<PAGE>   1

                                                                   EXHIBIT 10.13

PARTIES     This Lease, executed in duplicate at Mountain View, California, this
            day of October 23, 1976, by and between RICHARD N. MOSEMAN, BONNIE
            MOSEMAN MILLER, and PROPERTIES INTERNATIONAL, allrent, INC., a
            California corporation, and ACUREX CORPORATION, a California
            corporation, hereinafter called respectively Lessor and Lessee,
            without regard to number or gender.

USE         WITNESSETH: That Lessor hereby leases to Lessee, and Lessee hires
            from Lessor, for the purpose of conducting therein machinery and
            electronics manufacturing, research and development, related
            administrative activities and executive offices, and for no other
            purpose, those certain premises with the appurtenances, situated in
            City of Mountain View, County of Santa Clara, State of California,
            and more particularly described as follows, to-wit:

PREMISES    That certain parcel of real property referred to as Assessor's
            parcel #159-43-005, commonly known as 555 Clyde Avenue, consisting
            of approximately 2.963 acres of land, more or less, more
            particularly described in Exhibit "A" attached hereto and made a
            part hereof, together with a two-story building to be constructed
            thereon by Lessor consisting of approximately 51,200 square feet of
            floor space, and related side improvements, hereinafter referred to
            as "the premises."

TERM        The term shall be for two hundred forty (240) calendar months
            commencing on the 1st day of June, 1977, and ending on the 31st day
            of May, 1997, at the rent hereafter provided, payable in lawful
            money of the United States of America, which Lessee agrees to pay to
            Lessor, without deduction or offset, at such place or places as may
            be designated from time to time by Lessor, in installments as
            follows:

RENTAL      Initial rental of Fifteen Thousand Six Hundred Sixteen Dollars
            ($15,616) per month. Rent for the month of June 1977 in the amount
            of Fifteen thousand Six Hundred Sixteen Dollars ($15,616) shall be
            payable upon the execution of this lease. Thereafter, rent shall be
            payable monthly, in advance, on the first day of each calendar month
            of the lease term, commencing with the first day of July 1977 and
            continuing on the first day of each calendar month thereafter during
            the lease term, subject to adjustment in the rental as provided in
            Paragraph 30 hereof.

            Provided Lessee faithfully performs its obligations hereunder, and
            is not then in default hereunder, Lessor hereby grants to Lessee the
            option to extend the lease term for sixty (60) months upon the
            expiration of the initial lease term. The option to extend shall be
            exercised by Lessee giving written notice of exercise to Lessor not
            less than one hundred eighty (180) days prior to the expiration of
            the initial lease term. Such extended term shall be upon all of the
            terms and provisions of this Lease, except for the rental which
            shall be determined by negotiations of the parties. In the event
            that the parties are unable to agree upon the rental within ninety
            (90) days after the exercise of the option by Lessee, then such
            option shall be null and void and of no force of effect, and the
            lease term shall expire and terminate upon the expiration of the
            initial lease term, if not sooner terminated pursuant to the
            provisions hereof.

SECURITY    The Lessee has deposited with the Lessor $15,000 as security for the
DEPOSIT     full and faithful performance of each and every term, provision,
            covenant, and condition of this lease. In the event the Lessee
            defaults on any of the terms, provisions, covenants or conditions of
            this lease, including, but not limited to the payment of rent, the
            Lessor may use, apply or retain the whole or any part of such
            security for the payment of any rent in default or for any other sum
            which the lessor may spend or be required to spend by reason of the
            Lessee's default. Should the Lessee faithfully and fully comply with
            all of the terms, provisions, covenants and conditions of this
            lease, the security, or any balance thereof, shall be returned to
            the Lessee, or at the option of the Lessor, to the last assignee of
            the Lessee's interest in this lease at the expiration of the term
            hereof, at the termination of any extension of the term or at the
            termination of the Lessee's occupancy of the premises, whichever is
            later.

CONSTRUC-
TION OF
IMPROVE-
MENTS;
POSSESSION


<PAGE>   2
ACCEPTANCE     2. By entry hereunder, upon commencement of the lease term Lessee
OF          accepts the premises as being in good sanitary order, condition and
PREMISES    repair, and accepts the building and other improvements in their
AND         condition. The Lessee agrees on the last day of the term hereof, or
COVENANT TO on sooner termination of this lease, to surrender the premises,
SURRENDER   together with all alterations, additions, and improvements which may
            have been made in, to, or on the premises by Lessor or Lessee, unto
            Lessor in good and sanitary order, condition and repair, excepting
            for such wear and tear as would be normal for the period of the
            Lessee's occupancy. The Lessee, on or before the end of the term or
            sooner termination of this Lease, shall remove all his or its
            personal property and trade fixtures from the premises and all
            property not so removed shall be deemed to be abandoned by the
            Lessee. If the premises be not surrendered at the end of the term or
            sooner termination of this lease, the Lessee shall indemnify the
            Lessor against loss or liability resulting from delay by the Lessee
            in so surrendering the premises including, without limitation, any
            claims made by any succeeding tenant founded on such delay. See
            Amendment 2.

USES           3. Lessee shall not commit, or suffer to be committed, any waste
PROHIBITED  upon the said premises, or any nuisance, or other act or thing which
            may disturb the quiet enjoyment of any other tenant in or around the
            buildings in which the demised premises may be located, or allow any
            sale by auction upon the premises, or allow the premises to be used
            for any improper, immoral, unlawful or objectionable purpose, or
            place any loads upon the floor, walls, or ceiling which endanger the
            structure, or place any harmful liquids in the drainage system of
            the building. No waste materials or refuse shall be dumped upon or
            permitted to remain upon any part of the leased premises outside of
            the building proper. No materials, supplies, equipment, finished
            products or semi-finished products, raw materials or articles of any
            nature shall be stored upon or permitted to remain on any portion of
            the leased premises outside of the buildings proper.

ALTERATIONS    4. The Lessee shall not make, or suffer to be made, any
AND         alterations or additions to the said premises, or any part thereof,
ADDITIONS   without the written consent of the Lessor first had and obtained by
            the Lessee; any addition or alteration to the said premises, except
            movable furniture and trade fixtures, shall become at once a part of
            the realty and belong to the Lessor. Alterations and additions which
            are not to be deemed as trade fixtures shall include heating,
            lighting, electrical systems, air-conditioning, partitioning,
            carpeting, or any other installation which has become an integral
            part of the leased premises. The Lessee will at all times permit
            notices of non-responsibility to be posted and to remain posted
            until the completion of alterations or additions which have been
            approved by the Lessor.

MAINTENANCE    5. Lessee shall, at its sole cost, keep and maintain said
OF PREMISES premises and appurtenances and every part thereof, including, but
            not limited to, glazing, sidewalks, parking areas, plumbing,
            electrical systems, heating and air conditioning installations, any
            store front, and the interior of the premises in good and sanitary
            order, condition, and repair. The Lessee agrees to water, maintain
            and replace, when necessary, any shrubbery and landscaping provided
            by Lessor on the leased premises. The Lessee hereby waives all right
            to make repairs at the expense of Lessor as provided in Section 1942
            of the Civil Code of the State of California, and all rights
            provided for by Section 1941 of said Civil Code.

FIRE AND       6. Lessee shall not use, or permit said premises, or any part
EXTENDED    thereof, to be used, for any purpose other than that for which the
COVERAGE    said premises are hereby leased; and no use, shall be made or
INSURANCE   permitted to be made of the said premises, nor acts done, which will
            cause a cancellation of any insurance policy covering said building,
            or any part thereof, nor shall Lessee sell or permit to be kept,
            used or sold, in or about said premises, any article which may be
            prohibited by the standard form of fire insurance policies. Lessee
            shall, at his sole cost and expense, comply with any and all
            requirements, pertaining to said premises, of any insurance
            organization or company, necessary for the maintenance of reasonable
            fire and public liability insurance, covering said building and
            appurtenances. The Lessor agrees to purchase and keep in force fire,
            and extended coverage insurance covering the leased premises in
            amounts not to exceed the actual insurable value of said premises.
            The Lessee agrees to pay to the Lessor as additional rent, on
            demand, the full cost of said insurance as evidenced by insurance
            billings to the Lessor. It is understood and agreed that Lessee's
            obligation under this paragraph will be pro-rated to reflect the
            commencement and termination dates of this lease. See Amendment 6.

