THIS CONVERTIBLE  PROMISSORY  NOTE, AND THE UNDERLYING  SECURITIES INTO WHICH IT
MAY BE CONVERTED,  HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED,  AND MAY NOT BE SOLD,  TRANSFERRED  ASSIGNED OR HYPOTHECATED UNLESS (i)
THERE IS AN  EFFECTIVE  REGISTRATION  STATEMENT  UNDER  SUCH ACT  COVERING  SUCH
SECURITIES  OR (ii) THE MAKER  RECEIVES  AN OPINION  OF  COUNSEL  FOR THE HOLDER
REASONABLY   SATISFACTORY  TO  THE  MAKER  STATING  THAT  SUCH  SALE,  TRANSFER,
ASSIGNMENT  OR  HYPOTHECATION  IS EXEMPT FROM THE  REGISTRATION  AND  PROSPECTUS
DELIVERY REQUIREMENTS OF SUCH ACT.

                           CONVERTIBLE PROMISSORY NOTE

$117,000.00                                                    February 28, 2005

      FOR VALUE RECEIVED, the undersigned, Cyber Defense Systems, Inc. (the
"Maker"), promises to pay to the order of Joseph Theismann (the "Holder"), at
the address set forth herein, or at such other place as the Holder may from time
to time designate by written notice to the Maker, the principal sum of
$117,000.00 paying the existing note herein attached as Exhibit A, together with
interest at the rate of 18% per annum, in accordance with the terms set forth
below.

      The Maker and the Holder further agree as follows:

      1. Payment.

      It is the intention of the Parties that this Note may be paid, and the
debt it evidences satisfied by, the payment of cash, or by the delivery of
shares of the Maker's Class A Common Stock, Par Value $0.001 per share (the
"Class A Common" or the "Payment Shares").

      Accordingly, the Parties agree as follows:

      (a) Beginning on April 30, 2005, and on the last day of each month for the
next succeeding 6 moths, the Maker shall reduce the principal balance of this
Note by an amount equal to 1/6 of the principal; provided, however, that the
last payment of principal, which shall be due on September 30, 2005, shall
include accrued and unpaid interest at the rate of 18% per annum.

      (b) The Maker may reduce the principal balance of this Note by the payment

            (i) in cash, in which case

<PAGE>

                  (A) that payment in cash which reduces the principal balance
            of this Note to Zero, shall include accrued and unpaid interest at
            the rate of 18% per annum; or, at the option of the Maker, and at
            any time during the term of this Note

            (ii) by the issuance and delivery by the Maker to the Holder of the
      Payment Shares, as that number of those shares may be adjusted for splits,
      reclassifications, etc., so as to enable the Maker to deliver the Payment
      Shares on a fully-diluted basis, in which case, and at that time,

                  (A) the Maker shall inform the Holder of the Maker's intent to
            reduce principal by the issuance of Payment Shares, so that the
            Holder may serve a Notice of Conversion upon the Maker as provided
            in this Note;

                  (B) the entire unpaid principal balance shall be due and
            payable;

                  (C) no accrued interest shall be due and owing;

                  (D) when Payment Shares evidencing the then entire unpaid
            principal balance of this Note are delivered to the Holder, the debt
            evidenced by this Note shall be satisfied; and

                  (E) the Holder shall not thereafter be entitled to demand and
            receive cash in payment of the principal and accrued interest
            evidenced by this Note

      2. Representations, Warranties and Undertakings of the Maker.

      In connection with this Note, the Maker represents to the Holder as
follows:

      (a) The Maker

            (i) is a corporation duly organized and validly existing under the
      laws of the State of Florida and is in good standing under such laws with
      its principal executive office located in the State of Florida; and

            (ii) the Maker has full power and legal capacity to enter into this
      Note.

      (b) The Payment Shares, when issued, shall be duly and validly issued,
authorized, fully paid, and non-assessable.

      (c) This Note constitutes valid and legally binding obligations of the
Maker, enforceable in accordance with its terms, except

            (i) as limited by applicable bankruptcy, insolvency, reorganization,
      moratorium, fraudulent conveyance, and any other laws of general
      application affecting enforcement of creditors' rights generally, and


                                       2
<PAGE>

            (ii) as limited by laws relating to the availability of specific
      performance, injunctive relief, or other equitable remedies.

      (d) The execution, delivery and performance of this Note will not result
in any material violation of, be in conflict with, or constitute a default
under, with or without the passage of time or the giving of notice

            (i) any provision of any judgment, decree or order to which the
      Maker is a party or by which it is bound; or

            (ii) any material contract, obligation or commitment to which the
      Maker is a party.

