Exhibit 10.50

THIS  SECURITY  HAS  NOT  BEEN  REGISTERED  WITH  THE  SECURITIES  AND  EXCHANGE
COMMISSION  OR THE  SECURITIES  COMMISSION  OF ANY  STATE  IN  RELIANCE  UPON AN
EXEMPTION  FROM  REGISTRATION  UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
"SECURITIES ACT"), AND, ACCORDINGLY,  MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT
TO AN EFFECTIVE  REGISTRATION  STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO
AN  AVAILABLE   EXEMPTION  FROM,  OR  IN  A  TRANSACTION  NOT  SUBJECT  TO,  THE
REGISTRATION   REQUIREMENTS  OF  THE  SECURITIES  ACT  AND  IN  ACCORDANCE  WITH
APPLICABLE  STATE  SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL TO
THE  TRANSFEROR  TO SUCH  EFFECT,  THE  SUBSTANCE  OF WHICH SHALL BE  REASONABLY
ACCEPTABLE TO THE COMPANY.

Original Issue Date: October 3, 2008

                                                                $---------------


                          10% SENIOR SECURED DEBENTURE
                              DUE DECEMBER 31, 2008

            THIS 10% SECURED DEBENTURE is one of a series of duly authorized and
issued 10% Senior Secured  Debentures of Intraop Medical  Corporation,  a Nevada
corporation,  having  a  principal  place  of  business  at 570 Del Rey  Avenue,
Sunnyvale,  CA 94085  (the  "Company"),  designated  as its 10%  Senior  Secured
Debenture, due December 31, 2008 (the "Debentures").

         FOR   VALUE    RECEIVED,    the    Company    promises    to   pay   to
__________________________   or  its  registered  assigns  (the  "Holder"),  the
principal sum of ___________________________  and 00/100 Dollars ($_________) on
the earlier of (i) the date that the Company has closed an  issuance,  or series
of  issuances,  of  securities  with gross  aggregate  proceeds  received by the
Company of not less than  $3,000,000 and (ii) December 31, 2008, or such earlier
date as this  Debenture  is  required  or  permitted  to be repaid  as  provided
hereunder (the "Maturity  Date"),  and to pay interest to the Holder on the then
outstanding principal amount of this Debenture in accordance with the provisions
hereof. This Debenture is subject to the following additional provisions:

         Section 1.  Definitions.  For the purposes  hereof,  in addition to the
terms defined  elsewhere in this Debenture:  (a) capitalized terms not otherwise
defined herein have the meanings given to such terms in the Purchase  Agreement,
and (b) the following terms shall have the following meanings:

                  "Business Day" means any day except  Saturday,  Sunday and any
         day which shall be a federal  legal  holiday in the United  States or a
         day on  which  banking  institutions  in the  State  of  New  York  are
         authorized or required by law or other government action to close.


                                       1
<PAGE>

                  "California  Courts"  shall  have  the  meaning  set  forth in
         Section 7(e).

                  "Change of Control Transaction" means the occurrence after the
         date  hereof of any of (i) an  acquisition  after the date hereof by an
         individual or legal entity or "group" (as described in Rule 13d-5(b)(1)
         promulgated  under  the  Exchange  Act),  other  than  pursuant  to the
         Transaction  Documents,  of effective control (whether through legal or
         beneficial  ownership of capital  stock of the Company,  by contract or
         otherwise) of in excess of 40% of the voting securities of the Company,
         or (ii) the Company merges into or consolidates  with any other Person,
         or any Person merges into or  consolidates  with the Company and, after
         giving  effect to such  transaction,  the  stockholders  of the Company
         immediately  prior  to  such  transaction  own  less  than  60%  of the
         aggregate  voting power of the Company or the successor  entity of such
         transaction,  or (iii) the Company sells or transfers its assets, as an
         entirety or  substantially  as an entirety,  to another  Person and the
         stockholders of the Company  immediately  prior to such transaction own
         less than 60% of the  aggregate  voting power of the  acquiring  entity
         immediately  after the  transaction,  (iv) a replacement at one time or
         within a three year period of more than  one-half of the members of the
         Company's  board of  directors  which is not  approved by a majority of
         those individuals who are members of the board of directors on the date
         hereof (or by those individuals who are serving as members of the board
         of directors on any date whose nomination to the board of directors was
         approved by a majority of the members of the board of directors who are
         members on the date hereof),  or (v) the execution by the Company of an
         agreement  to which  the  Company  is a party or by which it is  bound,
         providing for any of the events set forth above in (i) or (iv).

