<PAGE>   1
                                                                   Exhibit 10.26

                          Aspect Medical Systems, Inc.
   requests that the marked portions of this document be granted confidential
        treatment pursuant to Rule 406 under the Securities Act of 1933.


PRIVILEGED AND CONFIDENTIAL
ATTORNEY-CLIENT AND WORK PRODUCT PRIVILEGES
FOR GE MARQUETTE ONLY


                          ASPECT MEDICAL SYSTEMS, INC.

                     OEM DEVELOPMENT AND PURCHASE AGREEMENT

         Agreement dated this 22nd day of December, 1999, by and between Aspect
Medical Systems, Inc, a Delaware corporation with its principal offices located
at Two Vision Drive, Natick, Massachusetts ("Aspect") and GE Marquette Medical
Systems, Inc. ("Marquette"), a Wisconsin corporation with its principal offices
located at 8200 W. Tower Ave., Milwaukee, Wisconsin for the purchase and/or
license by Marquette of products under the terms and conditions contained in
this Agreement.

1.       BACKGROUND.

         1.1      Aspect is a developer, manufacturer and distributor of medical
                  devices, equipment, related hardware, software and related
                  products and accessories.

         1.2      Marquette is a developer, manufacturer and distributor of
                  medical devices, equipment, related hardware, software and
                  related products and accessories, including multiparameter
                  patient monitors.

         1.3      Marquette desires to integrate Aspect's BIS and EEG technology
                  into Marquette's multiparameter patient monitors.

         1.4      Aspect agrees to sell and/or license to Marquette the products
                  described below, subject to the terms and conditions contained
                  in this Agreement.

2.       DEFINITIONS.

         "ASPECT'S BISPECTRAL INDEX" or "BIS" is Aspect's proprietary processed
         EEG parameter that measures the hypnotic effects of anesthetic and
         sedative agents on the brain during surgery.

         "ASPECT'S EEG PARAMETERS" or "EEG" are Aspect's processed EEG
         parameters including Spectral Edge frequency, Median Frequency,
         Suppression Ratio, EMG and SQI (Signal Quality Index).

         "MARQUETTE PATIENT MONITOR" means any multi-parameter modular patient
         monitoring systems manufactured by or for Marquette. When the BIS/EEG
         Module Development


<PAGE>   2

         Project is complete, the Marquette BIS/EEG module will allow the
         Marquette Patient Monitor to display BIS and certain EEG data
         (waveforms, numerics, status info), and provide setup and operation
         information (user interface), alarming, and network connectivity.

         "MARQUETTE BIS/EEG MODULE" is the sum of all components involved in
         integrating the BIS and EEG with Marquette Patient Monitors.

         "DSC CABLE" is a cable used to connect the DSC-2 or DSC-4 to the
         Marquette BIS/EEG Engine.

         "MARQUETTE BIS/EEG ENGINE" is the processing unit for deriving the BIS
         and EEG data from the raw EEG signal and consists of Aspect's "BIS
         Engine" board modified for Marquette.

         "DIGITAL SIGNAL CONVERTER-2" (or "DSC-2") is used to amplify the analog
         EEG signals as acquired by the BIS sensors and convert it from analog
         to digital signals. The DSC-2 is used by Marquette BIS/EEG Module
         customers to obtain the BIS.

         "DIGITAL SIGNAL CONVERTER-4" (or "DSC-4") is used to amplify the analog
         EEG signals as acquired by the Zipprep electrodes and convert it from
         analog to digital signals. The DSC-4 is used by Marquette BIS/EEG
         Module customers to obtain 2 or 4-channel EEG data only.

         "ASPECT BIS/EEG MODULE KIT" means the bundle of all components of the
         Marquette BIS/EEG Module that are developed and manufactured by or for
         Aspect and licensed/sold to Marquette under this Agreement: DSC-2,
         DSC-4, DSC Cable, Marquette BIS/EEG Engine, and Module Cable.

         "ASPECT BIS SENSOR" means a single use disposable sensor manufactured
         by Aspect for use with the A2000 or with the Aspect BIS/EEG Module Kit
         and that is required to generate Aspect's Bispectral Index.

         "A2000" means Aspect's stand-alone BIS monitor for use with the Aspect
         BIS Sensor and that generates Aspect's Bispectral Index.

         "ASPECT PRODUCTS" means Aspect BIS/EEG Module Kit and any other product
         that can be ordered by Marquette as listed in Exhibit A (Aspect
         Products and Purchase Prices).

         "SOFTWARE" means Aspect software programs in binary code form which are
         designed for use with the Aspect BIS/EEG Module Kit.

         "DOCUMENTATION" means the BIS Engine Serial Interface Specification.

         "TERRITORY" shall mean all countries in which Marquette is permitted
         under this Agreement to distribute Aspect Products.

         "PARTY" or "PARTIES" shall mean Aspect and Marquette each individually
         or jointly.



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<PAGE>   3
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


3.       BIS/EEG MODULE DEVELOPMENT PROJECT.

         3.1      PROJECT TIMING. The overall project duration is expected to be
                  at least [**]. The product introduction is targeted for the
                  annual meeting of the [**], but if such target can not be
                  satisfied the product introduction shall be targeted for no
                  later than the annual meeting of [**]. A preliminary outline
                  of the development project is attached to this Agreement as
                  Exhibit C.

         3.2      PROJECT MANAGEMENT.

                  (a)      Each Party shall appoint a "Project Manager" who
                           shall oversee and manage the joint project on a
                           day-to-day basis.

                  (b)      The Project Managers shall meet regularly based on
                           the project needs to assess the project status and
                           discuss and resolve any issues or problems. These
                           meetings may be held face-to-face or as telephone or
                           video conferences.

                  (c)      Each Party shall bear its own communication and
                           travel costs.

                  (d)      All communication in conjunction with this Agreement
                           shall be directed to the appropriate person and
                           address as listed in Exhibit D (Contact
                           Persons/Addresses).

         3.3      MARQUETTE RESPONSIBILITIES.

                  (a)      Marquette shall develop the Marquette BIS/EEG Module
                           according to mutually agreed specifications at
                           Marquette's own cost.

                  (b)      Marquette shall develop, design and test the modular
                           integration of the components of the Aspect BIS/EEG
                           Module Kit with the Marquette Patient Monitors

         3.4      ASPECT RESPONSIBILITIES.

                  (a)      Aspect shall design, develop, and test the Aspect
                           BIS/EEG Module Kit according to the mutually agreed
                           specifications. The costs for Aspect to complete this
                           project, for which preliminary estimates are included
                           in Exhibit C, shall be borne by Marquette. [**] of
                           total estimated project costs shown on Exhibit C
                           shall be paid by Marquette within [**] days of the
                           date on which this Agreement is signed by both
                           parties; [**] of total estimated project costs, shown
                           on Exhibit C shall be paid [**] days thereafter, and
                           the final payment of the remaining actual project
                           costs (including labor at Aspect's standard labor
                           rates) shall be paid upon the project's completion.
                           Any [**] the [**] will be [**]; provided, however,
                           that Marquette shall not pay over [**] toward
                           non-recurring engineering ("NRE") and tooling to
                           Aspect.



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4.       PURCHASE AND SALE OBLIGATIONS; LICENSES.

         4.1      GENERAL. Subject to the terms and conditions of this
                  Agreement, Aspect agrees to sell to Marquette the Aspect
                  Products listed on Exhibit A (Aspect Products and Purchase
                  Prices). The components of the Aspect BIS/EEG Module Kits
                  purchased from Aspect under this Agreement shall only be used
                  as components in, incorporated into, or integrated with,
                  systems and products which Marquette sells or leases to
                  third-party users in the regular course of business. The
                  components of the Aspect BIS/EEG Module Kits shall only be
                  resold, leased, rented, licensed or otherwise transferred to
                  third parties for use as a part of an Marquette BIS/EEG Module
                  or as replacement parts used in Marquette BIS/EEG Modules and
                  Marquette shall only sell Aspect approved accessories
                  including cables and sensor products in connection with any
                  Marquette BIS/EEG Module. During the term of this Agreement,
                  Marquette agrees that it may offer complementary but not
                  directly competitive products to the Marquette BIS/EEG Module.
                  Marquette products other than the Marquette BIS/EEG Module
                  that display a parameter claiming to be a measure of the
                  hypnotic effect of anesthesia, are considered to be directly
                  competitive products for purposes of this Section 4.1.

         4.2      DISTRIBUTION OF ASPECT BIS SENSORS. Aspect hereby grants to
                  Marquette a non-exclusive right to distribute Aspect BIS
                  Sensors solely to Marquette customers outside of North America
                  who have purchased Marquette BIS/EEG Modules. Prices for
                  Aspect BIS Sensors purchased by Marquette hereunder shall be
                  as set forth in Exhibit A (Aspect Products and Purchase
                  Prices).

         4.3      ASPECT SOFTWARE LICENSE. Aspect hereby grants to Marquette a
                  non-exclusive and non-transferable worldwide license, without
                  the right to sublicense (except to purchasers of Marquette
                  BIS/EEG Modules), during the term of the Agreement to use the
                  Software and related Documentation provided by Aspect solely
                  in connection with operation of the components of Aspect
                  BIS/EEG Module Kit in the Marquette BIS/EEG Module.
                  Thereafter, Aspect grants to Marquette a right to use the
                  Software and related Documentation used in conjunction with
                  the Marquette BIS/EEG Modules being sold by Marquette on the
                  date of termination with respect to service and support of
                  installed Marquette BIS/EEG Modules for a period of 10 years,
                  after termination of the Agreement. All rights granted to
                  Marquette customers to use the Marquette BIS/EEG Modules shall
                  survive any termination of this Agreement as long as such
                  customers remain in compliance with the terms of use for such
                  Marquette BIS/EEG Modules. Marquette shall not disclose,
                  furnish, transfer, distribute or otherwise make available the
                  Software, the Documentation or any portion thereof in any form
                  to any third party (other than to purchasers of Marquette
                  BIS/EEG Modules and to Marquette's subdistributors) and shall
                  not duplicate the Software, the Documentation or any part
                  thereof (other than for Marquette's internal use as provided
                  above). Title to and ownership of any and all proprietary
                  rights in or related to the Software and the Documentation
                  therefor shall at all times remain with Aspect or its
                  licensor(s). Nothing in this Agreement shall be construed as a
                  sale of any rights in the Software or the Documentation. All
                  references in this Agreement to sale, resale or purchase of
                  the



                                      -4-
<PAGE>   5
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                  Aspect BIS/EEG Module Kits or the components thereof, or
                  references of like effect, shall, with respect to the Software
                  and the Documentation mean licenses or sublicenses of the
                  Software and the Documentation pursuant to this Section 4.
                  Marquette shall not disassemble, decompile or otherwise
                  reverse engineer the Software or any part thereof, except if
                  Aspect is required under applicable law to permit Marquette to
                  reverse engineer any Software. In such event, Marquette may
                  reverse engineer the Software but only to the extent Aspect is
                  required to permit such reverse engineering. Marquette shall
                  retain and shall not alter or obscure any notices, markings or
                  other insignia affixed to the Software, the Documentation or
                  any part thereof at the time it receives such Software or such
                  Documentation.