      (e) From shares of its authorized, but un-issued Class A Common, the Maker
shall reserve a sufficient number of shares thereof, adjusted for splits,
reclassifications, etc. to enable the Maker to deliver the Payment Shares on a
fully-diluted basis.

      (f) There is no action, suit or proceeding pending, or to the knowledge of
the Maker, threatened against the Maker, before any court or arbitrator or any
government body, agency or official, which would have a material adverse affect
on Maker's operations or financial condition.

      (g) There is no fact known to the Maker that has not been publicly
disclosed by the Maker or disclosed in writing to the Holder which could
reasonably be expected to have a material adverse effect on the condition
(financial or otherwise) or in the earnings, business affairs, properties or
assets of the Maker, or could reasonably be expected to materially and adversely
affect the ability of the Maker to perform its obligations pursuant to this
Note.

      (h) The information furnished by the Maker to Holder for purposes of or in
connection with this Agreement or any transaction contemplated hereby, does not
contain any untrue statement of material fact or omit to state a material fact
necessary in order to make the statements contained therein, in light of the
circumstances under which they are made, not misleading.

      (i) The Maker is a publicly-held corporation whose shares of Class A
Common Stock are publicly traded and quoted on the OTC Electronic Bulletin Board
(the "OTC-BB"), under the symbol "CYDF", and the Maker is required to, and does
file, periodic reports with the United States Securities and Exchange
Commission.

      (j) William C. Robinson, the CEO of the Maker, is also the CEO and
Chairman of the Board of Directors of Proxity. Proxity specializes in the
deployment and integration of security protection technology and government
contract fulfillment. Trading in the Common Stock of Proxity is reported in the
inter-dealer quotation system maintained by the National Quotation Bureau, Inc.
and the Pink Sheets under the symbol "PRXT." Mr. Robinson is also the General
Partner of Cherokee Raiders, L.P., a family limited partnership ("Cherokee").

      Both Proxity and Cherokee are Affiliates of the Maker.


                                       3
<PAGE>

      (k) As at February 1, 2005, the Capitalization of the Maker consisted of

            (i) 200,000,000 shares of Class A Common Stock, Par Value $0.001 per
      share, each share having one vote on matters brought before the
      stockholders of which 25,921,562 shares are issued and outstanding and
      owned by the following persons or groups:

                 Name                                        Number
                  of                                       of Shares of
              Shareholder                                  Class A Owned

               Cherokee                                      6,750,000
               Proxity                                      18,750,000
               Others (Including
               Members of the Public)                          421,562

               TOTAL                                        25,921,562

            (ii) 200,000,000 shares of Class B Common Stock, Par Value $0.001
      per share, each share having 1,000 votes on matters brought before the
      stockholders, of which 150,000 shares are issued and outstanding and owned
      by the following persons:

                 Name                                         Number
                  of                                        of Shares of
              Shareholder                                   Class B Owned

               Cherokee                                        150,000

            (iii) 2 shares of Class C Common Stock, Par Value $0.001 per share,
      each share having one vote on matters brought before the stockholders, of
      which 2 shares are issued and outstanding and owned by the following
      persons:

                     Name                                       Number
                     of                                      of Shares of
                 Shareholder                                 Class C Owned

                  Cherokee                                        1
                  Proxity                                         1

            (iv) 100,000,000 shares of Class A Preferred Stock, Par Value $0.001
      per share, of which no shares are issued and outstanding.


                                       4
<PAGE>

      (l) As at February 1, 2005, Cherokee and Proxity, who are Affiliates of
the Maker, owned a total of 25,500,000 shares of the Class A Common Stock, Par
Value $0.001 per share, of the Maker, or 98.37 % of the Issued and Outstanding
Class A Common Stock of the Maker. In addition, Cherokee owns 150,000 shares of
the Class B Common Stock, Par Value $0.001 per share, of the Maker, each of
which Class B shares is entitled to 1,000 votes on matters brought before the
Shareholders. Thus, the Maker is controlled by its Affiliates, Cherokee and
Proxity.

      (m) As at February 1, 2004, Cherokee owned or had control of
88,60,000shares of the Common Stock, Par Value $0.001 per share, of Proxity, or
31.47 % of the Issued and Outstanding Common Stock of Proxity, there being
300,000,000 shares Authorized, of which 281,545,000 shares are Issued and
Outstanding.