                  "Common  Stock" means the common  stock,  par value $0.001 per
         share,  of the Company and stock of any other class of securities  into
         which such  securities may hereafter have been  reclassified or changed
         into.

                  "Debenture  Register"  shall  have the  meaning  set  forth in
         Section 2(b).

                  "Event of Default" shall have the meaning set forth in Section
         6.

                  "Exchange Act" means the  Securities  Exchange Act of 1934, as
         amended, and the rules and regulations promulgated thereunder.

                  "Fundamental  Transaction"  shall mean (A) the Company effects
         any merger or consolidation of the Company with or into another Person,
         (B) the  Company  effects any sale of all or  substantially  all of its
         assets in one or a series of related transactions, (C) any tender offer
         or  exchange  offer  (whether  by the  Company  or  another  Person) is
         completed  pursuant to which  holders of Common Stock are  permitted to
         tender or exchange their shares for other securities, cash or property,
         or (D) the Company effects any  reclassification of the Common Stock or
         any  compulsory  share  exchange  pursuant to which the Common Stock is
         effectively  converted into or exchanged for other securities,  cash or
         property.


                                       2
<PAGE>

                  "Late Fees" shall have the meaning set forth in Section 2(c).

                  "Monthly Payment Amount" shall mean the interest to be paid on
         each  Monthly  Payment  Date  in  accordance  with  the  terms  of this
         Debenture.

                  "Monthly  Payment  Date"  means  the last  day of each  month,
         commencing  on the first  such date after the  Original  Issue Date and
         ending upon December 31, 2008.

                  "Original  Issue  Date"  shall  mean  the  date  of the  first
         issuance of this Debenture regardless of the number of transfers of any
         Debenture  and  regardless  of the number of  instruments  which may be
         issued to evidence such Debenture.

                  "Permitted   Indebtedness"   shall  mean  the  individual  and
         collective  reference  to the  following:  (a) up to, in the  aggregate
         during the term of this Debenture,  $2,000,000 of new Indebtedness, (b)
         Indebtedness  incurred in connection with the Purchase  Agreement,  (c)
         Indebtedness existing on the date of the Purchase Agreement,  (d) up to
         $6,000,000 in connection  with the  Company's  revolving  inventory and
         sales  contract  financing  agreement  with E.U.  Capital and (e) up to
         $1,040,000  of  Indebtedness  related to  Mobetron  S/N 28 to be placed
         under lease to a customer in Fort Meyers, Florida.

                  "Permitted  Lien"  shall mean the  individual  and  collective
         reference to the following:  (a) Liens for taxes, assessments and other
         governmental  charges  or  levies  not  yet  due or  Liens  for  taxes,
         assessments and other governmental charges or levies being contested in
         good faith and by appropriate  proceedings for which adequate  reserves
         (in the good faith judgment of the management of the Company) have been
         established  in  accordance  with GAAP;  (b) Liens imposed by law which
         were  incurred in the ordinary  course of business,  such as carriers',
         warehousemen's  and mechanics' Liens,  statutory  landlords' Liens, and
         other similar Liens arising in the ordinary course of business, and (x)
         which do not individually or in the aggregate  materially  detract from
         the  value of such  property  or assets or  materially  impair  the use
         thereof in the  operation  of the  business of the Company or (y) which
         are being  contested in good faith by  appropriate  proceedings,  which
         proceedings have the effect of preventing the forfeiture or sale of the
         property or asset  subject to such Lien;  and (c) Liens on  Receivables
         and the  Company's  "inventory"  (as such term is used in the  Security
         Agreement) incurred solely in connection with a Permitted  Indebtedness
         under clause (a) and (e) of the definition of Permitted Indebtedness.