ABANDON-       7. Lessee shall not vacate or abandon the premises at any time
MENT        during the term; and if Lessee shall abandon, vacate or surrender
            said premises, or be dispossessed by process of law, or otherwise,
            any personal property belonging to Lessee and left on the premises
            shall be deemed to be abandoned, at the option of Lessor, except
            such property as may be mortgaged to Lessor.

FREE FROM      8. Lessee shall keep the demised premises and the property in
LIENS       which the demised premises are situated, free from any liens arising
            out of any work performed, materials furnished, or obligations
            incurred by Lessee.

COMPLIANCE     9. Lessee shall, at his sole cost and expense, comply with all
WITH        of the requirements of all Municipal, State and Federal authorities
GOVERN-     now in force, or which may hereafter be in force, pertaining to the
MENTAL      said premises, and shall faithfully observe in the use of the
REGULA-     premises all Municipal ordinances and State and Federal statutes now
TIONS       in force or which may hereafter be in force. The judgment of any
            court of competent jurisdiction, or the admission of Lessee in any
            action or proceeding against Lessee, whether Lessor be a party
            thereto or not, that Lessee has violated any such ordinance or
            statute in the use of the premises, shall be conclusive of that fact
            as between Lessor and Lessee.

INDEMNIFI-     10. The Lessee, as a material part of the consideration to be
CATION OF   rendered to the Lessor, hereby waives all claims against the Lessor
LESSOR AND  for damages to goods, wares and merchandise, and all other personal
LESSEE'S    property in, upon, or about said premises and for injuries to
LIABILITY   persons in or about said premises, from any cause arising at
INSURANCE   anytime, excepting claims arising from the Lessor's negligence, and
            the Lessee will hold the Lessor exempt and harmless from any damage
            or injury to any person, or to the goods, wares and merchandise and
            all other personal property of any person, arising from the use of
            the premises by the Lessee, or from the failure of the Lessee to
            keep the premises in good condition and repair, as herein provided.
            The Lessee shall secure and keep in force a bodily injury and
            property damage policy covering the leased premises, including
            parking areas, insuring the Lessee and naming the Lessor as an
            additional insured. A copy of said policy shall be delivered to the
            Lessor and the minimum limits of coverage thereof shall be
            $1,000,000 for any single or multiple injuries and $100,000 property
            damage, and the Lessee shall obtain a written obligation on the part
            of the insurer to give the Lessor written notification before any
            cancellation thereof.

ADVERTISE-     11. Lessee will not place or permit to be placed, in, upon or
MENTS AND   about the said premises any unusual or extraordinary signs, or any
SIGNS       signs not approved by the city or other governing authority. The
            Lessee will not place, or permit to be placed, upon the premises,
            any signs, advertisements or notices without the written consent of
            the Lessor first had and obtained. Any sign so placed on the
            premises shall be so placed upon the understanding and agreement
            that Lessee will remove same at the termination of the tenancy
            herein created and repair any damage or injury to the premises
            caused thereby, and if not so re- [REST OF SENTENCE ILLEGIBLE]

<PAGE>   3
UTILITIES      12. Lessee shall for water, gas, heat, light, power, telephone
            service and all other services supplied to the said premises.

ATTORNEY'S     13. In case suit should be brought for the possession of the
FEES        premises, for the recovery of any sum due hereunder, or because of
            the breach of nay other covenant herein, the losing party shall pay
            to the prevailing party a reasonable attorney's fee, which shall be
            deemed to have accrued on the commencement of such action and shall
            be enforceable whether or not such action is prosecuted to
            judgement.

INSOL-         14. Either (a) the appointment of a receiver to take possession
VENCY or    of all or substantially all of the assets of Lessee, or (b) a
BANK-       general assignment by Lessee for the benefit of creditors, or (c)
RUPTCY      any action taken or suffered by Lessee under any insolvency or
            bankruptcy act shall constitute a breach of this lease by Lessee.
            See Amendment 14.

DEFAULT        15. In the event of any breach of this lease by the Lessee, or an
            abandonment of the premises by the Lessee, the Lessor has the option
            of 1) removing all persons and property from the premises and
            repossessing the premies in which case any of the Lessee's property
            which the Lessor removes from the premises may be stored in a public
            warehouse or elsewhere at the cost of, and for the account of
            Lessee, or 2) allowing the Lessee to remain in full possession and
            control of the premises. If the Lessor chooses to repossess the
            premises, the lease will automatically terminate in accordance with
            provisions of the California Civil Code, Section 1951.2. In the
            event of such termination of the lease, the Lessor may recover from
            the Lessee: 1) the worth at the time of award of the unpaid rent
            which had been earned at the time of termination including interest
            at 10% per annum; 2) the worth at the time of award of the amount by
            which the unpaid rent which would have been earned after termination
            until the time of award exceeds the amount of such rental loss that
            the Lessee proves could have been reasonably avoided including
            interest at 10% per annum; 3) the worth at the time of award of the
            amount by which the unpaid rent for the balance of the term after
            the time of award exceeds the amount of such rental loss that the
            Lessee proves could be reasonably avoided; and 4) any other amount
            necessary to compensate the Lessor for all the detriment proximately
            caused by the Lessee's failure to perform his obligations under the
            lease or which in the ordinary course of things would be likely to
            result therefrom. If the Lessor chooses not to repossess the
            premises, but allows the Lessee to remain in full possession and
            control of the premises, then in accordance with provisions of the
            California Civil Code, Section 1951.4, the Lessor may treat the
            lease as being in full force and effect, and may collect from the
            Lessee all rents as they become due through the termination date of
            the lease as specified in the lease. For the purposes of this
            paragraph, the following do not constitute a termination of Lessee's
            right to possession:
            a) Acts of maintenance or preservation or efforts to relet the
            property.
            b) The appointment of a receiver on the initiative of the Lessor to
            protect his interest under this lease.

SURRENDER      16. The voluntary or other surrender of this lease by Lessee, or
OF LEASE    a mutual cancellation thereof, shall not work a merger, and shall,
            at the option of Lessor, terminate all or any existing subleases or
            subtenancies, or may, at the option of Lessor, operate as an
            assignment to him of any or all such subleases or subtenancies.

TAXES          17. The Lessee shall be liable for all taxes levied against
            personal property and trade or business fixtures, and agrees to pay,
            as additional rental, during the term of this lease and any
            extension thereof, all real estate taxes and the yearly installments
            of any special assessments levied against the leased premises after
            the commencement date of this lease. It is understood and agreed
            that the Lessee's obligation under this paragraph will be pro-rated
            to reflect the commencement and termination dates of this lease.

NOTICES        18. See Amendment 18.

ENTRY BY       19. Lessee shall permit Lessor and his agents to enter into and
LESSOR      upon said premises at all reasonable times for the purpose of
            inspecting the same or for the purpose of maintaining the building
            in which said premises are situated, or for the purpose of making
            repairs, alterations or additions to any other portion of said
            building, including the erection and maintenance of such
            scaffolding, canopies, fences and props as may be required without
            any rebate of rent and without any liability to Lessee for any loss
            of occupation or quiet enjoyment of the premises thereby
            occasioned; and shall permit Lessor and his agents, at any time
            within 180 days prior to the expiration of this lease, to place upon
            said premises any usual or ordinary "For Sale" or "to lease" signs
            and exhibit the premises to prospective tenants at reasonable
            hours.

