properties or
assets are subject. Neither the execution and delivery of the Transaction
Documents nor the issuance of the Shares, nor the consummation or performance of
any transaction contemplated hereby or thereby, has constituted or resulted in
or will constitute or result in a default or violation of, create a conflict
with, trigger any "change of control" or other right of any Person under, or
require any consent, waiver, release or approval under or with respect to, any
term or provision of any of the foregoing documents, instruments, judgments,
agreements, decrees, orders, statutes, rules and regulations.

         2.6. Title to Assets; Intellectual Property Rights. (a) The Company has
good and marketable title in fee to such of its fixed assets as are real
property, and good and merchantable title to all of its other assets, now
carried on its books, free of any mortgages, pledges, charges, liens, security
interests or other encumbrances. The Company enjoys peaceful and undisturbed
possession under all leases under which it is operating, and all said leases are
valid and subsisting and in full force and effect.

<PAGE>   10

              (b) The Company owns or has a valid right to use patents, patent
applications, patent right, trade secrets, confidential business information,
formula, processes, laboratory notebooks, algorithms, copyrights, mask works,
claims of infringement against third parties, licenses, permits, license rights,
contract rights with employees, consultants and third parties, trademarks,
trademark rights, inventions and discoveries, and all other intellectual
property, including, without limitation, all other such rights generally
classified as intangible, intellectual property assets in accordance with GAAP
(collectively the, "Intellectual Property Rights") being used to conduct its
business as now operated and as now proposed by the Company to be operated and
to the best of the Company's knowledge, the conduct of its business as now
operated and as now proposed to be operated does not and will not conflict with
or infringe upon the Intellectual Property Rights of others. To the best of the
Company's knowledge, no claim is pending or threatened against the Company
and/or its officers, employees and consultants to the effect that any such
Intellectual Property Right owned or licensed by the Company, or which the
Company otherwise has the right to use, is invalid or unenforceable by the
Company.

              (c) The Company has taken all reasonable measures to protect and
preserve the security, confidentiality and value of its Intellectual Property
Rights, including its trade secrets and other confidential information. The
Company is and will be the exclusive owner of all right, title and interest in
its Intellectual Property Rights as purported to be owned by the Company, and
such Intellectual Property Rights are valid and in full force and effect. The
Company has not received notice of and, to the best of the Company's knowledge
there are no claims that the Company's Intellectual Property Rights or the use
or ownership thereof by the Company infringes, violates or conflicts with any
such right of any third party.

         2.7. Taxes. Except as set forth on Schedule 2.7, the Company has
accurately prepared and timely filed all federal, state and other tax returns
required by law to be filed by it, has paid or made provision for the payment of
all taxes shown to be due and all additional assessments, and adequate
provisions have been made and are reflected in the Company's financial
statements for all current taxes and other charges to which the Company is
subject and which are not currently due and payable.

         2.8. Disclosure. There is no fact within the knowledge of the Company
or any of its executive officers which has not been disclosed herein or in
writing by them to the Purchaser and which materially adversely affects, or in
the future in their opinion may, insofar as they can now foresee, materially
adversely affect the business, operations, properties, Intellectual Property
Rights, assets or condition, financial or other, of the Company. Without
limiting the foregoing, the Company has no knowledge that there exists, or there
is pending or planned, any patent, invention, device, application or principle
or any statute, rule, law, regulation, standard or code which would materially
adversely affect the business, operations, Intellectual Property Rights, affairs
or financial condition of the Company.

         2.9. Brokers or Finders. No Person has or will have, as a result of the
transactions contemplated by this Agreement, any right, interest or valid claim
against or upon the Purchaser

<PAGE>   11

for any commission, fee or other compensation as a finder or broker because of
any act or omission by the Company or its respective agents.

         2.10. Capitalization; Status of Capital Stock. As of the date hereof,
the Company had a total authorized capitalization consisting of 100,000,000
shares of Common Stock, .01 par value and 10,000,000 Preferred Stock, .01 par
value. As of Nov 30, 2000, 16,424,000 shares of Common Stock were issued and
outstanding. All the outstanding shares of capital stock of the Company have
been duly authorized, and are validly issued, fully paid and non-assessable.
Other than the Class A. Preferred Stock, none of the Company's outstanding
securities or authorized capital stock or the Shares is subject to any rights of
redemption, repurchase, rights of first refusal, preemptive rights or other
similar rights, whether contractual, statutory or otherwise, for the benefit of
the Company, any stockholder, or any other Person. There are no restrictions on
the transfer of shares of capital stock of the Company other than those imposed
by relevant federal and state securities laws and as otherwise contemplated by
this Agreement. There are no agreements, understandings, trusts or other
collaborative arrangements or understandings concerning the voting or transfer
of the capital stock of the Company to which the Company is a party. The Company
does not have outstanding, and has no obligation to grant or issue, any "phantom
stock" or other right measured by the profits, revenues or results of operations
of the Company or any portion thereof; or any similar rights.

         2.11. SEC Reports. The Company has furnished the Purchaser with true
and complete copies of its reports on Form 8-K filed July 4, 2000., Form 10-QSB
for the quarter Oct. 26, 2000, and its Transitional Report on Form 10-SB12G/A
for Aug. 31, 2000 (the "Current Reports") which constitute the only documents
that the Company was required to file with the SEC since January 8, 2001. As of
their respective filing dates, the Current Reports and all other filings made by
the Company under the Act or the Securities Exchange Act of 1934, as amended
(the "1934 Act")(collectively, the "SEC Reports"), complied with the
requirements of the Act or the 1934 Act, as the case may be, and none of such
filings contained any untrue statement of a material fact or omitted to state
any 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.