         4.4      EXCLUSIVITY. Except to the extent Marquette and Aspect may
                  agree in the future to undertake co-marketing programs
                  pursuant to Section 22, nothing in this Agreement shall be
                  construed to grant Aspect any license to sell, distribute or
                  license to any third party the Marquette BIS/EEG Module, the
                  Marquette BIS/EEG Engine, or the Aspect BIS/EEG Module Kit. It
                  is understood, however, that Aspect sells, distributes, and
                  licenses to other third parties both generic and customized
                  Aspect BIS/EEG Engines and Aspect BIS/EEG Module Kits to meet
                  the needs of other OEM customers, and nothing in this
                  Agreement shall prohibit Aspect from continuing to sell,
                  distribute, or license these products or components thereof to
                  customers other than Marquette.

         4.5      STANDARD OF CARE; PRIORITY. In connection with Aspect's
                  performance of its obligations hereunder, Aspect shall use
                  commercially reasonable efforts in the performance of its
                  obligations hereunder and will do so with the same degree of
                  care, skill and prudence customarily exercised when engaged in
                  similar activities for itself.

5.       ROYALTIES AND COMMISSIONS.

         5.1      ROYALTIES ON PURCHASES OF ASPECT MODULE KITS. For each Aspect
                  BIS/EEG Module Kit that Marquette purchases from Aspect,
                  Marquette shall pay a royalty fee and a price for all
                  components of the Aspect BIS/EEG Module Kit. Royalty fees and
                  component prices are specified in Exhibit A (Aspect Products
                  and Purchase Prices); provided that the prices specified in
                  Exhibit A shall not apply to the [**] for the [**] a [**] in
                  [**] for [**] as part [**] agreement pursuant to [**], as [**]
                  will be [**] to [**] at the [**] described in Exhibit A.
                  Aspect BIS/EEG Module Kits sold by Aspect under this
                  Agreement, [**], will be priced based on the Royalty fees and
                  component prices specified in Exhibit A.

         5.2      [**]. For [**] Aspect [**] by Aspect to Marquette [**] in
                  North America for [**] with [**] or with Aspect [**] as part
                  of any [**] pursuant to Section [**],


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<PAGE>   6
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                  Aspect shall [**] Marquette a [**] to [**] of the [**] by
                  Aspect for [**] Aspect [**]. Aspect shall [**] such [**] to
                  Marquette on a [**]. With such [**], Aspect shall [**] to
                  Marquette a [**] of Marquette [**] to which such [**], the
                  [**] of [**] in that [**], and the [**] from the [**] of the
                  [**] by Aspect. This [**] shall be [**] to Marquette no later
                  than [**] the end of [**]. In the event that Aspect's
                  standalone BIS monitors and/or the BIS modules of other
                  manufacturers have also been installed at such sites in
                  addition to Marquette BIS modules, [**] will be [**] to a [**]
                  only on [**] for [**] with [**]. The Parties will agree upon a
                  reasonable [**] for [**] the number of [**] with [**] in such
                  an event (e.g. a [**] determination based on the [**] of [**]
                  of [**] at [**] during the period) and [**] the [**] to
                  Marquette accordingly. To facilitate [**], Marquette will be
                  responsible for providing Aspect with [**] of the [**],
                  the [**].

6.       SCOPE OF DELIVERY

         6.1      PURCHASE ORDERS. Purchase orders (via Fax, e-mail, other
                  electronic transmission or paper) for Aspect Products to be
                  purchased under this Agreement (the "Orders") must be received
                  by Aspect during the term of this Agreement and must specify a
                  delivery date in accordance with the lead-time schedule
                  outlined below under Section 6(e). All Marquette Purchase
                  Orders shall make reference to the appropriate engineering
                  drawing or manufacturing reference numbers. There is no
                  minimum volume commitment required for each purchase order.

         6.2      ORDER ACKNOWLEDGEMENTS. Marquette purchase orders shall be
                  acknowledged by Aspect within 5 days after receipt of the
                  order, provided that the order is technically correct and that
                  the requested delivery time is within the agreed lead time and
                  that the latest forecast provided by Marquette is not exceeded
                  by more than [**] and the quantity ordered does not exceed by
                  more than [**] of the quantity ordered in the preceding month.
                  If the requested delivery time is less than the agreed lead
                  time, or if Marquette's latest forecast is exceeded by more
                  than [**], or if the quantity ordered exceeds by more than
                  [**] the quantity ordered in the preceding month, Aspect shall
                  use reasonable efforts to complete the requirements of such
                  nonconforming orders within seventy (70) days from the date it
                  receives such nonconforming order and to acknowledge such
                  orders within 10 days of its receipt. Order acknowledgements
                  shall not be unreasonably withheld.

         6.3      FORECASTS. Marquette shall furnish to Aspect a non-binding
                  quarterly forecast during the term of this Agreement with the
                  number and type of Aspect Products for which Marquette expects
                  to submit orders for the following twelve months.



                                      -6-
<PAGE>   7
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


         6.4      CANCELLATION CHARGES. In the event of the cancellation of any
                  Order by Marquette, Marquette shall be liable for the payment
                  of cancellation charges based on the number of days prior to
                  scheduled delivery date that written notice of cancellation is
                  received by Aspect, as outlined below:

<TABLE>
                  <S>                                                            <C>
                  [Greater than] 10 weeks prior to acknowledged delivery        [**]
                  6 - 10 weeks prior to acknowledged delivery                   [**] of order value
                  4 - 6 weeks prior to acknowledged delivery                    [**] of order value
                  2 - 4 weeks prior to acknowledged delivery                    [**] of order value
                  [Less than] 2 weeks prior to acknowledged delivery            [**] of order value
</TABLE>

         6.5      COMMITMENT. Except as set forth in Section 6.4, Marquette has
                  no commitment to purchase any minimum quantity of Aspect
                  Products or Aspect BIS Sensors pursuant to this Agreement.
                  Except as set forth in Section 6.4, unless agreed otherwise in
                  writing by the parties, Marquette shall not be responsible or
                  in any way liable to Aspect or any third party with respect to
                  any component purchase commitments or production arrangements
                  in excess of the amounts or in advance of the times necessary
                  to meet Marquette's delivery schedules set forth in its
                  Orders.

         6.6      LEAD TIMES. Lead times for the Aspect BIS/EEG Module Kit are
                  expected to be [**] days. Late deliveries are subject to late
                  fees of [**] per month (pro-rated daily. In the event of late
                  deliveries by Aspect, Aspect will also promptly reimburse
                  Marquette for expedited shipment charges that Marquette incurs
                  as a direct result of late shipments of the Aspect BIS/EEG
                  Module Kit from Aspect .

7.       PRICES.

         7.1      PURCHASE PRICES. The prices of Aspect Products purchased by
                  Marquette hereunder (the "Purchase Prices") which are ordered
                  during the term of the Agreement shall be as set forth in
                  Exhibit A (Aspect Products and Purchase Prices).

         7.2      PURCHASE PRICE CHANGES. In consideration of the market
                  situation and after consultation with Marquette, the Purchase
                  Prices set forth in Exhibit A (Aspect Products and Purchase
                  Prices) shall be reviewed 12 months after first delivery of
                  production units and annually thereafter. Any price adjustment
                  shall become effective only after mutual agreement between
                  both Parties. [**], Aspect shall have the right [**] during
                  the term of this Agreement to increase the Purchase Price of
                  the Aspect Products without the consent of Marquette by an
                  equivalent amount by delivering reasonable documentation
                  supporting such increase and by giving Marquette written
                  notice of the increase not less than [**] days prior to the
                  date upon which the increased Purchase Price is to become
                  effective. [**] shall apply to orders for Aspect Products
                  accepted by Aspect prior to or during such [**] day period
                  which are to be delivered within [**] days of the date of such
                  notice.



                                      -7-
<PAGE>   8
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                  Notwithstanding anything to the contrary in this Section 7.2,
                  [**] unless [**] reasonable efforts to [**] of the [**] which
                  have [**] in [**] and, [**] reasonable efforts, was not [**]
                  to [**].

         7.3      PURCHASE PRICE REDUCTIONS. Aspect may reduce the Purchase
                  Price of any Aspect Product at any time. Such reduction shall
                  be applicable to all Aspect Products shipped after the date of
                  the reduction. [**] the [**] of the [**] for the [**] by [**]
                  as provided in Section 7.2, Aspect shall reduce the Purchase
                  Prices for all Aspect Products (excluding license fees and
                  volume discounts) by not less than [**] per year. The first
                  price reduction will be effective on the [**] anniversary of
                  the introduction of the Marquette BIS/EEG Module, and the
                  second price reduction shall be effective on the [**]
                  anniversary of the introduction of the Marquette BIS/EEG
                  Module.

         7.4      [**]. In no case shall the [**] by any other Party that has
                  [**] with Aspect [**] of this Agreement for [**] under [**]
                  terms and conditions.

         7.5      TAXES. All prices for Aspect Products are exclusive of all
                  federal, state and local taxes, levies and assessments, and
                  Marquette shall be responsible for the payment of all such
                  taxes, levies and/or assessments imposed on Aspect Products
                  purchased and/or licensed by Marquette hereunder, excluding
                  taxes based on Aspect's net income from the transaction.
                  Marquette shall be responsible for providing in a timely
                  manner all documentation, in the nature of exemption
                  certificates or otherwise, necessary to allow Aspect to
                  refrain from collections, such as sales tax, which it would
                  otherwise be obligated to make.

8.       TERMS OF PAYMENT.

         8.1      INVOICES. Marquette shall pay to Aspect the Purchase Price for
                  all Aspect Products shipped hereunder within forty-five (45)
                  days after the receipt of Aspect's invoice. Nothing herein
                  shall affect Aspect's right to withhold shipment or otherwise
                  exercise its rights under Section 23 (Termination) hereof in
                  the event of Marquette's failure to make payment when due for
                  Aspect Products delivered to Marquette. Marquette shall have
                  the right to provide Aspect with a specific address to which
                  Aspect will send invoices for Aspect Products purchased under
                  this Agreement.

         8.2      LATE PAYMENT CHARGE. Subject to applicable law, service and/or
                  interest charges not exceeding the lesser of [**] per month or
                  the highest amount permitted by law may, at the election of
                  Aspect, be assessed on amounts past due more than [**] days
                  (that is, more than [**] days after the payment due date as
                  specified in Section 8.1).

9.       SHIPMENT AND DELIVERY.

         9.1      DELIVERY LOCATION. Each shipment must indicate the exact
                  address of the recipient on the outside of the packaging as
                  follows:



                                      -8-
<PAGE>   9
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.

                                      [TBD]

         9.2      DELIVERY TERMS. All shipments hereunder shall be FOB Aspect's
                  Massachusetts point of origin (Incoterms 1990). All Aspect
                  Products shall be deemed delivered and subject to Marquette's
                  dominion and control only when placed in the possession of a
                  carrier designated by Marquette, properly packed and ready for
                  shipment to Marquette. Aspect shall cooperate with Marquette
                  in the documentation and proof of loss claims promptly
                  presented by Marquette to the appropriate carrier and/or
                  insurer.

         9.3      DELIVERY DATE AND DATE OF DISPATCH. The requested delivery
                  date shall be specified on the Marquette Purchase Order
                  provided that such delivery date must be at least [**] days
                  after the date Aspect receives the Order; provided, however,
                  that Aspect shall use its reasonable efforts to deliver the
                  Order as early as reasonably possible (taking other customer
                  demands on Aspect into account). Aspect shall utilize
                  reasonable efforts to ensure that the order is delivered in
                  accordance with Aspect's order acknowledgement and that the
                  date of dispatch is ten (10) days prior to the delivery date.
                  Late delivery penalties to Aspect will apply as specified in
                  Section 6.6 of this Agreement.