DESTRUC-       20. See Amendment 20.
TION OF
PREMISES

ASSIGN-        21. Lessee shall not assign this lease, or any interest therein,
MENT        and shall not subject the said premises or any part thereof, or any
AND         right or privilege appurtenant thereto, or suffer any other person
SUBLET-     (the agents and servants of Lessee excepted) to occupy or use the
TING        said premises, or any portion thereof, without the written consent
            of Lessor first had and obtained, and a consent to one assignment,
            subletting, occupation or use by any other person, shall not be
            deemed to be a consent to any subsequent assignment, subletting,
            occupation or use by another person. Any such assignment or
            subletting without such consent shall be void, and shall, at the
            option of the Lessor, terminate this lease. This lease shall not,
            nor shall any interest therein, be assignable, as to the interest of
            Lessee, by operation of law, without the written consent of Lessor.
            The Lessor, however, cannot unreasonably  withhold consent to
            sublet, assign, or both.
<PAGE>   4
CONDEMNA-      22. See Amendment 22.
TION

EFFECT OF      23. The term "Lessor" as used in this lease, means only the owner
CONVEYANCE  for the time being of the land and building containing the premises,
            so that, in the event of any sale of said land or building, or in
            the event of a lease of said building, the Lessor shall be and
            hereby is entirely freed and relieved of all covenants and
            obligations of the Lessor hereunder, and it shall be deemed and
            construed, without further agreement between the parties and the
            purchaser at any such sale, or the Lessee of the building, that the
            purchaser or Lessee of the building has assumed and agreed to carry
            out any and all covenants and obligations of the Lessor hereunder.
            If any security be given by the Lessee to secure the faithful
            performance of all or any of the covenants of this lease on the part
            of Lessee, the Lessor may transfer and deliver the security, as
            such, to the purchaser at any such sale or the Lessee of the
            building, and thereupon the Lessor shall be discharged from any
            further liability in reference thereto. See Amendment 23.


SUBORDINA-     24. Lessee agrees that this lease may, at the option of Lessor,
TION        be subject and subordinate to any mortgage, deed of trust or other
            instrument of security which has been or shall be placed on the land
            and building or land or building of which the premises form a part,
            and this subordination is hereby made effective without any further
            act of Lessee. The Lessee shall, at any time hereinafter, on demand,
            execute any instruments, releases, or other documents that may be
            required by any mortgagee, mortgagor, or trustor or beneficiary
            under any deed of trust for the purpose of subjecting and
            subordinating this lease to the lien of any such mortgage, deed of
            trust or other instrument of security, provided the holder of such
            encumbrance agrees to recognize Lessee's interest hereunder if
            Lessee is not then in default.

WAIVER         25. The waiver by Lessor of any breach of any term, covenant or
            condition, herein contained shall not be deemed to be a waiver of
            such term, covenant or condition or any subsequent breach of the
            same or any other term, covenant or condition therein contained. The
            subsequent acceptance of rent hereunder by Lessor shall not be
            deemed to be a waiver of any preceding breach by Lessee of any term,
            covenant or condition of this lease, other than the failure of
            Lessee to pay the particular rental so accepted, regardless of
            Lessor's knowledge of such preceding breach at the time of
            acceptance of such rent.

HOLDING        26. Any holding over after the expiration of the said term,
OVER        with the consent of Lessor, shall be construed to be a tenancy from
            month to month, at a rental to be negotiated by Lessor and Lessee
            prior to the expiration of said term, and shall otherwise be on the
            terms and conditions herein specified, so far as applicable.

SUCCESSORS     27. The covenants and conditions herein contained shall, subject
AND         to the provisions as to assignment, apply to and bind the heirs,
ASSIGNS     successors, executors, administrators and assigns of all of the
            parties hereto; and all of the parties hereto shall be jointly and
            severally liable hereunder.

TIME           28. Time is of the essence of this lease.

MARGINAL       29. The marginal headings or titles to the paragraphs of this
CAPTIONS    lease are not a part of this lease and shall have no effect upon the
            construction or interpretation of any part thereof. This instrument
            contains all of the agreements and conditions made between the
            parties hereto and may not be modified orally or in any other manner
            than by an agreement in writing signed by all of the parties hereto
            or their respective successors in interest.

Amendment Nos. 1, 2, 6, 11, 14, 18, 20, 22, and 23 and the additional
Paragraphs 30, 31, 32, 33, 34, 35, and 36 attached hereto are incorporated
herein and hereby made a part of this lease.








IN WITNESS WHEREOF, Lessor and Lessee have executed these presents, the day and
year first above written.

            LESSOR                                        LESSEE


/s/ RICHARD N. MOSEMAN                       ACUREX CORPORATION
----------------------------------           -----------------------------------
RICHARD N. MOSEMAN

/s/ BONNIE MOSEMAN MILLER                    By
----------------------------------           -----------------------------------
BONNIE MOSEMAN MILLER

PROPERTIES INTERNATIONAL, allrent,           By  /s/ TIMOTHY P. CARLSON
INC., a California corporation               -----------------------------------
----------------------------------

By /s/ SALLY MOSEMAN, President
----------------------------------
   SALLY MOSEMAN, President

<PAGE>   5
                                                                        10/23/76


           ADDENDUM TO LEASE DATED OCTOBER 23, 1976 BETWEEN RICHARD
        N. MOSEMAN, BONNIE MOSEMAN MILLER, AND PROPERTIES INTERNATIONAL,
       ALLRENT, INC., A CALIFORNIA CORPORATION, HEREAFTER REFERRED TO AS
                 "LESSOR," AND ACUREX CORPORATION, A CALIFORNIA
                CORPORATION, HEREAFTER REFERRED TO AS "LESSEE."


            Lessor and Lessee further agree as follows:

Amendment 1 - Construction of Improvements; Possession

      (a) Lessor shall construct the building and shell substantially in
accordance with the site plan attached hereto as Exhibit "B" and the sheet
entitled "Project Items - Shell" attached hereto as a part of Exhibit "C." Said
building shell shall also be constructed substantially in accordance with
working drawings, plans and specifications (herein called the "plans") to be
prepared by Lessor's architect and to be received by Lessee prior to its signing
of this Lease. Lessee's signing of this Lease shall be deemed to constitute
Lessee's approval of the plans, subject only to Lessee's right, subject to
Lessor's prior written approval, which will not be unreasonably withheld, to
request certain minor adjustments in the plans regarding the location of
exterior doors to allow for balanced door access for future uses. Approval of
plans by Lessee does not relieve Lessor of responsibility of providing a
building meeting requirements of all bodies having jurisdiction. Lessor shall
give Lessee at least thirty (30) days' notice prior to the anticipated
completion date and permit Lessee to enter upon the premises to install Lessee's
fixtures and equipment.

      (b) Lessor shall contribute the maximum amount of Five Hundred Thousand
Dollars ($500,000) to defray the cost of construction and installation by
Lessor's contractor of the interior improvements after completion of the
building shell. Any additional cost of interior improvements in excess of Five
Hundred Thousand Dollars ($500,000) shall be paid by Lessee. The interior
improvements to be constructed for the Five Hundred Thousand Dollar ($500,000)
contribution thereto by Lessor are referred to in the sheet entitled "Project
Items in $500,000 Interior" which is a part of Exhibit "C" attached hereto. Said
sum of Five Hundred Thousand Dollars ($500,000) to be contributed by Lessor for
the interior improvements shall be used for the construction and installation of
typical, multipurpose interior improvements usable by normal occupants of
industrial buildings. Said sum of Five Hundred Thousand Dollars ($500,000) shall
not be used to defray the cost of any specialized or extraordinary type interior
improvements. None of the items referred to in the sheet entitled "Project Items
in $500,000 Interior" which is a part of Exhibit "C" attached hereto shall be
deleted without Lessor's prior written consent, which consent shall not be
unreasonably withheld. Plans for the interior improvements shall be supplied by
Lessee to Lessor as follows: (i) plans for the sewage and other plumbing
facilities for the restrooms and cafeteria and for all
<PAGE>   6


underground electric boxes prior to the commencement of construction of the
building shell, and (ii) all other interior plans no later than thirty (30) days
after the commencement of construction of the shell.

