<PAGE>

                                 LEASE AGREEMENT

                                     Between

                         STRATUS 7000 WEST JOINT VENTURE

                                  as Landlord,

                                       and

                            SILICON LABORATORIES INC.

                                   as Tenant,

               Covering approximately 34,531 rentable square feet
                    of the Building known (or to be known) as

                        7000 West at Lantana, Building 1

                                   located at

                         7000 West William Cannon Drive

                               Austin, Texas 78735

<PAGE>

                            BASIC LEASE INFORMATION

<TABLE>
<S>                      <C>
Lease Date:              October 27, 1999

Tenant:                  Silicon Laboratories Inc.

Tenant's Address:        4635 Boston Lane
                         ---------------------------
                         Austin Texas 78735
                         ---------------------------

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

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

Contact:                 John McGovern

Telephone:               (512) 416-8500
                         ---------------------------

Landlord:                Stratus 7000 West Joint Venture

Landlord's
Address:                 c/o Stratus Management, L.L.C.
                         98 San Jacinto, Suite 220
                         Austin, Texas 78701

Contact:                 Rick Lindley

Telephone:               478-5788

Premises:                Suite No. ____ containing approximately 34,531 rentable
                         square feet on the second floor of the Building. The
                         Premises are outlined on the plan attached to the Lease
                         as EXHIBIT A-1. The Premises are measured using 1996
                         BOMA useable standards multiplied by the Building
                         Factor of 1.0881.

Building:                7000 West at Lantana Building 1, which contains
                         66,606 of rentable square feet and is located or to be
                         located on the land described on EXHIBIT A attached
                         hereto (the "LAND").

Project:                 7000 West at Lantana, which includes the Building,
                         one (1) other office building known (or if not yet
                         constructed, to be known) as Building 2 and related
                         parking facilities and commons areas, as shown on
                         EXHIBIT A-2 attached hereto.

Development:             All improvements within the Project plus all other
                         improvements owned by Landlord and Landlord's
                         affiliates in an area in the Lantana Corporate Center
                         bounded by William Cannon Drive West on the west,
                         Southwest Parkway on the north, and Vega running on the
                         southern boundary.

Term:                    Seventy-six (76) months, commencing the later of: i)
                         February 1, 2000 or ii) the date upon which the Work
                         improvements set forth in EXHIBIT D have been
                         Substantially Completed (the "Commencement Date") and
                         ending at 5:00 p.m., May 31, 2006, subject to
                         adjustment based on the date of Substantial Completion
                         and earlier termination as provided in the Lease.

Substantial Completion:  The term "Substantially Completed" or "Substantial
                         Completion" shall mean that, in the opinion of the
                         architect and space planner that prepared the Working
                         Drawings, such Work has been substantially completed in
                         accordance with the Working Drawings, the Premises are
                         in good and satisfactory condition, with the exception
                         of completion of minor details of construction,
                         mechanical adjustments or decorations which do not
                         materially interfere with Tenant's use of the Premises
                         that remain to be performed (items normally referred to
                         as "punch list" items), and the City of Austin has
                         issued a certificate of occupancy for the Premises;
                         provided, however, that if and to the extent
                         Substantial Completion would have occurred earlier but
                         for any Tenant Delays (as defined in Exhibit D),
                         Substantial Completion shall be deemed to have occurred
                         on the date it would have occurred but for those Tenant
                         Delays.

                                       i
<PAGE>


Basic Rental:            (i) for month 1-6, $22,301.27 per month, which is based
                         on an Annual Basic Rental of $15.50 per rentable square
                         foot, but only on 17,265.5 square feet (1/2 of the
                         Premises) (i.e., the rent on 1/2 of the Premises is
                         being abated for six months); provided, however, that,
                         during months 1-6, Tenant shall pay Basic Rent to
                         Landlord for any space occupied by Tenant for office
                         use (as contrasted to storage) over and above 17,265.5
                         square feet on a per diem basis at a rate of $15.50 per
                         rentable square foot/year; (ii) for months 7-24,
                         $44,602.54 per month, which is based on an annual Basic
                         Rental of $15.50 per rentable square foot on the full
                         34,531 square feet; (iii) for months 25-48, $47,480.12
                         per month, which is based on an annual Basic Rental of
                         $16.50 per rentable square foot and (iv) for months
                         49-76, $48,918.92 per month, which is based on an
                         annual Basic Rental of $17.00 per rentable square foot.

Security Deposit:        $64,745.62 in cash and the Letter of Credit (as defined
                         in Section 6)

Rent:                    Basic Rental, Tenant's Proportionate Share of Basic
                         Costs and all other sums that Tenant may owe to
                         Landlord under the Lease.

Permitted Use:           General office use including ancillary uses related to
                         general office use, including the operation of vending
                         machines within the Premises for use by Tenant's
                         employees and visitors.

Tenant's
Proportionate
Share:                   51.84%, which is the percentage obtained by dividing
                         (a) the 34,531 rentable square feet in the Premises by
                         (b) the 66,606 rentable square feet in the Building.

Tenant's Estimated
Proportionate Share
of Basic Costs:          Costs of $7.00 per rentable square foot ($20,143.08 per
                         month) beginning on the Commencement Date and on the
                         first day of each calendar month thereafter through
                         December 31, 2000; provided, however, that Tenant's
                         Estimated Proportionate Share of Basic Costs shall be
                         abated as to 17,265.5 square feet out of the total
                         34,531 square feet within the Premises for months 1-6
                         (I.E., the estimated amount of Tenant's Proportionate
                         Share of Basic Costs for months 1-6 of the Lease is
                         $10,071.54 per month). Notwithstanding the foregoing,
                         during months 1-6, Tenant shall pay Tenant's Estimated
                         Proportionate Share of Basic Costs to Landlord for any
                         space occupied by Tenant over and above 17,265.5 square
                         feet on a per diem basis billed monthly in arrears at a
                         rate of $7.00 per rentable square foot/year.
                         Furthermore, the abatements provided for in this
                         paragraph shall apply to utilities, as described in
                         paragraph 4 of Exhibit C attached hereto, so long as
                         the HVAC system, lighting (except basic and emergency
                         lighting) and all office machinery and equipment is
                         operated during the abatement period only in that
                         certain approximately 17,265.5 square feet of the
                         Premises shown on Exhibit A-1 attached hereto as the
                         "Initial Space". If the HVAC system, lighting (except
                         basic and emergency lighting) or any office machinery
                         or equipment is operated in portions of the Premises
                         other than the Initial Space during months 1-6, Tenant
                         shall pay Tenant's Estimated Proportionate Share of the
                         utility portion of Basic Costs to Landlord for all of
                         the Premises on a per diem basis billed monthly in
                         arrears. Beginning on January 1, 2001 and thereafter,
                         the costs shall be paid by Tenant as set forth in
                         Section 4(c) of the Lease.
Initial
Liability
Insurance Amount:        $3,000,000.00

Maximum
Construction
Allowance:               $24.00 per rentable square foot

Building's
Proportionate
Share:                   The percentage obtained by dividing (a) the 66,606
                         rentable square feet contained within Building by (b)
                         the number of completed rentable square feet contained
                         within the Project; provided that Landlord and Tenant
                         acknowledge that the Building's Proportionate Share be
                         adjusted as additional completed rentable square feet
                         are added to or subtracted from the Project. Currently,
                         the Building's Proportionate Share equals 100%.
</TABLE>

                                       ii
<PAGE>

The foregoing Basic Lease Information is incorporated into and made a part of
the Lease identified above. If any conflict exists between any Basic Lease
Information and the Lease, then the Lease shall control.

                       LANDLORD:  STRATUS 7000 WEST JOINT VENTURE
                                  a Texas joint venture

                             By:  OLY LANTANA, L.P., a Texas limited
                                  partnership, Joint Venturer

                                  By:  OLY LANTANA, GP, L.L.C., a Texas limted
                                       liability company, its General Partner

                                       By: /s/ Hal R. Hall
                                          ------------------------------
                                       Name:
                                             ---------------------------
                                       Title:
                                             ---------------------------

                             By:  STRATUS 7000 WEST, LTD., a Texas limited
                                  partnership, Joint Venturer

                                  By:  STRS, L.L.C., a Delaware limited
                                       liability company, its General Partner

                                       By:  STRATUS PROPERTIES INC., a Delaware
                                            limited liability company, its
                                            sole member

                                            By: /s/ William H. Armstrong
                                               ------------------------------
                                                William H. Armstrong, III
                                                President and CEO

                       TENANT: SILICON LABORATORIES INC.


                             By: /s/ Navdeep S. Sooch
                                -----------------------------
                                Navdeep S. Sooch
                                Chairman and CEO


                                       iii
<PAGE>


                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                      Page
                                                                      ----
<S>                                                                    <C>
DEFINITIONS AND BASIC PROVISIONS.......................................  1

LEASE GRANT............................................................  1

TERM...................................................................  1

RENT...................................................................  1
        (a)  Payment...................................................  1
        (b)  Consumer Price Index Increases to Basic Rental............  1
        (c)  Basic Costs...............................................  1
        (d)  Annual Cost Statement.....................................  1
        (e)  Restoration of Services; Abatement........................  2

DELINQUENT PAYMENT; HANDLING CHARGES...................................  2

SECURITY DEPOSIT.......................................................  2

LANDLORD'S OBLIGATIONS.................................................  3
        (a)  Services..................................................  3
        (b)  Excess Utility Use........................................  3
        (c)  Discontinuance............................................  4
        (d)  Adjustments to Basic Costs................................  4

IMPROVEMENTS; ALTERATIONS; REPAIRS; MAINTENANCE........................  4
        (a)  Improvements; Alterations.................................  4
        (b)  Repairs; Maintenance......................................  4
        (c)  Performance of Work.......................................  5
        (d)  Mechanic's Liens..........................................  5

USE....................................................................  5

ASSIGNMENT AND SUBLETTING..............................................  5
        (a)  Transfers; Consent........................................  5
        (b)  Cancellation..............................................  6
        (c)  Additional Compensation...................................  6

INSURANCE; WAIVERS; SUBROGATION; INDEMNITY.............................  6
        (a)  Tenant's Insurance........................................  6
        (b)  Landlord's Insurance......................................  6
        (d)  Waiver of Negligence Claims; No Subrogation...............  7
        (e)  Indemnity.................................................  7

SUBORDINATION ATTORNMENT; NOTICE TO LANDLORD'S MORTGAGEE...............  7
        (a)  Subordination.............................................  7
        (b)  Attornment................................................  7
        (c)  Notice to Landlord's Mortgagee............................  7

RULES AND REGULATIONS..................................................  7

CONDEMNATION...........................................................  7
        (a)  Taking - Landlord's and Tenant's Right....................  7
        (b)  Taking - Landlord's Rights................................  8
        (c)  Award.....................................................  8

FIRE OR OTHER CASUALTY.................................................  8
        (a)  Repair Estimate...........................................  8
        (b)  Landlord's and Tenant's Rights............................  8
        (c)  Landlord's Rights.........................................  8
        (d)  Repair Obligation.........................................  8

TAXES..................................................................  8

EVENTS OF DEFAULT......................................................  8

REMEDIES...............................................................  9

                                       iv
<PAGE>

PAYMENT BY TENANT; NON-WAIVER..........................................  9
        (a)  Payment by Tenant......................................... 10
        (b)  No Waiver................................................. 10

SURRENDER OF PREMISES.................................................. 10

HOLDING OVER........................................................... 10

CERTAIN RIGHTS RESERVED BY LANDLORD.................................... 10

SUBSTITUTION SPACE..................................................... 10

MISCELLANEOUS.......................................................... 11
        (a)  Landlord Transfer......................................... 11
        (b)  Landlord's Liability...................................... 11
        (c)  Force Majeure............................................. 11
        (d)  Brokerage................................................. 11
        (e)  Estoppel Certificates..................................... 11
        (f)  Notices................................................... 11
        (g)  Separability.............................................. 11
        (h)  Amendments; and Binding Effect............................ 11
        (i)  Quiet Enjoyment........................................... 11
        (j)  Joint and Several Liability............................... 11
        (k)  Captions.................................................. 11
        (l)  No Merger................................................. 11
        (m)  No Offer.................................................. 12
        (n)  Exhibits.................................................. 12
        (o)  Entire Agreement.......................................... 12

HAZARDOUS SUBSTANCES................................................... 12

LANDLORD'S LIEN........................................................ 13

SPECIAL PROVISIONS..................................................... 13
</TABLE>

                                       v
<PAGE>

                            LIST OF DEFINED TERMS

<TABLE>
<CAPTION>
                                                             Page
                                                              No.
<S>                                                          <C>
Affiliate...................................................   6
Annual Cost Statement.......................................   1
Basic Cost.................................................. C-1
Basic Lease Information.....................................   1
Building....................................................   i
Casualty....................................................   8
Commencement Date...........................................   i
Construction Allowance...................................... D-2
Damage Notice...............................................   8
Development.................................................   i
Event of Default............................................   8
Initial Liability Insurance Amount..........................   6
Land........................................................   i
Landlord....................................................   1
Landlord's Mortgagee........................................   7
Lease.......................................................   1
Loss........................................................   6
Mortgage....................................................   7
Parking Facilities.......................................... E-1
Primary Lease...............................................   7
Taking......................................................   7
Taxes....................................................... C-1
Tenant......................................................   1
Tenant Delay................................................ D-1
Total Construction Costs.................................... D-1
Transfer....................................................   5
Work........................................................ D-1
Working Drawings............................................ D-1

</TABLE>

                                       vi
<PAGE>


                                      LEASE

THIS LEASE AGREEMENT (this "LEASE") is entered into as of OCTOBER 27 1999,
between Stratus 7000 West Joint Venture,  a Texas joint venture ("LANDLORD"),
and Silicon Laboratories, Inc. (TENANT").

DEFINITIONS
AND BASIC
PROVISIONS

               1.   The definitions and basic provision set forth in the Basic
          Lease Information (the "BASIC LEASE INFORMATION") executed by Landlord
          and Tenant contemporaneously herewith are incorporated herein by
          reference for all purposes.

LEASE
GRANT          2.   Subject to the terms of this Lease, Landlord leases to
          Tenant, and Tenant leases from Landlord, the Premises.

TERM           3.   If the Commencement Date is not the first day of a calendar
          month, then the Term shall be extended by the time between the
          Commencement Date and the first day of the next month. If this Lease
          is executed before the Premises become available and ready for
          occupancy by Tenant, then (a) Tenant's obligation to pay Rent
          hereunder shall be waived until Landlord tenders possession of the
          Premises to Tenant, (b) the Term shall be extended by the time between
          the scheduled Commencement Date and the date on which Landlord tenders
          possession of the Premises to Tenant (which date will then be defined
          as the Commencement Date), (c) Landlord shall not be in default
          hereunder or be liable for damages therefor, and (d) Tenant shall
          accept possession of the Premises when Landlord tenders possession
          thereof to Tenant. By occupying the Premises, Tenant shall be deemed
          to have accepted the Premises in their condition as of the date of
          such occupancy, subject to the performance of punch-list items that
          remain to be performed by Landlord, if any. Tenant shall execute and
          deliver to Landlord, within ten days after Landlord has requested
          same, a letter confirming (1) the Commencement Date, (2) that Tenant
          has accepted the Premises, and (3) that Landlord has performed all of
          its obligations with respect to the Premises (except for punch-list
          items specified in such letter).

RENT           4.   (a)  PAYMENT. Tenant shall timely pay to Landlord the Basic
          Rental and all additional sums to be paid by Tenant to Landlord under
          this Lease, including the amounts set forth in EXHIBIT C, without
          deduction or set off except as otherwise expressly provided in Section
          7(d), at Landlord's Address (or such other address as Landlord may
          from time to time designate in writing to Tenant). Basic Rental,
          adjusted as herein provided, shall be payable monthly in advance. The
          first monthly installment of Basic Rental shall be payable upon the
          Commencement Date of this Lease; thereafter, monthly installments of
          Basic Rental shall be due on the first day of the second full calendar
          month of the Term and continuing on the first day of each succeeding
          calendar month during the Term. Basic Rental for any fractional month
          at the beginning of the Term shall be prorated based on 1/365 of the
          current annual Basic Rental for each day of the partial month this
          Lease is in effect, and shall be due on the Commencement Date.