10.      ACCEPTANCE.

         Any Aspect Product shipped hereunder may be subjected to inspection and
performance testing by Marquette, to confirm that it functions in accordance
with Aspect's applicable product specifications in effect at the time of
delivery of such Aspect Products to Marquette . Marquette shall provide written
notice to Aspect of the rejection of any such Aspect Product within [**] days of
the date of receipt of any Aspect Product. Aspect shall have [**] days from
receipt of a notice from Marquette rejecting an Aspect Product either, at its
option, to make any necessary repairs to the defective Aspect Product or to
replace it. If Aspect replaces an Aspect Product, Marquette shall dispose of the
replaced Aspect Product in accordance with Aspect's instructions and at Aspect's
expense. Marquette's sole remedy for rejected Aspect Products shall be limited
to prompt repair or replacement of such Aspect Products.

11.      WARRANTY.

         11.1     GENERAL. Aspect warrants solely to Marquette that Aspect
                  Products (including Software) delivered hereunder shall
                  perform substantially in accordance with the specifications in
                  Exhibit B (Aspect's Standard Module Kit) or other applicable
                  product specifications as published by Aspect in effect at the
                  time of delivery of such Aspect Product (including Software),
                  and shall be free from defects in materials and workmanship,
                  when given normal, proper and intended usage, for twelve (12)
                  months from the date of shipment of the Marquette BIS/EEG
                  Module at Marquette's end customer site or eighteen (18)
                  months from the date of shipment by Aspect to Marquette,
                  whichever is less. Aspect agrees, during the applicable
                  warranty period, to repair or replace (at Aspect's option) all
                  defective Aspect Products within thirty (30) days after the
                  date of return to Aspect and without cost (including shipping)
                  to Marquette. In the event that Aspect is unable to repair or
                  replace such defective Aspect Products


                                      -9-
<PAGE>   10


                  within such thirty (30) day period, Aspect agrees to refund to
                  Marquette the amounts paid to Aspect for such defective Aspect
                  Products. This warranty shall not apply to expendable
                  components and supply items, such as, but not limited to,
                  cables, fuses and bulbs (or disposable items such as an Aspect
                  BIS Sensor after the expiration date marked on the Sensor
                  packaging); nor shall Aspect have any obligation under this
                  Agreement to make repairs or replacements which are required
                  by normal wear and tear, or which result, in whole or in part,
                  from catastrophe, fault or negligence of Marquette, or anyone
                  claiming through or on behalf of Marquette, or from improper
                  or unauthorized use of Aspect Products, or use of Aspect
                  Products in a manner for which they were not designed, or by
                  causes external to Aspect Products such as, but not limited
                  to, power or air conditioning failure.

         11.2     WARRANTY PROCEDURES. Marquette shall notify Aspect of any
                  Aspect Products which it believes to be defective during the
                  applicable warranty period and which are covered by the
                  warranties set forth in Section 11.1. At Aspect's option, such
                  Aspect Products shall be returned by Marquette to Aspect's
                  designated facility for examination and testing, or may be
                  repaired on site by Aspect. Aspect shall either repair or
                  replace, within thirty (30) days of receipt by Aspect, any
                  such Aspect Product found to be so defective and promptly
                  return such Aspect Products to Marquette. Transportation and
                  insurance costs shall be borne by Aspect. Should Aspect's
                  examination and testing not disclose any defect covered by the
                  foregoing warranty, Aspect shall so advise Marquette and
                  dispose of or return the Aspect Product in accordance with
                  Marquette's instructions and at Marquette's sole expense, and
                  Marquette shall reimburse Aspect for such transportation and
                  insurance costs.

         11.3     REPAIR WARRANTY. Aspect warrants its repair work and/or
                  replacement parts for the duration of the original warranty
                  period as set forth in Section 10(a) or at least six (6)
                  months, whichever is longer.

         11.4     DISCLAIMER OF WARRANTIES. THE PROVISIONS OF THE FOREGOING
                  WARRANTIES ARE IN LIEU OF ANY OTHER WARRANTY, WHETHER EXPRESS
                  OR IMPLIED, WRITTEN OR ORAL (INCLUDING ANY WARRANTY OF
                  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

12.      SERVICE AND SUPPORT.

         12.1     SERVICE AND SUPPORT. Marquette shall be responsible for
                  providing installation, customer training, service and support
                  (including repair) to its end customers for the Aspect
                  Products Marquette sells to such customers, and Marquette
                  shall bear all related costs incurred for labor, parts, or
                  travel to perform such service.

         12.2     CENTRAL REPAIR SERVICE. For the term of this Agreement, Aspect
                  agrees to provide central repair service (as opposed to field
                  service) to Marquette for Aspect Products sold hereunder.



                                      -10-
<PAGE>   11


         12.3     SERVICE TRAINING. Aspect agrees to provide initial service
                  training to a mutually agreed upon number of Marquette service
                  representatives prior to the market release of the EEG/BIS
                  module, as well as periodic (annually at a minimum) ongoing
                  training for existing and new Marquette service personnel.

         12.4     SERVICE PERIOD. For a period of seven (7) years following the
                  last delivery to Marquette of the applicable Aspect Product
                  ordered by Marquette hereunder, Aspect shall use its
                  reasonable efforts to make available repair service (or at
                  Aspect's sole discretion, exchange units for the Aspect
                  Products) for purchase by Marquette and third party users of
                  the Aspect products at Aspect's then-current prices for such
                  repair services and exchange units. After expiry of this seven
                  (7) year period, Aspect may, in its sole discretion, continue
                  to supply repair services (and/or exchange units for the
                  Aspect Products) subject to the mutual written agreement of
                  the Parties.

         12.5     SERVICE REPORTING. Aspect shall maintain a complete record of
                  all repair activities performed on any Aspect products
                  received for repair, and shall provide Marquette with a
                  quarterly report on all service actions including failure and
                  repair statistics at a sub-assembly level Service Reports for
                  each product shall be sent electronically by email to a
                  designated procurement and technical marketing engineer
                  (Contact Persons shown in Exhibit D, Contact Persons /
                  Addresses). Root cause analysis is to be performed and
                  reported by Aspect to Marquette in case of abnormal failures,
                  incidents and malfunctions.

13.      QUALITY ASSURANCE.

         13.1     CERTIFICATION STATUS. Both parties agree to maintain ISO900x,
                  EN460x, European directive 93/42/EEC Annex II ("MDD AX-II")
                  certification status and compliance with the U.S. Food and
                  Drug Administration's ("FDA") Quality System Regulation
                  ("QSR"), the European Medical Device Directive ("MDD"), and
                  other appropriate regulations pertinent to the development,
                  manufacturing and marketing of medical products similar to the
                  Aspect Products.

         13.2     ASPECT PRODUCT COMPLIANCE. All Aspect Products sold by Aspect
                  under this Agreement shall fully comply with the above quality
                  requirements and guidelines (MDD AX-II, FDA QSR, etc.)

         13.3     QA AND REGULATORY AUDITS. Aspect shall permit Marquette's
                  Quality Assurance department to conduct a reasonable audit of
                  its facilities at a mutually agreed upon date after the date
                  of this Agreement for the purpose of approving its status as
                  an OEM supplier, and reasonable periodic audits thereafter for
                  the purpose of confirming continuing compliance with
                  applicable quality and regulatory requirements and guidelines.
                  Such audits shall be scheduled with at least thirty (30) days
                  advance notice during normal business hours and shall not take
                  place more than once per calendar year.

14.      REGULATORY MATTERS.



                                      -11-
<PAGE>   12

         14.1     ASPECT PRODUCTS. Aspect shall assume full regulatory
                  responsibility for the Aspect Products, including obtaining
                  and maintaining all applicable governmental authorizations and
                  regulatory approvals required to distribute the Aspect BIS/EEG
                  Module Kit. Both Parties shall work together to develop a
                  regulatory plan which defines precisely what these regulatory
                  and localization requirements are for all countries where the
                  Marquette BIS/EEG Module is intended to be sold. In
                  particular, Aspect shall be responsible for generating its own
                  Device Master Record for the Aspect BIS/EEG Module Kit. It is
                  understood that the Aspect BIS/EEG Module Kit shall be a
                  component of the Marquette BIS/EEG Module. Marquette shall be
                  responsible for obtaining and maintaining all applicable
                  governmental authorizations and regulatory approvals required
                  to distribute the combination of Aspect and Marquette products
                  in the Marquette BIS/EEG Module as provided in Section 14.3.

         14.2     MARQUETTE PATIENT MONITORS. Marquette shall assume full
                  regulatory responsibility for the Marquette Patient Monitors,
                  including obtaining and maintaining all applicable
                  governmental authorizations and regulatory approvals required
                  to distribute the Marquette Patient Monitors in all countries
                  in the Territory.

         14.3     MARQUETTE BIS/EEG MODULE. Marquette shall assume the
                  regulatory responsibility for the combination of the Aspect
                  and Marquette components in the Marquette BIS/EEG Module.
                  Aspect shall fully support Marquette as required in the
                  process of obtaining regulatory approvals by making available
                  to Marquette any required information, data, certificates, or
                  technical files in the requested formats.

         14.4     INTERNATIONAL REGULATORY RESPONSIBILITIES. For bringing the
                  Aspect Products into the market in countries affected by the
                  European Medical Device Directive ("MDD"), Aspect is the
                  legally responsible manufacturer under the MDD. The Aspect
                  Products shall be marked accordingly.

         14.5     PRODUCT COMPLAINTS AND INCIDENT REPORTING. Marquette and
                  Aspect shall inform each other in writing immediately about
                  any event that may require incident reporting in any country.
                  Marquette and Aspect shall inform each other in writing within
                  two (2) business days of a customer complaint regarding the
                  Marquette BIS/EEG Module, the Aspect Products, or (within the
                  Territory) Aspect BIS Sensors. Both parties will cooperate and
                  use commercially reasonable efforts to resolve such customer
                  complaints. Closure of any customer complaint relating to the
                  Marquette BIS/EEG Module will occur when Marquette notifies
                  Aspect that the problem is resolved. Closure of any customer
                  complaint relating solely to Aspect Products or Aspect Sensors
                  will occur when Aspect notifies Marquette that the problem is
                  resolved.

         14.6     RECALLS. In the event of any recall of an Aspect Product
                  required by either a governmental agency, by Aspect, or by
                  Marquette for safety or efficacy reasons which is the result
                  of Aspect's failure to supply Aspect Products that (1) conform
                  in all material respects to the applicable published
                  specifications (including the



                                      -12-
<PAGE>   13
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                  specifications set forth in Exhibit B (Aspect's Standard
                  Module Kit)) or (2) are free from defects in material and
                  workmanship (when given normal, proper and intended usage),
                  Aspect agrees to repair or replace at its own costs all Aspect
                  Products subject to the recall and previously delivered to
                  Marquette. Aspect also agrees to consult with Marquette to
                  establish a reasonable process for managing the recall and
                  Aspect shall be [**] (including, but not limited to [**] that
                  are consistent with the recall process agreed to by the
                  Parties. In the event that Aspect at its sole discretion
                  requests a recall that is not required by a governmental
                  agency for safety or efficacy reasons, Aspect shall be
                  responsible for determining the scope of the recall, including
                  the number of units, timeframe for the recall, and criteria
                  for completion. Marquette agrees to maintain all necessary
                  sales records to facilitate the recall.