      (c) Lessor and Lessee shall cooperate in the construction of the building
and interior improvements, and they shall each use their best efforts to
prosecute the work to completion in a prompt and diligent manner in order that
said building and improvements may be substantially completed on the premises on
or before May 1, 1977 (the "Completion Date"). If, by the Completion Date, the
premises are not substantially completed because of delays for causes beyond
Lessor's control (such as, without limitation, strikes, lockouts, labor
troubles, inability to procure materials, failure of power or other utilities or
services, restrictive governmental laws or regulations, riots, insurrection,
wars, inclement weather, acts of God, or breach of this lease by Lessee), then
(i) Lessor shall not have any liability to Lessee for any consequential loss or
damage, nor shall this Lease be void or voidable, but this Lease shall remain
valid and continue in full force and effect, and (ii) the time for completion of
the premises shall be extended for a period of time which equals the aggregate
period of any delay or delays in prosecution of Lessor's work.

Amendment 2 - Acceptance of Premises and Covenant to Surrender

      Lessee shall have ninety (90) days following the date of occupancy of the
premises within which to notify Lessor in writing of any material defects in the
premises, which defects Lessor shall correct as promptly as possible.

Amendment 6 - Fire and Extended Coverage Insurance

      If at any time during the term of this Lease, or any extensions thereof,
Lessee obtains a firm written bid from a responsible broker representing a
responsible insurance company qualified to do business in California and
satisfactory to Lessor for the same fire and extended coverage insurance which
is then in effect on the premises at a lower premium, then Lessor will at
Lessor's option either purchase the insurance from Lessee's broker, commencing
with the next premium term, cause Lessor's insurance broker to meet the lower
price, or credit the Lessee with the price difference.

      Lessor shall have no obligation to insure against loss by Lessee to any
leasehold improvements, fixtures, furniture or other personal property
installed by Lessee at Lessee's expense in or about the premises occurring from
any cause whatsoever and Lessee shall have no interest in the proceeds  of any
insurance carried by Lessor, except as provided in Amendment 20 hereof.

Amendment 11 - Advertisements and Signs

      Lessor will not unreasonably withhold Lessor's consent to the installation
on the premises by Lessee, at Lessee's expense, of

                                       2.
<PAGE>   7
normal business signs, provided that the location and design thereof have been
approved in advance by Lessor's architect.

Amendment 14 -- Insolvency or Bankruptcy

     Lessee shall have thirty (30) days following the happening of any such
event referred to in (a), (b), or (c) of Paragraph 14 hereof within which to
cure any such breach. If Lease fails to cure any such breach within said thirty
(30) day period, then Lessor, at Lessor's option, may terminate this lease
upon giving ten (10) days prior written notice of termination to Lessee.

Amendment 18 -- Notices

     All notices to be given to Lessor or Lessee shall be given in writing and
delivered personally to Lessor or to an officer of Lessee, or by depositing the
same in the United States mail, postage prepaid, and addressed to the parties
as follows:

          To Lessor:     c/o Miss Sally Moseman
                         c/o Properties International
                         1631 Filbert Street
                         San Francisco, California 94123

          To Lessee:     Acurex Corporation
                         485 Clyde Avenue
                         Mountain View, California 94040

     Either party may designate a different address for notice by giving
written notice thereof to the other party in the manner referred to above.

Amendment 20 -- Destruction of Premises

     In the event of a partial destruction of the said premises during the said
term for any cause other than uninsured damages by earthquake, or by any other
uninsured casualty, Lessor shall forthwith repair the same, provided such
repairs can be made within ninety (90) days under the laws and regulations of
State, Federal, County or Municipal authorities, but such partial destruction
shall in no way annul or void this lease, except that Lessee shall be entitled
to a proportionate reduction of rent while such repairs are being made, such
proportionate reduction to be based upon the extent to which the making of
such repairs shall interfere with the business carried on by Lessee in the said
premises. If such partial destruction is caused by earthquake or by any other
uninsured casualty, or if such repairs cannot be made within ninety (90) days,
Lessor may, at Lessor's option, make same within a reasonable time, but not to
exceed one hundred eighty (180) days, and this lease shall continue in full
force and effect and the rent shall be proportionately reduced as aforesaid in
this paragraph provided. In the event that Lessor does not so elect to repair
the damage caused by an uninsured casualty, or in the event that Lessor does
not so elect to make such

                                       3.
<PAGE>   8
repairs which cannot be made within ninety (90) days, or such repairs cannot be
made under such laws and regulations, this lease may be terminated at the
option of either party, provided that such option to terminate is exercised by
giving written notice to the other party within fifteen (15) days after the
date of notice by Lessor to Lessee of Lessor's intention not to make repairs.
In respect to any partial destruction which Lessor is obligated to repair or
may elect to repair under the terms of this paragraph, the provisions of
Section 1932, Subdivision 2, and of Section 1933, Subdivision 4, of the Civil
Code of the State of California are waived by Lessee. A total destruction of
the building in which the said premises may be situated shall terminate this
lease. In the event of any dispute between Lessor and Lessee relative to the
provisions of this paragraph, they shall each select an arbitrator, the two
arbitrators so selected shall select a third arbitrator and the three
arbitrators so selected shall hear and determine the controversy and their
decision thereon shall be final and binding upon both Lessor and Lessee, who
shall bear the cost of such arbitration equally between them. In the event that
Lessor is obligated to repair damage, or elects to repair damage, in accordance
with this paragraph, Lessor's obligation shall be limited to the construction of
the building, interior improvements, and site work initially constructed by
Lessor, at Lessor's expense, and Lessee shall construct and install, at Lessee's
expense, all other leasehold improvements, fixtures, and equipment originally
installed by Lessee. If Lessor is obligated or elects to repair damage to
interior improvements which Lessor originally financed pursuant to Amendment
1(b) Lessor will allow Lessee to make such repairs to complete the interior as
previously constructed. If Lessee so requests Lessor shall make available to
Lessee that portion of any insurance proceeds Lessor receives as a result of the
damage to the premises which are allocated by Lessor's insurance company for
repair of interior improvements originally installed by Lessor pursuant to
Amendment 1(b) hereof. Lessee's obligation to repair the interior improvements
shall be limited to the insurance proceeds made available to Lessee for such
purposes.

Amendment 22 -- Condemnation

     If any part of the premises shall be taken for any public or quasi-public
use, under any statute or by right of eminent domain or private purchase in
lieu thereof, and a part thereof remains which is susceptible, of occupation
hereunder, this lease shall, as to the part so taken, terminate as of the date
title shall vest in the condemnor or purchaser, and the rent payable hereunder
shall be adjusted so that the Lessee shall be required to pay for the remainder
of the term only such portion of such rent as the value of the part remaining
after such taking bears to the value of the entire premises prior to such
taking. If all of the premises, or such part thereof be taken so that there
does not remain a portion reasonably suitable for the continued use and
occupancy by Lessee for the purposes specified in the use clause above, this
lease shall thereupon terminate. If a part or all of the premises be taken, all

                                       4.
<PAGE>   9
compensation awarded upon such taking shall go to the Lessor and the Lessee
shall have no claim thereto; provided, however, that Lessee shall be entitled
to remove any trade fixtures supplied by Lessee from that portion or all of the
premises condemned, or alternatively, if a separate allocation is made in the
condemnation award for Lessee's trade fixtures, Lessee shall be entitled to
receive that part of the condemnation award specifically designated as
compensation for the taking of any trade fixtures supplied and paid for by
Lessee.