               (b)  CONSUMER PRICE INDEX INCREASES TO BASIC RENTAL.
          (Intentionally Omitted.)

               (c)  BASIC COSTS. Beginning on January 1, 2001 and thereafter,
          Tenant shall pay to Landlord, on the first day of each calendar month,
          an amount equal to the product of (1) 1/12 of the estimated Basic
          Costs (as described on EXHIBIT C), multiplied by (2) Tenant's
          Proportionate Share. From time to time during any calendar year after
          calendar year 2000, Landlord may in good faith estimate and
          re-estimate the Proportionate Share of Basic Costs to be due by Tenant
          for that calendar year and deliver a copy of the estimate or
          re-estimate to Tenant. Thereafter, the monthly installments of
          estimated Basic Costs payable by Tenant shall be appropriately
          adjusted in accordance with the estimations so that, by the end of the
          calendar year in question, Tenant shall have paid all of its
          Proportionate Share of Basic Costs as estimated in good faith by
          Landlord.

               (d)  ANNUAL COST STATEMENT. By April 1 of each calendar year, or
          as soon thereafter as practicable, Landlord shall furnish to Tenant a
          statement of Landlord's actual Basic Costs (the "ANNUAL COST
          STATEMENT") for the previous year (including calendar year 2000)
          adjusted as provided in Section 4.(e). If the Annual Cost Statement
          reveals that Tenant paid more for Basic Costs than

                                       1
<PAGE>


          Tenant's Proportionate Share of Basic Costs in the year for which such
          statement was prepared, then Landlord shall credit Tenant for such
          excess during the following year; likewise, if Tenant paid less than
          Tenant's Proportionate Share of Basic Costs, then Tenant shall pay
          Landlord such deficiency within 30 days after delivery of the Annual
          Cost Statement in question; provided, however, that in no event shall
          Tenant's Proportionate Share of Basic Costs in any year (commencing
          with calendar year 2001) exceed the immediately preceding year's
          Proportionate Share of Basic Costs by more than six percent (6%) of
          such preceding year's Proportionate Share of Basic Costs, excluding
          Tenant's Proportionate Share of Basic Costs for insurance, taxes and
          utilities (none of which shall be subject to such yearly six percent
          (6%) maximum increase). Notwithstanding the foregoing, it is hereby
          acknowledged that the 6% cap on controllable Basic Costs shall be
          calculated on a cumulative basis (i.e., if the increase in costs in
          any given year is less than 6% then the difference between the actual
          percentage increase and 6% may be carried over to be used in
          subsequent years in which the increase exceeds 6%). Further, the
          parties acknowledge that for purposes of calculating the cap on Basic
          Costs in calendar year 2001, adjustments shall be made (subject to the
          limitations in Section 4(e) below) in order to reflect any abatements
          of the Basic Costs granted to Tenant for calendar year 2000, as
          provided in the Basic Lease Information.

               (e)  ADJUSTMENTS TO BASIC COSTS. With respect to any calendar
          year or partial calendar year in which the Building is not occupied to
          the extent of 95% of the rentable area thereof, the Basic Costs for
          such period shall, for the purposes hereof, be increased to the amount
          which would have been incurred had the Building been occupied to the
          extent of 95% of the rentable area thereof.

               (f)  AUDIT RIGHTS. Tenant and its agents shall have the right,
          upon ten (10) days' written notice, to audit, inspect and copy the
          books and records relating to the Basic Costs during normal business
          hours. If any audit shall accurately reflect a discrepancy between the
          actual Basic Costs and the amount shown on any Annual Cost Statement
          previously furnished Tenant, the parties shall reconcile the
          discrepancy. Tenant shall not be permitted to audit periods earlier
          than the immediately preceding two (2) years.

DELINQUENT
PAYMENT;
HANDLING
CHARGES        5.   All payments required of Tenant hereunder shall bear
          interest from the date due until paid at the maximum lawful rate.
          Alternatively, Landlord may charge Tenant a fee equal to 5% of the
          delinquent payment to reimburse Landlord for its cost and
          inconvenience incurred as a consequence of Tenant's delinquency. In no
          event, however, shall the charges permitted under this Section 5 or
          elsewhere in this Lease, to the extent the same are considered to be
          interest under applicable law, exceed the maximum lawful rate of
          interest. The interest and the 5% fee referenced in this Section 5
          shall begin to accrue and only be payable by Tenant on the tenth
          (10th) day following written notice from Landlord notifying Tenant of
          Tenant's delinquency; provided, however, that in the event Landlord
          gives to Tenant notice of Tenant's delinquency two (2) times in any
          calendar year, the interest and the 5% fee referenced in this Section
          5 shall begin to accrue and be payable by Tenant immediately (without
          notice) upon Tenant's third (3rd) delinquency (and any subsequent
          delinquencies) in such calendar year.

SECURITY
DEPOSIT        6.   Contemporaneously with the execution of this Lease, Tenant
          shall pay to Landlord, in immediately available funds, the Security
          Deposit, which shall be held by Landlord without liability for
          interest and as security for the performance by Tenant of its
          obligations under this Lease. The Security Deposit is not an advance
          payment of Rent or a measure or limit of Landlord's damages upon an
          Event of Default (defined below). Landlord may, from time to time and
          without prejudice to any other remedy, use all or a part of the
          Security Deposit upon and after an Event of Default to perform any
          obligation which Tenant was obligated, but failed, to perform
          hereunder. Following any such application of the Security Deposit,
          Tenant shall pay to Landlord on demand the amount so applied in order
          to restore the Security Deposit to its original amount. Within a
          reasonable time after the Term ends, provided Tenant has performed all
          of its obligations hereunder, Landlord shall return to Tenant the
          balance of the Security Deposit not applied to satisfy Tenant's
          obligations. If Landlord transfers its interest in the Premises, then
          Landlord shall assign the Security Deposit to the transferee and
          Landlord thereafter shall have no further liability for the return of
          the Security Deposit.

          In addition to the cash Security Deposit above, Tenant shall deposit
          with Landlord on or before the thirtieth (30th) day after the date
          hereof, either additional cash or irrevocable stand-by letter(s) of
          credit in the amount of $500,000.00 (whether one or more, the "LETTER
          OF CREDIT"), which shall be held and/or applied by Landlord in
          accordance with this Section 6; however, the Letter of Credit is not
          an advance rental deposit or a measure of Landlord's damages for an
          Event of Default (defined below). The Letter of Credit shall be

                                       2
<PAGE>

          issued by a bank reasonably acceptable to Landlord and shall otherwise
          be in such form and contain such terms as are reasonably acceptable to
          Landlord. The Letter of Credit will be structured as successive one-
          year obligations for the entire term with rights to draw on the Letter
          of Credit of a substitute letter of credit of the proper amount is not
          in place within twenty (20) business days before expiration of the
          Letter of Credit. Landlord hereby approves Imperial Bank as the
          acceptable provider of the Letter of Credit in such form and terms set
          forth in EXHIBIT I "Letter of Credit Pro Form Wording." The amount of
          the Letter of Credit shall be decreased by 16.67% on each anniversary
          of the Commencement Date, so long as no Event of Default exists. Upon
          an Event of Default, Landlord may, in addition to all other rights and
          remedies afforded Landlord hereunder or by law, cash the Letter of
          Credit (as the same may have been reduced) and notify Tenant of such
          action and use and hold the same as a cash security deposit, which
          shall include the right to use any portion thereof to satisfy Tenant's
          unperformed obligations hereunder, without prejudice to any of
          Landlord's other remedies. If so used, Tenant shall pay Landlord an
          amount that will restore the Letter of Credit to its then amortized
          balance upon request. The Letter of Credit will be returned to Tenant
          within 30 days after the end of the Term, provided that Tenant has
          fully and timely performed its obligations hereunder throughout the
          Term. If Landlord sells its interest in the Building, the Letter of
          Credit shall be transferred to such purchaser, and Tenant hereby
          agrees to cooperate in effectuating any such transfer. Notwithstanding
          the foregoing, the Letter of Credit shall be returned to Tenant, so
          long as no Event of Default exists, if either of the following shall
          occur: (1) if Tenant is a privately owned company, an audited
          financial statement is provided to Landlord showing twelve (12)
          consecutive months' aggregate revenues in excess of $80,000,000.00 and
          an aggregate net operating income in excess of $8,000,000.00 for such
          12 consecutive months; or (2) if Tenant is a publicly owned company,
          Securities and Exchange Commission filings containing financial
          statements are provided to Landlord showing four quarters' aggregate
          revenues in excess of $80,000,000.00 and a net operating income in
          excess of $8,000,000.00 (such period may include unaudited quarterly
          periods provided that they are filed with the Securities and Exchange
          Commission).

LANDLORD'S
OBLIGATIONS

               7.   (a)  SERVICES. Provided no Event of Default exists, Landlord
          shall furnish to Tenant (1) water (hot and cold) at those points of
          supply provided for general use of tenants of the Building; (2) heated
          and refrigerated air conditioning as appropriate, during normal
          business hours, and at such temperatures and in such amounts as are
          reasonably considered by Landlord to be standard; (3) janitorial
          service, in compliance with Tenant's confidential and proprietary
          procedures, to the Premises on weekdays other than holidays for
          Building-standard installations (Landlord reserves the right to bill
          Tenant separately for extra janitorial service required for
          non-standard installations) and such window washing as may from time
          to time in Landlord's judgment be reasonably required; provided,
          however, that Landlord, at its option, may decide to cease providing
          janitorial service to the Premises, in which event Tenant will be
          responsible for providing its own janitorial service and Tenant's
          Proportionate share of Basic Costs shall be equitably reduced to
          reflect the same; (4) elevators for ingress and egress to the floor on
          which the Premises are located, in common with other tenants, provided
          that Landlord may reasonably limit the number of elevators to be in
          operation at times other than during customary business hours and on
          holidays; (5) replacement of Building-standard light bulbs and
          fluorescent tubes; and (6) electrical current during normal business
          hours at a power capacity of 4 watts per rentable space foot for
          lighting and outlets ("Normal Usage"). Landlord shall maintain the
          common areas of the Building in reasonably good order and condition,
          except for damage occasioned by Tenant, or its employees, agents or
          invitees. If Tenant desires any of the services specified in this
          Section 7.(a) at any time other than times herein designated, such
          services shall be supplied to Tenant upon the written request of
          Tenant delivered to Landlord before 3:00 p.m. on the business day
          preceding such extra usage (except for heated and refrigerated air
          conditioning, which shall be immediately available to Tenant through
          use of an automated "on-demand" system to be installed by Landlord or,
          in the event such automated "on-demand" system is not available due to
          system failure, immediately provided by Landlord upon verbal request
          from Tenant, so long as such request is made during normal business
          hours), and Tenant shall pay to Landlord the cost of such services,
          which shall be provided at the same rate charged other tenants in the
          Building, within ten days after Landlord has delivered to Tenant an
          invoice therefor. As used herein, the term "normal business hours"
          shall mean from 7:00 a.m. to 7:00 p.m. Monday through Friday and from
          8:00 a.m. to 1:00 p.m. on Saturdays, except for legal holidays. Based
          on a letter from Southwestern Bell, Landlord has confirmed fiber
          optics are to be provided to a point adjacent to the outside of the
          Building or at the telecommunications building at the northwest corner
          of Rialto and William Cannon. The provider of such fiber optics shall
          be Southwestern Bell. Tenant, if it so desires at Tenant's cost, shall
          be responsible and Landlord grants all consents for obtaining fiber
          optics telecommunications service to the Premises from a point
          adjacent to the outside of the building or the telecommunication
          building (without additional rent for using risers or feeder space or
          otherwise); provided that in doing so Tenant shall not adversely
          affect the Building or Building systems or interfere with other
          tenants or building operations; and provided further that, Landlord
          has or will designate the Building as a multi-tenant building with
          Southwestern Bell, thereby making the Premises the point of
          demarcation for Tenant's fiber optics service.

               (b)  EXCESS UTILITY USE. Landlord shall use reasonable efforts
          to furnish electrical current for special lighting, computers and
          other equipment whose electrical energy consumption exceeds Normal
          Usage through the then-existing feeders and risers serving the
          Building and the Premises (not to exceed, however, 6.5 watts per
          rentable square foot), and Tenant shall pay to Landlord the cost of
          such service within ten days after Landlord has delivered to Tenant an
          invoice therefor. Landlord may determine the amount of such additional

                                       3
<PAGE>

          consumption and potential consumption by either or both: (1) a survey
          of standard or average tenant usage of electricity in the Building
          performed by a reputable consultant selected by Landlord and paid for
          by Tenant; or (2) a separate meter in the Premises installed,
          maintained, and read by Landlord, at Tenant's expense. Tenant shall
          not install any electrical equipment requiring special wiring or
          requiring electrical current in excess of Normal Usage unless approved
          in advance by Landlord. The use of electricity in the Premises shall
          not exceed the capacity of existing feeders and risers to or wiring in
          the Premises. Any risers or wiring required to meet Tenant's excess
          electrical requirements shall, upon Tenant's written request, be
          installed by Landlord, at Tenant's cost, if, in Landlord's sole and
          absolute judgment, the same are necessary and shall not cause
          permanent damage or injury to the Building or the Premises, cause or
          create a dangerous or hazardous condition, entail excessive or
          unreasonable alterations, repairs, or expenses, or interfere with or
          disturb other tenants of the Building. If Tenant uses machines or
          equipment (other than general office machines, personal computers and
          electronic data processing equipment) in the Premises which affect the
          temperature otherwise maintained by the air conditioning system or
          otherwise overload any utility, Landlord may install supplemental air
          conditioning units or other supplemental equipment in the Premises,
          and the cost thereof, including the cost of installation, operation,
          use, and maintenance, shall be paid by Tenant to Landlord within ten
          days after Landlord has delivered to Tenant an invoice therefor.

               (c)  DISCONTINUANCE. Landlord's obligation to furnish services
          under Section 7.(a) shall be subject to the rules and regulations of
          the supplier of such services and governmental rules and regulations.
          Landlord may, upon not less than 30-days' prior written notice to
          Tenant, discontinue any such service to the Premises, provided
          Landlord first arranges for a fully functioning, equivalent capacity
          direct connection thereof through the supplier of such service. Tenant
          shall, however, be responsible for contracting with the supplier of
          such service and for paying all deposits for, and costs relating to,
          such service.

               (d)  RESTORATION OF SERVICES; ABATEMENT. Landlord shall use
          reasonable efforts to restore any service that becomes unavailable;
          however, such unavailability shall (i) not render Landlord liable for
          any damages caused thereby, (ii) be a constructive eviction of Tenant,
          (iii) constitute a breach of any implied warranty, or, except as
          provided in the next sentence, or (iv) entitle Tenant to any abatement
          of Tenant's obligations hereunder. However, if Tenant is prevented
          from making reasonable use of the Premises for more than 15
          consecutive days (or 5 consecutive days if the reason for such
          unavailability is within the reasonable control of Landlord) because
          of the unavailability of any such service, Tenant shall, as its
          exclusive remedy therefor, be entitled to a reasonable abatement of
          Rent for each consecutive day (after such 15-day or 5-day period, as
          applicable) that Tenant is so prevented from making reasonable use of
          the Premises. Notwithstanding the foregoing, Tenant has the right to
          terminate the Lease effective sixty (60) days after Tenant notifies
          Landlord in writing of a material utility service (not including fiber
          optics) discontinuance, unless such utility service is restored within
          such 60-day period.