                  "Person" means a corporation,  an association,  a partnership,
         organization,  a business,  an  individual,  a government  or political
         subdivision thereof or a governmental agency.

                  "Purchase  Agreement" means the Debenture Purchase  Agreement,
         dated as of the date hereof, to which the Company,  the original Holder
         and other investors signatory thereto are parties, as amended, modified
         or supplemented from time to time in accordance with its terms.


                                       3
<PAGE>

                  "Trading  Day" means a day on which the Common Stock is traded
         on a Trading Market.

                  "Trading  Market" means the following  markets or exchanges on
         which the Common  Stock is listed or quoted for  trading on the date in
         question:  the Nasdaq SmallCap Market, the American Stock Exchange, the
         New York Stock Exchange, the Nasdaq National Market or the OTC Bulletin
         Board.

                  "Transaction  Documents"  shall have the  meaning set forth in
         the Purchase Agreement.


         Section 2.        Payments.

                  a) Monthly Payment.  On each Monthly Payment Date, the Company
         shall pay the Monthly Payment Amount.

                  b) Balloon  Payment.  On the Maturity  Date,  all  outstanding
         principal,  plus accrued but unpaid  interest  thereon,  plus all other
         outstanding  amounts  due to the  Holder  shall  be paid to the  Holder
         (except  that,  if such date is not a Business  Day,  then such payment
         shall be due on the next succeeding Business Day).

                  c) Interest  Calculations.  Interest  on the then  outstanding
         principal  amount of this Debenture shall accrue at the rate of 10% per
         annum,  payable on the Monthly  Payment Date and on the Maturity  Date.
         Interest  shall be  calculated on the basis of a 360-day year and shall
         accrue daily  commencing  on the Original  Issue Date until  payment in
         full of the  principal  sum,  together  with  all  accrued  and  unpaid
         interest and other  amounts  which may become due  hereunder,  has been
         made.  Interest hereunder will be paid to the Person in whose name this
         Debenture  is  registered  on  the  records  of the  Company  regarding
         registration   and  transfers  of  this   Debenture   (the   "Debenture
         Register").

                  d) Late Fee.  All overdue  accrued  and unpaid  interest to be
         paid hereunder shall entail a late fee at the rate of 18% per annum (or
         such lower  maximum  amount of interest  permitted to be charged  under
         applicable  law) ("Late Fees") which will accrue  daily,  from the date
         such  interest  is due  hereunder  through  and  including  the date of
         payment.

                  e)  Prepayment.  The  Company may prepay all or any portion of
         the  principal  amount of this  Debenture  without  the  prior  written
         consent of the Holder at any time.

         Section 3. Registration of Transfers and Exchanges.

                  a) Different Denominations. This Debenture is exchangeable for
         an  equal  aggregate   principal  amount  of  Debentures  of  different
         authorized  denominations,  as requested by the Holder surrendering the
         same. No service charge will be made for such  registration of transfer
         or exchange;  provided,  however,  the Company shall not be required to
         exchange this Debenture for  denominations  of less than the greater of
         $50,000 and the principal amount of this Debenture then outstanding. No
         service  charge  will be made  for such  registration  of  transfer  or
         exchange.


                                       4
<PAGE>

                  b) Investment Representations.  This Debenture has been issued
         subject to certain  investment  representations  of the original Holder
         set forth in the Purchase Agreement and may be transferred or exchanged
         only in compliance with the Purchase  Agreement and applicable  federal
         and state securities laws and regulations.

                  c) Reliance on Debenture Register. Prior to due presentment to
         the Company for transfer of this  Debenture,  the Company and any agent
         of the  Company  may treat the Person in whose name this  Debenture  is
         duly  registered on the Debenture  Register as the owner hereof for the
         purpose  of  receiving  payment  as herein  provided  and for all other
         purposes,  whether or not this  Debenture  is overdue,  and neither the
         Company nor any such agent shall be affected by notice to the contrary.