         14.7     DELEGATION. Marquette may at its sole discretion delegate some
                  of the obligations under this Section 14 to its
                  sub-distributors.

         14.8     TRACEABILITY. For the purpose of facilitating product
                  traceability, all Products purchased from Aspect by Marquette
                  shall require identification of an internal order number and
                  tracking code.

15.      PRODUCT CHANGES; DISCONTINUED PRODUCTS; FUTURE PRODUCTS; CONTINUED
         SUPPLY.

         15.1     PRODUCT CHANGES. Aspect shall have the right, at any time and
                  from time to time, to make substitutions and modifications to
                  Aspect Products, provided that such substitutions or
                  modifications shall not materially affect form, fit, function,
                  reliability, serviceability, performance, functional
                  interchangeability or interface capability of Aspect Products.
                  In the event that any proposed substitution or modification
                  affects, in Aspect's reasonable judgment, the form, fit,
                  function, reliability, serviceability, performance, functional
                  interchangeability or interface capability of an Aspect
                  Product, Aspect shall give Marquette written notice of such
                  proposed substitution or modification at least [**] days prior
                  to its taking effect and Marquette shall have the right,
                  during such [**] day period and for [**] days thereafter, to
                  order Aspect Products without such substitution or
                  modification for delivery up to [**] days after such
                  substitution or modification takes effect. Aspect shall
                  provide the appropriate verification and validation
                  information for evaluating the effect of the change on the
                  Marquette BIS/EEG Module.

         15.2     DISCONTINUED PRODUCTS. Aspect agrees to notify Marquette in
                  writing not less than [**] in advance of the discontinuance of
                  any Aspect Product. Marquette shall be able to place orders
                  for at least [**] after receipt of the written notice in any
                  case. In addition, Marquette shall be entitled to determine
                  its lifetime-buy quantities and place a corresponding last
                  purchase order.

         15.3     FUTURE PRODUCTS. The Aspect Products are designed for use in
                  measuring the effects of anesthetic and sedative agents on the
                  brain during surgery. In the event that Aspect develops a
                  product involving this or a different type of index, patient



                                      -13-
<PAGE>   14

                  sensor, or application, Aspect and Marquette agree to discuss
                  in good faith a new agreement for the purchase of such new
                  product or products by Marquette.

16.      OWNERSHIP AND PROTECTION OF RESULTS.

         16.1     NO TRANSFER OF OWNERSHIP. It is expressly agreed that neither
                  Aspect nor Marquette shall transfer to the other Party any
                  patent rights, copyrights or other intellectual property of
                  any kind that either Party owns as of the Effective Date of
                  this Agreement.

         16.2     MODELS, PATTERNS, DIES, ETC. Aspect shall retain the title to
                  and possession of any models, patterns, dies, molds, jigs,
                  fixtures, and other tools made for or obtained in connection
                  with this Agreement and related to the Aspect Products, even
                  if made for, obtained by or paid for by Marquette.

         16.3     DEVELOPMENTS. If there are developments (including patentable
                  inventions) conceived, created or reduced to practice under
                  this Agreement then the rights to such developments shall be
                  retained (a) by Aspect if conceived, created and reduced to
                  practice solely by Aspect, or (b) by Marquette, if solely
                  conceived, created and reduced to practice by Marquette, or
                  (c) jointly by Marquette and Aspect (without any duty to
                  account to the other) if jointly developed by Marquette and
                  Aspect, provided that:

                           (i)      Marquette shall assign to Aspect all rights
                                    to any developments conceived, created or
                                    reduced to practice by Marquette solely
                                    relating to the Aspect BIS/EEG Module Kit;
                                    and

                           (ii)     Aspect shall assign to Marquette all rights
                                    to any development solely relating to the
                                    Marquette Patient Monitor.

17.      DOCUMENTATION AND TRAINING.

Aspect agrees to provide Marquette with such product literature, operations and
maintenance manuals, and other information and training (including training to
avoid possible misrepresentation of Aspect's Bispectral Index) as is mutually
agreed, to enable Marquette to properly sell and maintain Aspect Products,
provided that in no event shall the source code or source listings of Aspect
Software be required to be disclosed or provided by Aspect to Marquette [**].
Aspect agrees to give Marquette the rights to use or reproduce its user
documentation for incorporation into Marquette documentation excluding source
code or source listings as previously mentioned. Such documentation should be
provided in an electronic format. Aspect shall be given the opportunity to
review and approve Marquette documentation that incorporates Aspect
documentation prior to publication. The training Aspect is required to provide
Marquette under this Section 17 shall begin at least three (3) months prior to
introduction of the Marquette BIS/EEG Module and shall be defined as part of the
Project's marketing plan.





                                      -14-
<PAGE>   15

18.      CONFIDENTIALITY.

No confidential information disclosed by either Party to the other in connection
with this Agreement shall be disclosed to any person or entity other than the
recipient Party's employees and contractors directly involved with the recipient
Party's use of such information who are bound by written agreement to protect
the confidentiality of such information, and such information shall otherwise be
protected by the recipient Party from disclosure to others with the same degree
of care accorded to its own confidential information of like importance. In
addition, each Party and its representatives shall use the confidential
information only for the purposes specified under this Agreement and such
information shall not be used for any other purpose without the prior written
consent of the disclosing Party. To be subject to this provision, information
must be delivered in writing and designated as proprietary or confidential, or
if initially delivered orally, must be identified at the time of disclosure, and
confirmed in writing as confidential within ten (10) days after such oral
disclosure. Information shall not be subject to this provision if it is or
becomes a matter of public knowledge without the fault of the recipient Party,
if it was a matter of written record in the recipient Party's files prior to
disclosure to it by the other Party, if it was or is received by the recipient
Party from a third person under circumstances permitting its unrestricted
disclosure by the recipient Party, or if it was independently developed by the
recipient Party without reference to the confidential information. Upon
termination of this Agreement, each Party shall promptly destroy all
confidential information of the other Party in the possession or control of such
Party and all copies thereof, provided that each Party may retain one copy
thereof for archival purposes. The obligations under this Section 18 shall
continue for both parties for a period of five (5) years after delivery by
Aspect to Marquette of the last Aspect Product under this Agreement, provided,
however that any [**] pursuant to [**] shall be maintained in confidence in
perpetuity. Marquette is entitled to transmit confidential information of Aspect
to Marquette subsidiaries and affiliated companies. In such, case these
subsidiaries and affiliated companies may only use such information to the same
extent as Marquette is entitled to use such information under this Agreement.
Marquette shall be responsible if any of these subsidiaries and affiliated
companies fail to comply with the confidentiality provisions of this Agreement.




                                      -15-
<PAGE>   16

19.      WARRANTIES AND INDEMNITIES.

         19.1     WARRANTIES BY ASPECT.

                  (a)      Aspect represents and warrants that it either has all
                           rights, title and interest in, or valid licenses to,
                           the Aspect Products and any related intellectual
                           property rights thereto. Aspect represents and
                           warrants that it has not granted in the Territory any
                           exclusive licenses or exclusive sublicenses in the
                           Aspect Products that would prevent it from granting
                           Marquette the licenses set forth in Section 4.3
                           (Aspect Software License). Aspect also represents and
                           warrants that it has the right and authority to
                           engage in the joint development of the Marquette
                           BIS/EEG module as contemplated hereunder and that to
                           its knowledge such activity will not infringe upon or
                           misappropriate any third party's intellectual
                           property rights.

                  (b)      Aspect warrants that it will deliver all Aspect
                           Products free from the rightful claims of any third
                           party for infringement of any Patents, Trademarks or
                           Copyrights or misappropriation of Trade Secrets.
                           Aspect also warrants that as of the date of this
                           Agreement, Aspect has received no notice of a claim
                           of infringement or misappropriation from any third
                           party regarding Aspect Products. Marquette's
                           exclusive remedy with respect to breach of any
                           warranty provided in this Section 19.1 shall be that
                           Aspect will defend at its own expense, and will pay
                           the costs and damages (including attorneys fees,
                           other professional fees and other costs of litigation
                           or settlement) made in settlement or awarded as a
                           result of, any action brought against Marquette or
                           any of Marquette's customers based on an allegation
                           of such infringement or misappropriation with respect
                           to any Aspect Product, provided that the
                           Indemnification Procedures set forth in Section 19.3
                           are followed. If an injunction is obtained against
                           Marquette's or its customers' use of an Aspect
                           Product by reason of an infringement or
                           misappropriation described above, or if in Aspect's
                           opinion an Aspect Product or any part thereof is
                           likely to become the subject of a claim of such
                           infringement or misappropriation, Aspect will, at its
                           option and its own expense procure the right for
                           Marquette and its customers to continue using such
                           Aspect Product, or replace or modify such Aspect
                           Product or any part thereof so that it becomes
                           non-infringing. If neither of the foregoing options
                           are reasonably available to Aspect, Aspect shall have
                           the right to discontinue supplying such Aspect
                           Products to Marquette. Aspect shall not have any
                           obligation to Marquette or its customers under any
                           provision of this Section if the infringement or
                           misappropriation claim is based upon the modification
                           of any Aspect Product not made by Aspect, the use of
                           Aspect Products in combination with any program or
                           equipment, or any part thereof, not furnished or
                           recommended in writing by Aspect, or the use of such
                           Aspect Products in a manner or environment, or for
                           any purpose, for which Aspect did not design or
                           license them.



                                      -16-

<PAGE>   17
                  (c)      In the event that any claim is brought against
                           Marquette as a result of personal injuries and/or
                           property damages resulting from that portion of the
                           Marquette BIS/EEG Module developed and manufactured
                           by Aspect, and provided further that such claims do
                           not arise as a result of the misuse of the Aspect
                           Products, or the use of the Aspect Products in an
                           application for which it was not designed by Aspect,
                           where such claim would not have occurred but for such
                           misuse or use, Aspect agrees that it shall indemnify
                           and hold Marquette and its directors, officers,
                           employees, representatives and agents harmless from
                           and against any damages, liabilities, costs and
                           expenses (including attorneys' and other professional
                           fees and other costs of litigation) arising out of
                           such claim, provided that the procedures set forth in
                           Section 19.3 are followed.

         19.2     WARRANTIES BY MARQUETTE.

                  (a)      Marquette represents and warrants that it either has
                           all rights, title and interest in, or valid license
                           to, the Marquette Patient Monitor and any related
                           intellectual property rights thereto. Marquette also
                           represents and warrants that it has the right and
                           authority to engage in the development of the
                           Marquette BIS/EEG Module as contemplated hereunder
                           and that to its knowledge such activity will not
                           infringe upon or misappropriate any third party's
                           intellectual property rights or violate the terms of
                           any agreement Marquette has entered into with a third
                           party.