               8.   (a)  IMPROVEMENTS: ALTERATIONS. Improvements to the Premises
          shall be installed at the expense of Tenant only in accordance with
          plans and specifications which have been previously submitted to and
          approved in writing by Landlord. After the initial Tenant improvements
          are made, no alterations or physical additions in or to the Premises
          may be made without Landlord's prior written consent. Tenant shall not
          paint or install lighting or decorations, signs, window or door
          lettering, or advertising media of any type on or about the Premises
          without the prior written consent of Landlord. All alterations,
          additions, or improvements (whether temporary or permanent in
          character, and including without limitation all air-conditioning
          equipment and all other equipment that is in any manner connected to
          the Building's plumbing system) made in or upon the Premises, either
          by Landlord or Tenant, shall be Landlord's property at the end of the
          Term and shall remain on the premises without compensation to Tenant.
          Approval by Landlord of any of Tenant's drawings and plans and
          specifications prepared in connection with any improvements in the
          Premises shall not constitute a representation or warranty of Landlord
          as to the adequacy or sufficiency of such drawings, plans and
          specifications, or the improvements to which they relate, for any use,
          purpose, or condition, but such approval shall merely be the consent
          of Landlord as required hereunder. Notwithstanding anything in this
          Lease to the contrary, Tenant shall be responsible for the cost of all
          work within the Premises required to comply with the retrofit
          requirements of the Americans with Disabilities Act of 1990, and all
          rules, regulations, and guidelines promulgated thereunder, as the same
          may be amended from time to time (the "ADA"), necessitated by any
          installations, additions, or alterations made in or to the Premises at
          the request of or by Tenant or by Tenant's use of the Premises (other
          than retrofit work whose cost has been particularly identified as
          being payable by Landlord in an instrument signed by Landlord and
          Tenant), and Landlord shall be responsible for the cost of all work
          required to comply with the ADA in connection with other areas of the
          Building. Notwithstanding the foregoing, all moveable partitions,
          cubical furniture and de-mountable wall systems are to be considered
          personal property of the Tenant (similar to furniture) and may be
          erected, moved, re-configured and removed, including minor electrical
          connections, without consent from Landlord provided that the Building
          is returned to its original or otherwise satisfactory condition after
          such removal.

               (b). REPAIRS; MAINTENANCE. Tenant shall maintain the Premises in
          a clean, safe, operable, attractive condition, and shall not permit or
          allow to remain any waste or damage to any portion of the Premises.
          Tenant shall repair or replace, subject to Landlord's direction and
          supervision any damage to the Building caused by Tenant or Tenant's
          agents, contractors, or invitees. If Tenant fails to make such repairs
          or replacements within 15 days after the occurrence of such damage,
          then Landlord may make the same at Tenant's cost. In lieu of having
          Tenant repair any such damage outside of the Premises, Landlord may
          repair

                                       4
<PAGE>

          such damage at Tenant's cost. The cost of any repair or replacement
          work performed by Landlord under this Section 8 shall be paid by
          Tenant to Landlord within ten days after Landlord has delivered to
          Tenant an invoice therefor.

               (c). PERFORMANCE OF WORK. All work described in this Section 8
          shall be performed only by Landlord or by contractors and
          subcontractors approved in writing by Landlord. Tenant shall cause all
          contractors and subcontractors to procure and maintain insurance
          coverage against risks, in such amounts, and with such companies as
          Landlord may reasonably require, and to procure payment and
          performance bonds reasonably satisfactory to Landlord covering the
          cost of the work. All such work shall be performed in accordance with
          all legal requirements and in a good and workmanlike manner so as not
          to damage the Premises, the primary structure or structural qualities
          of the Building, or plumbing, electrical lines, or other utility
          transmission facility. All such work which may affect the HVAC,
          electrical system, or plumbing must be approved by the Building's
          engineer of record.

               (d). MECHANIC'S LIENS. Tenant shall not permit any mechanic's
          liens to be filed against the Premises or the Building for any work
          performed, materials furnished or obligation incurred by or at the
          request of Tenant. If such a lien is filed, then Tenant shall, within
          ten days after Landlord has delivered notice of the filing to Tenant,
          either pay the amount of the lien or diligently contest such lien and
          deliver to Landlord a bond or other security reasonably satisfactory
          to Landlord. If Tenant fails to timely take either such action, then
          Landlord may pay the lien claim without inquiry as to the validity
          thereof, and any amounts so paid, including expenses and interest,
          shall be paid by Tenant to Landlord within ten days after Landlord has
          delivered to Tenant an invoice therefor.

USE            9.   Tenant shall occupy and use the Premises only for the
          Permitted Use and shall comply with all laws, orders, rules, and
          regulations relating to the use, condition, and occupancy of the
          Premises. The Premises shall not be used for any use which is
          disreputable or creates extraordinary fire hazards or results in an
          increased rate of insurance on the Building or its contents or the
          storage of any hazardous materials or substances. If, because of
          Tenant's acts, the rate of insurance on the Building or its contents
          increases, Tenant shall pay to Landlord the amount of such increase on
          demand, and acceptance of such payment shall not constitute a waiver
          of any of Landlord's other rights. Tenant shall conduct its business
          and control its agents, employees, and invitees in such a manner as
          not to create any nuisance or interfere with other tenants or Landlord
          in its management of the Building.

ASSIGNMENT
AND
SUBLETTING     10.  (a)  TRANSFERS; CONSENT. Tenant shall not, without the prior
          written consent of Landlord (which shall not be unreasonably withheld,
          conditioned or delayed), (1) assign, transfer, or encumber this Lease
          or any estate or interest herein, whether directly or by operation of
          law, (2) permit any other entity to become Tenant hereunder by merger,
          consolidation, or other reorganization, (3) if Tenant is an entity
          other than a corporation whose stock is publicly traded, permit the
          transfer of an ownership interest in Tenant so as to result in a
          change in the current control of Tenant, (4) sublet any portion of the
          Premises, (5) grant any license, concession, or other right of
          occupancy of any portion of the Premises, or (6) permit the use of the
          Premises by any parties other than Tenant (any of the events listed in
          Sections 10.(a)(1) through 10.(a)(6) being a "TRANSFER"). If Tenant
          requests Landlord's consent to a Transfer, then Tenant shall provide
          Landlord with a written description of all terms and conditions of the
          proposed Transfer, copies of the proposed documentation, and the
          following information about the proposed transferee: name and address;
          reasonably satisfactory information about its business and business
          history; its proposed use of the Premises; banking, financial, and
          other credit information; and general references sufficient to enable
          landlord to determine the proposed transferee's creditworthiness and
          character. Tenant shall reimburse Landlord for its reasonable
          attorneys' fees and other expenses incurred in connection with
          considering any request for its consent to a Transfer. If Landlord
          consents to a proposed Transfer, then the proposed transferee shall
          deliver to Landlord a written agreement whereby it expressly assumes
          the Tenant's obligations hereunder; however, any transferee of less
          than all of the space in the Premises shall be liable only for
          obligations under this Lease that are properly allocable to the space
          subject to the Transfer, and only to the extent of the rent it has
          agreed to pay Tenant therefor. Landlord's consent to a Transfer shall
          not release Tenant from performing its obligations under this Lease,
          but rather Tenant and its transferee shall be jointly and severally
          liable therefor. Landlord's consent to any Transfer shall not waive
          Landlord's rights as to any subsequent Transfers. If an Event of
          Default occurs while the Premises or any part thereof are subject to a
          Transfer, then Landlord, in addition to its other remedies, may
          collect directly from such transferee all rents becoming due to Tenant
          and apply such rents against Rent. Tenant authorizes its transferees
          to make payments of rent directly to Landlord upon receipt of notice
          from Landlord to do so provided such notice states that an Event of
          Default has occurred and is continuing. Notwithstanding the foregoing,
          Tenant may assign the Lease or sublease all or any portion of the
          Premises without Landlord's consent to any of the following (a
          "Permitted Transferee"), provided that the Permitted Transferee's
          financial condition, creditworthiness and business reputation
          following the transfer are equal to or exceed those of Tenant: (i) any
          successor corporation or other entity resulting from a merger or
          consolidation of Tenant; (ii) any purchaser of all or substantially
          all of Tenant's assets; or (iii) any entity which controls, is
          controlled by, or is under common control with Tenant; provided
          further, however, that a Permitted Transferee shall also include a
          sublessee that is an entity in which Tenant owns or controls greater
          than fifty percent (50%) of the ownership interests [or the right to
          vote such

                                       5
<PAGE>


          ownership interest] and is in the same or similar business as Tenant
          without regard to such sublessee's financial condition or
          creditworthiness. Tenant shall give Landlord thirty (30) days prior
          written notice of such assignment or sublease. Any Permitted
          Transferee (other than a sublessee) shall assume in writing all of
          Tenant's obligations under this Lease. Tenant shall nevertheless at
          all times remain fully responsible and liable for the payment of rent
          and the performance and observance of all of Tenant's other
          obligations under this Lease. Nothing in this paragraph is intended to
          nor shall permit Tenant to transfer its interest under this Lease as
          part of a fraud or subterfuge to intentionally avoid its obligations
          under this Lease (for example, transferring its interest to a shell
          corporation that subsequently files a bankruptcy), and any such
          transfer shall constitute a Default hereunder.

               (b)  CANCELLATION. Landlord may, within ten (10) days after
          submission of Tenant's written request for Landlord's consent to a
          Transfer (except to a Permitted Transfer), cancel this Lease (or, as
          to a subletting or assignment, cancel as to the portion of the
          Premises proposed to be sublet or assigned) as of the date the
          proposed Transfer was to be effective. Notwithstanding the foregoing,
          Landlord shall not have a cancellation right with respect to a
          sublease that covers less than fifty percent (50%) of the Premises
          and is for less than three (3) years. If Landlord cancels this Lease
          as to any portion of the Premises, then this Lease shall cease for
          such portion of the Premises and Tenant shall pay to Landlord all
          Rent accrued through the cancellation date relating to the portion
          of the Premises covered by the proposed Transfer. Thereafter,
          Landlord may lease such portion of the Premises to the prospective
          transferee (or to any other person) without liability to Tenant.

               (c) ADDITIONAL COMPENSATION. Tenant shall pay to Landlord,
          immediately upon receipt thereof, one-half (1/2) of all compensation
          received by Tenant for a Transfer that exceeds the sum of the Basic
          Rental and Tenant's share of Basic Costs allocable to the portion of
          the Premises covered thereby; provided, however, that Tenant shall be
          allowed to recoup its reasonable out of pocket expenses incurred in
          such Transfer (attorney's fees, brokerage commissions and costs of
          retrofitting the Premises) from such excess compensation before paying
          one-half (1/2) of such excess compensation to Landlord.
          Notwithstanding the foregoing, Tenant shall not be required to pay to
          Landlord additional compensation received by Tenant for a Transfer if
          (i) such Transfer is to a Permitted Transferee or (ii) such additional
          compensation is in the form of non-monetary compensation such as
          assignment of intellectual properties or warrants for shares of stock.

INSURANCE;
WAIVERS;
SUBROGATION;
INDEMNITY      11.  (a)  TENANT'S INSURANCE. Tenant shall at its expense procure
          and maintain throughout the Term the following insurance policies: (1)
          comprehensive general liability insurance in amounts of not less than
          a combined single limit of $3,000,000 (the "INITIAL LIABILITY
          INSURANCE AMOUNT") or such other amounts as Landlord may from time to
          time reasonably require, insuring Tenant, Landlord, Landlord's agents
          and their respective affiliates against all liability for injury to or
          death of a person or persons or damage to property arising from the
          use and occupancy of the Premises by Tenant, (2) contractual liability
          insurance coverage sufficient to cover Tenant's indemnity obligations
          hereunder, (3) insurance covering the full value of Tenant's property
          and improvements, and other property (including property of others),
          in the Premises, (4) workman's compensation insurance, containing a
          waiver of subrogation endorsement reasonably acceptable to Landlord,
          and (5) business interruption insurance. Tenant's insurance shall
          provide primary coverage to Landlord when any policy issued to
          Landlord provides duplicate or similar coverage, and in such
          circumstance Landlord's policy will be excess over Tenant's policy.
          Tenant shall furnish certificates of such insurance and such other
          evidence satisfactory to Landlord of the maintenance of all insurance
          coverages required hereunder, and Tenant shall obtain a written
          obligation on the part of each insurance company to notify Landlord at
          least 30 days before cancellation or a material change of any such
          insurance. All such insurance policies shall be in form, and issued by
          companies, reasonably satisfactory to Landlord, The term "AFFILIATE "
          shall mean any person or entity which, directly or indirectly,
          controls, is controlled by, or is under common control with the party
          in question.

               (b)  LANDLORD'S INSURANCE. Landlord shall, during the term,
          maintain in full force the following insurance: (i) commercial general
          liability insurance insuring against any liability due to injury or
          death to any person or loss of or damage to property arising out of
          the operations of Landlord at the Building and/or arising out of the
          common areas, with coverage limits at least three million dollars
          ($3,000,000.00) per occurrence (which coverage may be through blanket
          or umbrella policies), and (ii) All-Risk Property insurance, issued by
          one or more insurance carriers covering the Building to the extent of
          its full replacement value (exclusive of improvements above building
          standard and foundation and excavation costs and other uninsurable
          parts).

               (c)  WAIVER OF NEGLIGENCE CLAIMS; NO SUBROGATION. Landlord shall
          not be liable to Tenant or those claiming by, through, or under Tenant
          for any injury to or death of any person or persons or the damage to
          or theft, destruction, loss, or loss of use of any property or
          inconvenience (a "LOSS") caused by casualty, theft, fire, third
          parties, or any other matter (including Losses arising through repair
          or alteration of any part of the Building, or failure to make repairs,
          or from any other cause), REGARDLESS OF WHETHER THE NEGLIGENCE OF ANY
          PARTY CAUSED SUCH LOSS IN WHOLE OR IN PART EXCEPT FOR GROSS NEGLIGENCE
          OR WILLFUL MISCONDUCT OF LANDLORD OR ITS AGENTS. Landlord and Tenant
          each waives any claim it might have against the other for any

                                       6
<PAGE>

          damage to or theft, destruction, loss, or loss of use of any property,
          to the extent the same is insured against under any insurance policy
          that covers the Building, the Premises, Landlord's or Tenant's
          fixtures, personal property, leasehold improvements, or business, or,
          in the case of Tenant's waiver, is required to be insured against
          under the terms hereof, REGARDLESS OF WHETHER THE NEGLIGENCE OR FAULT
          OF THE OTHER PARTY CAUSED SUCH LOSS; HOWEVER, LANDLORD'S WAIVER SHALL
          NOT INCLUDE ANY DEDUCTIBLE AMOUNTS ON INSURANCE POLICIES CARRIED BY
          LANDLORD OR APPLY TO ANY COINSURANCE PENALTY WHICH LANDLORD MIGHT
          SUSTAIN. Each party shall cause its insurance carrier to endorse all
          applicable policies waiving the carrier's rights of recovery under
          subrogation or otherwise against the other party.

               (d)  INDEMNITY. Subject to Section 11.(b), Tenant shall defend,
          indemnify, and hold harmless Landlord and its agents from and against
          all claims, demands, liabilities, causes of action, suits, judgments,
          and expenses (including reasonable attorneys' fees) for any Loss
          arising from any occurrence on the Premises or from Tenant's failure
          to perform its obligations under this Lease (other than a Loss arising
          from the sole or gross negligence or willful acts of Landlord or its
          agents), even though caused or alleged to be caused by the joint,
          comparative, or concurrent negligence or fault of Landlord or its
          agents. THIS INDEMNITY PROVISION IS INTENDED TO INDEMNIFY LANDLORD AND
          ITS AGENTS AGAINST THE CONSEQUENCES OF THEIR OWN NEGLIGENCE OR FAULT
          AS PROVIDED ABOVE WHEN LANDLORD OR ITS AGENTS ARE JOINTLY,
          COMPARATIVELY, OR CONCURRENTLY NEGLIGENT WITH TENANT. This indemnity
          provision shall survive termination or expiration of this Lease.