         Section 4. Intentionally Omitted.

         Section 5. Negative Covenants. So long as any portion of this Debenture
is outstanding, the Company will not directly or indirectly:

                  a) other than  Permitted  Indebtedness,  enter  into,  create,
         incur,  assume,  guarantee  or  suffer to exist  any  indebtedness  for
         borrowed money of any kind,  including but not limited to, a guarantee,
         on or with  respect  to any of its  property  or  assets  now  owned or
         hereafter  acquired  or any  interest  therein or any income or profits
         therefrom;

                  b) other than  Permitted  Liens,  enter into,  create,  incur,
         assume or suffer to exist any liens of any kind,  on or with respect to
         any of its  property or assets now owned or  hereafter  acquired or any
         interest therein or any income or profits therefrom;

                  c) amend its  certificate  of  incorporation,  bylaws or other
         charter  documents so as to materially and adversely  affect any rights
         of the Holder;

                  d)  repay,   repurchase  or  offer  to  repay,  repurchase  or
         otherwise acquire more than a de minimis number of shares of its Common
         Stock or Common Stock Equivalents;

                  e)  enter  into  any  agreement  with  respect  to  any of the
         foregoing; or

                  f)  pay  cash  dividends  or   distributions   on  any  equity
         securities of the Company.

         Section 6. Events of Default.

                  a) "Event of Default",  wherever used herein, means any one of
         the  following  events  (whatever  the reason  and  whether it shall be
         voluntary or involuntary or effected by operation of law or pursuant to
         any  judgment,  decree or order of any  court,  or any  order,  rule or
         regulation of any administrative or governmental body):


                                       5
<PAGE>

                           i. any  default in the  payment of (A) the  principal
                  amount of any Debenture, or (B) interest (including Late Fees)
                  on, or liquidated damages in respect of, any Debenture, as and
                  when the same shall  become due and  payable  (whether  on the
                  Maturity Date or by acceleration or otherwise)  which default,
                  solely in the case of an  interest  payment  or other  default
                  under clause (B) above, is not cured, within 5 Trading Days;

                           ii. the Company  shall fail to observe or perform any
                  other covenant or agreement contained in (A) this Debenture or
                  (B) any of the other Transaction  Documents,  which failure is
                  not cured, if possible to cure, within the earlier to occur of
                  (A) 15 Trading  Days after  notice of such default sent by the
                  Holder or by any other  Holder and (B) 20  Trading  Days after
                  the Company  shall  become or should have become aware of such
                  failure;

                           iii. a default or event of  default  (subject  to any
                  grace or cure period provided for in the applicable agreement,
                  document  or  instrument)  shall  occur  under  (A) any of the
                  Transaction  Documents  or (B) any other  material  agreement,
                  lease,  document or  instrument  to which the Company is bound
                  and which  default or event of  default  could have a Material
                  Adverse Effect on the Company;

                           iv. any  representation  or warranty made herein,  in
                  any other  Transaction  Documents shall be untrue or incorrect
                  in any  material  respect  as of the date  when made or deemed
                  made;

