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                                                                    EXHIBIT 10.2

                             DEMAND PROMISSORY NOTE

$200,000.00                                                     JANUARY 21, 2003

         FOR VALUE RECEIVED, the undersigned, DIASYS CORPORATION ("Maker")
hereby promises to pay to the order of MORRIS SILVERMAN ("Payee") on demand, in
lawful money of the United States and in immediately available funds, the
principal amount of Two Hundred Thousand and No/100 Dollars ($200,000.00).
Interest payable on this Note shall be calculated on the basis of one year of
three hundred sixty-five (365) days for the number of days elapsed. This Note
shall bear simple interest at the rate of eight percent (8%) per annum.

     1.  Principal and Interest Repayment; Prepayment Permitted. Repayment of
         principal and accrued interest on this Note prior to demand shall be in
         such amount and at such times in the sole discretion of Maker. This
         Note may be prepaid in whole or in part at any time, including by means
         of Payee's cancellation of all or a portion of amounts owed by Maker
         pursuant to this Note. Payments hereunder shall be applied first to
         accrued and unpaid interest and then to the unpaid principal balance of
         this Note.

     2.  Default. The entire unpaid amount of principal and interest under this
         Note shall, at the option of Payee, become due and payable upon ten
         (10) days' written notice to Maker upon the occurrence of any of the
         following events of default (the "Events of Default"):

         a)       There shall be an entry of a decree or order for relief by a
                  court having jurisdiction:

                  (i)   in respect of Maker in any involuntary case under the
         federal bankruptcy laws or any other applicable federal or state
         bankruptcy, insolvency or other similar law, as now or hereafter in
         effect; or

                  (ii)  appointing a receiver, liquidator, assignee, trustee,
         sequestrator (or similar official) of Maker or of any substantial part
         of Maker's property, and the continuance of any such decree or order
         remains unstayed and in effect for a period of ninety (90) consecutive
         days; or

         b)       There shall be:

                  (i)   the commencement by Maker of a voluntary case under the
         federal bankruptcy laws or any other applicable federal or state
         bankruptcy, insolvency or other similar law, as now or hereafter in
         effect;

                  (ii)  the consent of Maker to the entry of any order for
         relief in an involuntary case under any such law;

                  (iii) the consent of Maker to the appointment of, or taking
         possession by, a receiver, liquidator, assignee, trustee, sequestrator
         (or other similar official) of Maker or of any substantial part of its
         property;

                  (iv)  the making by Maker of a general assignment for the
         benefit of creditors;

                  (v)   the admission by Maker in writing of its inability
         generally to pay its debts as they become due; or

                  (vi)  the taking of any action by Maker in furtherance of any
         such action.

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         No failure or delay on the part of Payee in the exercise of any power,
right or remedy in this Note shall operate as a waiver thereof, and no exercise
or waiver of any single power, right or remedy, or the partial exercise thereof,
shall affect Payee's rights with respect to any and all other rights, remedies
and powers. The remedies provided in this Note are cumulative and not exclusive
of any remedies provided by law.

     3.  Illinois Law. This Note shall be governed by the laws of the State of
         Illinois. Any action to enforce this Note shall be instituted in the
         state or federal courts situated in Illinois.

                                          DIASYS CORPORATION

                                          By: /s/ Marshall Witzel
                                             ---------------------------------
                                          Its: Chief Executive Officer
                                              --------------------------------

                                       2<PAGE>

                                                                    EXHIBIT 10.3

                             DEMAND PROMISSORY NOTE

$140,000.00                                                       MARCH 24, 2003

         FOR VALUE RECEIVED, the undersigned, DIASYS CORPORATION ("Maker")
hereby promises to pay to the order of MORRIS SILVERMAN ("Payee") on demand, in
lawful money of the United States and in immediately available funds, the
principal amount of One Hundred and Forty Thousand and No/100 Dollars
($140,000.00). Interest payable on this Note shall be calculated on the basis of
one year of three hundred sixty-five (365) days for the number of days elapsed.
This Note shall bear simple interest at the rate of eight percent (8%) per
annum.

     1.  Principal and Interest Repayment; Prepayment Permitted. Repayment of
         principal and accrued interest on this Note prior to demand shall be in
         such amount and at such times in the sole discretion of Maker. This
         Note may be prepaid in whole or in part at any time, including by means
         of Payee's cancellation of all or a portion of amounts owed by Maker
         pursuant to this Note. Payments hereunder shall be applied first to
         accrued and unpaid interest and then to the unpaid principal balance of
         this Note.