      (n) Mr. Robinson, who is the CEO of Proxity, and of the Maker, and of
Cyber Aero, together with his wife and children own 6,047,027 shares, or 2.15 %
of the Issued and Outstanding Common Stock of Proxity.

      (o) As a result of a merger of a former subsidiary of the Maker called On
Alert Systems, Inc. into the Maker, the Maker has assumed prior obligations
which On Alert had to either Cherokee or Proxity, so that, as at February
1,2005, the Maker was indebted to Cherokee and Proxity in excess of
approximately $1,507,271.24.

      3. Representations and Warranties of the Holder.

      In connection with this Note, the Holder represents to the Maker as
follows:

      (a) The Holder will transfer the $117,000.00 contemplated by this Note, to
the Maker within seven business days of the execution of this note.

      (b) The Holder has full power and legal capacity to enter into this Note.

      (c) This Note constitutes valid and legally binding obligations of the
Holder, enforceable in accordance with its terms, except

            (i) as limited by applicable bankruptcy, insolvency, reorganization,
      moratorium, fraudulent conveyance, and any other laws of general
      application affecting enforcement of creditors' rights generally, and

            (ii) as limited by laws relating to the availability of specific
      performance, injunctive relief, or other equitable remedies.

      (d) The execution, delivery and performance of this Note will not result
in any material violation of, be in conflict with, or constitute a default
under, with or without the passage of time or the giving of notice

            (i) any provision of any judgment, decree or order to which the
      Holder is a party or by which it is bound; or


                                       5
<PAGE>

            (ii) any material contract, obligation or commitment to which the
      Holder is a party.

      (e) The Holder is not, and on the Maturity Date, will not be, an affiliate
of the Maker.

      (f) The Holder is an "accredited investor" as defined in Rule 501 of
Regulation D promulgated under the Securities Act of 1933, as amended (the
"Securities Act"), and the Holder is accepting this Note and the Payment Shares
for his own account.

      (f) The Holder understands that (i) this Note and the Payment Shares are,
and when issued, respectively, will not be registered under the Securities Act;
(ii) that they are being offered and sold to the Holder in reliance on specific
exemptions from the registration requirements of Federal and State securities
laws; and (iii) that the Maker is relying upon the truth and accuracy of the
representations, warranties, agreements, acknowledgments and understandings of
the Holder set forth herein in order to determine the applicability of such
exemptions and the suitability of the Holder and any purchaser from the Holder
to acquire this Note and the Payment Shares.

      (g) The Holder has had an opportunity to receive and review all material
information and financial data and to discuss with the officers of the Maker,
all questions relating to the securities, financial condition, operations and
prospects of Maker have been answered to the Holder's satisfaction, and, in that
connection, the Holder has had the opportunity to review those filings made by
the Maker with the United States Securities and Exchange Commission.

      (h) The Holder acknowledges that the acceptance of this Note and the
Payment Shares involve a high degree of risk. The Holder has such knowledge and
experience in financial and business matters that he is capable of evaluating
the merits and risks of accepting this Note and the Payment Shares, and the
Holder can afford a complete loss of his investment. The Holder understands that
this Note and the Payment Shares are not being registered under the 1933 Act, or
under any state securities laws, and therefore, the Holder must bear the
economic risk of this investment for an indefinite period of time.

      4. Receipt of the Payment Shares.

      (a) To receive the Payment Shares in payment and in satisfaction of the
then principal unpaid balance of this Note, the Holder shall

            (i) complete and sign a notice of conversion (the "Notice of
      Conversion") in the form attached hereto as Exhibit B and deliver it,
      together with original of this Note, to the Maker at the Maker's address
      set forth below; and

            (ii) sign such other documents or instruments as may be necessary or
      appropriate to complete the conversion.


                                       6
<PAGE>

      (b) Within five (5) business days of receipt by the Maker of the Notice of
Conversion, the Maker shall deliver (a) stock certificate(s) representing the
Payment Shares, the number of which shares shall adjusted for splits,
reclassifications, etc. to enable the Maker to deliver the Payment Shares on a
fully-diluted basis.

      (c) Until registered pursuant to the Securities Act, or until otherwise
eligible to be sold pursuant to an exemption therefrom, the Payment Shares shall
be "Restricted", as the term "Restricted is defined pursuant to Rule 144
promulgated under the Securities Act, and the Payment Shares shall bear a
Restrictive Legend.