SUBORDINATION
ATTORNMENT;
NOTICE TO
LANDLORD'S
MORTGAGEE

               12.  (a)  SUBORDINATION. This Lease is subordinate to any deed
          of trust, mortgage, or other security instrument (a "MORTGAGE"),
          or any ground lease, master lease, or primary lease (a "PRIMARY
          LEASE"), that now or hereafter covers all or any part of the
          Premises (the mortgagee under any Mortgage or the lessor under any
          Primary Lease is referred to herein as "LANDLORD'S MORTGAGEE"). The
          provisions of this Section 12(a) shall be self-operative, and no
          further instrument shall be required to effect such subordination;
          however, Landlord shall deliver to Tenant, and Tenant shall execute
          from time to time within ten days after delivery to Tenant, an
          instrument from each Landlord's Mortgagee evidencing the
          subordination of this Lease to any such Mortgage or Primary Lease
          (which instrument shall include a non-disturbance provision in
          favor of Tenant and shall be on Landlord's Mortgagee's standard
          form). Notwithstanding the foregoing, Landlord, Tenant and
          Landlord's Mortgagee shall execute and deliver a Subordination,
          Non-disturbance and Attornment Agreement in the form attached as
          Exhibit "H" hereto within ten (10) days after the date hereof.

               (b)  ATTORNMENT. Tenant shall attorn to any party succeeding to
          Landlord's interest in the Premises, whether by purchase, foreclosure,
          deed in lieu of foreclosure, power of sale, termination of lease, or
          otherwise, upon such party's request, and shall execute such
          agreements confirming such attornment as such party may reasonably
          request.

               (c)  NOTICE TO LANDLORD'S MORTGAGEE. Tenant shall not seek to
          enforce any remedy it may have for any default on the part of the
          Landlord without first giving written notice by certified mail, return
          receipt requested, specifying the default in reasonable detail, to any
          Landlord's Mortgagee whose address has been given to Tenant, and
          affording such Landlord's Mortgagee the same opportunity as given to
          Landlord to perform Landlord's obligations hereunder, except as
          otherwise may be provided in any applicable subordination,
          non-disturbance and attornment agreement executed by Landlord, Tenant
          and Landlord's Mortgagee.

RULES
AND
REGULATIONS

               13.  Tenant shall comply with the rules and regulations of the
          Building which are attached hereto as EXHIBIT B. Landlord may, from
          time to time, change such rules and regulations for the safety, care,
          or cleanliness of the Building and related facilities, provided that
          such changes are reasonable, applicable to all tenants of the Building
          evenly enforced and will not unreasonably interfere with Tenant's use
          of the Premises. Tenant shall be responsible for the compliance with
          such rules and regulations by its employees, agents, and invitees.

CONDEMNATION

               14.  (a)  TAKING - LANDLORD'S AND TENANT'S RIGHTS. If any part of
          the Building is taken by right of eminent domain or conveyed in lieu
          thereof (a "TAKING"), and such Taking prevents Tenant from conducting
          its business in the Premises in a manner reasonably comparable to that
          conducted immediately before such Taking, then Landlord may, at its
          expense, relocate Tenant to office space reasonably comparable to the
          Premises within five miles of Premises, provided that Landlord
          notifies Tenant of its intention to do so prior to the effective date
          of the Taking. Such relocation may be for a portion of the remaining
          Term or the entire Term. Landlord shall complete any such relocation
          within 180 days after Landlord has notified Tenant of its intention to
          relocate Tenant. If Landlord does not elect to relocate Tenant
          following such Taking, then Tenant may terminate this Lease as of the
          date of such Taking by giving written notice to Landlord within

                                       7
<PAGE>


          60 days after the Taking, and Rent shall be apportioned as of the date
          of such Taking. If Landlord does not relocate Tenant and Tenant does
          not terminate this Lease, then Rent shall be adjusted on a reasonable
          basis as to that portion of the Premises rendered untenantable by the
          Taking. Correspondingly, the Letter of Credit obligation will be
          adjusted on a reasonable basis in the event of partial Taking or
          eliminated entirely in the event of Lease termination.

               (b)  TAKING - LANDLORD'S RIGHTS. If any material portion, but
          less than all, of the Building becomes subject to a Taking, or if
          Landlord is required to pay any of the proceeds received for a Taking
          to Landlord's Mortgagee, then this Lease, at the option of Landlord,
          exercised by written notice to Tenant within 30 days after such
          Taking, shall terminate and Rent shall be apportioned as of the date
          of such Taking. If Landlord does not so terminate this Lease and does
          not elect to relocate Tenant, then, subject to Tenant's rights under
          14(a), this Lease will continue, but if any portion of the Premises
          has been taken, Basic Rental shall adjust as provided in the last
          sentence of Section 14.(a).

               (c) AWARD. If any Taking occurs, then Landlord shall receive the
          entire award or other compensation for the Land, the Building, and
          other improvements taken, and Tenant may separately pursue a claim
          against the condemner for the value of Tenant's personal property
          which Tenant is entitled to remove under this Lease, moving costs,
          loss of business, and other claims it may have.

FIRE OR
OTHER
CASUALTY       15.  (a)  REPAIR ESTIMATE. If the Premises or the Building are
          damaged by fire or other casualty (a "CASUALTY"), Landlord shall,
          within 60 days after such Casualty, deliver to Tenant a good faith
          estimate (the "DAMAGE NOTICE") of the time needed to repair the damage
          caused by such Casualty.

               (b)  LANDLORD'S AND TENANT'S RIGHTS. If a material portion of the
          Premises or the Building is damaged by Casualty such that Tenant is
          prevented from conducting its business in the Premises in a manner
          reasonably comparable to that conducted immediately before such
          Casualty and Landlord estimates in good faith that the damage caused
          thereby cannot be repaired within 270 days after the date of casualty,
          then Tenant may terminate this Lease by delivering written notice to
          Landlord of its election to terminate within 30 days after the Damage
          Notice has been delivered to Tenant. If Tenant does not terminate this
          Lease, then (subject to Landlord's rights under Section 15.(c))
          Landlord shall repair the Building or the Premises, as the case may
          be, as provided below, and Rent for the portion of the Premises
          rendered untenantable by the damage shall be adjusted on a reasonable
          basis from the date of damage until the completion of the repair.

               (c)  LANDLORD'S RIGHTS. If a Casualty damages a material portion
          of the Building, and Landlord makes a good faith determination that
          restoring the Premises would be uneconomical, or if Landlord is
          required to pay any insurance proceeds arising out of the Casualty to
          Landlord's Mortgagee (such that Landlord would be required to pay
          $100,000.00 or more of its own funds to restore the Building), then
          Landlord may, terminate this Lease by giving written notice of its
          election to terminate within 30 days after the Damage Notice has been
          delivered to Tenant, and Basic Rental hereunder shall be abated as of
          the date of the Casualty.

               (d)  REPAIR OBLIGATION. If neither party elects to
          terminate this Lease following a Casualty, then Landlord shall, within
          a reasonable time after such Casualty, commence to repair the Building
          and the Premises and shall proceed with reasonable diligence to
          restore the Building and Premises to substantially the same condition
          as they existed immediately before such Casualty; however, Landlord
          shall not be required to repair or replace any part of the furniture,
          equipment, fixtures, and other improvements which may have been placed
          by, or at the request of, Tenant or other occupants in the Building or
          the Premises, except for initial improvements pursuant to Exhibit D,
          and Landlord's obligation to repair or restore the Building or
          Premises shall be limited to the extent of the insurance proceeds
          actually received by Landlord for the Casualty in question. If
          Landlord fails to substantially complete the rebuilding and repair of
          the Premises within one (1) year after the date of the casualty, then
          this Lease shall terminate thirty (30) days after Landlord receives
          written notice, if any, from Tenant that Tenant has elected to
          terminate this Lease pursuant to this paragraph; provided that, if
          Landlord substantially completes such rebuilding and repairs prior to
          the expiration of thirty (30) days following Landlord's receipt of
          Tenant's termination notice, this Lease shall not so terminate and
          shall continue in full force and effect.

TAXES          16.  Tenant shall be liable for all taxes levied or assessed
          against personal property, furniture, or fixtures placed by Tenant in
          the Premises. If any taxes for which Tenant is liable are levied or
          assessed against Landlord or Landlord's property and Landlord elects
          to pay the same, or if the assessed value of Landlord's property is
          increased by inclusion of such personal property, furniture or
          fixtures and Landlord elects to pay the taxes based on such increase,
          then Tenant shall pay to Landlord, upon demand, that part of such
          taxes for which Tenant is primarily liable hereunder.

EVENTS OF
DEFAULT        17.  Each of the following occurrences shall constitute an "EVENT
          OF DEFAULT":

                                       8
<PAGE>

               (a)  Tenant's failure to pay Rent, or any other sums due from
          Tenant to Landlord under the Lease when due and such failure continues
          for ten (10) days following written notice from Landlord notifying
          Tenant of Tenant's failure to pay when due; provided, however, that in
          the event Landlord gives to Tenant notice of Tenant's failure to pay
          when due two (2) times in any calendar year, Tenant's failure to pay
          when due the third (3rd) time in such calendar year shall constitute
          an Event of Default immediately without any notice thereof required
          from Landlord;

               (b)  Tenant's failure to perform, comply with, or observe any
          agreement or obligation of Tenant under this Lease (other than a
          payment obligation) on or before the thirtieth (30th) day following
          written notice of such failure or longer time if not curable within
          thirty (30) days provided Tenant is in diligent pursuit to cure such
          failure and in any event such cure is commenced within thirty (30),
          and completed within ninety (90) days, after written notice;

               (c)  the filing of a petition by or against Tenant in any
          bankruptcy or other insolvency proceeding; (2) seeking any relief
          under any state or federal debtor relief law; (3) for the appointment
          of a liquidator or receiver for all or substantially all of Tenant's
          property or for Tenant's interest in this Lease; or (4) for the
          reorganization or modification of Tenant's capital structure; provided
          that Tenant shall have sixty (60) days following the commencement of
          an involuntary proceeding to have such proceeding dismissed before
          such proceeding shall constitute an Event of Default; and

               (d)  the admission by Tenant that it cannot meet its obligations
          as they become due or the making by Tenant of an assignment for the
          benefit of its creditors.

REMEDIES       18.  Upon any Event of Default, Landlord may, in addition to all
          other rights and remedies afforded Landlord hereunder or by law or
          equity, take any of the following actions:

               (a)  Terminate this Lease by giving Tenant written notice
          thereof, in which event, Tenant shall pay to Landlord the sum of (1)
          all Rent accrued hereunder through the date of termination, (2) all
          amounts due under Section 19.(a), and (3) an amount equal to (A) the
          total Rent that Tenant would have been required to pay for the
          remainder of the Term discounted to present value at a per annum rate
          equal to the "Prime Rate" as published on the date this Lease is
          terminated by The Wall Street Journal, Southwest Edition, in its
          listing of "Money Rates", minus (B) the then present fair rental value
          of the Premises for such period, similarly discounted; or

               (b)  Terminate Tenant's right to possession of the Premises
          without terminating this Lease by giving written notice thereof to
          Tenant, in which event Tenant shall pay to Landlord (1) all Rent and
          other amounts accrued hereunder to the date of termination of
          possession, (2) all amounts due from time to time under Section
          19.(a), and (3) all Rent and other sums required hereunder to be paid
          by Tenant during the remainder of the Term, diminished by any net sums
          thereafter received by Landlord through reletting the Premises during
          such period. Landlord shall use reasonable efforts to relet the
          Premises on such terms and conditions as Landlord in its sole
          discretion may determine (including a term different from the Term,
          rental concessions, and alterations to, and improvement of, the
          Premises); however, Landlord shall not be obligated to relet the
          Premises before leasing other portions of the Building. Landlord shall
          not be liable for, nor shall Tenant's obligations hereunder be
          diminished because of, Landlord's failure to relet the Premises or to
          collect rent due for such reletting provided Landlord shall use
          reasonable efforts as set forth herein. Tenant shall not be entitled
          to the excess of any consideration obtained by reletting over the Rent
          due hereunder. Reentry by Landlord in the Premises shall not affect
          Tenant's obligations hereunder for the unexpired Term; rather,
          Landlord may, from time to time, bring action against Tenant to
          collect amounts due by Tenant, without the necessity of Landlord's
          waiting until the expiration of the Term. Unless Landlord delivers
          written notice to Tenant expressly stating that it has elected to
          terminate this Lease, all actions taken by Landlord to exclude or
          dispossess Tenant of the Premises shall be deemed to be taken under
          this Section 18.(b). If Landlord elects to proceed under this Section
          18.(b), it may at any time elect to terminate this Lease under Section
          18.(a).

               Additionally, without notice, Landlord may alter locks or other
          security devices at the Premises to deprive Tenant of access thereto,
          and Landlord shall not be required to provide a new key or right of
          access to Tenant. Notwithstanding the foregoing, Tenant will be
          granted access to the premises for the sole purpose of removal of all
          materials, including documentation, electronic media, computers,
          computers containing electronic media, diagrams, pictures or any other
          property that is confidential or proprietary information of the Tenant
          or of third parties with such access granted to Tenant prior to
          Landlord re-entering the premises; provided that a representative of
          Landlord may be present to insure that Tenant does not remove any
          unauthorized materials. Either party may request such removal within
          three (3) business days or earlier based on compelling business
          reasons by either party for more immediate access.

PAYMENT BY
TENANT;
NON-WAIVER     19.  (a)  PAYMENT BY TENANT. Upon any Event of Default, Tenant
          shall pay to Landlord all costs incurred by Landlord (including court
          costs and reasonable attorneys' fees and expenses) in (1) obtaining
          possession of the Premises, (2) removing and storing Tenant's or any
          other occupant's property, (3) repairing, restoring, altering,
          remodeling, or otherwise putting the Premises into condition
          acceptable to a new tenant, (4) if

                                       9
<PAGE>

          Tenant is dispossessed of the Premises and this Lease is not
          terminated, reletting all or any part of the Premises (including
          brokerage commissions, cost of tenant finish work, and other costs
          incidental to such reletting), (5) performing Tenant's obligations
          which Tenant failed to perform, and (6) enforcing, or advising
          Landlord of, its rights, remedies, and recourses arising out of the
          Event of Default.

               (b)  NO WAIVER. Landlord's acceptance of Rent following an
          Event of Default shall not waive Landlord's rights regarding such
          Event of Default. No waiver by Landlord of any violation or breach
          of any of the terms contained herein shall waive Landlord's rights
          regarding any future violation of such term or violation of any
          other term.

SURRENDER  OF
PREMISES       20.  No act by Landlord shall be deemed an acceptance of a
          surrender of the Premises, and no agreement to accept a surrender
          of the Premises shall be valid unless the same is made in writing
          and signed by Landlord. At the expiration or termination of this
          Lease, Tenant shall deliver to Landlord the Premises with all
          improvements located thereon in good repair and condition,
          reasonable wear and tear (and condemnation and fire or other
          casualty damage, as to which Sections 14 and 15 shall control)
          excepted, and shall deliver to Landlord all keys to the Premises.
          Provided that Tenant has performed all of its obligations
          hereunder, Tenant may remove all unattached trade fixtures,
          furniture, and personal property placed in the Premises by Tenant
          (but Tenant shall not remove any such item which was paid for, in
          whole or in part, by Landlord). Additionally, Tenant shall remove
          such alterations, additions, improvements, trade fixtures,
          equipment, wiring, and furniture that is installed or placed in the
          Premises by Tenant as Landlord may request, except for initial
          improvements pursuant to Exhibit D. Tenant shall repair all damage
          caused by such removal. All items not so removed shall be deemed to
          have been abandoned by Tenant and may be appropriated, sold,
          stored, destroyed, or otherwise disposed of by Landlord without
          notice to Tenant and without any obligation to account for such
          items. The provisions of this Section 20 shall survive the end of
          the Term.

