
<PAGE>   1
                                                            EXHIBIT 10.16

                               SUBLEASE AGREEMENT                    

1. PARTIES.

      This Sublease dated June 3, 1996, is made by and between Metrika
      Laboratories, Inc. a California corporation (hereinafter "Sublandlord")
      and PenWare, Inc., a Delaware corporation (hereinafter "Subtenant"). This
      Sublease shall be effective on the date on which Guzik Investments, L.P.
      (hereinafter "Master Landlord") consents in writing to the fully executed
      Sublease (the "Effective Date").

2. PREMISES.

      Sublandlord hereby subleases to Subtenant and Subtenant hereby subleases
      from Sublandlord for the term, at the rental rate, and upon all of the
      conditions set forth herein, the Sublease Premises situated in the City of
      Sunnyvale, Santa Clara County, State of California, commonly known as 510
      Oakmead Parkway, Sunnyvale, California 94086, and described as
      approximately 7,800 square feet of research & development/office space; as
      identified in Exhibit A (the "Sublease Premises").

3. TERM.

      3.1   The term of this Sublease shall commence on July 1, 1996 or the date
            on which Sublandlord has delivered legal possession of the Sublease
            Premises to Subtenant in the condition required by this Sublease
            (the "Commencement Date") and shall expire on June 30, 1999.

      3.2   Sublandlord shall deliver possession of the Sublease Premises in the
            condition required by this Sublease on or before July 1, 1996. If
            for any reason whatsoever, possession is not so delivered by such
            date, Subtenant shall have the right to terminate the Sublease at
            any time thereafter, until such possession is delivered, by written
            notice to Sublandlord, whereupon any monies previously paid by
            Subtenant hereunder shall promptly be reimbursed to Subtenant.

      3.3   In the event Subtenant, with Sublandlord's consent, takes possession
            prior to the Commencement Date, such occupancy shall be subject to
            all of the provisions of this Sublease and shall not advance the
            termination date of this Sublease, and Subtenant shall pay pro-rated
            rent for the period ending with the Commencement Date, based upon
            the rental rates set forth herein (calculated on the basis of a
            30-day month).

4. RENT.

      4.1   Commencing on the Commencement Date, the rental rate to be paid by
            Subtenant to Sublandlord on a Gross basis (Subtenant shall pay for
            their own janitorial and utility charges) shall be as follows:

            Month 01                         $0.00
            Months 02 - 12                   $1.05/Gross/SF/Month
            Months 13 - 24                   $1.15/Gross/SF/Month
            Months 25 - 36                   $1.20/Gross/SF/Month

      4.2   Sublease rent shall be payable on or before the first day of each
            and every calendar month. If any rent payment or any other sum due
            from Subtenant is not received by Sublandlord within five (5) days
            after Subtenant's receipt of a notice of delinquency, Subtenant
            shall pay a late charge equal to six (6) percent of such overdue
            amount.
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5. USE.

      5.1   The Sublease Premises shall be used and occupied by Subtenant for
            sales, marketing, hardware and software development, light
            industrial research & development, general office, and all other
            related legal uses subject to Sublandlord's, and Master Landlord's
            approval which shall not be unreasonably withheld as well as any and
            all applicable government approvals. But for no other use without
            the prior written consent of the Sublandlord and Master Landlord,
            which Sublandlord and Master Landlord may withhold in its sole
            discretion.

      5.2   Subtenant, at Subtenant's expense, shall comply promptly with all
            applicable statutes, ordinances, rules, regulations, orders,
            restrictions of record and requirements in effect during the
            sublease term hereof regulating the use of the Sublease Premises.

      5.3   Subject to the terms and conditions of this Sublease, Subtenant
            hereby accepts the Sublease Premises in its existing condition,
            subject to all applicable zoning, municipal, county and state laws,
            ordinances and regulations governing and regulating the use of the
            Sublease Premises, and accepts this Sublease subject thereto,
            provided, however, Sublandlord upon the Commencement Date shall
            deliver the Sublease Premises with the roof, plumbing, electrical,
            heating and air conditioning systems all in good working order and
            repair.

