FORM OF BRIDGE NOTE EXTENSION AND CONVERSION March 15, 1999 Ladies and Gentlemen: This letter agreement sets forth our mutual agreement with respect the Convertible Promissory Note, dated October 9, 1997, in the principal amount of $25,000.00 issued...

                                     FORM OF
                      BRIDGE NOTE EXTENSION AND CONVERSION

March 15, 1999

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Ladies and Gentlemen:

This letter agreement sets forth our mutual agreement with respect the
Convertible Promissory Note, dated October 9, 1997, in the principal amount of
$25,000.00 issued by LSC, Incorporated (the "Company") to you (the "Note"),
pursuant to the Bridge Loan Agreement, dated September 11, 1997, among the
Company and the other purchasers of Convertible Promissory Notes (the
"Agreement"). As you will recall, on July 15, 1998, you agreed to amend the Note
and the Agreement. The Company is requesting that you agree to further amend the
Note and the Agreement as set forth in this letter agreement.

1.       MATURITY DATE. Section 2 of the Agreement and the first paragraph of
         the Note are each hereby amended to the extent necessary to provide
         that the Note will be due and payable on the earlier of (a) thirty (30)
         days after the initial closing of the Financing, as defined in the
         Agreement, or (b) December 31, 1999.

2.       WARRANT. In exchange for your agreement to extend the Note, the Company
         will grant to you a warrant (the "Warrant") to purchase ________ shares
         of Common Stock (which is equal to 50% of the principal amount of the
         Note, divided by $3.20 per share, which is 80% of the anticipated per
         share price in the financing that the Company has been conducting. The
         Warrant will be exercisable for a period of five years from the date of
         issuance at an exercise price equal to the lesser of (a) $3.20 per
         share or (b) 80% of the per share price of the Company's next equity
         financing that raises gross proceeds of at least two hundred fifty
         thousand dollars ($250,000), if such financing occurs on or before
         December 31, 2000. The Warrant again will be in the same form as the
         warrant attached as Exhibit B to the Agreement. The Company will issue
         the Warrant to you promptly after receipt of a signed copy of this
         letter agreement from you.

3.       CONVERSION. Section 2 of the Agreement and Section 2.1 of the Note are
         each hereby amended to the extent necessary to provide that the
         conversion price of the Note will not exceed $4.00 per share.




March 15, 1999
Page 2


Please execute a copy of this letter agreement and return it to us acknowledging
your agreement to amend the Note and the Agreement and convert principal and
interest under the Note into shares of Common Stock of the Company, as set forth
above.

LSC, INCORPORATED


By:
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     X. X. (Xxxx) Xxxxxx,
     President and Chief Executive Officer


ACKNOWLEDGED AND AGREED TO
AS OF ____________________, 1999


By:
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