                           v. (i) the Company shall  commence a case, as debtor,
                  a case under any applicable  bankruptcy or insolvency  laws as
                  now or hereafter in effect or any  successor  thereto,  or the
                  Company    commences   any   other    proceeding   under   any
                  reorganization,  arrangement,  adjustment  of debt,  relief of
                  debtors, dissolution, insolvency or liquidation or similar law
                  of  any  jurisdiction  whether  now  or  hereafter  in  effect
                  relating to the Company  thereof or (ii) there is  commenced a
                  case  against  the  Company  thereof,   under  any  applicable
                  bankruptcy or  insolvency  laws, as now or hereafter in effect
                  or any  successor  thereto  which  remains  undismissed  for a
                  period of 60 days;  or (iii) the Company is  adjudicated  by a
                  court of competent  jurisdiction insolvent or bankrupt; or any
                  order of  relief  or other  order  approving  any such case or
                  proceeding is entered; or (iv) the Company thereof suffers any
                  appointment  of  any  custodian  or  the  like  for  it or any
                  substantial part of its property which continues  undischarged
                  or  unstayed  for a  period  of 60  days;  or (v) the  Company
                  thereof  makes  a  general   assignment  for  the  benefit  of
                  creditors;  or (vi) the  Company  shall fail to pay,  or shall
                  state that it is unable to pay, or shall be unable to pay, its
                  debts  generally  as they  become  due;  or (vii) the  Company
                  thereof shall call a meeting of its  creditors  with a view to
                  arranging a composition,  adjustment or  restructuring  of its
                  debts;  or  (viii)  the  Company  thereof  shall by any act or
                  failure to act expressly  indicate its consent to, approval of
                  or acquiescence in any of the foregoing; or (ix) any corporate
                  or  other  action  is  taken by the  Company  thereof  for the
                  purpose of effecting any of the foregoing;


                                       6
<PAGE>

                           vi.  the  Company   shall   default  in  any  of  its
                  obligations  under any  mortgage,  credit  agreement  or other
                  facility,  indenture  agreement,  factoring agreement or other
                  instrument under which there may be issued,  or by which there
                  may be secured or  evidenced  any  indebtedness  for  borrowed
                  money or money due under any long term  leasing  or  factoring
                  arrangement  of the Company in an amount  exceeding  $250,000,
                  whether  such  indebtedness  now exists or shall  hereafter be
                  created and such  default  shall  result in such  indebtedness
                  becoming or being  declared due and payable  prior to the date
                  on which it would otherwise become due and payable.

                           vii.  the  Company  shall be a party to any Change of
                  Control Transaction or Fundamental Transaction, shall agree to
                  sell or  dispose  of all or in excess of 33% of its  assets in
                  one or more  transactions  (whether  or not  such  sale  would
                  constitute a Change of Control Transaction) or shall redeem or
                  repurchase  more than a de minimis  number of its  outstanding
                  shares  of  Common  Stock or other  equity  securities  of the
                  Company  (other than  repurchases of shares of Common Stock or
                  other equity securities of departing officers and directors of
                  the  Company;  provided  such  repurchases  shall  not  exceed
                  $250,000,  in the  aggregate,  for all officers and  directors
                  during the term of this Debenture);

                           viii. the Company shall redeem more than a de minimis
                  number of Common Stock Equivalents; and

                           ix. other than  Permitted  Liens,  the Company  shall
                  fail,  at any  time,  to  have  a  perfected,  first  priority
                  security  interest  in  all  Collateral  (as  defined  in  the
                  Security  Agreement) and all other assets pledged to Holder as
                  security for the loan evidenced by this Debenture.

                  b)  Remedies  Upon Event of  Default.  If any Event of Default
         occurs,  the full  principal  amount of this  Debenture,  together with
         interest and other  amounts  owing in respect  thereof,  to the date of
         acceleration  shall become, at the Holder's  election,  immediately due
         and  payable in cash.  Commencing  5 days after the  occurrence  of any
         Event of Default  that  results in the  eventual  acceleration  of this
         Debenture, the interest rate on this Debenture shall accrue at the rate
         of 18% per annum, or such lower maximum amount of interest permitted to
         be  charged  under  applicable  law.  Upon the  payment  in full of all
         amounts owing under this Debenture the Holder shall promptly  surrender
         this  Debenture to or as directed by the  Company.  The Holder need not
         provide and the Company hereby waives any presentment,  demand, protest
         or other notice of any kind, and the Holder may immediately and without
         expiration  of any grace  period  enforce any and all of its rights and
         remedies  hereunder  and  all  other  remedies  available  to it  under
         applicable  law.  Such  declaration  may be  rescinded  and annulled by
         Holder at any time prior to payment hereunder and the Holder shall have
         all rights as a Debenture  holder until such time,  if any, as the full
         payment  under this  Section  shall have been  received  by it. No such
         rescission or annulment shall affect any subsequent Event of Default or
         impair any right consequent thereon.