Amendment 23 - Effect of Conveyance

      In the event of the sale or transfer by Lessor of the premises prior to
the completion of the building and improvements to be constructed on the
property by Lessor, Lessor shall not be freed and relieved of Lessor's
covenants and obligations hereunder until delivery to Lessee of the completion
notice as provided for in Paragraph 35 hereof.

Paragraph 30 - Rental Adjustments

      (a) The initial monthly rental of Fifteen Thousand Six Hundred Sixteen
Dollars ($15,616) is based upon the building to be constructed on the premises
consisting of 51,200 square feet, with the rental computed at the rate of
$0.305 per square foot; and is further based upon Lessor contributing the
maximum amount of Five Hundred Thousand Dollars ($500,000) for interior
improvements after completion of the building shell. Any additional cost of
interior improvements in excess of Five Hundred Thousand Dollars ($500,000),
shall be paid by Lessee. If the total cost of the interior improvements is less
than Five Hundred Thousand Dollars ($500,000) but not less than Four Hundred
Fifty Thousand Dollars ($450,000), the initial monthly rental shall be reduced
by an amount equal to one percent (1%) per month of the amount by which the cost
of said interior improvements is less than Five Hundred Thousand Dollars
($500,000). No reduction in the initial monthly rental shall be given in the
event the total cost of the interior improvements is less than Four Hundred
Fifty Thousand Dollars ($450,000). There is attached hereto as a part of Exhibit
"C" a description of the project items and interior improvements which the
parties hereby agree represent a full and complete list of said items. The
parties agree to execute an amendment to this lease reflecting the adjustment in
the monthly rental, if applicable, upon completion of construction.

      (b) The initial monthly rental, as adjusted pursuant to sub-paragraph (a)
above of this Amendment 30, shall be adjusted as of June 1, 1982, June 1, 1987,
and June 1, 1992, each of which is hereafter referred to as a "rent adjustment
date," to reflect changes in the cost of living from the commencement date of
the lease term to each rent adjustment date. The adjustments, if any, in the
monthly rental shall be calculated on the basis of changes in the United States
Department of Labor, Bureau of Labor Statistics Consumer Price Index, Subgroup
"all items," for San Francisco-Oakland (1967=100), hereafter referred to as the
"CPI." The CPI for May 1977 is hereafter referred to as the "base CPI." The
monthly rental for the five (5) year period commencing June 1, 1982, and for
each five (5) year



                                       5.

<PAGE>   10
period commencing June 1, 1982, and for each five (5) year period after each
successive rent adjustment date thereafter, of the lease term shall be adjusted
by the percentage increase or decrease, if any , in the CPI as of the month of
May immediately prior to the rent adjustment date over the base CPI; provided,
however, that for the period June 1, 1982 through May 31, 1987 the monthly
rental shall not exceed one hundred twenty percent (120%) of the initial monthly
rental; for the period June 1, 1987 through May 31, 1992 the monthly rental
shall not exceed one hundred forty percent (140%) of the initial monthly rental;
and for the period June 1, 1992 through May 31, 1997 the monthly rental shall
not exceed one hundred sixty percent (160%) of the initial monthly rental; and
provided further that the amount of the monthly rental increase for any of the
five (5) year periods over the preceding five (5) year period shall not exceed
twenty percent (20%) of the initial monthly rental. Notwithstanding the
foregoing, the monthly rental at all times during the lease term shall not be
less than the initial monthly rental of Fifteen Thousand Six Hundred Sixteen
Dollars ($15,616), adjusted by the provisions of subparagraph (a) above of this
Amendment 30. When the monthly rental for each five (5) year period commencing
with a rent adjustment date is determined, Lessor shall give Lessee written
notice to that effect indicating how the new monthly rental figure was computed.
If at any rental adjustment date there shall not exist a Consumer Price Index in
the same format as referred to in this paragraph, the parties shall substitute
any official index published by the Bureau of Labor Statistics or successor or
similar governmental agency, as may then be in existence which shall be most
nearly comparable thereto. If the parties are unable to agree upon a successor
index, the parties shall refer their choice of a successor index to arbitration
to be conducted by three arbitrators, one to be selected by Lessor, one to be
selected by Lessee, and the third to be selected by said first two chosen
arbitrators. Said arbitrators shall make a report in writing signed by each of
them within twenty (20) days after their selection. The expenses of the
arbitration shall be borne equally by the parties hereto and the report of the
majority of the arbitrators shall be binding upon both Lessor and Lessee.

Paragraph 31 - Memorandum of Lease

     This lease shall not be recorded; provided that if either party requests
the other party to do so, the parties shall execute a Memorandum of Lease in
recordable form which shall refer to the parties, the premises, and the terms
of the lease.

Paragraph 32 - Waiver of Subrogation

     The parties release each other, and their respective authorized
representatives, from any claims for damage to any person or to the premises
and to the fixtures, personal property, Lessee's improvements, and alterations
of either Lessor or Lessee in or on the premises that are caused by or result
from risks insured against under any insurance policies carried by the parties
and in force at the time of any such damage.

     Each party shall cause each insurance policy obtained by it to provide
that the insurance company waives all right of recovery by way of subrogation
against either party in connection with any damage covered by any policy.
Neither party shall be liable to the other for any damage caused by fire or any
of the risks insured against under any insurance policy required by this lease.
If any insurance policy cannot be obtained with a waiver of subrogation, or is
obtainable only by the payment of an additional premium charge above that
charged by insurance companies issuing policies without


                                       6.

<PAGE>   11
waiver of subrogation, the party undertaking to obtain the insurance shall
notify the other party of this fact. The other party shall have a period of ten
(10) days after receiving the notice either to place the insurance with a
company that is reasonably satisfactory to the other party and that will carry
the insurance with a waiver of subrogation, or to agree to pay the additional
premium if such a policy is obtainable at additional cost. If the insurance
cannot be obtained or the party in whose favor a waiver of subrogation is
desired refuses to pay the additional premium charged, the other party is
relieved of the obligation to obtain a waiver of subrogation rights with
respect to the particular insurance involved.

Paragraph 33 - Tennis Court
---------------------------

     Lessee shall give Lessor written notice of the first to occur of the
following events:

          (a)     The lease rights or the right to use the adjoining Hetch
Hetchy area has terminated or is no longer in effect for any reason, or

          (b)     Three (3) months prior to the expiration of the lease term or
any renewal thereof.

Upon giving such written notice, Lessee shall, if requested to do so by Lessor,
remove that portion of the tennis court which is situated on the premises and
replace that area with landscaping which is consistent with the original
landscaping of the area, subject to Lessor's approval.

Paragraph 34 - Financing
------------------------

     This lease and Lessor's obligations hereunder are conditional upon Lessor
obtaining a commitment for a construction loan and permanent financing for
construction of the building and improvements to be erected on the premises,
upon terms and conditions reasonably acceptable to Lessor, within thirty (30)
days after approval by the parties of the final plans and specifications for
the building and improvements. Lessor agrees to exercise all reasonable efforts
to obtain said financing. If Lessor is unable to obtain said financing within
said thirty (30) day period, Lessor shall promptly give written notice thereof
to Lessee. Lessee shall have forty-five (45) days following, the receipt of
said notice from Lessor within which to obtain financing through Lessee's own
agents. Lessor shall accept financing for the project with a loan obtained by
Lessee, provided that the loan amount is between $1,250,000 and $1,350,000 for
a loan term of from twenty-five (25) years to thirty (30) years, at an interest
rate of not to exceed nine and three-fourths percent (9-3/4%) per annum, and a
maximum loan fee of not more than one (1) point. If Lessee is unable to obtain
said financing for Lessor within said forty-five (45) day period, Lessor may
then terminate this lease by giving written notice of termination to Lessee.