HOLDING
OVER           21.  If Tenant fails to vacate the Premises at the end of the
          Term, then Tenant shall be a tenant at will and, in addition to all
          other damages and remedies to which Landlord may be entitled for
          such holding over, Tenant shall pay, in addition to the other Rent,
          a daily Basic Rental equal to the greater of (a) 150% of the daily
          Basic Rental payable during the last month of the Term, or (b) the
          prevailing rental rate in the Building for similar space.

CERTAIN RIGHTS
RESERVED BY
LANDLORD       22.  Provided that the exercise of such rights does not
          unreasonably interfere with Tenant's occupancy of the Premises,
          Landlord shall have the following rights:

               (a)  to decorate and to make inspections, repairs,
          alterations, additions, changes, or improvements, whether
          structural or otherwise, in and about the Building, or any part
          thereof; for such purposes, to enter upon the Premises and, during
          the continuance of any such work, to temporarily close doors,
          entryways, public space, and corridors in the Building; to
          interrupt or temporarily suspend Building services and facilities;
          and to change the arrangement and location of entrances or
          passageways, doors, and doorways, corridors, elevators, stairs,
          restrooms, or other public parts of the Building;

               (b) to take such reasonable measures as Landlord deems
          advisable for the security of the Building and its occupants,
          including without limitation searching all persons entering or
          leaving the Building; evacuating the Building for cause, suspected
          cause, or for drill purposes; temporarily denying access to the
          Building; and closing the Building after normal business hours and
          on Saturdays, Sundays, and holidays, subject, however, to Tenant's
          right to enter when the Building is closed after normal business
          hours under such reasonable regulations as Landlord may prescribe
          from time to time which may include by way of example, but not of
          limitation, that persons entering or leaving the Building, whether
          or not during normal business hours, identify themselves to a
          security officer by registration or otherwise and that such persons
          establish their right to enter or leave the Building;

               (c)  to change the name by which the Building is designated; and

               (d)  to enter the Premises accompanied by Tenant at all
          reasonable hours and upon giving Tenant reasonable notice (except
          in the case of any emergency) to show the Premises to prospective
          purchasers, lenders, or tenants (provided the space shall only be
          shown to prospective tenants in conjunction with reletting the
          Premises), subject to reasonable Tenant security and
          confidentiality procedures.

MISCELLANEOUS  24.  (a)  LANDLORD TRANSFER. Landlord may transfer, in whole
          or in part, the Building and any of its rights under this Lease. If
          Landlord assigns its rights under this lease, and the assignee
          assumes all Landlord's obligation under this Lease, then Landlord
          shall thereby be released from any further obligations hereunder
          arising after the date of such transfer.

                                      10
<PAGE>


               (b)  LANDLORD'S LIABILITY. The liability of Landlord to Tenant
          for any default by Landlord under the terms of this Lease shall be
          limited to Tenant's actual direct, but not consequential, damages
          therefor and shall be recoverable from the interest of Landlord in
          the Building and the Land, and Landlord shall not be personally
          liable for any deficiency. This section shall not be deemed to
          limit or deny any remedies which Tenant may have in the event of
          default by Landlord hereunder which do not involve the personal
          liability of Landlord.

               (c)  FORCE MAJEURE. Other than for Tenant's monetary
          obligations under this Lease and obligations which can be cured by
          the payment of money (e.g., maintaining insurance), whenever a
          period of time is herein prescribed for action to be taken by
          either party hereto, such party shall not be liable or responsible
          for, and there shall be excluded from the computation for any such
          period of time, any delays due to strikes, riots, acts of God,
          shortages of labor or materials, war, governmental laws,
          regulations (including inability to obtain necessary permits due to
          no fault of Landlord or its contractors or agents), or
          restrictions, or any other causes of any kind whatsoever which are
          beyond the control of such party.

               (d)  BROKERAGE. Landlord and Tenant each warrant to the other
          that it has not dealt with any broker or agent in connection with
          the negotiation or execution of this Lease, except for Insignia/ESG
          of Texas, Inc. (Landlord's exclusive agent) and Colliers Oxford
          Commercial (Tenant's exclusive agent). Tenant and Landlord shall
          each indemnify the other against all costs, expenses, reasonable
          attorneys' fees, and other liability for commissions or other
          compensation claimed by any broker or agent claiming the same by,
          through, or under the indemnifying party.

               (e)  ESTOPPEL CERTIFICATES AND FINANCIAL INFORMATION. From
          time to time, Tenant shall furnish to any party designated by
          Landlord, within ten days after Landlord has made a request
          therefor, a certificate signed by Tenant confirming and containing
          such factual certifications and representations as to this Lease as
          Landlord may reasonably request. From time to time, Landlord shall
          furnish to any party designated by Tenant, within ten days after
          Tenant has made a request therefor, a certificate signed by
          Landlord confirming and containing such factual certifications and
          representations as to this Lease as Tenant may reasonably request.
          Further, from time to time (but not more often than once in any
          given six (6) month period), within ten days after Landlord's
          request therefor, Tenant shall furnish to Landlord or Landlord's
          Mortgagee the most recent annual financial statements for Tenant.

               (f)  NOTICES. All notices and other communications given
          pursuant to this Lease shall be in writing and shall be (1) mailed
          by first class, United States Mail, postage prepaid, certified,
          with return receipt requested, and addressed to the parties hereto
          at the address specified in the Basic Lease Information, (2) hand
          delivered or delivered by overnight delivery service to the
          intended address, or (3) sent by prepaid telegram, cable, facsimile
          transmission, or telex followed by a confirmatory letter. Notice
          sent by certified mail, postage prepaid, shall be effective three
          business days after being deposited in the United States Mail; all
          other notices shall be effective upon delivery to the address of
          the addressee. The parties hereto may change their addresses by
          giving notice thereof to the other in conformity with this
          provision.

               (g)  SEPARABILITY. If any clause or provision of this Lease is
          illegal, invalid, or unenforceable under present or future laws,
          then the remainder of this Lease shall not be affected thereby and
          in lieu of such clause or provision, there shall be added as a part
          of this Lease a clause or provision as similar in terms to such
          illegal, invalid, or unenforceable clause or provision as may be
          possible and be legal, valid, and enforceable.

               (h)  AMENDMENTS; AND BINDING EFFECT. This Lease may not be
          amended except by instrument in writing signed by Landlord and
          Tenant. No provision of this Lease shall be deemed to have been
          waived by Landlord unless such waiver is in writing signed by
          Landlord, and no custom or practice which may evolve between the
          parties in the administration of the terms hereof shall waive or
          diminish the right of Landlord to insist upon the performance by
          Tenant in strict accordance with the terms hereof. The terms and
          conditions contained in this Lease shall inure to the benefit of
          and be binding upon the parties hereto, and upon their respective
          successors in interest and legal representatives, except as
          otherwise herein expressly provided. This Lease is for the sole
          benefit of Landlord and Tenant, and, other than Landlord's
          Mortgagee, no third party shall be deemed a third party beneficiary
          hereof.

               (i)  QUIET ENJOYMENT. Provided Tenant has performed all of the
          terms and conditions of this Lease to be performed by Tenant,
          Tenant shall peaceably and quietly hold and enjoy the Premises for
          the Term, without hindrance from Landlord or any party claiming by,
          through, or under Landlord, subject to the terms and conditions of
          this Lease.

               (j)  JOINT AND SEVERAL LIABILITY. If there is more than one
          Tenant, then the obligations hereunder imposed upon Tenant shall be
          joint and several.

               (k)  CAPTIONS. The captions contained in this Lease are for
          convenience of reference only, and do not limit or enlarge the
          terms and conditions of this Lease.

               (l)  NO MERGER. There shall be no merger of the leasehold
          estate hereby created with the fee

                                      11
<PAGE>


          estate in the Premises or any part thereof if the same person
          acquires or holds, directly or indirectly, this Lease or any
          interest in this Lease and the fee estate in the leasehold Premises
          or any interest in such estate.

               (m)  NO OFFER. The submission of this Lease to Tenant shall
          not be construed as an offer, nor shall Tenant have any right under
          this Lease unless Landlord executes a copy of this Lease and
          delivers it to Tenant.

               (n)  EXHIBITS. All exhibits and attachments hereto are
          incorporated herein by this reference.

                       Exhibit A      -  Land
                       Exhibit A-1   -  Outline of Premises
                       Exhibit A-2    -  Project
                       Exhibit B      -  Building Rules and Regulation
                       Exhibit C      -  Basic Costs
                       Exhibit D      -  Tenant Finish-Work
                       Exhibit E      -  Parking
                       Exhibit F      -  Extension Option
                       Exhibit G      -  Right of First Refusal
                       Exhibit H      -  Subordination, Non-disturbance and
                                         Attornment Agreement
                       Exhibit I      -  Pro Forma Letter of Credit
                       Exhibit J      -  Confidentiality Agreement

               (o)  ENTIRE AGREEMENT. This Lease constitutes the entire
          agreement between Landlord and Tenant regarding the subject matter
          hereof and supersedes all oral statements and prior writings
          relating thereto. Except for those set forth in this Lease, no
          representations, warranties, or agreements have been made by
          Landlord or Tenant to the other with respect to this Lease or the
          obligations of Landlord or Tenant in connection therewith.

HAZARDOUS
SUBSTANCES     25.  The term "HAZARDOUS SUBSTANCES," as used in this Lease
          shall mean pollutants, contaminants, toxic or hazardous wastes, or
          any other substances, the removal of which is required or the use
          of which is restricted, prohibited or penalized by any
          "ENVIRONMENTAL LAW," which term shall mean any Law relating to
          health, pollution, or protection of the environment. Tenant hereby
          agrees that a). no activity will be conducted on the Premises that
          will produce any Hazardous Substances, except for such activities
          that are part of the ordinary course of Tenant's business
          activities (the "PERMITTED ACTIVITIES") provided such Permitted
          Activities are conducted in accordance with all Environmental Laws
          and have been approved in advance in writing by Landlord; b). the
          Premises will not be used in any manner for the storage of any
          Hazardous Substances except for any temporary storage of such
          materials that are used in the ordinary course of Tenant's business
          (the "PERMITTED MATERIALS") provided such Permitted Materials are
          properly stored in a manner and location satisfying all
          Environmental Laws and approved in advance in writing by Landlord;
          c). no portion of the Premises will be used as a landfill or a
          dump; d). Tenant will not install any underground tanks of any
          type; e). Tenant will not cause any surface or subsurface
          conditions to exist or come into existence that constitute, or with
          the passage of time may constitute a public or private nuisance;
          f). Tenant will not permit any Hazardous Substances to be brought
          onto the Premises, except for the Permitted Materials, and if so
          brought or found located thereon, the same shall be immediately
          removed by Tenant, with proper disposal, and all required cleanup
          procedures shall be diligently undertaken pursuant to all
          Environmental Laws; g). Tenant will maintain on the Premises a list
          of all materials stored at the Premises for which a material safety
          data sheet (an "MSDS") was issued by the producers or manufacturers
          thereof, together with copies of the MSDS's for such materials, and
          shall deliver such list and MSDS copies to Landlord upon Landlord's
          request therefor; and h). Tenant shall remove all Permitted
          Materials from the Premises in a manner acceptable to Landlord
          before Tenant's right to possess the Premises is terminated. If at
          any time during or after the Term, the Premises are found to be so
          contaminated or subject to such conditions, Tenant shall defend,
          indemnify and hold Landlord harmless from all claims, demands,
          actions, liabilities, costs, expenses, damages and obligations of
          any nature arising from or as a result of the use of the Premises
          by Tenant, except for any conditions or contamination caused by
          Landlord. The foregoing indemnity shall survive termination or
          expiration of this Lease. Unless expressly identified on an
          addendum to this Lease, as of the date hereof there are no
          "Permitted Activities" or "Permitted Materials" for purposes of the
          foregoing provision and none shall exist unless and until approved
          in writing by the Landlord. Landlord may enter the Premises and
          conduct environmental inspections and tests therein as it may
          reasonably require from time to time, provided that Landlord shall
          use reasonable efforts to minimize the interference with Tenant's
          business. Such inspections and tests shall be conducted at
          Landlord's expense, unless they reveal the presence of Hazardous
          Substances brought by Tenant or its employees, representatives or
          agents to the Premises (other than Permitted Materials or those
          placed in the Premises by Landlord) or that Tenant has not complied
          with the requirements set forth in this Section 25, in which case
          Tenant shall reimburse Landlord for the cost thereof within ten
          days after Landlord's request therefor. In no event shall Tenant be
          liable for Hazardous Substances on the Premises prior to the
          Commencement Date, unless brought to the Premises by Tenant or its
          employees, representatives or agents.


                                       12
<PAGE>

LANDLORD'S
LIEN           26. Tenant shall have the right to grant any security
          interests in Tenant's removable furniture, fixtures and equipment
          located in the Premises for the purpose of securing any
          indebtedness provided by a third party. Tenant may also lease such
          furniture, fixtures and / or equipment from one or more equipment
          lessors and grant security interests in such furniture, fixtures
          and/or equipment to such equipment lessors in connection with such
          leases. Upon request Landlord will execute one or more consent
          and/or subordination agreements subordinating any landlord's lien
          rights held by Landlord to any such security interests or leases.
          Notwithstanding the foregoing, in no event will Tenant have the
          right to grant any lien, mortgage or security interest in any
          portion of the Building or in this Lease.

SPECIAL PROVISIONS

               27.  Landlord agrees that Tenant may, at Tenant's expense,
erect and maintain lettering bearing Tenant's name at the top position of the
monument sign associated with the Building, such lettering to represent fifty
percent (50%) of the graphical portion of such monument sign which is
designated for use by tenants (subject to Landlord's reasonable approval of
the size, design, form, content and location of such sign). If any other
tenant in the Building which leases less space than the Premises is permitted
to place signage on the Building, Tenant shall also be permitted to install
and maintain a sign bearing Tenant's name on the exterior of the Building
[such sign to be (i) larger than such other tenant's sign in proportion to the
amount by which the square footage of the Premises exceeds the square footage
of such other tenant's premises and (ii) mutually agreed to by Landlord and
Tenant as to design, form, content and location]. Tenant shall be solely
responsible for all costs of designing, installing and repairing such
signage, diligently construct such building signage to completion in a good
and workmanlike manner and maintain such signage in an attractive condition,
and comply with all governmental codes and regulations. Upon termination or
expiration of this Lease, Tenant shall remove such signage and repair any
damage to the Building caused thereby at its sole cost and expense.
Notwithstanding anything to the contrary contained in this Lease, Tenant
hereby indemnifies and holds Landlord harmless against any claims, costs or
expenses (including reasonable attorneys fees) in connection with any damages
to property or injuries to persons arising out of the installation, removal
or maintenance of such building signage.

          28.  Notwithstanding any thing contained in this Lease to the
contrary, Landlord's obligations hereunder are specifically conditioned upon
Landlord achieving Substantial Completion of the Premises not later than
August 1, 2000, which date shall be extended day-for-day for each day of
Tenant Delay (the "Outside Date"). In the event Landlord does not achieve
Substantial Completion of the Premises by the Outside Date, Tenant, as
Tenant's sole and exclusive remedy, may terminate this Lease in writing at
any time after the Outside Date and before Landlord achieves Substantial
Completion of the Premises. In the event Tenant terminates this Lease
pursuant to this paragraph, Landlord will return all advance payments of rent
and Security Deposits theretofore paid to Landlord by Tenant and all Letters
of Credit theretofore delivered to Landlord by Tenant and will reimburse and
refund Tenant all monies theretofore paid by Tenant to Landlord as part of
Total Construction Costs (in accordance with Exhibit D); provided, however,
in no event shall such reimbursement of amounts paid for Total Construction
Costs exceed an amount equal to the product of $6.00 multiplied by the number
of rentable square feet within the Premises.

