CONFIDENTIAL  TREATMENT  REQUESTED  BY U.S.  WIRELESS  DATA,  INC.  FOR  CERTAIN
INFORMATION CONTAINED IN PARAGRAPH 4 OF THIS AGREEMENT



U.S. WIRELESS DATA(R) INC.
Delivering The New Standard In Transaction Processing

September 18, 1997


Mr. David Ivy, Sr.
Unicard Systems, Inc.
13800 Montfort #155
Dallas, TX 75240


Dear David,

I am writing this letter of  understanding  to outline the terms of an agreement
between U.S.  Wireless Data and Unicard  Systems,  Inc. The execution of a final
agreement will result in a high speed, efficient and cost effective solution for
providing both Unicard processing and credit card transaction processing for the
current and future customers of Unicard Systems, Inc.

I have outlined  below the basic terms and  conditions  of an agreement  between
U.S.  Wireless Data ("USWD") and Unicard  Systems,  Inc. ("USI") for your review
and acceptance:

         1. Unicard  desires to incorporate  U.S.  Wireless Data's TRANZ Enabler
and CDPD wireless services to speed up the Unicard authorization process for its
current and future customers.

         2. USI  agrees  to  utilize  USWD's  TRANZ  Enabler  and CDPD  wireless
services as its  exclusive  wireless  product and  service  offering.  The TRANZ
Enabler  is  compatible  for use with the  Verifone  Zon Jr.,  TRANZ 330 and 380
terminals.

         3. USI and USWD also desire to offer credit card transaction processing
services to USI's current and future customers.

         4. USWD will provide its TRANZ Enabler and wireless  services to USI at
a rental rate of * per month.  This rental fee includes the TRANZ  Enabler,  and
CDPD wireless  services  (includes IP address,  monthly service fee and air time
usage up to 20 KB per month).  The first * monthly  rental charge will be due 30
days after  receipt of  shipment  of the units with  subsequent  monthly  rental
payments due on the first day of each month.

         5. USWD has  developed a CDPD version of the USI  terminal  application
software and has certified it for use on the USI host. The application  software
is jointly  owned by USWD and USI and may not be  licensed  for use to any other
customers without the written consent of both parties.

         6. USWD will provide USI with  detailed CDPD coverage maps to determine
CDPD coverage at all proposed deployment sites.

         7.  USWD will  provide  warranty  and  support  services  for its TRANZ
Enabler  under  normal wear and tear  conditions.  USWD will  provide USI with a
replacement   pool  (5  units)  to  swap  out  damaged  units.  Any  damaged  or
malfunctioning  units will be repaired by USWD and put back into the replacement
pool.  The  replacement  pool will be provided to USI on a no cost basis and may
only be used for replacing defective or damaged units.

         8. In the  event  that a unit is lost,  stolen  or part of a  "midnight
move",  then USWD  would  apply 50% of the rental  payments  made to date by USI
towards a $500 replacement  cost. Units damaged due to abuse will be repaired on
a time and materials basis.

         9.  USI will  become a  registered  agent  of USWD for the  purpose  of
offering credit card transaction  processing  services to its current and future
customers.

* CONFIDENTIAL TREATMENT HAS BEEN REQUESTED BY U.S. WIRELESS DATA, INC. FOR THIS
PORTION OF THIS DOCUMENT PURSUANT TO COMMISSION RULE 24b-2. THE OMITTED MATERIAL
HAS BEEN FILED SEPARATELY WITH THE COMMISSION.

                                       -4-
<PAGE>
         10. USWD will develop and certify a single USI and Credit Card terminal
application  for use with a Verifone  TRANZ 330 or 380  terminal.  This terminal
application will allow a merchant to process membership cards with USI or credit
cards with USWD's  credit card  processor.  USWD will develop  this  application
software at its own expense and will  retain 100%  ownership  of the code.  USWD
will  license  the  hybrid  application  software  to USI  free  of  charge  for
utilization only with USI's current and future customer base.

         11.  USI and USWD  agree to split any  recurring  revenue  earned  from
credit card transaction  processing on an equal (50/50) basis. Recurring revenue
is defined as the margin  between USWD's "buy rate" and the discount rate quoted
to the  merchant  net of any  fixed  monthly  costs.  USWD will fund USI for its
portion of recurring  revenue  earned on the 20th of each month.  The  recurring
revenue fees only apply to Visa and Mastercard  transactions.  American  Express
and  Discover  quote  discount  rates to the  merchant  directly,  and we cannot
participate  in any  recurring  discount  rate  fees for AMEX or  Discover  Card
transactions.

         12. USI will provide USWD with an initial  purchase order for 400 units
with   specified   delivery   dates  upon  the  acceptance  of  this  letter  of
understanding.

         13. Upon the signing of the acceptance of this letter of understanding,
USI agrees to allow USWD to issue a press release  describing the general nature
of this agreement.

         * #14 below
I believe this outline covers the basic terms of an agreement that can make this
relationship a mutual success for our respective companies. If agreeable, please
indicated  by signing  below and  return it to me with a purchase  order for the
first 400 units at your earliest convenience.  Upon receiving your acceptance, I
will  have  our  legal  firm  draft  a  formal  agreement  to be  executed  that
incorporates the terms and conditions stated above.

Sincerely,                         Accepted this 18th day of September, 1997

By: /s/ Rod Stambaugh                     By:  /s/ David M. Ivy  
    -----------------                     -----------------------
Name: Rod Stambaugh                       Name:  David M. Ivy 
Title:President                           Title: President    

cc:  Evon Kelly, CEO


         14. The parties agree that certain trade secrets, customer lists and/or
other techniques used in the present business of USI will or may be disclosed to
USWD. Therefore, USWD agrees that it will not offer the same services covered by
this  agreement to any other  company for  purposes of private  club  membership
management in Texas.

<PAGE>

UNICARD SYSTEMS, INC.
---------------------
                                                             13800 MONTFORT #155
                                                             DALLAS, TEXAS 75240
                                                           OFFICE (972) 385-4000
                                                              FAX (972) 991-8114


TO:               U.S. WIRELESS DATA
                  4851 INDEPENDENCE ST. #189
                  WHEAT RIDGE, COLORADO 80033


                                 PURCHASE ORDER

DATE:    SEPTEMBER 18, 1997

NUMBER:  97-155-HW

AUTHORIZED BY:      /s/ David M. Ivy, President


AMOUNT ORDERED         ITEM          UNIT COST     SHIPPING DATE

         400       TRANZ Enabler         *               **

*        Per contract agreement

**       100 Units ASAP
         300 Units as directed prior to 6-1-98




                            SATELLITE UNICARD NETWORK
                                 THE SUN SYSTEM