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                                                                   EXHIBIT 10.16





                                     A NOTE



         U.S.$4,200,000.00                                       August 5, 1998



                  FOR VALUE RECEIVED, UNITED PETROLEUM CORPORATION, a
corporation organized and existing under the laws of Delaware, CALIBUR SYSTEMS,
INC., a corporation organized and existing under the laws of Tennessee, and
JACKSON-UNITED PETROLEUM CORPORATION, a corporation organized and existing under
the laws of Kentucky (each a "Borrower" and, collectively, the "Borrowers"),
hereby jointly and severally promise to pay to the order of INFINITY INVESTORS
LIMITED, a Nevis West Indies corporation (the " Lender"), in lawful money of the
United States of America in immediately available funds, to Citibank, New York
City, ABA No. 021000089, Credit to Bear Stearns Acct. No. 0925-3186, f/c/o
Infinity Investors Limited, Acct. No. 102-05092 or such other location as the
Lender may from time to time specify, on the Maturity Date (as defined in the
Amended, Restated and Consolidated Credit Agreement, dated as of August 5, 1998
(as modified, supplemented or amended from time to time, the "Credit
Agreement")) the principal sum of U.S.$4,200,000.00 (Four Million, Two-Hundred
Thousand United States Dollars) or, if less, the unpaid principal amount of the
Calibur Consolidated Loan (as defined in the Credit Agreement) made by the
Lender pursuant to the Credit Agreement (or, in either case, so much thereof as
shall not have been repaid or paid).

                  The Borrowers promise also to pay interest on the unpaid
principal amount of the Calibur Consolidated Loan in like money to said account
from the date such Calibur Consolidated Loan is made until paid at the rates and
at the times provided in Section 2.5 of the Credit Agreement.

                  This Note is the A Note referred to in the Credit Agreement,
between the Borrowers and the Lender, and is entitled to the benefits of the
Credit Agreement and the other Credit Documents (as defined in the Credit
Agreement). As provided in the Credit Agreement, this A Note is subject to
voluntary prepayments and mandatory repayments, in whole or in part.

                  In case an Event of Default (as defined in the Credit
Agreement) shall occur and be continuing, the principal of and accrued interest
on this A Note may be declared to be due and payable in the manner and with the
effect provided in the Credit Agreement.

                  The Borrowers hereby waive presentment, demand, protest or
other notice of any kind in connection with this A Note.


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                  This A Note shall be construed in accordance with and be
governed by the law of the State of New York of the United States of America.

                                          UNITED PETROLEUM CORPORATION,
                                          a Delaware corporation



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

                                          CALIBUR SYSTEMS, INC.,
                                          a Tennessee corporation

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

                                          JACKSON-UNITED PETROLEUM
                                          CORPORATION, a Kentucky corporation



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