                                       7.
<PAGE>   12
Paragraph 35 - Occupancy

     In the event the premises are not completed and available for occupancy on
the commencement date of this lease as set forth in the paragraph entitled
"Term" on page 1, the term of this lease shall commence on that date which
Lessee commences operations in the premises which shall not be more than thirty
(30) days after delivery by Lessor to Lessee of notice of completion of the
construction contemplated by Amendment 1(a) hereto. Promptly upon commencement
of the lease term, Lessee agrees to execute and deliver to Lessor a letter
confirming the commencement date and termination date of this lease.

Paragraph 36 - FAA Approval

     This lease and Lessor's obligations hereunder are conditioned upon Lessee
delivering to Lessor prior to commencement of construction described in
Amendment 1(a) hereto of a copy of a current approval by the Federal Aviation
Administration as well as the Commanding Officer, Naval Air Station, Moffett
Field, of the construction of the premises which are the subject of this lease.


                                         /s/ RICHARD N. MOSEMAN
                                         --------------------------------------
                                         RICHARD N. MOSEMAN


                                         /s/ BONNIE MOSEMAN MILLER
                                         --------------------------------------
                                         BONNIE MOSEMAN MILLER

                                         PROPERTIES INTERNATIONAL, allrent, INC


                                         By /s/ SALLY MOSEMAN
                                           ------------------------------------
                                            SALLY MOSEMAN, President
                                                         "Lessor"


                                         ACUREX CORPORATION


                                         By
                                           ------------------------------------


                                         By /s/ [Signature Illegible]
                                           ------------------------------------
                                           V.P.
                                                         "Lessee"





                                       8.
<PAGE>   13
APPLICATION NO. SJ-379416                                             SCHEDULE C
--------------------------------------------------------------------------------


The land referred to herein is described as follows:

ALL THAT CERTAIN REAL PROPERTY IN THE CITY OF MOUNTAIN VIEW, COUNTY OF SANTA
CLARA, STATE OF CALIFORNIA, DESCRIBED AS FOLLOWS:

ALL OF LOT 3 AS SHOWN UPON THAT CERTAIN MAP ENTITLED, "TRACT NO. 3813", WHICH
MAP WAS FILED FOR RECORD DECEMBER 28, 1964 IN BOOK 189 OF MAPS, PAGE 32, IN THE
OFFICE OF THE RECORDER OF THE COUNTY OF SANTA CLARA, STATE OF CALIFORNIA.



Exhibit "A"

<PAGE>   14
                              [MAP OF TRACT 3813]


Exhibit "A"


<PAGE>   15
                      [SITE PLAN OF PROPOSED BUILDING #5]


Exhibit "B"

<PAGE>   16
PROJECT ITEMS - SHELL


Included                               Excluded
-------------------------------------------------------------------------------

2-story concrete tilt-up natural       change charges
  concrete
                                       overhang
approximately 25,600 sq ft
  each floor                           tennis court, incremental cost above
                                         basis by lessee
bronze glass with anodized frames
                                       sky lights
one 3000-pound elevator
                                       natural convection
two interior stair wells

primary fire sprinklers

roof insulation

excavating/grading/paving

landscaping

irrigation/drainage

utilities to building
  with/2000 AMPS, 480 volts























Exhibit "C"
<PAGE>   17
                                                                     EXHIBIT "C"

PROJECT ITEMS IN $500,000 INTERIOR

<TABLE>
<CAPTION>
Included in $500,000                    Excluded in $500,000
------------------------------------    ----------------------------------------
<S>                                     <C>

Architectural fee budgeted              Architectural budget beyond
  of $15,000                              $15,000

Heat/vent/air conditioning               Change charges
  with economizer
                                         Window coverings
Complete electrical
                                         All other improvements to
Finished restroom cores                    and/or equipment for cafeteria

Ceilings                                 Telephone equipment

Flooring                                 Items which could be termed
                                           special purpose items or
Drop fire sprinklers                       unusual items not consistent
                                           with normal R&D buildings
Roof screens                               in the area, to be approved
                                           by lessor and/or lender
Entrance lobby

Partitioning and doors based on
  Acurex May 3 drawing

Cafeteria with:
  asbestos flooring (vinyl)
  drop ceiling
  heating/air conditioning
  sprinklers

All other items not included in
  shell items

Exhibit "C"
</TABLE>

<PAGE>   18
                                                                October 23, 1976

Acruex Corporation
485 Clyde Avenue
Mountain View, California 94040

                 Re: Lease for 555 Clyde Avenue, Mountain View

Gentlemen:

         Reference is hereby made to the Lease dated October 23, 1976 between
Richard N. Moseman, Bonnie Moseman Miller, and Properties International,
allrent, Inc., as lessor, and Acurex Corporation, as lessee, covering premises
at 555 Clyde Avenue, Mountain View, California.

         Commencement of construction of the building and improvements has been
delayed because of the protracted lease negotiations between the parties. Lessor
is now uncertain that the completion date of May 1, 1977 referred to in
Amendment 1(c) of the Lease can be achieved on a normal construction schedule,
even without delays beyond lessor's control. Therefore, the parties agree that
so long as lessor exercises due diligence in prosecuting the work of
construction to completion, lessor shall not be liable to lessee for any
damages, and lessee shall not have any right to terminate the Lease, in the
event construction is not completed by lessor on or before May 1, 1977. The
rental adjustment dates under Paragraph 30(b) shall be adjusted accordingly.

         Notwithstanding the provisions of Paragraph 36 of the Lease, regarding
FAA approval, if lessee does not deliver to lessor on or before November 8,
1976 the approval in writing by the Federal Aviation Administration, as well as
the Commanding Officer, Naval Air Station, Moffett Field, of the construction
of the premises which are the subject of the Lease, either lessor or lessee may
terminate this Lease upon delivering written notice of termination to the other
on or before 5:00 P.M. on November 10, 1976. In the event this Lease is so
terminated, Acurex shall pay lessor $3,000 for preconstruction costs incurred
by lessor through the date of termination.

         If the provisions of this letter are acceptable, please sign at the
space below indicating your approval and acceptance hereof.

                                          Very truly yours,

                                          PROPERTIES INTERNATIONAL, allrent, INC

The foregoing is accepted                            /s/ SALLY MOSEMAN
and approved.                             By ___________________________________
                                                  Sally Moseman, President
ACUREX CORPORATION

         /s/ [Signature Illegible]
By ___________________________________

Dated: October 23, 1976
<PAGE>   19
                                   AGREEMENT

Reference is made to Paragraph 30 - Rental Adjustments - of that certain Lease,
as amended, dated October 23, 1976 between Richard N. Moseman, Bonnie Moseman
Miller, and Properties International, allrent, Inc., a California corporation,
Lessor, and Acurex Corporation, a California corporation, Lessee, demising the
property commonly referred to as 555 Clyde Avenue, Mountain View, California
94043.

It is hereby understood and agreed that any additional costs of interior
improvements in excess of $500,000.00 will be paid by Lessee in a timely manner
upon presentation of appropriate bills by the Contractor. All parties hereunder
are aware that a take-out commitment for a long term loan has been issued by
The Penn Mutual Life Insurance Company and expires on October 2, 1977. As a
result, interior improvements are to be made and paid for in a timely manner so
that the construction lender hereunder will have ample time to refinance its
loan according to the abovementioned take-out commitment.



Dated: February 1, 1977


Construction Lender:                    Lessor:

UNITED CALIFORNIA BANK                  ----------------------------------
                                        Richard N. Moseman
                                        /s/ Bonnie Moseman Miller by Sally
                                        Moseman as attorney-in-fact
By /s/ R. B. DEWITT
   ---------------------------          ----------------------------------
   R. B DeWitt, Vice President          Bonnie Moseman Miller


Lessee:

Acurex Corporation, a                   Properties-International, allrent, Inc.
California corporation                  California corporation

By /s/ [Signature Illegible]            By /s/ SALLY MOSEMAN
   --------------------------              -------------------------------
                                           Sally Moseman, President


<PAGE>   20
                      SECOND LEASE MODIFICATION AGREEMENT

          THIS AGREEMENT is made and entered into as of October 14, 1992, by and
among RICHARD N. MOSEMAN, BONNIE MOSEMAN MILLER and PAULINE NYE MOSEMAN, as
Trustee of the Pauline Nye Moseman Trust dated October 3, 1983 (collectively
"Lessor"), ACUREX ENVIRONMENTAL CORPORATION, a California corporation ("Lessee")
and ACUREX CORPORATION, a California corporation ("Acurex").

