Exhibit 4.1

                                 PROMISSORY NOTE


$100,000.00                                                       April 28, 2004

         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. (hereinafter referred to as "Payee"), the principal sum of
One Hundred Thousand Dollars  ($100,000.00).  The principal and interest on this
Note shall be due and payable in lawful  money of the United  States of America.
All  correspondence and notices should be mailed to the offices of Payee at 8200
Springwood Drive, Suite 230, Irving , Texas 75063, 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 six and  one-half  percent (6 1/2
%).  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 May 1, 2004.

         2.     Payment of Note.  The  principal  balance  of,  and all  accrued
unpaid  interest  on,  this Note shall be due and  payable  on August 28,  2004,
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  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 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 of
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.     Successors and Assign.  This Note shall bind Maker's  successors
and assigns.

         9.     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.

         10.    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.

         11.    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: /S/ RICHARD B. POWELL
                                        ----------------------------------------
                                        Richard B. Powell
                                        Vice President, Chief Accounting Officer





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