      (d) The conversion price shall be equal to a figure which is 50% of the
preceding 30 day average closing bid price not to exceed $1.17 a share for the
Maker's Class A Common as reported on the OTC Electronic Bulletin Board (the
"OTC-BB"), or any exchange on which shares of the Maker's Common Stock are
traded, for any trading day on which the Notice of Exchange is received by the
Maker (the "Conversion Price"). To determine the number of Payment Shares
issuable upon conversion, the Maker shall divide the dollar amount of the debt
evidenced by this Note by the Conversion Price. Upon conversion, Maker shall
deliver a check to Holder for payment of any fractional share that remains
outstanding.

      (e) No interest shall be paid on, or with respect to, a principal balance
which is reduced by Conversion.

      (f) By way of example to avoid future misunderstandings, if the Maker were
to be indebted to the Holder in what was then an unpaid principal amount of, for
example $200,000.00, and the Holder served a Notice of Conversion on a day in
which the highest closing bid price of the Maker's Class A Common Stock as
reported on the OTC Electronic Bulletin Board was $4.00 per share, the Holder
would be entitled to receive 100,000 shares of Class A Common Stock having a
market value of $400,000.00, as follows:

            (i) The preceding 30 day average of the closing bid average closing
      bid price of the Maker's Class A Common Stock as reported on the OTC
      Electronic Bulletin Board on that day was $4.00;

            (ii) 50% of $2.34 is $1.17;

            (iii) $117,000.00 divided by $1.17 is 100,000 shares;

            (iv) market price of $1.17 times 100,000 shares is $117,000.00; and

            (v) upon receipt of the Payment Shares, the Note would be satisfied

      5. Registration.

      (a) If, within 120 days from the receipt of the Payment Shares, the
Restrictive Legend affixed to the Certificate(s) evidencing such shares has not
been removed, then the Maker shall be required, upon the demand of the Holder,
and at the Maker's expense, to affect the registration of all of the Payment
Shares under the Securities Act. The Maker shall file such a Registration
Statement within 30 days of Holder's demand, and the Maker shall use its good
faith diligent efforts to cause such Registration Statement to become effective
as soon as practicable thereafter.


                                       7
<PAGE>

      (b) The Maker and the Holder shall cooperate in good faith in connection
with the furnishings of information required for such registration and the
taking of such other actions as may be legally or commercially necessary in
order to effect such registration. Such good faith diligent efforts shall
include, but not be limited to, promptly responding to all comments received
from the staff of the SEC, providing the Holder's counsel with a contemporaneous
copy of all written communications from and to the staff of the SEC with respect
to such Registration Statement and promptly preparing and filing amendments to
such Registration Statement which are responsive to the comments received from
the staff of the SEC.

      (c) Once declared effective by the SEC, the Maker shall cause such
Registration Statement to remain effective until the earlier of (i) the sale by
the Holder of all Payment Shares registered or (ii) 120 days after the Effective
Date of such Registration Statement.

      (d) In the event the Maker undertakes to file a Registration Statement
with respect to the Payment Shares (or a Registration Statement which includes
the Payment Shares along with other securities of the Maker), upon the
effectiveness of such Registration Statement, the Holder shall have the option
to sell the Payment Shares pursuant to such Registration Statement.

      6. Default.

      If one or more of the following described event (the "Events of Default")
shall occur and continue for 30 days, unless a different time frame is noted
below:

      (a) the failure of the Maker to make any payment, whether in cash or with
Payment Shares, when due; or

      (b) the failure of the Maker to reserve a sufficient number of shares of
its authorized, but un-issued Class A Common, adjusted for splits,
reclassifications, etc. to enable the Maker to deliver the Payment Shares on a
fully-diluted basis; or

      (c) any of the representations or warranties made by the Maker herein, or
in any certificate or financial or other written statements heretofore or
hereafter furnished by or on behalf of the Maker in connection with the
execution and delivery of this Note shall be false or misleading in any material
respect at the time made; or

      (d) the Maker shall (i) become insolvent; (ii) admit in writing its
inability to pay its debts generally as they mature; (iii) make an assignment
for the benefit of creditors or commence proceedings for its dissolution; (iv)
apply for or consent to the appointment of a trustee, liquidator or receiver for
its or for a substantial part of its property or business; (v) file a petition
for bankruptcy relief, consent to the filing of such petition or have filed
against it an involuntary petition for bankruptcy relief, all under federal or
state laws as applicable; or

      (e) the failure of the Maker to timely file and timely process a
Registration Statement with respect to the Payment Shares, as contemplated by
Section 5, hereof, then, or at any time thereafter, unless cured, and in each
and every such case, unless such Event of Default shall have been waived in
writing by the Holder (which waiver shall not be deemed to be a waiver of any
subsequent default) at the option of the Holder and in the Holder's sole
discretion, the Holder may consider this Note immediately due and payable,
without presentment, demand, protest or (further) notice of any kind (other than
notice of acceleration), all of which are hereby expressly waived, anything
herein or in any note or other instruments contained to the contrary
notwithstanding, and the Holder may immediately, and without expiration of any
period of grace, enforce any and all of the Holder's rights and remedies
provided herein or any other rights or remedies afforded by law.