6. MASTER LEASE.

      6.1   This Sublease is subject and subordinate to that certain Standard
            Industrial/Commercial Single-Tenant Lease-Net dated August 30, 1995
            and Addendum to Standard Industrial/Commercial Single-Tenant
            Lease-Net dated August 30, 1995 and Second Addendum to Lease dated
            August 30, 1995 between Guizik Investments, L.P. ("Landlord"), and
            Metrika Laboratories, Inc., a California corporation ("Tenant'), a
            copy of which is attached hereto as Exhibit "B" (collectively, the
            "Master Lease"). The Master Premises as identified in the Master
            Lease consists of approximately 35,737 rentable square feet (the
            "Master Premises"), as identified in Exhibit A, constitutes the
            Master Premises. Subtenant shall not commit nor permit to be
            committed on the Sublease Premises any act or omission which shall
            violate any term or condition of the Master Lease.

      6.2   Subtenant shall assume and perform the obligations of Tenant
            (Sublandlord) in said Master Lease, to the extent said terms and
            conditions are applicable to the Sublease Premises, except for those
            provisions of the Master Lease which are directly contradicted by
            this Sublease, in which event the terms of this Sublease shall
            control over the Master Lease. Therefore, for the purpose of this
            Sublease, wherever the term "Landlord" or "Lessor" is employed in
            the Master Lease, it shall be deemed to mean the Sublandlord herein,
            and wherever the term "Tenant" or "Lessee" is employed in the Master
            Lease, it shall be deemed to mean the Subtenant herein;
            additionally, the term "Premises" shall be deemed to refer to the
            Sublease Premises. The foregoing notwithstanding, Sublandlord shall
            not have any obligation to perform the obligations of Master
            Landlord under the Master Lease which require Master Landlord to
            incur any cost or expense, such as, by way of example and not
            limitation, the obligation to repair or rebuild all or any part of
            the Sublease Premises. Sublandlord shall, however, use diligent
            efforts to enforce any such obligations of Master Landlord under the
            Master Lease. Any consent of Sublandlord required hereunder, whether
            specified herein or through incorporation of the Master Lease, shall
            include to the extent required by the Master Lease, the consent Of
            Master Landlord.

      6.3   All of the terms and conditions contained in the Master Lease are
            incorporated herein except for the following sections as outlined
            below:

            6.3.1 Standard Industrial/Commercial Single-Tenant Lease-Net:

                  Sections 1.3, 1.5, 1.6, 1.7, 1.10, 1.11, 3, 4, 7, 12, 13.4,
                  15, 19, 26, & 39.
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            6.3.2 Addendum to Standard Industrial/Commercial Single-Tenant
            Lease-Net: 49, 50, 52, 53, 55, 56, 58.

      6.4   Sublandlord shall indemnify and hold Subtenant harmless of and
            from all liability, judgements, costs, penalties and expenses,
            damages, claims, or demands, including reasonable attorney's
            fees, to the extent the same are caused by or arise in
            connection with (i) the negligence or willful misconduct of
            Sublandlord or its employees, agents, contractors or invitees
            occurring on or about the Master Premises or Sublease
            Premises; and (ii) the failure by Sublandlord to comply with
            or perform its obligations under the Master Lease and/or this
            Sublease. Likewise, Subtenant shall indemnify and hold
            Sublandlord and Master Landlord harmless of and from all
            liability, judgements, costs, penalties and expenses, damages,
            claims, or demands, including reasonable attorney's fees, to
            the extent the same are caused by or arise in connection with
            the i) failure by Subtenant to comply with or perform its
            obligations under the Master Lease (assumed by Subtenant
            hereunder) and/or this Sublease or Subtenant's use or
            occupancy of the Sublease Premises, or iii) Subtenant's
            negligent or willful acts or omissions, or Subtenant's failure
            to vacate the Sublease Premises strictly in accordance with
            the terms of the Sublease.