                  (b)      Marquette warrants that as of the date of this
                           Agreement, Marquette has received no notice of a
                           claim of infringement or misappropriation from any
                           third party regarding the Marquette Patient Monitor
                           or any other Marquette-supplied component of the
                           Marquette BIS/EEG Module. Aspect's exclusive remedy
                           with respect to breach of any warranty provided in
                           this Section 19.2 shall be that Marquette will defend
                           at its own expense, and will pay the costs and
                           damages (including attorneys fees, other professional
                           fees and other costs of litigation or settlement)
                           made in settlement or awarded as a result of, any
                           action brought against Aspect or any of Aspect's
                           customers based on an allegation of such infringement
                           or misappropriation with respect to any Marquette
                           Patient Monitor or any other Marquette-supplied
                           component of the Marquette BIS/EEG Module, provided
                           that the Indemnification Procedures set forth in
                           Section 19.3 are followed. If an injunction is
                           obtained against Aspect's or its customers' use of a
                           Marquette Patient Monitor or any other
                           Marquette-supplied component of the Marquette BIS/EEG
                           Module by reason of an infringement or
                           misappropriation described above, or if in
                           Marquette's opinion a Marquette Patient Monitor or
                           any other Marquette-supplied component of the
                           Marquette BIS/EEG Module or any part thereof is
                           likely to become the subject of a claim of such
                           infringement or misappropriation, Marquette will, at
                           its option and its own expense procure the right for
                           Aspect and its customers to continue using such
                           Marquette Patient Monitor or any other
                           Marquette-supplied component of the Marquette



                                      -17-
<PAGE>   18
                           BIS/EEG Module, or replace or modify such Marquette
                           Patient Monitor or any other Marquette-supplied
                           component of the Marquette BIS/EEG Module or any part
                           thereof so that it becomes non-infringing. Marquette
                           shall not have any obligation to Aspect or its
                           customers under any provision of this Section 19.2 if
                           the infringement or misappropriation claim is based
                           upon the use of Marquette Patient Monitors or any
                           other Marquette-supplied component of the Marquette
                           BIS/EEG Modules in combination with any program or
                           equipment, or any part thereof, not furnished or
                           recommended in writing by Marquette, or the use of
                           such Marquette Patient Monitors or any other
                           Marquette-supplied component of the Marquette BIS/EEG
                           Modules in a manner or environment, or for any
                           purpose, for which Marquette did not design or
                           license them.

                  (c)      In the event that any claim is brought against Aspect
                           as a result of personal injuries and/or property
                           damages resulting from the Marquette BIS/EEG Module,
                           and provided further that such claims do not arise as
                           a result of the defective design or operation of that
                           portion of the Marquette BIS/EEG Module developed or
                           manufactured by Aspect, Marquette agrees that it
                           shall indemnify and hold Aspect and its directors,
                           officers, employees, representatives and agents
                           harmless from and against any damages, liabilities,
                           costs and expenses (including attorneys' and other
                           professional fees and other costs of litigation)
                           arising out of such claim, provided that the
                           procedures set forth in Section 19.3 are followed.

         19.3     INDEMNIFICATION PROCEDURES.

                  (a)      In the event that any person intends to claim
                           indemnification pursuant to this Agreement, (an
                           "Indemnitee"), it shall promptly notify the
                           indemnifying Party (the "Indemnitor") in writing of
                           such alleged liability, provided that the failure to
                           promptly notify the Indemnitor shall not relieve the
                           Indemnitor of any obligation under this Agreement
                           except to the extent such failure to provide prompt
                           notice adversely impairs the Indemnitor's ability to
                           defend against the claim, suit or proceeding.

                  (b)      The Indemnitor shall have the sole right to control
                           the defense and settlement thereof, provided, that
                           (i) the Indemnitor may not consent to imposition of
                           any obligation or restriction on the Indemnitee in
                           any settlement unless mutually agreed among Aspect
                           and Marquette (ii) Indemnitor shall keep Indemnitee
                           fully informed and permit the Indemnitee to
                           participate (at Indemnitee's expense) as the
                           Indemnitee may reasonably request and (iii)
                           Indemnitee may, without affecting its right to
                           indemnity hereunder, defend and settle any such
                           claim, suit or proceeding if Indemnitor declines to
                           defend against such claim, suit or proceeding or
                           Files for Bankruptcy. The Indemnitee shall cooperate
                           with the Indemnitor and its legal representatives in
                           the investigation of any action, claim or liability
                           covered by this Agreement.




                                      -18-
<PAGE>   19

                  (c)      The Indemnitee shall not, except at its own cost,
                           voluntarily make any payment or incur any expense
                           with respect to any claim or suit without the prior
                           written consent of Indemnitor, which Indemnitor shall
                           not be required to give, provided that the Indemnitee
                           may, without affecting its right to indemnity
                           hereunder, defend and settle any such claim, suit or
                           proceeding if the Indemnitor declines to take
                           responsibility or Files for Bankruptcy.

20.      TRADEMARKS.

         20.1     TRADEMARKS.

                  (a)      OWNERSHIP. Marquette acknowledges and agrees that
                           Aspect is the sole and exclusive owner of all right,
                           title and interest in, or has valid licenses to the
                           trademarks (the "Aspect Trademarks") identified on
                           Exhibit E (Aspect Trademarks). Aspect acknowledges
                           and agrees that Marquette is the sole and exclusive
                           owner of all right, title and interest in and to the
                           trademarks (the "Marquette Trademarks") identified on
                           Exhibit F (Marquette Trademarks). Each Party
                           recognizes the value of the other Party's Trademarks
                           and the good will associated with the other Party's
                           Trademarks. Marquette agrees that its use of the
                           Aspect Trademarks and any good will arising therefrom
                           shall inure to the benefit of Aspect. Aspect agrees
                           that its use of the Marquette Trademarks and any good
                           will arising therefrom shall inure to the benefit of
                           Marquette. Nothing contained herein shall create, nor
                           shall be construed as an assignment of, any right,
                           title or interest in or to the Aspect Trademarks to
                           Marquette, or the Marquette Trademarks to Aspect,
                           other than the grant of the licenses in Section 20.1
                           (c) below; it being acknowledged and agreed that all
                           other right, title and interest in and to the Aspect
                           Trademarks is expressly reserved by Aspect and its
                           licensors, and all other right, title and interest in
                           and to the Marquette Trademarks is expressly reserved
                           by Marquette. Each Party shall keep the other Party's
                           Trademarks free from all liens, mortgages or other
                           encumbrances. Each Party agrees that it shall not
                           attack or otherwise challenge the title, validity or
                           any other rights of the other Party in or to its
                           Trademarks.

                  (b)      NOTICE. All Marquette BIS/EEG Modules that use the
                           Aspect Trademarks shall be accompanied, where
                           reasonable and appropriate, by a proprietary notice
                           consisting of the following elements:

                           (i)      The statement "[insert trademark(s)] is a
                                    trademark(s) of [or licensed to] Aspect
                                    Medical Systems, Inc."

                           (ii)     Marquette shall include the "(TM)" or "(R)"
                                    symbol, as instructed by Aspect, after the
                                    first prominent use of the Aspect Trademark
                                    in the Marquette Patient Monitor and related
                                    materials. Marquette shall have a period of
                                    sixty (60) days in which to begin to use the




                                      -19-
<PAGE>   20
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                                    "(R)" symbol in replacement of the "(TM)"
                                    symbol upon receiving instructions to do so
                                    by Aspect for all new stock of such
                                    materials. Marquette may continue to deliver
                                    stocked literature before the change becomes
                                    effective.

                  Marquette shall reproduce copyright and trademark notices of
                  Aspect on the "splash screen" or in the same location where
                  Marquette reproduces its own copyright and trademark notices .

                  (c)      LICENSE. Each Party hereby grants to the other a
                           nonexclusive, worldwide, royalty-free license
                           (without the right to sublicense) to use the other
                           Party's Trademarks to designate and promote Aspect
                           Products in conjunction with Marquette BIS/EEG
                           Modules. Neither Party shall have any other right to
                           use, display or utilize the other Party's Trademarks
                           for any other purpose or in any other manner.

                  (d)      QUALITY STANDARDS.

                           (i)      INSPECTION. Upon reasonable notice and
                                    request, each Party will furnish to the
                                    other samples of its applicable advertising
                                    and promotional materials as necessary to
                                    allow the requesting Party to monitor
                                    compliance with this Agreement.

                           (ii)     COMPLIANCE. Aspect acknowledges the high
                                    standards of quality and excellence
                                    established by Marquette with respect to
                                    products bearing Marquette's trademarks.
                                    Marquette acknowledges the high standards of
                                    quality and excellence established by Aspect
                                    with respect to products bearing the Aspect
                                    Trademarks. Each Party agrees that Marquette
                                    BIS/EEG Modules with which both parties'
                                    Trademarks are used shall be of such quality
                                    so as to maintain such high standards and to
                                    reflect well upon both Parties. Each Party
                                    agrees to adhere to its own or the following
                                    quality standards (whichever may be more
                                    rigorous) for use of the other Party's
                                    Trademarks in connection with the Marquette
                                    BIS/EEG Module:

                                    -        In order to ensure that the
                                             Marquette BIS/EEG Module
                                             distributed under both parties'
                                             Trademarks complies with the
                                             consistent quality standards of
                                             each Party, all Marquette BIS/EEG
                                             Modules distributed by or for
                                             Marquette which bear an Aspect
                                             Trademark shall conform to those
                                             commercially reasonable standards
                                             which Aspect provides to Marquette
                                             in writing. Marquette shall cause
                                             each major new release of such
                                             Marquette BIS/EEG Modules to comply
                                             with such standards or remove the
                                             Aspect Trademark(s) from any such
                                             new release, which does not comply
                                             with such standards. Marquette
                                             shall have a period of [**] in
                                             which to bring newly manufactured
                                             Marquette



                                      -20-
<PAGE>   21
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                                             BIS/EEG  Modules into compliance
                                             with any commercially reasonable
                                             standard provided to it in writing
                                             by Aspect following the date of
                                             receipt of such standard.

                                    -        Each Party acknowledges that if
                                             Marquette BIS/EEG Modules bearing
                                             both Parties' Trademarks fail to
                                             satisfy the quality standards set
                                             forth above, the substantial good
                                             will which each Party has built and
                                             now possess in its own products and
                                             Trademarks shall be impaired.

                  (e)      PROTECTION AND INFRINGEMENT. Each Party agrees to
                           cooperate with and assist the other Party in
                           obtaining, maintaining, protecting, enforcing and
                           defending the other Party's proprietary rights in and
                           to its Trademarks. In the event that either Party
                           learns of any infringement, threatened infringement
                           or passing-off of the other Party's Trademarks, or
                           that any third party claims or alleges that the other
                           Party's Trademarks infringe the rights of the third
                           party or are otherwise liable to cause deception or
                           confusion to the public, the Party obtaining such
                           information shall notify the other Party giving the
                           particulars thereof, and if such claims or
                           allegations relate to this Agreement, the Marquette
                           BIS/EEG Module, the Aspect BIS/EEG Kit or Aspect
                           Products sold hereunder, shall provide necessary
                           information and assistance reasonably requested by
                           such other Party in the event that such other Party
                           decides that proceedings should be commenced.

                  (f)      TERMINATION. In addition to the termination rights
                           set forth in Section 23 hereof, in the event that
                           either Party is in material breach of any provision
                           of this Section 20, the non-breaching Party may, upon
                           [**] days written notice, terminate the license
                           granted in Section 20.1 (c) if the breaching Party
                           does not cure such breach or default within such [**]
                           day period. In addition to the provisions of Section
                           23 hereof, upon termination of the license granted in
                           Section 20.1 (c), or upon termination of this
                           Agreement, for whatever cause:

                           (i)      each Party shall immediately cease and
                                    desist from any further use of the other
                                    Party's Trademarks and any trademarks
                                    confusingly similar thereto, either directly
                                    or indirectly;

                           (ii)     All rights in the Aspect Trademarks granted
                                    to Marquette hereunder shall immediately
                                    revert to Aspect, and all rights in the
                                    Marquette Trademarks granted to Aspect
                                    hereunder shall immediately revert to
                                    Marquette;

                           (iii)    In the event that this Agreement is
                                    terminated for any reason other than a
                                    material breach or material default by
                                    Marquette, Marquette shall thereafter to
                                    dispose of all of the unsold Marquette
                                    Patient Monitors bearing the Trademarks and
                                    advertising and promotional



                                      -21-
<PAGE>   22
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                                    materials relating thereto which had been
                                    completed by it prior to such termination,
                                    provided such Marquette Patient Monitors and
                                    materials were in the process of manufacture
                                    before such termination.