          29.  Notwithstanding anything contained in this Lease to the
contrary, if Landlord fails to deliver the nondisturbance agreement to Tenant
contemplated by Section 12(a) hereof executed by Landlord and Landlords'
Mortgagee within thirty (30) days after the date this Lease is signed by
Landlord and Tenant, Tenant shall have the right to terminate this Lease upon
written notice to Landlord at any time prior to delivery of such agreement.

          30.  Contemporaneously herewith, Landlord shall execute and deliver
to Tenant a Confidentiality Agreement in the form of Exhibit "J" attached
hereto.

LANDLORD AND TENANT EXPRESSLY DISCLAIM ANY IMPLIED WARRANTY THAT THE PREMISES
ARE SUITABLE FOR TENANT'S INTENDED COMMERCIAL PURPOSE, AND TENANT'S
OBLIGATION TO PAY RENT HEREUNDER IS NOT DEPENDENT UPON THE CONDITION OF THE
PREMISES OR THE PERFORMANCE BY LANDLORD OF ITS OBLIGATIONS HEREUNDER EXCEPT
AS OTHERWISE EXPRESSLY PROVIDED HEREIN, AND, EXCEPT AS OTHERWISE EXPRESSLY
PROVIDED HEREIN, TENANT SHALL CONTINUE TO PAY THE RENT, WITHOUT ABATEMENT,
SETOFF, DEDUCTION, NOTWITHSTANDING ANY BREACH BY LANDLORD OF ITS DUTIES OR
OBLIGATIONS HEREUNDER, WHETHER EXPRESS OR IMPLIED.

                                      13
<PAGE>


DATED as of the date first written above.

                 LANDLORD:

                 STRATUS 7000 WEST JOINT VENTURE
                 a Texas joint venture

                 By:  OLY LANTANA, L.P., a Texas limited
                      partnership, Joint Venturer

                      By:  OLY LANTANA, GP, L.L.C., a Texas
                           limited liability company, its General Partner



                           By: /s/ Hal R. Hall
                              -------------------------
                           Name:
                                -----------------------
                           Title:
                                 ----------------------

                      By: STRATUS 7000 WEST, LTD., a Texas limited
                          partnership, Joint Venturer

                          By:  STRS, L.L.C., a Delaware limited liability
                               company, General Partner

                               By STRATUS PROPERTIES INC., a Delaware
                                  limited liability company, its sole member


                               By: /s/ William H. Armstrong, III
                                  ---------------------------------------
                                  William H. Armstrong, III
                                  President and CEO


                          TENANT:

                          SILICON LABORATORIES, INC.



                                    By: /s/ Navdeep S. Sooch
                                       ---------------------------------------
                                       Navdeep S. Sooch
                                       Chairman and CEO

                                     14
<PAGE>


                                    EXHIBIT A

                                      LAND

                              PROPERTY DESCRIPTION

Lot 6, Block A, LANTANA LOT 6, BLOCK A, a subdivision in Travis County, Texas,
according to the map or plat thereof, recorded in Volume 100, Page(s) 1-2 of the
Plat Records of Travis County, Texas, as corrected by instrument recorded in
Volume 13064, Page 278 of the Real Property Records of Travis County, Texas.











                                       A-1
<PAGE>


                                  EXHIBIT A-1

                              OUTLINE OF PREMISES



                                  [FLOOR PLAN]



                                    LEVEL 2



                                  [FLOOR PLAN]



                                    LEVEL 1

                                     A-1-1

<PAGE>

                                  EXHIBIT A-1

                                    PROJECT


                                  [FLOOR PLAN]








                                                     LANTANA CORPORATE CENTER
                                                     STRATUS PROPERTIES, INC.

                                     A-2-1

<PAGE>


                                    EXHIBIT B

                         BUILDING RULES AND REGULATIONS

     The following rules and regulations shall apply to the Premises, the
Building, the parking garage associated therewith, the Land and the
appurtenances thereto:

1.   Sidewalks, doorways, vestibules, halls, stairways, and other similar
     areas shall not be obstructed by tenants or used by any tenant for
     purposes other than ingress and egress to and from their respective
     leased premises and for going from one to another part of the Building.

2.   Plumbing, fixtures and appliances shall be used only for the purposes
     for which designed, and no sweepings, rubbish, rags or other unsuitable
     material shall be thrown or deposited therein. Damage resulting to any
     such fixtures or appliances from misuse by a tenant or its agents,
     employees or invitees, shall be paid by such tenant.

3.   No signs, advertisements or notices shall be painted or affixed on or to
     any windows or doors or other part of the Building without the prior
     written consent of Landlord. No nails, hooks or screws shall be driven
     or inserted in any part of the Building except by Building maintenance
     personnel. No curtains or other window treatments shall be placed
     between the glass and the Building standard window treatments.

4.   Landlord shall provide and maintain an alphabetical directory for all
     tenants in the main lobby of the Building.

5.   Landlord shall provide all door locks in each tenant's leased premises,
     at the cost of such tenant, and no tenant shall place any additional
     door locks in its leased premises without Landlord's prior written
     consent. Landlord shall furnish to each tenant a reasonable number of
     keys and card keys to such tenant's leased premises, at such tenant's
     cost, and no tenant shall make a duplicate thereof.

6.   Movement in or out of the Building of furniture or office equipment, or
     dispatch or receipt by tenants of any bulky material, merchandise or
     materials which require use of elevators or stairways, or movement
     through the Building entrances or lobby shall be conducted under
     Landlord's supervision at such times and in such a manner as Landlord
     may reasonably require. Each tenant assumes all risks of and shall be
     liable for all damage to articles moved and injury to persons or public
     engaged or not engaged in such movement, including equipment, property
     and personnel of Landlord if damaged or injured as a result of acts in
     connection with carrying out this service for such tenant.

7.   Landlord may prescribe weight limitations and determine the locations
     for safes and other heavy equipment or items, which shall in all cases
     be placed in the Building so as to distribute weight in a manner
     acceptable to Landlord which may include the use of such supporting
     devices as Landlord may require. All damages to the Building caused by
     the installation or removal of any property of a tenant, or done by a
     tenant's property while in the Building, shall be repaired at the
     expense of such tenant.

8.   Corridor doors, when not in use, shall be kept closed. Nothing shall be
     swept or thrown into the corridors, halls, elevator shafts or stairways.
     No birds or animals shall be brought into or kept in, on or about any
     tenant's leased premises. No portion of any tenant's leased premises
     shall at any time be used or occupied as sleeping or lodging quarters.

9.   Tenant shall cooperate with Landlord's employees in keeping its leased
     premises neat and clean. Tenants shall not employ any person for the
     purpose of such cleaning other than the Building's cleaning and
     maintenance personnel.

10.  Tenant shall not make or permit any improper, objectionable or
     unpleasant noises or odors in the Building or otherwise interfere in any
     way with other tenants or persons having business with them.

11.  No machinery of any kind (other than normal office equipment) shall be
     operated by any tenant on its leased area without Landlord's prior
     written consent, nor shall any tenant use or keep in the Building any
     flammable or explosive fluid or substance.

12.  Landlord will not be responsible for lost or stolen personal property,
     money or jewelry from tenant's leased premises or public or common areas
     regardless of whether such loss occurs when the area is locked against
     entry or not.

13.  All mail chutes located in the Building shall be available for use by
     Landlord and all tenants of the Building according to the rules of the
     United States Postal Service.

                                      B-1
<PAGE>


                                   EXHIBIT C

                                  BASIC COSTS

The term "BASIC COST" shall mean all expenses and disbursements of every kind
(subject to the limitations set forth below) which Landlord incurs, pays or
becomes obligated to pay in connection with the ownership, operation, and
maintenance of the Building (including the associated parking facilities),
determined in accordance with generally accepted federal income tax basis
accounting principles consistently applied, including but not limited to the
following:

1.   Wages and salaries (including reasonable management fees) of all
     employees engaged in the operation, repair, replacement, maintenance,
     and security of the Building, including taxes, insurance and benefits
     relating thereto;

2.   All supplies and materials used in the operation, maintenance, repair,
     replacement, and security of the Building;

3.   Annual cost of all capital improvements made to the Building which
     although capital in nature can reasonably be expected to reduce the
     normal operating costs of the Building, as well as all capital
     improvements made in order to comply with any law hereafter promulgated
     by any governmental authority, as amortized over the useful economic
     life of such improvements as determined by Landlord in its reasonable
     discretion (without regard to the period over which such improvements
     may be depreciated or amortized for federal income tax purposes);

4.   Cost of all utilities, other than the cost of utilities actually
     reimbursed to Landlord by the Building's tenants (including Tenant under
     Section 7.(b) of this Lease);

5.   Cost of any insurance applicable to the Building and Landlord's personal
     property used in connection therewith;

6.   Cost of repairs, replacements, and general maintenance of the Building;
     and

7.   Cost of service or maintenance contracts with independent contractors
     for the operation, maintenance, repair, replacement, or security of the
     Building (including, without limitation, alarm service, window cleaning,
     and elevator maintenance).

The term "Basic Cost" shall also mean the Building's Proportionate Share of
Taxes (described below) and all expenses and disbursements of every kind
(subject to the limitations set forth below) which Landlord incurs, pays or
becomes obligated to pay in connection with the ownership, operation and
maintenance of the common areas of the Project (including the associated
parking facilities, driveways and landscaped areas), determined in accordance
with generally accepted federal income tax basis accounting principles
consistently applied, including but not limited to the following:

     (1)  Annual cost of all capital improvements made to the common areas
          which although capital in nature can reasonably be expected to
          reduce the normal operating costs of the Project, as well as all
          capital improvements made in order to comply with any law hereafter
          promulgated by any governmental authority, as amortized over the
          useful economic life of such improvements as determined by Landlord
          in its reasonable discretion (without regard to the period over
          which such improvements may be depreciated or amortized for federal
          income tax purposes);

     (2)  Cost of all utilities for the common areas of the Project
          (including, without limitation, landscape irrigation and parking
          lot lighting), other than the costs of utilities actually
          reimbursed to Landlord by the tenants of the Project;

     (3)  Cost of any insurance applicable to the common areas of the Project
          and Landlord's personal property used in connection therewith;

     (4)  Cost of repairs, replacements and general maintenance of the common
          areas of the Project; and

     (5)  Cost of service or maintenance contracts with independent
          contractors for the operation, maintenance, repair and replacement
          of the common area improvements.

As used herein the term "TAXES" shall mean all taxes and assessments and
governmental charges whether federal, state, county or municipal and whether
they be by taxing or management districts or authorities presently taxing or
by others, subsequently created or otherwise, and any other taxes and
assessments attributable to the Project (or its operation), including the
buildings and the grounds, parking areas, driveways and alleys around the
buildings, excluding, however, federal and state taxes on income and Texas
State Franchise Tax. If the present method of taxation changes so that in
lieu of the whole or any part of any Taxes levied on the Project, there is
levied on Landlord a capital tax directly on the rents received therefrom or
a franchise tax, assessment, or charge based, in whole or in part, upon such
rents, then all such taxes, assessments, or charges, or the part thereof so
based, shall

                                     C-1
<PAGE>

be deemed to be included within the term "Taxes" for the purposes hereof.

     There are specifically excluded from the definition of the term "Basic
Cost" (a) costs for capital improvements made to the Building, other than
capital improvements described in subparagraphs 3 and (1) above of this
Exhibit and except for items which, though capital for accounting purposes,
are properly considered maintenance and repair items, such as painting of
common areas, replacement of carpet in elevator lobbies, and the like; for
repair, replacements and general maintenance paid by proceeds of insurance or
by Tenant or other third parties, and alterations attributable solely to
tenants of the Building other than Tenant; for interest, amortization or
other payments on loans to Landlord; for depreciation of the Building; for
leasing commissions; for legal expenses, other than those incurred for the
general benefit of the Building's tenants (e.g., tax disputes); for
renovating or otherwise improving space for occupants of the Building or
vacant space in the Building; for overtime or other expenses of Landlord in
curing defaults or performing work expressly provided in this Lease to be
borne at Landlord's expense; for federal income taxes imposed on or measured
by the income of Landlord from the operation of the Building for state income
taxes, net profits taxes, Texas Franchise taxes, estate and inheritance
taxes, any utilities charged directly to and paid by Tenant or any other
tenant of the Building or the Project; any amortization costs or rental
expenses incurred with respect to machinery, equipment or improvements
installed for the exclusive benefit of another tenant in the Project;
improvements installed for the exclusive benefit of another tenant of the
Project; management fees that exceed customary and standard management fees
paid in arms length transactions and leasing and brokerage commissions and
legal fees incurred in connection with Landlord's leasing of the Building or
the Project or involving disputes with other tenants of the Project; personal
property taxes owed by other tenants of any building of the Project;
penalties and interest for late payment of taxes due by Landlord and timely
paid by Tenant, or due to violation of laws or governmental regulations;
costs of work or services furnished or performed on behalf of other tenants
at such tenant's costs; fees payable to affiliates of Landlord outside the
range of fees payable for similar services in the Austin area in an arms
length transaction; capital repairs or improvements made to the Building
which are covered by Landlord's warranties under the Lease or which are
performed to correct design or structural defects or to bring the Building
into conformity with applicable building codes in effect at the time of the
construction of the Building; expenses in connection with special services
for the exclusive benefit of another tenant in the Project.

                                     C-2
<PAGE>


                                   EXHIBIT D

                               TENANT FINISH-WORK

         1.       Landlord, at its sole cost and expense, shall complete
construction of the following components of the Premises: a) 14 VAV tenant
boxes installed on each floor (diffusers and duct work not installed), b)
perimeter fan-powered boxes installed along with related duct work and
diffusers c). mechanically suspended lay-in acoustical tile ceiling grid with
acoustical tile inventory stored on the floor of the Premises, d). recessed
fluorescent light fixtures, up to a maximum of one fixture per 120 rentable
square feet contained within the Premises, stored on the floor of the
Premises, and e). sprinkler heads installed pursuant to FBA 13 standards in
the Premises and other improvements set forth in Annex 1 to Exhibit D not
otherwise set forth in this work letter. All such construction shall be
completed by Landlord in a good and workmanlike manner and in accordance with
all applicable laws and regulations (including all handicap accessibility
laws).

         2.       On or before November 5, 1999, Tenant, at its sole cost and
expense, shall provide to Landlord for its approval final working drawings,
prepared by STG Partners, Inc., of all improvements that Tenant proposes to
install in the Premises; such working drawings shall include the partition
layout, ceiling plan, electrical outlets and switches, telephone outlets,
drawings for any modifications to the mechanical and plumbing systems of the
Building, and detailed plans and specifications for the construction of the
improvements called for under this Exhibit in accordance with all applicable
governmental laws, codes, rules, and regulations. Further, if any of Tenant's
proposed construction work will affect the Building's HVAC, electrical,
mechanical, or plumbing systems, then the working drawings pertaining thereto
shall be prepared by or reviewed by the Building's engineer of record, whom
Tenant shall at its cost engage for such purpose. As used herein, "WORKING
DRAWINGS" shall mean the final working drawings approved by Landlord, as
amended from time to time by any approved changes thereto, and "WORK" shall
mean all improvements to be constructed in accordance with and as indicated
on the Working Drawings. Approval by Landlord of the Working Drawings shall
not be a representation or warranty of Landlord that such drawings are
adequate for any use, purpose, or condition, or that such drawings comply
with any applicable law or code, but shall merely be the consent of Landlord
to the performance of the Work. Tenant shall, at Landlord's request, sign the
Working Drawings to evidence its review and approval thereof. All changes in
the Work must receive the prior written approval of Landlord, and in the
event of any such approved change Tenant shall, upon completion of the Work,
furnish Landlord with an accurate, reproducible "as-built" plan (e.g., sepia)
of the improvements as constructed, which plan shall be incorporated into
this Lease by this reference for all purposes. Landlord shall promptly review
and approve all such drawings and Landlord's approvals shall not be
unreasonably withheld, conditioned or delayed.