7. CONDITION OF PREMISES UPON DELIVERY.

      Sublandlord, in a good and workmanlike manner and at Sublandlord's sole
      cost and expense, shall pay for the following:

      7.1   Clean the Sublease Premises throughout.

      7.2   Paint the Sublease Premises throughout.        
           
      7.3   Replace the ceiling tiles where necessary.

      7.4   Replace burnt out lights.

      7.5   Remove the wall that is currently covering the door to the front
            entrance of the Sublease Premises.

      7.6   Subtenant shall have sixty (60) days from the Commencement Date of
            the Sublease to report any defects or problems with the following
            building operating systems that serve the Sublease Premises:

            7.6.1 Air conditioning systems.

            7.6.2 Heating Systems.

            7.6.3 Electrical systems.

            Upon the expiration of the sixty (60) day period, Subtenant shall be
            responsible for the maintenance and repair of items 7.6.1, 7.6.2 and
            7.6.3 should any problems occur due to Subtenant's occupancy of the
            Sublease Premises.

S. WAIVER OF SUBROGATION.

Unless this waiver shall invalidate their insurance policies or make it
impossible to obtain insurance, Sublandlord and Subtenant release each other
from all liability for injury to any person or damage to any property that is
caused by or results in a risk which is actually insured against, or which is
required to be insured against under this Sublease. Each party shall use its
best efforts to cause each insurance policy it obtains to provide that the
insurer there under waives all right of recovery by way of subrogation as
required herein in connection with any injury or damage covered by the policy.
If such insurance policy cannot be obtained with such waiver of subrogation then
the party obtaining such insurance shall immediately notify the other party of
the fact. If such waiver of subrogation is only available at additional cost,
then the party for whose benefit the waiver would be obtained shall pay such
additional cost or waive the benefits of this section. The insurance that the
Subtenant is required to carry under Section 8 of the Master Lease shall name
both Sublandlord and Master Landlord as additional insured thereunder.
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9. TENANT IMPROVEMENTS.

      9.1   Upon mutual agreement between Subtenant and Sublandlord and Master
            Landlord. Subtenant will have the right to hire a contractor and/or
            subcontractors of its choice to complete its tenant work rather than
            use the Sublandlord's and/or Master Landlord's contractor and/or
            subcontractor, subject to Master Landlord's approval.

      9.2   Sublandlord agrees that Subtenant may, following written consent by
            the Sublandlord, which shall not be unreasonably withheld, and
            Master Landlord, in its discretion and at Subtenant's expense, from
            time to time during the term of this Sublease, make alterations and
            additions in and to the Sublease Premises. No such alterations or
            additions may diminish the value of the Sublease Premises. All work
            with respect to any alterations or additions shall be done in a good
            and workmanlike manner, and diligently prosecuted to completion.
            Subtenant shall remove alterations or additions upon termination of
            this Sublease, and shall repair any damage caused by such removal.

10. SECURITY DEPOSIT AND PRE-PAY RENT.

      10.1  Subtenant shall pay a security deposit to Sublandlord equal to
            Sixteen Thousand Three Hundred Eighty Dollars and no/100
            ($16,380.00) upon execution of this Sublease Agreement. Said
            security deposit shall be refunded to Subtenant at the expiration of
            earlier termination of the Sublease term.

      10.2  Subtenant shall pre-pay to Sublandlord the second month's rent which
            is equal to Eight Thousand One Hundred Ninety Dollars and no/1 00
            ($8,190.00) upon execution of this Sublease Agreement.

11. BROKERS.

      11.1  Sublandlord warrants and represents that they have dealt with no
            real estate broker in connection with this Sublease other than CB
            Commercial Real Estate Group, Inc., a California Corporation
            (hereinafter, "CB Commercial").

      11.2  Sublandlord has authorized CB Commercial to be its representative,
            and Subtenant has authorized Randy Scott of Cornish & Carey
            (hereinafter, "Cornish & Carey") to be its representative in this
            real estate transaction.

      11.3  All commissions shall be payable in full upon execution of the
            Sublease by Sublandlord to CB Commercial in accordance with to a
            separate agreement ("Schedule of Sale and Lease Commissions").
            Accordingly, CB Commercial shall split such commissions with Cornish
            & Carey on a 50/50 percentage basis.

