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                                                                   EXHIBIT 10.15


                                PROMISSORY NOTE
                                        

                                                       Dated:  December 31, 1997



Principal Amount:  $79,340.45                          State of Colorado

     FOR VALUE RECEIVED, the undersigned hereby jointly and severally promise to
pay to the order of Matrix Capital Corporation.

Seventy-nine Thousand Three Hundred Forth and 45/100...................., the
sum of Dollars ($79,340.45                        ), together with interest
thereon at the rate of Prime. Per annum on the unpaid balance. Said sum shall be
paid in the manner following:

     All principal and interest shall be due on December 31, 1998.

     All payment shall be first applied to interest and the balance to
principal. This note may be prepaid, at any time, in whole or in part, without
penalty. All prepayments shall be applied in reverse order of maturity.

     This note shall at the option of any holder hereof be immediately due and
payable upon the failure to make any payment due hereunder within   N/A   days
of its due date.

     This note at the option of any holder hereof may be extended on an annual
basis for increments of one (1) year. The terms and interest rate will remain
constant.

     In the event this note shall be in default, and placed with an attorney for
collection, then the undersigned agree to pay all reasonable attorney's fees and
costs of collection. Payments not made within five (5) days of due date shall be
subject to a late charge of 2% of said payment. All payments hereunder shall be
made to such address as may from time to time be designed by any holder hereof.

     The undersigned and all other parties to this note, whether as endorsers,
guarantors or sureties, agree to remain fully bound hereunder until this note
shall be fully paid and waive demand, presentment and protest and all notices
thereto and further agree to remain bound, notwithstanding any extension,
renewal, modification, waiver, or other indulgence by any holder or upon the
discharge or release of any obligor hereunder to this note, or upon the
exchange, substitution, or release of any collateral granted as security for
this note. No modification or indulgence by any holder hereof shall be binding
unless in writing: and any indulgence on any one occasion shall not be an
indulgence for any other or future occasion. Any modification or change of
terms, hereunder granted by any holder hereof, shall be valid and binding upon
each of the undersigned, notwithstanding the acknowledgment of any of the
undersigned, and each of the undersigned does hereby irrevocably grant to each
of the others a power of attorney to enter into any such modification on their
behalf. The rights of any holder hereof shall be 
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cumulative and not necessarily successive. This note shall take effect as sealed
instrument and shall be construed, governed and enforced in accordance with the
laws of the State first appearing at the head of this note. The undersigned
hereby execute this note as principals and not as sureties.

Signed in the presence of:


                /s/
-----------------------------------
David W. Kloos, Matrix Capital Corporation


                                   GUARANTY


     We the undersigned jointly and severally guaranty the prompt and punctual
payment of all monies due under the aforesaid note and agree to remain bound
until fully paid.

In the presence of:


                /s/
-----------------------------------
D. Mark Spencer