                                       8
<PAGE>

      7. Waivers.

      (a) The Maker waives demand, presentment, protest, notice of protest,
notice of dishonor, and all other notices or demands of any kind or nature with
respect to this Note other than the initial demand for payment.

      (b) The Maker agrees that a waiver of rights under this Note shall not be
deemed to be made by Holder unless such waiver shall be in writing, duly signed
by Holder, and each such waiver, if any, shall apply only with respect to the
specific instance involved and shall in no way impair the rights of Holder or
the obligations of Maker in any other respect at any other time.

      (c) The Maker agrees that in the event Holder accepts partial payment of
this Note, such acceptance shall not be deemed to constitute a waiver of any
right to demand the entire unpaid balance of this Note at any time in accordance
with the terms of this Note.

      8. Collection Costs.

      If the indebtedness represented hereby is not paid in full when due, the
Maker will, upon demand, pay to the Holder the amount of any and all reasonable
costs and expenses, including, without limitation, the reasonable fees and
disbursements of its counsel (whether or not suit is instituted) and of any
experts and agents, which the Holder may incur in connection with the following:
(i) the enforcement of this Note, and (ii) the enforcement of payment of all
obligations of Maker by any action or participation in, or in connection with
the U. S. Bankruptcy Code, or any successor statute hereto.

      9. Assignment of Note.

      (a) The Maker may not assign its obligations under this Note without the
prior written consent of the Holder, which consent may be withheld in the
Holder's sole discretion.

      (b) The Holder may not negotiate this Note without the prior written
consent of the Maker, which consent may be withheld in the Maker's sole
discretion.


                                       9
<PAGE>

      (c) Any attempted assignment or negotiation hereof except as provided for
herein shall be null and void and of no force and effect against the person
attempting to assign or negotiate this Note.

      10. Applicable Law; Resolution of Disputes; Venue; Jurisdiction; Waiver of
Jury Trial.

      (a) This Note and all questions relating to its validity, interpretation,
performance and enforcement (including, without limitation, provisions
concerning limitations of actions), shall be governed by and construed in
accordance with the laws of the State of Florida, notwithstanding any
conflict-of-laws doctrines of such state or other jurisdiction to the contrary,
and without the aid of any canon, custom or rule of law requiring construction
against the draftsman.

      (b) The Parties hereby waive trial by jury.

            IN THAT CONNECTION, THE PARTIES WAIVE THE RIGHT TO A TRIAL BY JURY
            IN ANY DISPUTE IN CONNECTION WITH OR RELATING TO THIS NOTE, ANY
            RELATED AGREEMENT OR ANY MATTERS DESCRIBED OR CONTEMPLATED HEREIN OR
            THEREIN, AND AGREES TO TAKE ANY AND ALL ACTION NECESSARY OR
            APPROPRIATE TO EFFECT SUCH WAIVER.

      (c) The Parties hereto irrevocably agree and consent that all disputes
concerning this Note or any claim or issue of any nature whatsoever arising from
or relating to this Note or to the corporate steps taken to enter into it
(including, without limitation, claims for alleged fraud, breach of fiduciary
duty, breach of contract, tort, etc.) which cannot be resolved within reasonable
time through discussions between the Parties, shall be resolved solely and
exclusively by means of arbitration to be conducted in St. Petersburg, Florida,
which arbitration will proceed in accordance with the rules of the Arbitration
then in force in St. Petersburg, Florida, for resolution of commercial disputes.

      (d) The Parties agree that Arbitrators themselves shall have the right to
determine and to arbitrate the threshold issue of arbitrability itself, that the
decision of the Arbitrators shall be final, conclusive, and binding upon the
Parties, and that a judgment upon the award may be obtained and entered in any
federal or state court of competent jurisdiction.