                              W I T N E S S E T H

          WHEREAS, Acurex and Richard N. Moseman, Bonnie Moseman Miller and
Properties International, Allrent, Inc., as lessor, entered into a lease, dated
October 23, 1976, for certain real property and improvements thereon located at
and commonly known as 555 Clyde Avenue, in the City of Mountain View, County of
Santa Clara, State of California (the "Real Property"), which lease has been
amended by a Letter Agreement dated October 23, 1976, an Agreement dated
February 1, 1977, an Agreement dated April 21, 1977 and a First Lease
Modification Agreement, dated August 11, 1977 (collectively, the "Lease");

          WHEREAS, Acurex is transferring, effective as of December 28, 1991,
all of the assets of its Environmental




<PAGE>   21
Systems Division ("ESD") to Lessee, in exchange for (i) 100 shares of the common
stock of Lessee (being all of the issued and outstanding shares of Lessee), and
(ii) the assumption by Lessee of ESD's obligations and liabilities (the "ESD
Transactions");

          WHEREAS, as a part of the ESD Transactions, Lessee has agreed pursuant
to the Contribution, Assignment and Assumption Agreement dated as of December
28, 1991 (the "Assignment and Assumption Agreement") to assume the liabilities
and obligations of Acurex as to the Lease;

          WHEREAS, Acurex continues to remain liable under the Lease for the
performance of any and all covenants and obligations of the lessee therein;

          WHEREAS, in July 1992, Pauline Nye Moseman, as Trustee of The Pauline
Nye Moseman Trust dated October 3, 1983 succeeded to the interest of Properties
International, Allrent, Inc. with regard to the Real Property; and


          WHEREAS, Lessor has agreed to consent to the assignment and assumption
of the Lease by Acurex to AEC provided, inter alia, Lessee and Acurex agree to
the following modification and amendment to the Lease.

                                      -2-



<PAGE>   22
                                   AGREEMENT

          NOW, THEREFORE, in consideration of the mutual covenants herein
contained and for other good and valuable consideration, the parties hereto
hereby agree as follows:

          1.  The following four (4) sentences of the section of the Lease
titled "Term" are hereby deleted from the Lease in their entirety:

          "Provided Lessee faithfully performs its obligations
          hereunder, and is not then in default hereunder, Lessor
          hereby grants to Lessee the option to extend the lease
          term for sixty (60) months upon the expiration of the
          initial lease term. The option to extend shall be
          exercised by Lessee giving written notice of exercise
          to Lessor not less than one hundred eighty (180) days
          prior to the expiration of the initial lease term. Such
          extended term shall be upon all except for the rental
          which shall be determined by negotiations of the parties.
          In the event that the parties are unable to agree upon
          the rental within ninety (90) days after the exercise of the
          option by Lessee, then such option shall be null and
          void and of no force of effect, and the lease term shall
          expire and terminate upon the expiration of the initial
          lease term, if not sooner terminated pursuant to the
          provisions hereof."

          2.  Except as modified and amended herein, the Lease shall remain in
full force and effect.

                                      -3-

<PAGE>   23
          3.   This Agreement is effective as of the date set forth above.


          IN WITNESS WHEREOF, the parties have executed this Agreement.



                                        /s/ RICHARD N. MOSEMAN
                                        -----------------------------------
                                        Richard N. Moseman

                                        /s/ BONNIE MOSEMAN MILLER
                                        ------------------------------------
                                        Bonnie Moseman Miller

                                        /s/ PAULINE NYE MOSEMAN
                                        ------------------------------------
                                          Pauline Nye Moseman, as Trustee
                                         of the Pauline Nye Moseman Trust
                                               dated October 3, 1983


                                         ACUREX ENVIRONMENTAL CORPORATION,
                                         a California corporation


                                         By /s/ [Signature Illegible] V.P. & CFO
                                            ------------------------------------


                                         ACUREX CORPORATION,
                                         a California corporation


                                         By /s/ [Signature Illegible] V.P. & CFO
                                            ------------------------------------


                                      -4-

<PAGE>   24
                               PARKING AGREEMENT

     THIS AGREEMENT is made and entered into on August 8, 1977, by and between
RICHARD N. MOSEMAN, BONNIE MOSEMAN MILLER, and PROPERTIES INTERNATIONAL,
allrent, INC., a California corporation, hereafter collectively referred to as
"Moseman," and ACUREX CORPORATION, a California corporation, hereafter referred
to as "Acurex."

RECITALS:
     A. Moseman, as lessor, and Acurex, as lessee, entered into a Lease dated
October 23, 1976, as amended August 8, 1977, hereafter referred to as the
"Lease," covering certain real property commonly known as 555 Clyde Avenue,
Mountain View, Santa Clara County, California, being Lot 3 as shown upon that
certain Map entitled "Tract No. 3813," which Map was filed for record December
28, 1964 in Book 189 of Maps, Page 32, in the Office of the Recorder of the
County of Santa Clara, State of California, hereafter referred to as the
"premises."

     B. Acurex is constructing a tennis court and handball court on the
premises as part of the building improvements currently under construction on
the premises. The construction of the tennis court and handball court, plus
certain landscaping to be installed by Moseman, has resulted in the development
on the premises of twenty-five (25) parking spaces and one (1) loading zone
less than required by the zoning ordinance of the City


<PAGE>   25
of Mountain View.
     C. Acurex has the use of certain Hetch-Hetchy property, hereafter referred
to as the "Hetch-Hetchy property," consisting of an eighty (80) foot wide
parcel extending four hundred (400) feet, more or less, easterly of Clyde Avenue
and located immediately to the south of the premises and contiguous thereto,
pursuant to a Land Use Permit dated march 14, 1973 granted to Acurex by the San
Francisco Water Department.
     D. Moseman and Acurex now wish by this Agreement to provide for certain
parking rights over a portion of the Hetch-Hetchy property for the benefit of
the premises, upon the terms and conditions contained herein.
     NOW THEREFORE, in consideration of the payment of the sum of Ten Dollars
($10.00) by Moseman to Acurex, and other good and valuable consideration, the
receipt and adequacy of which are hereby acknowledged, the parties agree as
follows:
     1. Except as otherwise provided herein, so long as the lease is in full
force and effect, and so long as Acurex has the right to use the Hetch-Hetchy
property for parking pursuant to the Land Use Permit with the San Francisco
Water Department, the equivalent of twenty-five (25) parking spaces and one (1)
loading space on the Hetch-Hetchy area will be allocated and set aside for use
as parking area by the occupant or occupants of the premises, without cost or
expense to the owner of the premises, or the occupant of the premises if other
than Acurex.
     2. Upon expiration or sooner termination of the



                                      -2-


<PAGE>   26
Lease, so long as Acurex continues to have the right to use the Hetch-Hetchy
area for parking purposes pursuant to the Land Use Permit, the equivalent of
twenty-five (25) parking spaces and one (1) loading space on the Hetch-Hetchy
area will be allocated and set aside by Acurex for use as parking area by the
occupant or occupants of the premises, upon the payment to Acurex monthly in
advance on the first day of each calendar month of an amount equal to
thirty-eight percent (38%) of the monthly amount payable by Acurex to the San
Francisco Water Department pursuant to the Land Use Permit, as such amount may
be adjusted by the San Francisco Water Department from time to time. The owner
of the premises may discontinue such use of the Hetch-Hetchy property at any
time upon giving thirty (30) days prior written notice to Acurex, and thereafter
the owner of the premises shall be relieved from the obligation to make such
payments to Acurex and Acurex shall have no further obligations under this
Agreement.