                                       7
<PAGE>

         Section 7. Miscellaneous.

                  a)  Notices.  Any and all notices or other  communications  or
         deliveries to be provided by the Holder hereunder,  including,  without
         limitation, any Notice of Conversion, shall be in writing and delivered
         personally,  by facsimile,  sent by a nationally  recognized  overnight
         courier  service,  addressed to the  Company,  at the address set forth
         above, Attn: Chief Financial Officer or such other address or facsimile
         number as the Company  may  specify for such  purposes by notice to the
         Holder  delivered in accordance with this Section.  Any and all notices
         or other  communications  or  deliveries  to be provided by the Company
         hereunder shall be in writing and delivered  personally,  by facsimile,
         sent by a nationally  recognized overnight courier service addressed to
         each Holder at the facsimile telephone number or address of such Holder
         appearing  on  the  books  of  the  Company,  or if no  such  facsimile
         telephone number or address appears, at the principal place of business
         of  the  Holder.  Any  notice  or  other  communication  or  deliveries
         hereunder  shall be deemed  given and  effective on the earliest of (i)
         the date of transmission,  if such notice or communication is delivered
         via  facsimile  at the  facsimile  telephone  number  specified in this
         Section  prior to 5:30 p.m.  (New York City time),  (ii) the date after
         the date of transmission,  if such notice or communication is delivered
         via  facsimile  at the  facsimile  telephone  number  specified in this
         Section  later  than  5:30 p.m.  (New  York City  time) on any date and
         earlier  than 11:59 p.m.  (New York City time) on such date,  (iii) the
         second  Business  Day  following  the  date  of  mailing,  if  sent  by
         nationally  recognized  overnight courier service,  or (iv) upon actual
         receipt by the party to whom such notice is required to be given.

                  b) Absolute  Obligation.  Except as expressly provided herein,
         no provision of this Debenture  shall alter or impair the obligation of
         the Company, which is absolute and unconditional,  to pay the principal
         of, interest and liquidated  damages (if any) on, this Debenture at the
         time, place, and rate, and in the coin or currency,  herein prescribed.
         This  Debenture  is a  direct  debt  obligation  of the  Company.  This
         Debenture  ranks pari passu with all other  Debentures now or hereafter
         issued under the terms set forth herein.

                  c)  Security  Interest.   This  Debenture  is  a  direct  debt
         obligation of the Company and, pursuant to the Security  Documents,  is
         secured by a first priority  security  interest in all of the assets of
         the  Company  and  certain  other  collateral  for the  benefit  of the
         Holders.

                  d) Lost or Mutilated  Debenture.  If this  Debenture  shall be
         mutilated,  lost,  stolen or  destroyed,  the Company shall execute and
         deliver,  in exchange and substitution  for and upon  cancellation of a
         mutilated  Debenture,  or in  lieu  of or in  substitution  for a lost,
         stolen or destroyed Debenture, a new Debenture for the principal amount
         of this Debenture so mutilated, lost, stolen or destroyed but only upon
         receipt  of  evidence  of  such  loss,  theft  or  destruction  of such
         Debenture,  and of the ownership hereof,  and indemnity,  if requested,
         all reasonably satisfactory to the Company.