      11.4  Broker Disclaimer. Sublandlord and Subtenant agree and accept that,
            except as otherwise expressly stated herein, broker has not made any
            investigation, determination, warranty or representation with
            respect to any of the following: (a) the legality of the present or
            any possible future use of the Sublease Premises under any federal,
            state or local law; (b) the physical condition or square footage of
            the Sublease Premises; (c) the terms of the Master Lease or any
            other relevant legal document or agreement; or (d) the presence or
            location of any hazardous materials on or about the property in
            which the Sublease Premises are located (including, but not limited
            to, asbestos, PCB's, other toxic, hazardous or contaminated
            substances, and underground storage tanks).

12. EARLY ACCESS.

      Prior to the Commencement Date, Subtenant shall be permitted access to the
      Sublease Premises in order to install equipment and furniture, lay
      telephone cable and conduct similar activities. Such access shall be free
      of rent so long as Subtenant does not conducts its business in the
      Sublease Premises prior to the
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      Commencement Date. During this period, Subtenant shall be responsible for
      their own janitorial and utilities. In the event, Subtenant substantially
      conduct its business prior to the Commencement Date of the Sublease, then
      rent shall commerce effectively on that date.

13. HAZARDOUS MATERIALS AND ENVIRONMENTAL MATTERS.

      In addition to Sublandlord's other indemnity obligations hereunder,
      Sublandlord shall indemnify, protect, defend and hold Subtenant harmless
      of and from all liability, judgements, costs, penalties and expenses,
      damages, claims or demands, including reasonable attorney's fees, arising
      from or in any way relating to any release, disposal, storage or use by
      Sublandlord or its employees, contractors or agents, or licensees of any
      chemicals or any toxic or Hazardous Materials in or about the Premises
      (including the Sublease Premises) before, on or after the Commencement
      Date, except to the extent that any of the foregoing results from the
      willful misconduct or negligent acts or omissions of the Subtenant or
      Subtenant's employees or agents. Likewise, Subtenant shall indemnify and
      hold Sublandlord and Master Landlord harmless of and from all liability,
      judgements, costs, penalties and expenses, damages, claims or demands,
      including reasonable attorney's fees, court costs and fees of experts and
      consultants arising from or in any way relating to any release, disposal,
      storage or use by Subtenant or its contractors or agents, or licensees of
      any chemicals or any toxic or hazardous materials in or about the Sublease
      Premises, except to the extent that any of the foregoing results from the
      willful misconduct or negligent acts or omissions of Sublandlord, Master
      Landlord, or any of their agents, employees, contractors or licensees.

      13.1  Subtenant Indemnity: Subtenant shall indemnify, defend and hold
            harmless Sublandlord and Master Landlord from and against all
            claims, suits, judgments, losses, costs, personal injuries, damages,
            and expenses of every type and nature ("Claims"), to the extent
            caused by the storage, use, release or disposal of Hazardous
            Materials on or about the Sublease Premises during the term of this
            Sublease by Subtenant or Subtenant's employees or agents.
            Notwithstanding anything to the contrary in this Sublease, Subtenant
            shall have no obligation to clean up or to comply with any law
            regarding, or to reimburse, indemnify, defend or hold harmless
            Sublandlord with respect to, any Hazardous Materials discovered on
            the Sublease Premises which were not introduced onto the Premises by
            Subtenant or Subtenant's employees or agents.

      13.2  Sublandlord Indemnity: Sublandlord shall indemnify, defend and hold
            harmless Subtenant from and against all claims, suits, judgments,
            losses, costs, personal injuries, damages, and expenses of every
            type and nature ("Claims"), directly or indirectly arising out of or
            in connection with any Hazardous Material present at any time on or
            about the Sublease Premises, or the violation of any environmental
            law relating to any such Hazardous Material except to the extent
            that any such claim resulting from the willful or negligent acts or
            omissions of Subtenant or Subtenant's employees or agents.