          3.  Moseman acknowledges receipt of a copy of the Land Use Permit. The
rights of Moseman and the occupants of the premises hereunder shall be subject
to the terms and conditions of said Land Use Permit, including, but not limited
to, the right of the San Francisco Water Department to revoke such right to use
the Hetch-Hetchy area for parking at any time.

          4.  (a) Acurex shall use all reasonable effort to renew the Land Use
Permit when it expires, and to maintain said Permit in effect during the term of
the Lease; provided, however, that Acurex shall no longer be required to provide
the owner of the premises with parking spaces on the Hetch-Hetchy property,

                                      -3-

<PAGE>   27
if at any time additional on-site parking area is placed on the premises in an
amount sufficient to satisfy the requirements of the City of Mountain View.

          (b) Following the expiration or sooner termination of the Lease,
Acurex may surrender voluntarily its right to use the Hetch-Hetchy property for
parking at any time and thereupon the parties shall be relieved of their
obligations hereunder, provided that Acurex gives Moseman, or the then owner of
the premises, at least ninety (90) days prior written notice of its intention
to do so, in order that Moseman, or the then owner of the premises, may seek to
acquire the parking rights on the Hetch-Hetchy property from the San Francisco
Water Department.

     5.   Acurex shall be responsible for obtaining the approval of the City of
Mountain View to the necessary variance and site plan and architectural
approval to permit the installation of the tennis court and handball court on
the portion of the premises to be devoted to such uses in lieu of parking area.
Moseman shall have no liability to Acurex if the City of Mountain View fails to
grant such approval, or, if after such approval is granted, the tennis court or
handball court or both must be removed in the event the City of Mountain View
requires additional on-site parking and loading spaces on the premises in
accordance with the plans previously approved by the City of Mountain View's
site plan and architectural review (Application 354-76AA).

     6.   Nothing contained herein shall be deemed to modify



                                      -4-
<PAGE>   28
or amend the Lease.

     7. This Agreement shall inure to the benefit of and shall be binding upon
the respective heirs, personal representatives, successors, and assigns of the
parties hereto.

     IN WITNESS WHEREOF, this Agreement has been entered into by the parties as
of the date set forth above.


                                        ----------------------------------------
                                        Richard N. Moseman

                                        /s/ BONNIE MOSEMAN MILLER
                                        ----------------------------------------
                                        Bonnie Moseman Miller

                                        PROPERTIES INTERNATIONAL, allrent, INC.,
                                        a California corporation

                                         By /s/ [Signature Illegible]
                                            ------------------------------------

                                         ACUREX CORPORATION,
                                         a California corporation

                                         By /s/ TIMOTHY P. CARLSON
                                            ------------------------------------

                                      -5-
<PAGE>   29
                               LESSEE'S STATEMENT

     The undersigned lessee of premises situated at 555 Clyde Avenue, City of
Mountain View, State of California acknowledges receipt of notice that lessor
has assigned or is about to assign all existing leases on said premises or any
part thereof as additional collateral security for the payment of a certain
promissory note of even date herewith payable to the order of _____________,
(said assignment being subject however, to lessor's rights to collect the rents
until default in the performance of the obligations in said note and deed of
trust securing the same, said deed of trust as recorded or about to be recorded
being hereby referred to for all details).

     The undersigned hereby certifies and represents to and covenants with the
said payee and the holder of said note from time to time as follows:

     1. The undersigned, as lessee under a certain lease entered into with
Richard N. Moseman, Bonnie Moseman Miller, Properties International, allrent,
Inc., as lessor, and dated October 23, 1976.

          See Addendum to Lessee's Statement attached hereto.

     2. The initial term of the lease commenced on October __, 1977 and will
end two hundred and forty months later.

     3. There have been no modifications or changes in the lease except as
follows:

          First Lease Modification Amendment dated August 11, 1977.

     4. No rent or other sum payable under said lease has been paid in advance
except as follows:

          First month's rent  $15,616.
          Security Deposit    $15,000.

     5. The undersigned has accepted the leased premises and has no defense,
set-off or counter-claim against the lessor under the lease or otherwise except
as follows:

          See Addendum to Lessee's Statement attached hereto.

     6. The undersigned has received no notice of any assignment of the lease
to any person other than the payee of said note except as follows:

          None

     7. The undersigned acknowledges notice that no prepayment or reduction of
rent, or modification or cancellation of said lease, will be valid as to the
holder of said note without consent of such holder.

          Yes

     8. The undersigned certify and represent that the above statements,
including any exceptions which have been added thereto, are full and complete
and that the payee and the holder of said note may rely and act upon them.

     Dated as of November 11, 1977.

Witness:


                                        /s/ TIMOTHY P. CARLSON            [SEAL]
-----------------------------------     ----------------------------------------
                                        Acurex Corporation
                                                                          [SEAL]
-----------------------------------     ----------------------------------------

<PAGE>   30
                        THIRD RENEWAL AMENDMENT TO LEASE

        This Renewal Amendment to the Lease Agreement dated October 23, 1976
(the "Lease") is made and entered into as of this 23rd day of November, 1997,
by and between Richard N. Moseman, Bonnie Moseman, Miller, Pauline Nye Moseman,
as Trustee of Pauline Nye Moseman Trust ("Lessor"), and Acurex Environmental
Corporation ("Lessee"), collectively referred to as the "Parties."

RECITALS:

1.      WHEREAS, Lessor and Lessee have entered into a Lease dated as of October
        23, 1976 have, by amendment, renewed such Lease continuously through and
        including November 22, 1997 with respect to certain premises located at
        555 Clyde Avenue, Mountain View, California, and

2.      WHEREAS the Parties wish to renew and amend the Sublease in terms of
        basic rent, and

3.      WHEREAS the Lessee continues to perform its obligations of the lease,
        the Lessor shall grant to extend the lease term for sixty (60) months
        upon the expiration of this amendment lease term.

4.      WHEREAS the option to extend has been exercised by Lessee giving written
        notice of exercise to Lessor six (6) months prior to the expiration of
        the terms of this agreement and the terms of the rent have been duly
        negotiated and agreed upon the parties

        NOW THEREFORE, in consideration of the mutual promises and covenants,
        and other good and valuable consideration contained herein, the Parties
        agree as follows:

AGREEMENT:

        1.      TERM is renewed so as to extend the Lease for sixty (60)
                calendar months commencing on the 23rd day of November, 1997 and
                ending on the 22nd day of November, 2002.

        2.      RENTAL is amended so as to require payment of base rent at the
                rate $38,400.00 per month during the Lease term.

        3.      Except as amended hereby, the Parties ratify and affirm that
                each and all of the terms, covenants and conditions of the
                Lease Agreement dated October 23, 1976, as amended, shall
                remain in full force and effect.

        IN WITNESS WHEREOF, the Lessor and Lessee execute this Amendment as of
the day and year first above written.

                                        /s/ RICHARD N. MOSEMAN
                                        ----------------------------------------
                                        Richard N. Moseman

                                        /s/ BONNIE MOSEMAN MILLER
                                        ----------------------------------------
                                        Bonnie Moseman Miller

                                        /s/ KENNA S. HELMS
                                        ----------------------------------------
                                        Vice President
                                        & Senior Trust Officer

                                        /s/ PAULINE NYE MOSEMAN
                                        ----------------------------------------
                                        Pauline Nye Moseman as Trustee of
                                        the Pauline Nye Moseman Trust
                                        dated October 3, 1983

                                        ACUREX ENVIRONMENTAL CORPORATION,
                                        a California Corporation


                                        /s/ HOWARD L. MORSE
                                        ----------------------------------------
                                        Howard L. Morse