                                       8
<PAGE>

                  e) Governing Law. All questions  concerning the  construction,
         validity,  enforcement  and  interpretation  of this Debenture shall be
         governed by and construed and enforced in accordance  with the internal
         laws of the State of  Delaware,  without  regard to the  principles  of
         conflicts of law thereof.  Each party agrees that all legal proceedings
         concerning  the   interpretations,   enforcement  and  defense  of  the
         transactions  contemplated by any of the Transaction Documents (whether
         brought against a party hereto or its respective affiliates, directors,
         officers, shareholders,  employees or agents) shall be commenced in the
         courts of the State of California located in Santa Clara County and the
         United States  District  Court for the Northern  District of California
         (the "California Courts"). Each party hereto hereby irrevocably submits
         to  the  exclusive  jurisdiction  of  the  California  Courts  for  the
         adjudication of any dispute hereunder or in connection herewith or with
         any transaction contemplated hereby or discussed herein (including with
         respect to the  enforcement of any of the Transaction  Documents),  and
         hereby irrevocably waives, and agrees not to assert in any suit, action
         or  proceeding,  any claim  that it is not  personally  subject  to the
         jurisdiction of any such court, or such California  Courts are improper
         or  inconvenient   venue  for  such   proceeding.   Each  party  hereby
         irrevocably  waives personal service of process and consents to process
         being served in any such suit,  action or  proceeding by mailing a copy
         thereof via  registered or certified  mail or overnight  delivery (with
         evidence  of  delivery)  to such  party at the  address  in effect  for
         notices to it under this  Debenture  and agrees that such service shall
         constitute  good and sufficient  service of process and notice thereof.
         Nothing  contained herein shall be deemed to limit in any way any right
         to serve  process in any manner  permitted  by law.  Each party  hereto
         hereby   irrevocably   waives,  to  the  fullest  extent  permitted  by
         applicable  law,  any and  all  right  to  trial  by jury in any  legal
         proceeding  arising  out  of or  relating  to  this  Debenture  or  the
         transactions  contemplated  hereby.  If either party shall  commence an
         action or proceeding to enforce any provisions of this Debenture,  then
         the prevailing  party in such action or proceeding  shall be reimbursed
         by the other party for its attorneys  fees and other costs and expenses
         incurred with the  investigation,  preparation  and prosecution of such
         action or proceeding.

                  f)  Modification;  Waiver.  No  modification  or waiver of any
         provision of this Debenture or consent to departure  therefrom shall be
         effective  without the written  consent of (i) the Company and (ii) the
         holders of at least 50% of the outstanding and unpaid  principal amount
         owing under all Debentures then outstanding and then shall be effective
         only in the specific instance and for the specific purpose for which it
         was given;  provided that no such  modification  or waiver shall change
         the Maturity Date on the  Debentures  or any provision  relating to any
         scheduled payment on the Debentures without the written consent of 100%
         of  the  outstanding  and  unpaid  principal  amount  owing  under  all
         Debentures then  outstanding.  The failure of the Company or the Holder
         to insist upon strict adherence to any term of this Debenture on one or
         more  occasions  shall not be considered a waiver or deprive that party
         of the right thereafter to insist upon strict adherence to that term or
         any other term of this Debenture. Any waiver must be in writing.


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<PAGE>

                  g)  Severability.  If  any  provision  of  this  Debenture  is
         invalid, illegal or unenforceable,  the balance of this Debenture shall
         remain in effect, and if any provision is inapplicable to any person or
         circumstance,  it shall  nevertheless  remain  applicable  to all other
         persons and  circumstances.  If it shall be found that any  interest or
         other amount deemed  interest due hereunder  violates  applicable  laws
         governing  usury,  the applicable  rate of interest due hereunder shall
         automatically  be  lowered  to  equal  the  maximum  permitted  rate of
         interest.  The Company covenants (to the extent that it may lawfully do
         so) that it shall not at any time insist upon,  plead, or in any manner
         whatsoever  claim  or take the  benefit  or  advantage  of,  any  stay,
         extension or usury law or other law which would prohibit or forgive the
         Company from paying all or any portion of the  principal of or interest
         on this Debenture as contemplated  herein,  wherever enacted, now or at
         any time  hereafter in force,  or which may affect the covenants or the
         performance  of this  indenture,  and the Company (to the extent it may
         lawfully do so) hereby  expressly  waives all  benefits or advantage of
         any such law,  and  covenants  that it will not,  by resort to any such
         law, hinder, delay or impeded the execution of any power herein granted
         to the Holder,  but will suffer and permit the  execution of every such
         as though no such law has been enacted.