     2.  Default. The entire unpaid amount of principal and interest under this
         Note shall, at the option of Payee, become due and payable upon ten
         (10) days' written notice to Maker upon the occurrence of any of the
         following events of default (the "Events of Default"):

         a)       There shall be an entry of a decree or order for relief by a
                  court having jurisdiction:

                  (i)   in respect of Maker in any involuntary case under the
         federal bankruptcy laws or any other applicable federal or state
         bankruptcy, insolvency or other similar law, as now or hereafter in
         effect; or

                  (ii)  appointing a receiver, liquidator, assignee, trustee,
         sequestrator (or similar official) of Maker or of any substantial part
         of Maker's property, and the continuance of any such decree or order
         remains unstayed and in effect for a period of ninety (90) consecutive
         days; or

         b)       There shall be:

                  (i)   the commencement by Maker of a voluntary case under the
         federal bankruptcy laws or any other applicable federal or state
         bankruptcy, insolvency or other similar law, as now or hereafter in
         effect;

                  (ii)  the consent of Maker to the entry of any order for
         relief in an involuntary case under any such law;

                  (iii) the consent of Maker to the appointment of, or taking
         possession by, a receiver, liquidator, assignee, trustee, sequestrator
         (or other similar official) of Maker or of any substantial part of its
         property;

                  (iv)  the making by Maker of a general assignment for the
         benefit of creditors;

                  (v)   the admission by Maker in writing of its inability
         generally to pay its debts as they become due; or

                  (vi)  the taking of any action by Maker in furtherance of any
         such action.

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         No failure or delay on the part of Payee in the exercise of any power,
right or remedy in this Note shall operate as a waiver thereof, and no exercise
or waiver of any single power, right or remedy, or the partial exercise thereof,
shall affect Payee's rights with respect to any and all other rights, remedies
and powers. The remedies provided in this Note are cumulative and not exclusive
of any remedies provided by law.

     3.  Illinois Law. This Note shall be governed by the laws of the State of
         Illinois. Any action to enforce this Note shall be instituted in the
         state or federal courts situated in Illinois.

                                          DIASYS CORPORATION

                                          By: /s/ Marshall Witzel
                                             ---------------------------------
                                          Its: Chief Executive Officer
                                              --------------------------------

                                       2<PAGE>
                                                                    EXHIBIT 10.4

                                 PROMISSORY NOTE

$25,000.00                                                       JANUARY 6, 2003

         FOR VALUE RECEIVED, DiaSys Corporation, a Delaware corporation (the
"Maker"), promises to pay to Stuart Robbins (the "Holder"), the principal amount
of Twenty-Five Thousand Dollars and No Cents ($25,000.00), together with
interest thereon, as hereinafter provided. Principal and interest shall be
payable in money of the United States of America lawful at such time for the
payment of public and private debts.

         This Note shall bear interest on the unpaid principal amount, from the
date hereof until paid in full, at the annual rate of nine percent (9%).
Interest shall be calculated based upon a 365-day year. Interest shall be
payable on the first business day of each calendar quarter commencing with April
1, 2003.

         The principal amount of this Note, together with any and all accrued
and unpaid interest thereon shall be fully and immediately payable upon demand
by the Holder made on or after April 1, 2003. Payment shall be made by wire
transfer of immediately available funds to the account of the Holder as
specified in writing prior to such payment. No penalty is payable upon
prepayment.

         In the event any provisions hereof shall result, for any reason and at
any time, in an effective rate of interest that exceeds the limit of the usury
or any other law applicable to the indebtedness evidenced hereby, all sums in
excess of those lawfully collectible as interest for the period in question
shall be (i) applied, to the extent of such excess, against the unpaid principal
amount evidenced hereby with the same force and effect as though the Holder had
agreed to accept such extra payment(s) as a prepayment or (ii) if the
indebtedness has been fully paid, refunded by the Holder to the Maker to the
extent of such excess.

         If (i) the Maker voluntarily commences a case or proceeding seeking
liquidation, reorganization, debt readjustment, moratorium or other relief under
any bankruptcy, insolvency or similar law (a "Proceeding"); (ii) an involuntary
proceeding is commenced against the Maker and such Proceeding shall remain
unstayed or undismissed for a period of thirty (30) days or (iii) a receiver or
trustee is appointed for the Maker or any portion of the Maker's assets and such
appointment is not vacated within thirty (30) days of such appointment, then all
amounts due and owing under this Note automatically shall become due and payable
without any notice or other action by the Holder.

         The provisions hereof shall be binding upon the successors and assigns
of the Maker and shall inure to the benefit of the Holder and his legal
representatives, successors and assigns.

         THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF NEW YORK WITHOUT GIVING EFFECT TO THE PRINCIPLES OF
CONFLICTS OF LAWS THEREOF.

         The Maker expressly waives presentment, notice of nonpayment, protest
and notice of protest and any other notice which might otherwise be required in
connection with the delivery, acceptance, performance, default or enforcement of
the payment of this Note.

         The Holder shall not be deemed by any act or omission to have waived
any right or remedy hereunder unless and only to the extent expressed in a
written instrument dated subsequent to the date hereof and executed by the
Holder, and any such waiver so expressed with respect to a singular event shall
not be interpreted as having a continuing effect on or as a waiver of any right
or remedy with respect to any subsequent event.

         IN WITNESS WHEREOF, the Maker has executed this Note as of the day and
year first above written.

                                         DIASYS CORPORATION

                                         By:  /s/ Todd M. DeMatteo
                                              -------------------------
                                              Name:   Todd M. DeMatteo
                                              Title:  President

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