                  (g)      PROMOTIONAL CLAIMS. The general form of any
                           promotional claims by Marquette regarding Aspect's
                           Bispectral Index technology and/or the integration of
                           Aspect's Bispectral Index technology in Marquette
                           Patient Monitors, and the specific form of the use of
                           Aspect's trade names and trademarks, and of intended
                           use claims regarding Aspect's Bispectral Index
                           technology, in promotional material, advertisement,
                           and/or in written technical literature shall be
                           subject to review and approval by Aspect prior to its
                           publication or display. The general form of any
                           promotional claims by Aspect regarding Marquette's
                           Patient Monitors or the integration of Aspect's
                           Bispectral Index technology in Marquette Patient
                           Modules, and the specific form of the use of
                           Marquette's trade names and Trademarks, and of
                           intended use claims regarding the Marquette BIS/EEG
                           Modules, in promotional material, advertisement,
                           and/or in written technical literature shall be
                           subject to review and approval by Marquette prior to
                           its publication or display.

21.      EXPORT.

Marquette shall not export, directly or indirectly, Aspect Products (including
when integrated into a Marquette Patient Monitor) or other products, information
or materials provided by Aspect hereunder, to any country for which the United
States requires any export license or other governmental approval at the time of
export without first obtaining such license or approval. It shall be Marquette's
responsibility to comply with the latest United States export regulations, and
Marquette shall defend and indemnify Aspect from and against any damages, fines,
penalties, assessments, liabilities, costs and expenses (including reasonable
attorneys' fees and court costs) arising out of any claim that Marquette Patient
Monitors or other products, information or materials provided by Aspect
hereunder were exported or otherwise shipped or transported in violation of
applicable laws and regulations.

22.      CO-MARKETING PROGRAM.

Marquette and Aspect will undertake co-marketing programs in the future in
certain geographies, including North America, consistent with the goals and
principles outlined in Exhibit F to this Agreement. The Parties further agree to
utilize their best efforts to finalize a definitive co-marketing agreement to
implement the goals outlined in Exhibit F within [**] days following the date on
which this OEM Development and Purchase Agreement is signed by both Parties.





                                      -22-
<PAGE>   23
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.



23.      TERM; DEFAULT AND TERMINATION.

         23.1     TERM AND RENEWAL. The initial term of this Agreement shall
                  commence on the Effective Date and shall continue for a period
                  of three (3) years following introduction of the Marquette
                  BIS/EEG Module. The term of this Agreement shall be renewed
                  automatically for successive twelve (12) month periods, unless
                  either Party provides written notice of termination to the
                  other Party at least sixty (60) days prior to expiration of
                  the Agreement.

         23.2     TERMINATION FOR GOOD CAUSE.

                  (a)      TERMINATION BY ASPECT. The Agreement may be
                           terminated by Aspect giving [**] prior
                           written notice to Marquette in the event Marquette
                           has not commercially introduced a Marquette BIS/EEG
                           Module by October 31, 2001.

                  (b)      TERMINATION BY MARQUETTE. The Agreement may be
                           terminated by Marquette giving [**] written notice
                           to Aspect if Aspect has failed to provide a Aspect
                           BIS/EEG Module Kit consistent with the specifications
                           outlined in Exhibit C to Marquette by December 31,
                           2000. Furthermore, Marquette will require prototype
                           Aspect BIS/EEG Module Kits in advance of the December
                           31, 2000 date, as follows in order to make the date
                           specified in Section 23.2(a): [**] then current
                           Aspect BIS/EEG Module Kit approximately 10-12 weeks
                           after the project commences; [**] then current Aspect
                           BIS/EEG Module Kits approximately five (5) months
                           thereafter; and approximately [**] then current
                           Aspect BIS/EEG Module Kits two (2) months thereafter.
                           Specific schedules and volumes for prototype Aspect
                           BIS/EEG Module Kits will be mutually agreed upon by
                           both Parties to meet the mutual timelines.

                  (c)      MATERIAL COMPETITIVE FEATURES. Either Party may
                           terminate this Agreement if the other Party's [**] do
                           not [**] for [**] the [**] of [**] and [**] on the
                           [**] . In order to exercise its rights under this
                           Section 23.2(c), a Party must provide [**] prior
                           written notice to the other Party, specifying in
                           reasonable detail the [**] or [**] that are [**].
                           Following receipt of such notification, the notified
                           Party shall have [**] to [**] in [**]. If at the end
                           of such [**] period, the notified Party is unable to
                           do so, the notifying Party may terminate the
                           Agreement; provided, that no such notification shall
                           be effective prior to [**].




                                      -23-
<PAGE>   24


         23.3     EVENTS OF DEFAULT. The following shall constitute events of
                  default under this Agreement:

                           (i)      if either Party assigns this Agreement or
                                    any of its rights or obligations hereunder
                                    without the prior written consent of the
                                    respective other Party, except: (a) as
                                    specifically permitted under this Agreement;
                                    or (b) in connection with the sale or other
                                    transfer of such Party's business to which
                                    this Agreement relates (the word "assign" to
                                    include, without limiting the generality
                                    thereof, a transfer of a majority interest
                                    in the Party) or

                           (ii)     if either Party shall neglect or fail to
                                    perform or observe any of its obligations to
                                    the other Party hereunder, including,
                                    without limiting the generality thereof, the
                                    timely payment of any sums due, and such
                                    failure is not cured within thirty (30) days
                                    (ten (10) days in the event of a default in
                                    the payment of amounts owed the other Party)
                                    after written notice thereof from the other
                                    Party; or

                           (iii)    if there is (w) a dissolution, termination
                                    of existence, liquidation, insolvency or
                                    business failure of either Party, or the
                                    appointment of a custodian or receiver of
                                    any part of either Party's property, if such
                                    appointment is not terminated or dismissed
                                    within thirty (30) days; (x) a composition
                                    or an assignment or trust mortgage for the
                                    benefit of creditors by either Party; (y)
                                    the commencement by either Party of any
                                    bankruptcy proceeding under the United
                                    States Bankruptcy Code or any other federal
                                    or state bankruptcy, reorganization,
                                    receivership, insolvency or other similar
                                    law affecting the rights of creditors
                                    generally; or (z) the commencement against
                                    either Party of any proceeding under the
                                    United States Bankruptcy Code or any other
                                    federal or state bankruptcy, reorganization,
                                    receivership, insolvency or other similar
                                    law affecting the rights of creditors
                                    generally, which proceeding is not dismissed
                                    within thirty (30) days ("File for
                                    Bankruptcy").

         23.4     REMEDIES. Upon any event of default, and in addition to any
                  other remedies either Party may have at law or in equity, the
                  non-defaulting Party may terminate the Agreement, cancel any
                  outstanding Order, refuse to make or take further Orders or
                  deliveries, cancel any discount given, and declare all
                  obligations immediately due and payable. Any such termination
                  or other action taken by the non-defaulting Party pursuant to
                  this Section 23.4 shall not relieve the defaulting Party of
                  its obligations hereunder and the non-defaulting Party shall
                  retain all legal and equitable remedies after such
                  termination.



                                      -24-
<PAGE>   25

  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


24.      INSURANCE.

Upon request, Aspect shall provide evidence of product liability, general
liability and property damage insurance against an insurable claim or claims
which might or could arise regarding Aspect products purchased from Aspect. Such
insurance shall contain a minimum limit of liability for bodily injury and
property damage of not less than 2,000,000 (two million) US$.

25.      **

         25.1     [**]. Aspect warrants that the [**], together with all [**],
                  as now exists or hereafter becomes available including but not
                  limited to, the then [**] of [**] for the [**] will have been
                  [**] at Marquette's expense [**] pursuant to an agreement
                  between [**] is reasonably satisfactory to Marquette, and
                  Aspect [**]. Such [**] shall be [**] to Marquette within
                  thirty (30) days from the execution date hereof that [**] have
                  been [**]. [**] by Aspect upon execution hereof to [**] upon
                  written notice thereof by Marquette promptly after any of the
                  following occurrences:

                  (a)      Aspect fails to [**] as it is required to do under
                           Sections [**] and [**] of this Agreement;

                  (b)      Aspect suspends or discontinues business or indicates
                           its intention to suspend or discontinue business.

         25.2     MARQUETTE'S RIGHT TO [**]. Upon the occurrence of any of the
                  above, Marquette shall have the right to [**].

         25.3     [**]. Marquette shall have the right to [**] at any
                  time, at its own cost, [**]; and the right to [**] Marquette
                  that it is the [**].

         25.4     DISPUTES. Should there be any dispute as to whether Marquette
                  shall be entitled to [**], then such dispute shall be resolved
                  in accordance with the terms and conditions set forth in
                  Section 26 (Dispute Resolution) of this Agreement.


                                      -25-
<PAGE>   26

26.      DISPUTE RESOLUTION

         26.1     GENERAL. Any dispute, controversy or claim arising out of or
                  relating to this Agreement or any related agreement or the
                  validity, interpretation, breach or termination thereof (a
                  "Dispute"), including claims seeking redress or asserting
                  rights under applicable law, shall be resolved in accordance
                  with the procedures set forth herein. Until completion of such
                  procedures, no Party may take any action not contemplated
                  herein to force a resolution of the Dispute by any judicial or
                  similar process, except to the limited extent necessary to;
                  (i) avoid expiration of a claim that might eventually be
                  permitted hereby; or (ii) obtain interim relief, including
                  injunctive relief, to preserve the status quo or prevent
                  irreparable harm.

         26.2     WAIVER. In connection with any Dispute, the parties expressly
                  waive and forego any right to (i) punitive, exemplary,
                  statutorily, enhanced or similar damages in excess of
                  compensatory damages and (ii) trial by jury.

         26.3     GOOD FAITH NEGOTIATIONS. Any Dispute relating to this
                  Agreement (a "Dispute") will be resolved first through good
                  faith negotiations between appropriate management-level
                  representatives of each Party having responsibility for the
                  sale or use of products involved.

         26.4     MEDIATION. If within sixty (60) day the parties are unable to
                  resolve the dispute through good faith negotiation, either
                  Party may submit a Dispute for resolution by mediation
                  pursuant to the Center for Public Resources Model Procedure
                  for Mediation of Business Disputes as then in effect. The
                  mediation shall be conducted in New York City. Mediation will
                  continue for at least thirty (30) days unless the mediator
                  chooses to withdraw sooner. At the request of either Party,
                  the mediator will be asked to provide an evaluation of the
                  Dispute and the parties' relative positions. Each Party shall
                  bear its own costs of mediation effort.

         26.5     ARBITRATION. After completion of any mediation effort, a Party
                  may submit the Dispute for resolution by arbitration pursuant
                  to the Non-Administered Arbitration Rules of the Center for
                  Public Resources as in effect on the date hereof, unless the
                  parties agree to adopt such rules as in effect at the time of
                  the arbitration. The arbitral tribunal shall be composed of
                  one arbitrator; and the arbitration shall be conducted in New
                  York. If the resolution of the Dispute is not found within the
                  terms of this Agreement, the arbitrator shall determine the
                  Dispute in accordance with the governing law of the Agreement,
                  without giving effect to any conflict of law rules or other
                  rules that might render such law inapplicable or unavailable.
                  The prevailing Party in any arbitration conducted under this
                  Section shall be entitled to recover from the other Party (as
                  part of the arbitral award or order) its reasonable attorneys'
                  fees and other costs of arbitration.