         2.12. Books and Records. The books of account, ledgers, order books,
records and documents of the Company accurately and completely reflect all
material information relating to the business of the Company, the location and
collection of its assets, and the nature of all transactions giving rise to the
obligations or accounts receivable of the Company.

<PAGE>   12

                                   ARTICLE III

                                  MISCELLANEOUS

         3.1. No Waiver; Cumulative Remedies. No failure or delay on the part of
any party to this Agreement in exercising any right, power or remedy hereunder
shall operate as a waiver thereof; nor shall any single or partial exercise of
any such right, power or remedy preclude any other or further exercise thereof
or the exercise of any other right, power or remedy hereunder. The remedies
herein provided are cumulative and not exclusive of any remedies provided by
law.

         3.2. Amendments; Waivers and Consents. Any provision in the Agreement
to the contrary notwithstanding, and except as hereinafter provided, changes in,
termination or amendments of or additions to this Agreement may be made, and
compliance with any covenant or provision set forth herein may be omitted or
waived, if either Party shall obtain consent thereto in writing from the other
Party. Any waiver or consent may be given subject to satisfaction of conditions
stated therein and any waiver or consent shall be effective only in the specific
instance and for the specific purpose for which given.

         3.3. Addresses for Notices. Any notice or other communication required
or permitted to be given hereunder shall be in writing and shall be mailed by
certified mail, return receipt requested, or delivered against receipt to
Company and/or to Purchaser at the addresses for each set forth above. Any
notice or other communication given by certified mail shall be deemed given at
the time of certification thereof, except for a notice changing a party's
address which shall be deemed given at the time of receipt thereof.

         3.4. Costs; Expenses and Taxes. Upon execution of this Agreement and
with each delivery of the Purchase Price as set forth in 1.3, the Company shall
pay no monies in the aggregate, to cover fees and disbursements of counsel to
the Purchaser incurred in connection with the negotiation, drafting and
completion of the Transaction Documents and all related matters. The Company
shall pay any and all stamp, or other similar taxes payable or determined to be
payable in connection with the execution and delivery of this Agreement, the
issuance of any securities and the other instruments and documents to be
delivered hereunder or thereunder, and agrees to save the Purchaser harmless
from and against any and all liabilities with respect to or resulting from any
delay in paying or omission to pay such taxes.

         3.5. Effectiveness; Binding Effect; Assignment. This Agreement shall be
binding upon and inure to the benefit of the Company, the Purchaser and the
respective successors and assigns.

         3.6. Survival of Representations and Warranties. All representations
and warranties made in the Transaction Documents, the Shares, or any other
instrument or document delivered in connection herewith or therewith, shall
survive the execution and delivery hereof or thereof.

<PAGE>   13

         3.7. Prior Agreements. The Transaction Documents executed and delivered
in connection herewith constitute the entire agreement between the parties with
respect to the subject matter set forth herein and supersede any prior
understandings or agreements concerning the subject matter hereof.

         3.8. Severability. The provisions of the Transaction Documents are
severable and, in the event that any court of competent jurisdiction shall
determine that any one or more of the provisions or part of a provision
contained therein shall, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provision or part of a provision of such Transaction
Document and the terms of the Shares shall be reformed and construed as if such
invalid or illegal or unenforceable provision, or part of a provision, had never
been contained herein, and such provisions or part reformed so that it would be
valid, legal and enforceable to the maximum extent possible.

         3.9. Governing Law; Venue. (a)This Agreement shall be enforced,
governed and construed in accordance with the laws of the State of Texas without
giving effect to choice of laws principles or conflict of laws provisions. Any
suit, action or proceeding pertaining to this Agreement or any transaction
relating hereto shall be brought to the state courts of, or the federal courts
in Dallas, Texas, and the undersigned hereby irrevocably consents and submits to
the jurisdiction of such courts for the purpose of any such suit, action, or
proceeding. Purchaser acknowledges and agrees that venue hereunder shall lie
exclusively in Dallas County.

              (b) Purchaser hereby waives, and agrees not to assert against the
Company, or any successor assignee thereof, by way of motion, as a defense, or
otherwise, in any such suit, action or proceeding, (i) any claim that the
Purchaser is not personally subject to the jurisdiction of the above-named
courts, and (ii) to the extent permitted by applicable law, any claim that such
suit, action or proceeding is brought in an inconvenient forum or that the venue
of any such suit, action or proceeding is improper or that this Agreement may
not be enforced in or by such courts.

         3.10. Headings. Article, section and subsection headings in this
Agreement are included herein for convenience of reference only and shall not
constitute a part of this Agreement for any other purpose.

         3.11. Counterparts. This Agreement may be executed in any number of
counterparts, all of which taken together shall constitute one and the same
instrument, and any of the parties hereto may execute this Agreement by signing
any such counterpart.

         3.12. Further Assurances. From and after the date of this Agreement,
upon the request of the Purchaser or the Company, the Company and the Purchaser
shall execute and deliver such instruments, documents and other writings as may
be reasonably necessary or desirable to confirm and carry out and to effectuate
fully the intent and purposes of the Transaction Documents and the Shares.

<PAGE>   14

         IN WITNESS WHEREOF, the parties hereto have caused this Stock Purchase
Agreement to be executed as of the date first above written.

                                    TBX RESOURCES INC. CORPORATION

                                    By:
                                          -------------------------------------
                                          Name: Tim P. Burroughs
                                          Title: President (TBX Resources Inc.)

                                    -------------------------------------------

                                    By:
                                          -------------------------------------
                                          Name:
                                          Title:

<PAGE>   15

                            STOCK PURCHASE AGREEMENT

                                  SCHEDULE 2.4
                                   LITIGATION

<PAGE>   16

                            STOCK PURCHASE AGREEMENT

                                  SCHEDULE 2.7
                                      TAXES

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00020-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00020-of-00352.parquet"}]]