         3.       After the Working Drawings have been approved, Landlord
shall cause the Work to be performed in accordance with the Working Drawings
and all applicable laws, rules, regulations, permits, required governmental
consents and entitlements. The contractor, Tenant and the interior design
architect may inspect the Work as it progresses. Landlord shall be available,
and cause its subcontractors and architect to be reasonably available, to
Tenant or the interior design architect from time to time, on reasonable
prior notice, as necessary or desirable to review the Work. Landlord shall
submit to Tenant the proposed construction schedule for the Work. Landlord
shall promptly inform Tenant of any material delays encountered in completing
the Work and shall promptly deliver to Tenant, and consult with Tenant with
respect to, all revisions of the construction schedules therefor.

         4.       Tenant Delays means any delay by Tenant in providing, or
change by Tenant to, the Working Drawings, any delay because of any
specification by Tenant of materials or installations in addition to or other
than Landlord's standard finish-out materials, or any other delays caused by
Tenant in completion of the Work. No Tenant Delays pursuant to the
immediately preceding sentence shall be deemed to have occurred unless
Landlord notifies Tenant in writing within ten (10) days after the initial
cause of the delay of the specific delay; provided that the date the Tenant
Delay is deemed to commence shall be the date of the initial cause of the
delay, not the date of the notice. There shall further be excluded from the
number of days of Tenant Delays any days of delay which are caused by any act
or omission of Landlord, its agents or contractors, including the failure to
timely provide to Tenant and/or its agents and representatives complete
information regarding the Building necessary for the preparation of the
Working Drawings. Subject to Section 28 of the Lease, if the Premises are not
ready for occupancy and the Work is not Substantially Completed on the
scheduled Commencement Date for any reason other than Tenant Delays, then the
obligations of Landlord and Tenant shall continue in full force and Basic
Rental and Tenant's Proportionate Share of Basic Costs shall be abated until
the date the Work is Substantially Completed, which date shall be the
Commencement Date.

         5.       Tenant shall bear the entire cost of performing the Work
(including, without limitation, costs of design, construction, labor and
materials, additional janitorial services, related taxes and insurance costs,
all of which costs are herein collectively called the "TOTAL CONSTRUCTION
COSTS") in excess of the Construction Allowance (hereinafter defined). Upon
approval of the Working Drawings, Landlord shall obtain bids for the Work
from at least three (3) contractors (all of whom shall be approved by Tenant,
which approval shall not unreasonably withheld). Tenant hereby acknowledges
that Landlord's construction contract with the general contractor for the
Work will include a liquidated damages provision whereby the General
Contractor will be liable to Landlord for liquidated damages if the Work is
not Substantially Complete by February 1, 2000. Such liquidated damages shall
be in the

                                     D-1
<PAGE>

amount of One Thousand and 00/100 Dollars ($1,000.00) per day for each day after
February 1, 2000 until the Work is Substantially Complete; provided, however,
that the contract may provide that the general contractor shall not be required
to pay any such liquidated damages if the reason for the delay is caused by
Tenant Delays or inability to obtain necessary governmental permits or
approvals. Following selection of a contractor, Tenant shall promptly execute a
work order agreement prepared by Landlord which identifies such drawings,
itemizes the Total Construction Costs and sets forth the Construction Allowance,
and pay to an escrow account in an acceptable financial institution to Landlord
50% of the amount by which the estimated Total Construction Costs exceed the
Construction Allowance. Payments from both the escrow account and directly from
Tenant will be paid at times and within proportion of construction draws on the
Total Construction Costs. Upon Substantial Completion of the Work and before
Tenant occupies the Premises to conduct business therein, Tenant shall pay to
Landlord an amount equal to the the Total Construction Costs (as adjusted for
any approved changes to the Work), less 1). the amount of the payments already
made by Tenant, 2). the amount of the Construction Allowance, and 3). the cost
reasonably estimated by Landlord for completing all "punch list" items; finally,
upon completion of the punch list items, Tenant shall pay to Landlord any
additional costs incurred in completing the same.

         6.       Landlord shall provide to Tenant a construction allowance (the
"CONSTRUCTION ALLOWANCE") equal to the lesser of a). $24.00 per rentable square
foot in the Premises or b). the Total Construction Costs, as adjusted for any
approved changes to the Work.

         7.       Landlord or its affiliate shall manage the Work, make
disbursements required to be made to the contractor, and act as a liaison
between the contractor and Tenant and coordinate the relationship between the
Work, the Building, and the Building's systems. In consideration for Landlord's
construction management services, Tenant shall pay to Landlord a construction
management fee equal to three and one-half percent (3-1/2%) of the Total
Construction Costs.

         8.       Except as set forth in this Exhibit, Tenant accepts the
Premises in their newly constructed condition on the date that this Lease is
entered into.

         9.       Landlord shall ensure that the right to require work under
warranties of all subcontractors, manufacturers and suppliers relating to items
for which Tenant is responsible for the maintenance and repair thereof be
enforceable by Tenant and, upon Tenant's written request, Landlord shall provide
a copy of any such warranty to Tenant.

         10.      Landlord shall require that the contractor provide a final
cleaning of the Premises immediately before Tenant's acceptance of Substantial
Completion, consisting of cleaning to a condition expected for a good building
cleaning and maintenance program.


                                     D-2
<PAGE>

                             ANNEX 1 TO EXHIBIT D

     -    Finished entrance, elevators and elevator lobbies

     -    Finished restrooms

     -    Perimeter walls insulated

     -    Perimeter walls and column enclosures installed and ready for paint

     -    Ceiling grid installed

     -    2 ft. X 2 ft. Tegular ceiling tile stacked on the floor

     -    Finished stairways

     -    Public/common area lighting installed

     -    Tenant space light fixtures stocked on floor, 1:120 RSF

     -    14 VAV tenant boxes installed on each floor (diffusers and ductwork
          are not installed)

     -    Perimeter fan-powered boxes installed along with related ductwork and
          diffusers

     -    Automated "on-demand" systems for after-hours HVAC

     -    Electrical capacity: (1) 4 watts per RSF available for tenant' use at
          electrical closet; (2) upgrade capability to 6.5 watts per RSF,
          provided by City of Austin Power and Light

     -    Water and Wastewater service provided by City of Austin

     -    Telephone services provided by Southwestern Bell

     -    Conduit providing access to fiber optic network at front of property
          along street right-of-way as well as between buildings.


                                     D-3
<PAGE>

                                  EXHIBIT E

                                   PARKING

      Tenant shall be permitted to use one hundred thirty (130) undesignated
vehicular parking spaces (including visitor and handicap) and twenty (20)
reserved covered parking spaces in the surface parking lot (the "PARKING
FACILITIES") associated with the Building during the Term at no charge and
subject to such terms, conditions and regulations as are from time to time
applicable to patrons of the Parking Facilities.

                                     E-1
<PAGE>

                                    EXHIBIT F

                                EXTENSION OPTION

     Provided no Event of Default exists and Tenant is occupying not less than
50% of the Premises at the time of such election, Tenant may renew this Lease
for one (1) additional period of five (5) years on the same terms provided in
this Lease (except as set forth below), by delivering written notice of the
exercise thereof to Landlord not later than two hundred seventy (270) days
before the expiration of the Term. On or before the commencement date of the
extended Term, Landlord and Tenant shall execute an amendment to this Lease
extending the Term on the same terms provided in this Lease, except as follows:

1.   The Basic Rental payable for each month during such extended Term shall be
     the prevailing market rental rate in Austin's suburban office market, at
     the commencement of such extended Term, for space of equivalent quality,
     size, utility and location; rental concessions, tenant improvements and
     refurbishment allowances, moving allowances, architectural allowances,
     parking rental concessions, brokerage commissions, other inducements, and
     all other relevant factors, provided each of the foregoing applies to
     renewals or is adjusted to reflect the fact that the determination of
     market rent is for a renewal, with the length of the extended Term and the
     credit standing of Tenant to be taken into account;

2.   Tenant shall have no further renewal options unless expressly granted by
     Landlord in writing; and

3.   Landlord shall lease to Tenant the Premises in their then-current
     condition, and Landlord shall not provide to Tenant any allowances (e.g.,
     moving allowance, construction allowance, and the like) or other tenant
     inducements.

4.   If Landlord and Tenant fail to agree on the fair market rental value of the
     Leased Premises on or before one hundred eighty (180) days prior to the
     expiration of the term of this Lease, Landlord and Tenant shall cooperate
     to appoint an independent appraiser or broker to determine the fair market
     rental value. If Landlord and Tenant cannot agree upon such an appraiser or
     broker within one hundred sixty-five (165) days prior to the expiration of
     the term of the Lease, Landlord and Tenant, respectively, shall, within
     five (5) days, each appoint an independent appraiser or broker to determine
     the fair market rental value. If such independent appraisers or brokers
     cannot agree on upon the fair market rental value within fifteen (15) days
     after the expiration of such five (5) day period, such independent
     appraisers or brokers shall appoint a third independent appraiser or
     broker, whose determination shall be conclusively binding on Landlord and
     Tenant so long as it is not less than the lower or more than the higher of
     the determinations of the two other appraisers or brokers.

     Tenant's rights under this Exhibit shall terminate if (a) this Lease or
Tenant's right to possession of the Premises is terminated, (b) Tenant assigns
any of its interest in the Lease or sublets any portion of the Premises (except
to a Permitted Transferee) or sublets more than 50% of the Premises (other than
to a Permitted Transferee) for the remaining term of the Lease or (c) Tenant
fails to timely exercise its option under this Exhibit, time being of the
essence with respect to Tenant's exercise thereof.


                                     F-1
<PAGE>

                                  EXHIBIT G

                            FIRST RIGHT OF REFUSAL

                                  BUILDING 1

Subject to Subsection B below, Landlord hereby grants to Tenant for the term of
the Lease a right of first refusal for certain space in Building 1, Building 2
and Building 3 as described below, to be exercised in accordance with
Subsections A-1, A-2 and A-3 below, as applicable.

     A-1. At such time as Landlord receives any bona fide offers from a third
party to lease all or any one or more of the portions of the Building
depicted as "Space A-1," "Space A-2" and "Space A-3" on EXHIBIT A-1
(collectively, the "BUILDING 1 ROFR SPACE"), Landlord shall give Tenant
written notice of such offer and such notice shall: (i) specify all material
terms and conditions of such third party offer and (ii) contain an offer to
Tenant under the same terms and conditions as the third party offer and give
Tenant five (5) days (excluding holidays) to accept such offer. Should Tenant
fail to exercise its right to lease such available Building 1 ROFR Space
within such five (5) day (excluding holidays) period, Landlord shall have the
right to lease such Building 1 ROFR Space to such third party. If Landlord
shall then fail to lease such Building 1 ROFR Space to such third party or
its affiliates on substantially the same terms as contained in the offer
within six (6) months, this right of first refusal shall remain in effect
with respect to such space. If Tenant exercises its right of first refusal
with respect to the Building 1 ROFR Space, such space shall be added to the
Premises for all purposes of this Lease, except as provided in C below.
Notwithstanding the foregoing, Tenant's right of first refusal for the
portions of the Building depicted as "Space A-2" on EXHIBIT A-1 is subordinate
and subject to that right of first refusal for such space granted under that
certain Lease Agreement dated September 15, 1999 between Landlord and
AtOutcome, Inc. and Tenant's rights of first refusal for the portions of the
building depicted as "Space A-3" on Exhibit A-1 is subordinate and subject to
that renewal option for such space granted under said AtOutcome, Inc. Lease.
This right of first refusal contained in this Subsection A-1 is contingent on
there being no material adverse changes in Tenant's financial condition at
the time of exercise from Tenant's financial condition on August 31, 1999.
This First Right of Refusal shall be applicable to any space that becomes
available during the term and is intended to be a continuous first right of
refusal.

     A-2. At such time as Landlord receives any bona fide offers from a third
party to lease any portion of Building 2 which would result (either initially or
through the exercise of any expansion rights or rights of first refusal
contained in such offer) in twenty-five percent (25%) or less of Building 2
remaining unleased (the "BUILDING 2 ROFR SPACE"), Landlord shall give Tenant
written notice of such offer and such notice shall (i) specify all material
terms and conditions of such third party offer and (ii) contain an offer to
Tenant under the same terms and conditions as the third party offer and give
Tenant five (5) days (excluding holidays) to accept such offer. Should Tenant
fail to exercise its right to lease such available Building 2 ROFR Space within
such five (5) day (excluding holidays) period, Landlord shall have the right to
lease such Building 2 ROFR Space to such third party and Tenant's right of first
refusal under this subsection A-2 shall be subject and subordinate to any right
of first refusal, expansion right and/or renewal granted under such lease to
such third party (provided such rights were contained in the offer presented to
Tenant). If Landlord shall fail to lease such Building 2 ROFR Space to such
third party or its affiliates on substantially the same terms as contained in
the offer within six (6) months then Tenant's right of first refusal with
respect to that Building 2 ROFR Space shall remain in effect with respect to
such space. The right of first refusal contained in this Subsection A-2 (i) is
contingent on there being no material adverse changes in Tenant's financial
condition at the time of exercise from Tenant's financial condition on August
31, 1999 and (ii) shall apply only to the initial lease up of Building 2 (i.e.,
once a space has been leased, the right of first refusal granted to Tenant shall
no longer apply to it).

     A-3. At such time as Landlord receives any bona fide offers from a third
party to lease any portion (the "BUILDING 3 ROFR SPACE") of the next speculative
building for office use built by Landlord in the Development ("BUILDING 3"),
Landlord shall give Tenant written notice of such offer and such notice shall
(i) specify all material terms and conditions of such third party offer and (ii)
contain an offer to Tenant under the same terms and conditions as the third
party offer and give Tenant five (5) days (excluding holidays) to accept such
offer. Determination of the speculative building status will be as follows:
within thirty (30) days after a building permit for shell construction is
granted, Landlord shall declare if the building is a build to suit. Should
Tenant fail to exercise its right to lease such available Building 3 ROFR Space
within such five (5) day (excluding holidays) period, Landlord shall have the
right to lease the Building 3 ROFR Space to such third party and Tenant's right
of first refusal under this Subsection A-3 shall be subordinate and subject to
any right of first refusal, expansion right and/or renewal right granted under
such lease to such third party (provided such right was contained in the offer
presented to Tenant). If Landlord shall fail to lease such Building 3 ROFR Space
to such third party or its affiliates on substantially the same terms as
contained in the offer within six (6) months, this right of first refusal shall
remain in effect with respect to such space. Notwithstanding the foregoing,
Tenant's right of first refusal under this Subsection A-3 shall (x) only be
applicable to space in a speculative building built by Landlord for office use
(i.e. shall not apply to any space in a build-to-suit building or building used
for non-office uses) (y) be effective only if prior to the date Landlord
receives the third party offer in question Tenant provides audited financial
statements (if available, and if not, unaudited statements certified by Tenant's
chief financial officer) to Landlord showing either total revenues in excess of
$40,000,000.00 for the previous two quarters or total revenues in excess of
$80,000,000.00 for the previous four quarters, and (z) apply only to the initial
lease up of Building 3 (i.e., once a space has been leased, the right of first
refusal granted to Tenant shall no longer apply to it).


                                     G-1
<PAGE>

     B.   Tenant's rights of first refusal as set forth in Subsections A-1, A-2
and A-3 above are subject to the conditions that: (i) on the date that Tenant
delivers its notice exercising its right of first refusal, no Event of Default
exists, (ii) Tenant shall not have assigned the Lease, or sublet any portion of
the Premises (except to a Permitted Transferee) and (iii) at the time that the
third party offer is received by Landlord, Tenant must have provided Landlord
with the financial information necessary to meet the respective financial
requirements in Subsection A-1, A-2 or A-3 as applicable. Tenant shall be deemed
to have met the requirement in (iii) above as it relates to Subsection A-1 or
A-2, so long as Tenant delivers to Landlord quarterly financial statements
showing no material adverse change in Tenant's financial condition since August
31, 1999.