         26.6     APPLICABLE LAW. The law applicable to the validity of this
                  arbitration provision, the conduct of the arbitration, the
                  challenge to or enforcement of any arbitral award or order or
                  any other question of arbitration law or procedure shall be




                                      -26-

<PAGE>   27

                  governed exclusively by the Federal Arbitration Act, 9 U.S.C.
                  sections 1-16; however, the award can be modified or vacated
                  on grounds cited in the Federal Arbitration Act or, if the
                  arbitrator's findings of facts are not supported by
                  substantial evidence or the conclusions of law are erroneous,
                  under the laws of the State of New York. The place of
                  arbitration shall be in New York City. The parties agree that
                  the federal and state courts located in the State of New York
                  shall have exclusive jurisdiction over any action brought to
                  enforce this arbitration provision, and each Party irrevocably
                  submits to the jurisdiction of said courts. Notwithstanding
                  the foregoing sentence, either Party may apply to any court of
                  competent jurisdiction, wherever situated, for enforcement of
                  any judgment on an arbitral award.

         26.7     TIME LIMIT. Except as time barred under any applicable statute
                  of limitation of lesser duration, any claim by either Party
                  shall be time-barred unless the asserting Party commences an
                  arbitration proceeding with respect to such claim within two
                  years after the cause of action has accrued.

         26.8     PROVISIONAL OR INTERIM JUDICIAL MEASURES. Notwithstanding any
                  other provision of this Agreement, the parties expressly agree
                  that prior to the first meeting of the arbitrator either shall
                  have the right to apply to any state or federal court in the
                  State of New York or any other court that would otherwise have
                  jurisdiction, for provisional or interim measures.

         26.9     CONSOLIDATED PROCEEDINGS. Each Party hereby consents to a
                  single, consolidated arbitration proceeding of multiple
                  claims, or claims involving more than two parties. The
                  prevailing Party or parties in any arbitration conducted under
                  this paragraph shall be entitled to recover from the other
                  Party or parties (as part of the arbitral award or order) its
                  or their reasonable attorneys' fees and other reasonable costs
                  of arbitration.

27.      GENERAL PROVISIONS.

         27.1     FORCE MAJEURE. In the event that either Party is prevented
                  from performing, or is unable to perform, any of its
                  obligations under this Agreement due to any act of God, fire,
                  casualty, flood, war, strike, lock out, failure of public
                  utilities, injunction or any act, exercise, assertion or
                  requirement of governmental authority, epidemic, destruction
                  of production facilities, insurrection, inability to procure
                  materials, labor, equipment, transportation or energy
                  sufficient to meet manufacturing needs, or any other cause
                  beyond the reasonable control of the Party invoking this
                  provision, and if such Party shall have used its best efforts
                  to avoid such occurrence and minimize its duration and has
                  given prompt written notice to the other Party, then the
                  affected Party's performance shall be excused and the time for
                  performance shall be extended for the period of delay or
                  inability to perform due to such occurrence.




                                      -27-
<PAGE>   28
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.

         27.2     PUBLICITY. Neither Party shall originate any publicity, news
                  release or other public announcement relating to this
                  Agreement or the existence of an arrangement between the
                  Parties without the prior written approval of the other Party,
                  except as otherwise required by law.

         27.3     WAIVER. The waiver by either Party of a breach or a default of
                  any provision of this Agreement by the other Party shall not
                  be construed as a waiver of any succeeding breach of the same
                  or any other provision, nor shall any delay or omission on the
                  part of either Party to exercise or avail itself of any right,
                  power or privilege that it has, or may have hereunder, operate
                  as a waiver of any right, power or privilege by such Party.

         27.4     NO AGENCY. Nothing contained in this Agreement shall be deemed
                  to constitute either Party as the agent or representative of
                  the other Party, or both Parties as joint venturers or
                  partners for any purpose. Neither Party shall be responsible
                  for the acts or omissions of the other Party, and neither
                  Party shall have authority to speak for, represent or obligate
                  the other Party in any way without prior written authority
                  from the other Party.

         27.5     SURVIVAL OF OBLIGATIONS. All obligations of either Party under
                  Sections 4.3 (but only insofar as it relates to the rights of
                  Marquette customers to continue using Marquette BIS/EEG
                  Modules), 5 (Royalties), 11 (Warranty), 12 (Service and
                  Support), 14 (Regulatory Matters), 16 (Ownership and
                  Protection of Results), 18 (Confidentiality), 19
                  (Indemnities), 20 (Trademarks), [**], 26 (Dispute Resolution),
                  and 27.6 (Limitation on Liability) shall survive the
                  expiration or termination of this Agreement and continue to be
                  enforceable.

         27.6     LIMITATION ON LIABILITY. EXCEPT AS PROVIDED IN SECTION 19,
                  EACH PARTY'S LIABILITY ARISING OUT OF THE MANUFACTURE, SALE OR
                  SUPPLYING OF ASPECT PRODUCTS OR THEIR USE OR DISPOSITION,
                  WHETHER BASED UPON WARRANTY, CONTRACT, TORT OR OTHERWISE,
                  SHALL NOT EXCEED THE SUM OF (i) THE TOTAL ACTUAL PURCHASE
                  PRICE PAID BY MARQUETTE FOR ALL ASPECT PRODUCTS PURCHASED
                  HEREUNDER; (ii) ALL AMOUNTS PAID BY MARQUETTE TO ASPECT FOR
                  PROJECT DEVELOPMENT COSTS PURSUANT TO SECTION 3.4 OF THIS
                  AGREEMENT; AND (iii) ALL AMOUNTS PAID BY MARQUETTE TO ASPECT
                  FOR SERVICE AND SUPPORT PURSUANT TO SECTION 12 OF THIS
                  AGREEMENT. IN NO EVENT SHALL EITHER PARTY BE LIABLE TO THE
                  OTHER PARTY FOR SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR OTHER
                  INDIRECT DAMAGES (INCLUDING, BUT NOT LIMITED TO, LOSS OF
                  PROFITS, LOSS OF DATA OR LOSS OF USE DAMAGES) ARISING OUT OF
                  THE MANUFACTURE, SALE OR SUPPLYING OF ASPECT PRODUCTS.




                                      -28-
<PAGE>   29

         27.7     SEVERABILITY. In the event that any provision of this
                  Agreement is held by a court of competent jurisdiction to be
                  unenforceable because it is invalid or in conflict with any
                  law of any relevant jurisdiction, the validity of the
                  remaining provisions shall not be affected and the rights and
                  obligations of the Parties shall be construed and enforced as
                  if the Agreement did not contain the particular provisions
                  held to be unenforceable.

         27.8     GOVERNING LAW. This Agreement shall be governed by and
                  construed in accordance with the laws of the Commonwealth of
                  Massachusetts, without reference to conflict of laws
                  principles, and shall not be governed by the U.N. Convention
                  on Contracts for the International Sale of Goods.

         27.9     NOTICES. Any notice or communication with regard to the
                  termination of or changes to this Agreement from one Party to
                  the other shall be in writing and either personally delivered
                  or sent via certified mail, postage prepaid and return receipt
                  requested addressed, to such other Party at the address of
                  such Party specified in this Agreement or such other address
                  as either Party may from time to time designate by notice
                  hereunder.

         27.10    ENTIRE AGREEMENT. This Agreement constitutes the entire
                  agreement between the Parties. No waiver, consent,
                  modification or change of terms of this Agreement shall bind
                  either Party unless in writing signed by both Parties, and
                  then such waiver, consent, modification or change shall be
                  effective only in the specific instance and for the specific
                  purpose given. There are no understandings, agreements,
                  representations or warranties, expressed or implied, not
                  specified herein regarding this Agreement or the Aspect
                  Products purchased and/or licensed hereunder. Only the terms
                  and conditions contained in this Agreement shall govern the
                  transactions contemplated hereunder, notwithstanding any
                  additional, different or conflicting terms which may be
                  contained in any Order or other document provided by one Party
                  to the other. Failure of Aspect to object to provisions
                  contained in any Order or other document provided by Marquette
                  shall not be construed as a waiver of the terms and conditions
                  of this Agreement nor an acceptance of any such provision.

         27.11    HEADINGS. Captions and headings contained in this Agreement
                  have been included for ease of reference and convenience and
                  shall not be considered in interpreting or construing this
                  Agreement.




                                      -29-
<PAGE>   30

         27.12    EXHIBITS: The following Exhibits shall be part of this
                  Agreement:

                  EXHIBIT A:    Aspect Products and Purchase Prices

                  EXHIBIT B:    Aspect's Standard BIS Module Kit

                  EXHIBIT C:    Development Project

                  EXHIBIT D:    Contact Persons/Addresses Prices

                  EXHIBIT E:    Aspect and Marquette Trademarks

         27.13    BENEFICIARIES. Except for the provisions of Section 19 hereof,
                  which are also for the benefit of the other Persons
                  indemnified, this Agreement is solely for the benefit of the
                  parties hereto and their respective affiliates, successors in
                  interest and permitted assigns and shall not confer upon any
                  other person any remedy, claim, liability, reimbursement or
                  other right in excess of those existing without reference to
                  this Agreement.

         27.14    ASSIGNMENT. Neither Party may assign or delegate this
                  Agreement or any rights or obligations under this Agreement
                  without the prior written consent of the other, which shall
                  not be unreasonably withheld; provided, however, that
                  Marquette may, without the prior written consent of Aspect,
                  assign and delegate this Agreement and any or all of its
                  rights and obligations hereunder to any of its affiliates
                  within the GE Medical Systems division of General Electric
                  Company, and provided that either party shall have the right
                  to assign this Agreement in connection with a sale of the
                  business of such party to which this Agreement relates.

         IN WITNESS WHEREOF, this Agreement has been duly executed as a sealed
instrument as of the date specified above.


Aspect Medical Systems, Inc.                 GE Marquette Medical Systems, Inc.


By: /s/ J. Breckenridge Engle                By: /s/ Kevin King
    ------------------------------               ------------------------------
    J. Breckenridge Engle                        Kevin King

Title: Chairman                              Title: Vice President and
       ---------------------------                  General Manager of
                                                    Global Marketing
                                                    ---------------------------



                                      -30-
<PAGE>   31
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.



                                    EXHIBIT A
                       ASPECT PRODUCTS AND PURCHASE PRICES

A)       ASPECT BIS/EEG MODULE KIT:

         Within thirty (30) days of the date of this Agreement, Marquette shall
[**] of the following [**] by giving Aspect written notice [**].

         [**]:

         List price for Aspect BIS/EEG Module Kit: [**] (includes [**] for
         components and [**] for BIS license)

         Volume discounts:

<TABLE>
<CAPTION>

--------------------------------------------------------------------------------
              QUANTITY
              PER YEAR         PRICE (COMPONENTS + LICENSE          DISCOUNT
              --------         ---------------------------          --------
          <S>                             <C>                         <C>

                [**]                      [**]                        [**]
                [**]                      [**]                        [**]
                [**]                      [**]                        [**]
</TABLE>
--------------------------------------------------------------------------------

         Exceptions to [**].