      13.3  Sublandlord and Subtenant Indemnity: Sublandlord and Subtenant shall
            indemnify, defend and hold harmless Master Landlord from and against
            all claims, suits, judgments, losses, costs, personal injuries,
            damages and expenses of every type and nature ("claims"), to the
            extent caused by the storage, use, release or disposal of Hazardous
            Materials on or about the Premises during the term of, in the case
            of Sublandlord, the Master Lease and, in the case of Subtenant, the
            term of this Sublease, by Sublandlord and Subtenant, as the case may
            be, or either of their employees or agents. Notwithstanding anything
            to the contrary in this Sublease, neither Sublandlord or Subtenant
            shall have no obligation to clean up or to comply with any law
            regarding or to reimburse, indemnify, defend or hold harmless Master
            Landlord with respect to, any Hazardous Materials discovered on the
            Sublease Premises which were not introduced onto the Sublease
            Premises by Sublandlord or Sublandlord's employees or agents, or by
            Subtenant or Subtenant's employees or agents, respectively.

      13.4  Sublandlord's Representations: To the best knowledge of Sublandlord,
            there are no Hazardous Materials present on or about the Sublease
            Premises and no action, proceeding, or claim is pending
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            or threatened concerning the Sublease Premises or the building
            concerning any Hazardous Material or pursuant to any environmental
            law, and Sublandlord is in full compliance with all environmental
            laws with respect to the Sublease Premises.

      13.5  Definition of Hazardous Materials: As used in this paragraph, the
            term "Hazardous Materials" shall mean any material or substance that
            is now or thereafter prohibited or regulated by any statute, law,
            rule, regulation, or ordinance or that is now or hereafter
            designated by any governmental authority to be radioactive, toxic,
            hazardous or otherwise a danger to health, reproduction or the
            environment.

      13.6  Indemnity Survival: The provisions and obligations of the foregoing
            Paragraphs and other Indemnity provisions shall survive the
            termination of this Sublease.

      13.7  Consent of Hazardous Materials: Storages, use and disposal (in
            compliance with applicable laws) of hazardous materials reasonably
            required for the operation of Subtenant's business, is subject to
            approval by Sublandlord and Master Landlord.

14. INTERPRETATION.

      In the event of any inconsistency between this written Sublease and the
      terms of the Master Lease incorporated herein by reference, the terms of
      this written Sublease shall control as between Sublandlord and Subtenant.

15. QUIET ENJOYMENT.

      Sublandlord covenants that so long as Subtenant keeps and substantially
      performs each and every term, provision and condition herein contained on
      the part of Subtenant to be kept and performed, Subtenant shall peacefully
      and quietly enjoy the Sublease Premises without hindrance or molestation
      by Sublandlord or any other person claiming by, through or under
      Sublandlord.

16. NOTICES.

      All communications, notices and demands of any kind which either party may
      be required or desires to give to or serve upon the other party shall be
      in writing and shall be personally delivered or sent by prepaid, first
      class mail, registered with return receipt requested. Any such notice
      shall be addressed to the parties as follows:

      If to Sublandlord                           If to Subtenant
      Michael Allen                               Aziz Valliani
      President & CEO                             President & CEO
      Metrika Laboratories, Inc.                  PenWare, Inc.
      510 Oakmead Parkway                         510 Oakmead Parkway
      Sunnvyale, CA 94086                         Sunnyvale, CA 94086

17. CONDITION PRECEDENT.

      This Sublease will not take effect unless and until it is approved by the
      Master Landlord. Should the Master Lease terminate for any reason, this
      Sublease shall also terminate simultaneously with Master Lease
      termination. Subtenant shall have no right to holdover.

IN WITNESS WHEREOF, Master Landlord, Sublandlord and Subtenant have signed this
Sublease to evidence their acceptance of and intent to be bound by the terms
hereof as of the Effective Date.
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SUBTENANT:                              SUBLANDLORD:

PenWare, Inc.                           Metrika Laboratories, Inc.
By  :___________________________        By  :___________________________________
     Aziz Valliani                           Michael Allen

Title  :President & CEO                 Title  :President & CEO

Dated  :________________________        Dated  :________________________________

MASTER LANDLORD:

Guizik Investments, L.P.

By     :________________________

Title  :________________________

Dated  :________________________