                  h) Next Business Day. Whenever any payment or other obligation
         hereunder shall be due on a day other than a Business Day, such payment
         shall be made on the next succeeding Business Day.

                  i) Headings. The headings contained herein are for convenience
         only,  do not  constitute  a part of this  Debenture  and  shall not be
         deemed to limit or affect any of the provisions hereof.

                  j) Usury.  To the extent it may  lawfully  do so, the  Company
         hereby  agrees not to insist upon or plead or in any manner  whatsoever
         claim,  and will resist any and all efforts to be compelled to take the
         benefit or advantage  of, usury laws  wherever  enacted,  now or at any
         time  hereafter  in force,  in  connection  with any  claim,  action or
         proceeding that may be brought by any Purchaser in order to enforce any
         right or remedy under any  Transaction  Document.  Notwithstanding  any
         provision to the contrary contained in any Transaction  Document, it is
         expressly  agreed and provided that the total  liability of the Company
         under the Transaction  Documents for payments in the nature of interest
         shall not exceed the Maximum Rate, and, without limiting the foregoing,
         in no event shall any rate of interest or default interest,  or both of
         them,  when  aggregated  with any other sums in the nature of  interest
         that  the  Company  may be  obligated  to  pay  under  the  Transaction
         Documents  exceed such Maximum  Rate.  It is agreed that if the maximum
         contract  rate  of  interest  allowed  by  law  and  applicable  to the
         Transaction  Documents  is  increased  or  decreased  by statute or any
         official  governmental  action  subsequent to the date hereof,  the new
         maximum  contract  rate of interest  allowed by law will be the Maximum
         Rate applicable to the Transaction Documents from the effective date of
         such increase or decrease forward, unless such application is precluded
         by applicable law. If under any circumstances  whatsoever,  interest in
         excess of the Maximum Rate is paid by the Company to any Purchaser with
         respect  to  indebtedness,   if  any,   evidenced  by  the  Transaction
         Documents, such excess shall be applied by such Purchaser to the unpaid
         principal  balance  of any  such  indebtedness  or be  refunded  to the
         Company,  the manner of handling such excess to be at such  Purchaser's
         election in the event any principal amount remains outstanding.


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<PAGE>

                  k)  Assumption.  Any  successor  to the  Company or  surviving
         entity in a Fundamental  Transaction shall (i) assume in writing all of
         the  obligations  of the  Company  under this  Debenture  and the other
         Transaction  Documents  pursuant  to  written  agreements  in form  and
         substance   satisfactory  to  the  Holder  (such  approval  not  to  be
         unreasonably withheld or delayed) prior to such Fundamental Transaction
         and (ii) to  issue to the  Holder  a new  debenture  of such  successor
         entity evidenced by a written instrument  substantially similar in form
         and substance to this Debenture,  including, without limitation, having
         a principal amount and interest rate equal to the principal amounts and
         the  interest  rates of the  Debentures  held by the  Holder and having
         similar ranking to this Debenture,  and satisfactory to the Holder (any
         such  approval  not  to  be  unreasonably  withheld  or  delayed).  The
         provisions  of this Section 7(k) shall apply  similarly  and equally to
         successive Fundamental Transactions and shall be applied without regard
         to any limitations of this Debenture.


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<PAGE>

         IN WITNESS  WHEREOF,  the Company has caused this  Debenture to be duly
executed by a duly authorized officer as of the date first above indicated.


                                          INTRAOP MEDICAL CORPORATION




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


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