      (e) In addition, the Parties waive, to the maximum extent permitted by
law, any objection, including any objection based on forum non conveniens, to
the bringing of any such proceeding in such forum.


                                       10
<PAGE>

      11. Notice.

      (a) Any notice, request, instruction or other document required by the
terms of this Agreement to be given to any other Party hereto shall be in
writing and shall be given either

            (i) by telephonic facsimile, in which case notice shall be
      presumptively deemed to have been given at the date and time displayed on
      the sender's transmission confirmation receipt showing the successful
      receipt thereof by the recipient; or

            (ii) by hand delivery or Federal Express or other method in which
      the date of delivery is recorded by the delivery service, in which case
      notice shall be presumptively deemed to have been given at the time that
      records of the delivery service indicate the writing was delivered to the
      addressee; or

            (iii) by prepaid telegram, in which case notice shall be
      presumptively deemed to have been given at the time that the records of
      the telegraphic agency indicate that the telegram was telephoned or
      delivered to the recipient or addressee, as the case may be; or

            (iv) by U.S. mail to be sent by "Priority Overnight" registered or
      certified mail, postage prepaid, with return receipt requested, in which
      case notice shall be presumptively deemed to have been given forty-eight
      (48) hours after the letter was deposited with the United States Postal
      Service.

      (b) Notice shall be sent:

            (i) If to the Maker, to:

                  Cyber Defense Systems, Inc.
                  10901 Roosevelt Boulevard
                  Suite 100-D
                  St. Petersburg, Florida 33716

                  Voice Telephone:                   (727)  577-0878
                  Cellular Telephone                 (504)  722-7402
                  Facsimile Telephone:               (727)  577-0878

            (ii) If to the Holder, to:

                  Joseph Theismann

                  Voice Telephone:                   (703)  671  - 6823
                  Facsimile Telephone:               (703)  779  - 8149


                                       11
<PAGE>

            (iii) or to such other address as a Party may have specified in
      writing to the other Parties using the procedures specified above in this
      Section.

      12. Miscellaneous.

      (a) This Note may be altered or modified only by prior written agreement
signed by the party against whom enforcement of any waiver, change,
modification, or discharge is sought.

      (b) The covenants, terms, and conditions contained in this Note apply to
and bind the heirs, successors, executors, administrators and assigns of the
Parties.

      (c) This Note constitutes a final written expression of all the terms of
the agreement between the Parties regarding the subject matter thereof, is a
complete and exclusive statement of those terms, and supersede all prior and
contemporaneous agreements, understandings, and representations between the
Parties.

      (d) If any provision or any word, term, clause or other part of any
provision of this Note shall be invalid for any reason, the same shall be
ineffective, but the remainder of this Note shall not be affected and shall
remain in full force and effect.

      IN WITNESS WHEREOF, the Maker and the Holder have executed this Note
intending it to be effective as of the date first set forth above.

              THE SIGNATURES ON THIS NOTE ARE ON THE FOLLOWING PAGE


                                       12
<PAGE>

                               MAKER:

                               Cyber Defense Systems, Inc.

                               By:
                                  ----------------------------------------------
                               William C. Robinson, as CEO, and not Individually

                               HOLDER:

                               Joseph Theismann

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

                 EXHIBIT A TO THIS NOTE FOLLOWS ON THE NEXT PAGE


                                       13
<PAGE>

                                    EXHIBIT A


                                       14
<PAGE>

                    EXHIBIT B TO CONVERTIBLE PROMISSORY NOTE

                              NOTICE OF CONVERSION

To:      William C. Robinson, CEO                    Dated:  March 9, 2005
         Cyber Defense Systems, Inc.
         10901 Roosevelt Boulevard
         Suite 100-D

      The  undersigned   hereby  requests  to  receive  payment  under,  and  in
satisfaction of the debt evidenced by, that certain Convertible  Promissory Note
in the Principal Amount of $117,000.00  between Cyber Defense Systems,  Inc., as
the Maker thereof,  and the Undersigned.  as the Holder thereof,  in the form of
100,000  shares of the Maker's Class A Common Stock,  Par Value $0.001 per share
(the "Payment Shares").

      The original Convertible Promissory Note is attached to this Letter.

      Please issue a certificate or certificates representing the Payment Shares
registered in the name of the Undersigned. as follows:

            Number of Certificates:            1

            Number of Shares in
            Each Certificate:                  100,000

      The certificate(s) should be delivered to me at

            5661 Columbia Pike
            Falls Church, VA 22041

      Thank you,

                                       Joseph Theismann

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

                                       15