         [**]: Assumes [**] of [**] and [**]:

         [**] (based on installed base of approximately [**] GE Marquette OR
         monitors at [**] /unit)

         [**] volume discounts according to the following schedule:


<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
              QUANTITY
              PER YEAR         PRICE (COMPONENTS ONLY)         DISCOUNT
              --------         -----------------------         --------
          <S>                             <C>                    <C>


                [**]                      [**]                   [**]
                [**]                      [**]                   [**]
                [**]                      [**]                   [**]
</TABLE>
--------------------------------------------------------------------------------


                                      -31-
<PAGE>   32
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


         Composite volume discount schedule [**] - for illustration
         purposes only:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                                           PRICE                     DISCOUNT
                                        (COMPONENTS                 (COMPONENTS
                QUANTITY                AND LICENSE                AND LICENSE)
                PER YEAR                   NOTE A                      NOTE A
                --------                -----------                ------------
          <S>                               <C>                         <C>

                  [**]                      [**]                        [**]
                  [**]                      [**]                        [**]
                  [**]                      [**]                        [**]

</TABLE>
--------------------------------------------------------------------------------

         Note A: assumes imputed BIS license fee of  [**]  per unit

B)       ASPECT BIS SENSOR:

         Transfer price to Marquette for distribution solely to Marquette
customers outside North America and solely for use with Marquette BIS/EEG
Modules: [**] of Aspect's list price in the U.S.

C)       ASPECT SPARE PARTS/ACCESSORY PRICES


<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                                         Aspect                     Marquette
         Orderable                     List Price                     Price
         Parts/Products                   (US$)                  (US$) - Note A
         --------------                ----------                --------------
         <S>                              <C>                         <C>

         DSC-2                            [**]                        [**]
         (replacement

         BIC Engine PCB                   [**]                        [**]
         (replacement)

         Sensor Cable                     [**]                        [**]
         (replacement)

         DSC-4                            [**]                        [**]
         (replacement)

         User Manual                      [**]                        [**]

</TABLE>
--------------------------------------------------------------------------------

                                      -32-
<PAGE>   33
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                       EXHIBIT B: SPECIFICATIONS ASPECT'S
                             STANDARD BIS MODULE KIT

Aspect's BIS Module Kit is designed specifically for OEM applications and allows
the integration of Aspect's BIS monitoring technology into OEM equipment. The
BIS Engine will interface to the patient via the Aspect BIS sensor and to the
OEM equipment utilizing a serial (RS-232) 3-wire interface and the necessary
power connections.

The BIS Module Kit consists of a Digital Signal Converter (DSC-2) that is placed
in proximity to the patient and a small circuit board that resides in the OEM
equipment. The DSC-2 is a small (palm sized) front-end to the BIS Engine circuit
board that provides the patient interface and performs the high performance
analog to digital conversion of the EEG signals. The EEG signals are transmitted
in digital format from the DSC-2 to the BIS engine circuit board via a 12 foot
cable that is hard wired at the DSC-2.

The small BIS Engine circuit board performs digital signal processing on the
digitized EEG signal and outputs the Bispectral Index to the OEM system via the
RS-232 serial connection. The board is constructed using double-sided surface
mount techniques. The connections to the BIS Engine circuit board are a serial
interface (RS-232), power, and DSC connections.

DETAILED TECHNICAL SPECIFICATIONS:

Digital Output:                     [**]
Main Parameters:                    [**]
Electrical Safety:                  [**]
Power:                              [**]
Artifact Rejection:                 [**]
Bispectral Index:                   [**]

DIGITAL SIGNAL CONVERTER (DSC-2)

Description:                        [**]
Weight:                             [**]
Dimensions:                         [**]
                                    [**]
Cable Length:                       [**]





                                      -33-
<PAGE>   34
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


         (a)      BIS Engine PCB

Physical:                           [**]
Processing Power:                   [**]

         (b)      Software Upgrades

The BIS engine software is stored in reprogrammable FLASH memory. Software
upgrades can be accomplished on-site or remotely via the serial interface.

         (c)      Serial Identifier

Each BIS engine is given a unique serial identifier. This allows for electronic
identification/tracking of every BIS Engine.




                                      -34-
<PAGE>   35
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                        EXHIBIT C: DEVELOPMENT PROJECT -
                               PRELIMINARY OUTLINE

1.       SCOPE

This preliminary outline describes a development project that Aspect would
perform for GE Marquette. This outline is based on notes from a meeting held at
Aspect on August 18, 1999. A more detailed project description needs to be
completed before the timetable and costs can be finalized.

2.       DEVELOPMENT TIMETABLE

A detailed project schedule needs to be developed. It is planned that the total
elapsed time of the project will be approximately [**].

3.       SOFTWARE PROJECT - [**]

Expanded BIS Engine Software Functionality: Aspect will [**] so that, in
addition to all of the functionality of the standard BIS Module Kit (described
in Attachment A), the system will [**] when a [**] is connected to the BIS
Engine circuit board. Upon connection of the [**], the BIS software will
automatically [**] processing. The BIS engine will then [**] including [**]. The
BIS engine will then transmit these [**] to the host system via the [**].

4.       TASKS

         Determine and Specify:
                  System Specifications (Aspect/GE Marquette) including hazard
                  analysis Software Specifications (Aspect)
         Develop/Implement (Aspect)
         Verification & Validation (Aspect)

After Aspect has validated the BIS/EEG module kit, GE Marquette will have the
responsibility to validate, with Aspect's assistance, the BIS/EEG module in the
GE Marquette system.

The approximate cost to complete this software project is [**].

DSC-4 Hardware Development Project

Conceptually, Aspect will [**] the [**] that is [**] . However, this [**]. A
preliminary review indicates that [**]. Additionally, there may be [**].
Therefore a small development budget needs to be established in order to bring
this product back on-line. An estimate of the project cost including engineering
and tooling is roughly [**]. A full review of the manufacturability of the DSC-4
needs to be completed before Aspect can commit to the actual development expense
and the transfer price of the DSC-4.





                                      -35-
<PAGE>   36
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                      EXHIBIT D: CONTACT PERSONS/ADDRESSES

CONTACT PERSONS AND RESPONSIBILITIES AT ASPECT:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------
                                                                              EMAIL
                                                                              PHONE NUMBER/
PERSON                     TITLE                    RESPONSIBILITY            FAX NUMBER
<S>                        <C>                     <C>                       <C>
--------------------------------------------------------------------------------------------------
[**]                       [**]                     [**]                      [**]
                                                                              [**]
                                                                              [**]
--------------------------------------------------------------------------------------------------
[**]                       [**]                     [**]                      [**]
                                                                              [**]
                                                                              [**]
--------------------------------------------------------------------------------------------------
[**]                       [**]                     [**]                      [**]
                                                                              [**]
                                                                              [**]
--------------------------------------------------------------------------------------------------
[**]                       [**]                     [**]                      [**]
                                                                              [**]
                                                                              [**]
--------------------------------------------------------------------------------------------------
[**]                       [**]                     [**]                      [**]
                                                                              [**]
                                                                              [**]
--------------------------------------------------------------------------------------------------
</TABLE>


MAILING ADDRESS:   Aspect Medical Systems, Inc.
                   2 Vision Drive
                   Natick, MA 01760-2059
                   USA

CONTACT PERSONS AND RESPONSIBILITIES AT GE MARQUETTE:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------
                                                                              EMAIL
                                                                              PHONE NUMBER/
PERSON                     TITLE                    RESPONSIBILITY            FAX NUMBER
<S>                        <C>                     <C>                       <C>
--------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------
</TABLE>

MAILING ADDRESS:  GE Marquette Medical Systems, Inc.



                                      -36-
<PAGE>   37

                          EXHIBIT E: ASPECT TRADEMARKS


TRADEMARK                               REFERENCE
---------                               ---------

Aspect(R)                               None*

A-2000(TM)                              A-2000 is a trademark of Aspect Medical
                                        Systems, Inc.

Bispectral Index(R)                     Bispectral is a registered trademark of
                                        Aspect Medical Systems, Inc.

                                        BIS logo is a registered trademark of
                                        Aspect Medical Systems, Inc.



*   This trademark is registered as a trademark to another company, and is used
    under license by Aspect Medical Systems.





                                      -37-
<PAGE>   38
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                         EXHIBIT F: CO-MARKETING PROGRAM

a)    Goals:

      -     to provide GE Marquette customers with access to BIS, and a seamless
            transition from Aspect's A-2000 BIS monitor to GE Marquette's BIS
            Module, during the period in which the BIS module is under
            development by GE Marquette

      -     to ensure that the field organizations of both Aspect and GE
            Marquette are properly incented to assist one another, and to work
            in collaboration, to promote the BIS technology, irrespective of the
            platform on which it is available.

      -     to minimize the likelihood that GE Marquette customers will be
            disposed to delay purchasing BIS until GE Marquette completes the
            development of a BIS module.

      -     to minimize the incremental costs to customers of exchanging one BIS
            platform for another when the module becomes available; and

      -     to encourage existing GE Marquette customers to remain loyal to GE
            Marquette, and to stimulate monitoring system sales to new
            customers, by offering a BIS solution that address current and
            future needs at a very attractive price.

b)    Term: beginning immediately following an announcement by GE Marquette and
      Aspect that GE Marquette intends to develop a BIS module until the module
      is launched. It is understood that the module will be launched
      approximately 2-3 months prior to becoming commercially available.

c)    Proposed Pricing: Aspect list price [**] per monitor. Aspect's current
      list prices vary from [**] per monitor depending on the number of monitors
      purchased. In addition to outright sales, the parties will also make
      available a fee-for-use program using equivalent terms. (Aspect would need
      to do the fee-for-use program - Marquette would just submit the referral
      to Aspect and Marquette would still exchange for the module at no module
      charge.) In exchange, customers will receive A-2000 monitors initially; as
      soon as the BIS module is available, the module will be exchanged for the
      monitor.

d)    Mechanics: following each sale under this program, Aspect will assume
      responsibility for installation, in-service, and clinical support for the
      A-2000. Following release of the BIS Module, Marquette will assume
      responsibility for installation and in-service of the module, at which
      time the used A-2000 will be returned to Aspect.

e)    [**]: proceeds from sale of the BIS platform (i.e. the A-2000 followed by
      the BIS Module) will be [**]. In the event GE Marquette fails to deliver a
      BIS module within a suitable period of time as specified in the Agreement.



                                      -38-
<PAGE>   39
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


f)    Sales rep compensation: it is understood that a compensation program for
      both field organizations will be established that appropriately ties rep
      compensation to success of the program.

g)    Elements of co-marketing program: customer lists to be shared, high
      priority accounts to be jointly identified and developed, co-promotional
      activities to be coordinated (e.g. trade shows, joint seminars and
      customer presentations, etc.); reimbursements to Marquette due quarterly
      with customer lists, selling price, number of sensors purchased by
      customer.

h)    Territory: U.S. and other countries to be discussed.

i)    Possible role of MVP: in the event MVP acts as a distributor for Aspect,
      the terms of their participation in the co-marketing program to be
      negotiated.

j)    Demonstration Equipment: for promotional purposes only (not to be sold to
      any end-user), Marquette will require five (5) demonstration Aspect A-2000
      Monitors. Terms of the transfer price for these demonstration units will
      be negotiated.

k)    BIS Sensor [**]: Marquette [**] BIS Sensors [**] as a result of the [**]
      to a [**].






                                      -39-