     C.   Promptly after Tenant's exercise of any right of first refusal with
respect to the Building as provided herein, Landlord shall execute and deliver
to Tenant an amendment to the Lease to reflect changes in the Premises, Basic
Rental, Tenant's Proportionate Share and any other appropriate terms changed by
the addition of the ROFR Space. Within 10 days thereafter, Tenant shall execute
and return the amendment; provided that the term for any such Building 1 ROFR
Space shall be the same as contained in the offer (i.e., it will not be
coterminous with the Lease).

     D.   Notwithstanding anything to the contrary contained herein, if Tenant
exercises its right of first refusal as to space in Building 2 or 3, then within
fifteen (15) days after such exercise, Landlord and Tenant shall enter into a
new lease for such space on the same form as this Lease except for any changes
necessary to reflect the business terms contained in the accepted third party
offer and to reflect differences in the Buildings. Each such lease will contain
a signage provision similar to Section 27 of this Lease, except that Tenant's
rights to monument signage (like building signage) shall only be triggered if
another tenant in the building in question (which tenant leases less space than
Tenant) is permitted to have monument signage, in which case the size of the
respective sign panels shall be based proportionately on the relative square
footage of each tenant's space.

     E.   If any individual employed by Tenant's broker is working on a
competing project in southwest Austin (including the Terrace), Tenant agrees to
not disclose any terms and conditions of any offer received from Landlord under
this Exhibit to that individual for a period of six (6) months after such offer.

     F.   Tenant shall not disclose the provisions and conditions of this right
of first refusal to any person or entity except to persons or entities providing
counsel or assistance to Tenant in connection with this Lease, including,
without limitation, attorneys, engineers, architects, and brokers, and as
required by valid court order or subpoena and disclosures required by the
Securities and Exchange Commission, federal securities law, current and future
lenders, and current and future investors.


                                     G-2
<PAGE>

                                    EXHIBIT H

WHEN RECORDED, RETURN TO:

Lynda Zimmerman, Esq.
Winstead Sechrest & Minick P.C.
5400 Renaissance Tower
1201 Elm Street
Dallas, Texas 75270

            SUBORDINATION, ATTORNMENT AND NON-DISTURBANCE AGREEMENT

     This SUBORDINATION, ATTORNMENT AND NON-DISTURBANCE AGREEMENT ("AGREEMENT")
is made and entered into as of October 29, 1999 by and between COMERICA
BANK-TEXAS, a state banking association ("BENEFICIARY"); STRATUS 7000 WEST JOINT
VENTURE, a Texas joint venture ("LESSOR"); and SILICON LABORATORIES, INC., a
Delaware Corporation, ("LESSEE").

                                  WITNESSETH:

     WHEREAS, Beneficiary is the owner and holder of that certain Promissory
Note ("NOTE") dated April 9, 1999, in the principal sum of SIX MILLION SIX
HUNDRED THOUSAND AND NO/100 DOLLARS ($6,600,000.00), secured by that certain
Deed of Trust ("DEED OF TRUST"), dated of even date with the Note, executed
by Lessor to a trustee in favor of Beneficiary, recorded on April 16, 1999,
as Document No. 1999009453 in the Offical Public Records of Travis County,
Texas, which Deed of Trust constitutes a lien on the land described in
EXHIBIT A attached hereto and incorporated herein by reference for all
purposes and the improvements now or hereafter located thereon ("PROPERTY");
and

     WHEREAS, Lessee is the holder of a leasehold estate in and to all or a
portion of the Property (the property which is the subject of such leasehold
estate being referred to as the "DEMISED PREMISES") pursuant to the terms of
that certain lease agreement ("LEASE") dated October 27, 1999, and executed by
and between Lessee, as the tenant, and Lessor, as the landlord; and

     WHEREAS, Lessor, Lessee and Beneficiary desire to confirm their
understandings with respect to the Lease and the Deed of Trust.

     NOW, THEREFORE, in consideration of the mutual and dependent covenants and
agreements herein contained, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged and confessed, the
parties hereto agree and covenant as follows:

     1.   SUBORDINATION. Subject to the terms of this Agreement, the Lease now
is, and shall at all times continue to be, subject, inferior and subordinate in
each and every respect to the lien of the Deed of Trust and to any and all
renewals, amendments, modifications, extensions, substitutions, replacements,
increases and/or consolidations of the Deed of Trust and/or Note, and the lien
of the Deed of Trust, and any and all renewals, amendments, modifications,
extensions, substitutions, replacements, increases and/or consolidations of the
Deed of Trust and/or the Note, shall be and remain, in each and every respect,
prior and superior to the Lease. This Agreement shall be the whole and only
agreement with regard to the subordination of the Lease to the lien of the Deed
of Trust and shall supersede and cancel, insofar as same may affect the priority
between the Deed of Trust and the Lease, any prior agreements or provisions
relating to the subordination of the Lease to the lien of the Deed of Trust,
including, without limitation, those provisions, if any, contained in the Lease
which provide for the subordination thereof to the lien of any deed of trust,
mortgage or other security agreement. Nothing herein contained shall be deemed
or construed as limiting or restricting the enforcement by Beneficiary of any of
the terms, covenants, provisions or remedies specified in the Deed of Trust,
whether or not consistent with the Lease, including (without

<PAGE>

limitation) any rights, remedies, privileges and recourses of Beneficiary with
respect to insurance proceeds and condemnation awards with respect to the
Demised Premises or the Property. The Lease is herein made subordinate to the
aforementioned instruments only and not to any other encumbrances placed upon or
against the Demised Premises. This provision is declared by Beneficiary and
Lessee to be effective and self-operative, without the execution of any further
instruments on the part of any of the parties hereto.

     2.   PURCHASER. As used herein, the term "PURCHASER" shall be deemed to
include Beneficiary and any of its successors and assigns, including anyone who
shall have succeeded to Lessor's interest in the Demised Premises by, through or
under judicial foreclosure sale, non-judicial foreclosure sale or other similar
proceedings brought pursuant to the Deed of Trust, deed in lieu of such
foreclosure, other proceedings brought by Beneficiary under or with respect to
the Note or Deed of Trust, or otherwise.

     3.   ATTORNMENT. If the interests of Lessor in and to the Demised Premises
become owned by Beneficiary or another Purchaser by reason of judicial
foreclosure, non-judicial foreclosure by the trustee under the Deed of Trust,
other proceedings brought by Beneficiary or Purchaser or by any other manner,
including, but not limited to, Beneficiary's exercise of its rights under any
collateral assignment(s) of leases and rents, whereby Purchaser succeeds to the
interest of the Lessor under the Lease, Lessee shall be bound to Purchaser in
accordance with all of the terms, covenants and conditions of the Lease for the
balance of the term thereof and any extension thereof duly exercised by Lessee
with the same force and effect as if Purchaser were the lessor under the Lease.
Lessee does hereby attorn to Purchaser, as its lessor, which attornment shall be
effective and self-operative, without the execution of any further instruments
on the part of any of the parties hereto, immediately upon Purchaser's
succeeding to the interest of the Lessor under the Lease; provided, however,
that Lessee shall be under no obligation to pay rent to Purchaser until Lessee
receives written notice from Purchaser that it has succeeded to the interest of
the Lessor under the Lease, and upon receipt of such notice, Lessee shall pay to
Purchaser all rental and other payments required under the Lease for the
duration of the term of the Lease and any extensions thereof duly exercised by
Lessee and lessor hereby consents to such payments. The respective rights and
obligations of Lessee and Purchaser upon such attornment, to the extent of the
then remaining balance of the term of the Lease and any extension thereof duly
exercised, shall be and are the same as now set forth therein, it being the
intention of the parties hereto for this purpose to incorporate the Lease in
this Agreement by reference, with the same force and effect as if expressly set
forth herein.

     4.   NON-DISTURBANCE. In the event of a foreclosure of the lien of the
Deed of Trust, so long as Lessee is not in default (beyond any period given
in the Lease to Lessee to cure such default) in the payment of rent or in the
performance of any of the terms, covenants or conditions of the Lease on
Lessee's part to be performed, Lessee's possession, use and occupancy of the
Demised Premises pursuant to the Lease shall not be extinguished or
terminated by such foreclosure nor interfered with or disturbed by Purchaser
during the term of the Lease and any extension thereof duly exercised by
Lessee. If at, or subsequent to, the time that Purchaser shall acquire, in
whatever manner, title to the Property or Lessor's title or interest in the
Demised Premises (subject to the Lease), or from time to time thereafter, any
default exists or occurs under the Lease, then Purchaser shall be entitled to
exercise or enforce any and all rights, privileges, remedies and recourses
which it may have against Lessee under or pursuant to the Lease or other
applicable law (including, without limitation, the termination of the Lease,
the dispossession of Lessee from the Demised Premises, or the prosecution of
an action for breach of the Lease), notwithstanding the provisions of this
Agreement.

     5.   PURCHASER'S OBLIGATIONS. If Purchaser shall succeed to the interest of
Lessor under the Lease, Purchaser shall be bound to Lessee under all of the
terms, covenants and conditions of the Lease and shall recognize and observe all
of Lessee's rights and privileges under this Lease; provided, however, that
Purchaser shall not be:

          (a)  liable for any act or omission of any prior lessor (including
     Lessor) under the Lease; or

          (b)  subject to any offsets or defenses which Lessee might have
     against any prior lessor (including Lessor) under the Lease; or

                                                                          page 2

<PAGE>

          (c)  bound by any rent, additional rent, advance rent or other
     monetary obligations which Lessee might have paid for more than the current
     month to any prior lessor (including Lessor) under the Lease and which is
     not delivered or paid to Purchaser at the time of Purchaser's succession to
     title to the Demised Premises, and all such rent or other monetary
     obligations shall remain due and owing, notwithstanding such advance
     payment, and with respect to which Lessee agrees to look solely to Lessor
     for refund or reimbursement; or

          (d)  bound by any security deposit of any type or advance rental
     deposit made by Lessee under the Lease which is not delivered or paid to
     Purchaser at the time of Purchaser's succession to title to the Demised
     Premises, and with respect to which Lessee agrees to look solely to Lessor
     for refund or reimbursement; or

          (e)  bound by any amendment, modification, supplementation,
     termination or cancellation of the Lease made without Beneficiary's or
     Purchaser's prior written consent and approval; or

          (f)  required to complete the construction of any improvements or
     otherwise perform the obligations of Lessor under the Lease in the event
     that Purchaser acquires title to the Property prior to full completion and
     acceptance by Lessee of improvements required under the Lease; or

          (g)  liable or responsible under or pursuant to the terms of the Lease
     after it ceases to own an interest in or to the Demised Premises.

     6.   REPRESENTATIONS. Lessor and Lessee represent, warrant and certify to
Beneficiary (and Purchaser), as of the date hereof, as follows:

          (a)  the Lease is presently in full force and effect;

          (b)  the Lease has not been cancelled, terminated, modified, amended,
     supplemented, replaced, restated or otherwise changed, either orally or in
     writing, except as herein expressly provided;

          (c)  all conditions or requirements specified in the Lease that could
     have been satisfied as of the date hereof have been fully satisfied;

          (d)  no rent under the Lease has been paid for more than the current
     rental period established in the Lease;

          (e)  no default (or any event, condition or circumstance, which with
     notice, grace or lapse of time could constitute a default) exists under
     said Lease;

          (f)  Lessee, as of this date, has no charge, lien or claim of offset
     under said Lease or otherwise against rents or other charges due or to
     become due under the Lease;

          (g)  the Lease constitutes the entire agreement between the Lessee and
     Lessor and that Purchaser shall have no liability or responsibility with
     respect to any security deposit or advance rental deposit made by the
     Lessee except to the extent actually delivered and paid to Purchaser
     concurrently with Purchaser's succession in interest to the Demised
     Premises;

          (h)  the only persons or entities in possession of the Demised
     Premises or having any right to the possession, use or occupancy of the
     Demises Premises (other than the record owner or holders of recorded
     easements) is Lessee; and

          (i)  Lessee has no right or interest in or under any contract, option
     or agreement (other than as shown in the Lease) involving the sale or
     transfer of the Demised Premises or the expansion of the Demised Premises
     or extension of the term of the Lease.

Lessor and Lessee further agree to execute and deliver to Beneficiary, promptly
upon request of Beneficiary and without charge, a written updated certification
of the representations, warranties and

                                                                          page 3

<PAGE>


certifications provided in this SECTION 6 to the extent then accurate (or if any
are not accurate, an explanation of the circumstances of any inaccuracy).

     7.   NEGATIVE COVENANTS. In the absence of the prior written consent of
Beneficiary (or Purchaser), Lessee agrees not to do any of the following: (a)
prepay the rent or other monetary obligations under the Lease for more than one
(1) month in advance, (b) enter into any agreement, whether oral or written,
with the Lessor to amend, modify, supplement, replace, restate or otherwise
change the Lease, (c) voluntarily surrender the Demised Premises or terminate
the Lease except as expressly provided for in the Lease to the contrary, and (d)
sublease or assign all or any portion of the Demised Premises or the Lease
except as expressly provided for in the Lease to the contrary.

     8.   DEFAULT. In the event Lessor shall fail to perform or observe any of
the terms, conditions or agreements in the Lease, Lessee shall, as a condition
precedent to any action with respect to such default under the Lease, give
written notice thereof to Beneficiary and Beneficiary shall have the right (but
not the obligation) to cure such default. Lessee shall not take any action with
respect to such default under the Lease, including without limitation any action
in order to terminate, rescind or avoid the Lease or to withhold any rent or
other monetary obligations thereunder except as expressly provided for in the
Lease to the contrary, for a period of thirty (3 0) days after receipt of such
written notice by Beneficiary; provided, however, that in the case of any
default which cannot with diligence be cured within said thirty (30) day period,
if Beneficiary shall proceed promptly to cure such default and thereafter
prosecute the curing of such default with diligence and continuity, the time
within which such default may be cured shall be extended for such period as may
be necessary to complete the curing of such default with diligence and
continuity.

     9.   NOTICES. All notices or other communications required or permitted to
be given pursuant to this Agreement shall be in writing and shall be considered
as properly given if (i) mailed by first class United States mail, postage
prepaid, registered or certified with return receipt requested; (ii) by
delivering same in person to the intended addressee; or (iii) by delivery to an
independent third party commercial delivery service for same day or next day
delivery and providing for evidence of receipt at the address of the intended
addressee. Notice so mailed shall be effective upon its deposit with the United
States Postal Service or any successor thereto; notice sent by a commercial
delivery service shall be effective upon delivery to such commercial delivery
service; notice given by personal delivery shall be effective only if and when
received by the addressee; and notice given by other means shall be effective
only if and when received at the office or designated address of the intended
addressee. For purposes of notice, the addresses of the parties shall be as set
forth below; provided, however, that either party shall have the right to change
its address for notice hereunder to any other location within the continental
United States by the giving of thirty (30) days notice to the other party in the
manner set forth herein.

          Beneficiary:     Comerica Bank-Texas
                           1601 Elm Street, 2nd Floor
                           Dallas, Texas 75201
                           Attention: National Real Estate Services

          Lessor:          Stratus 7000 West Joint Venture
                           98 San Jacinto Boulevard
                           Suite 220
                           Austin, Texas 78701
                           Attn: William H. Armstrong, III

          Lessee:          Silicon Laboratories, Inc.
                           4635 Boston Lane
                           Austin, Texas 78735

     10.  COUNTERPARTS. To facilitate execution, this instrument may be
executed in as many counterparts as may be convenient or required. It shall not
be necessary that the signature or acknowledgment of, or on behalf of, each
party, or that the signature of all persons required to bind any party, or the
acknowledgment of such party, appear on each counterpart. All counterparts
shall collectively constitute a single instrument. It shall not be necessary in
making proof of this instrument to produce or account for more than a single
counterpart containing the respective


                                                                          page 4

<PAGE>


signatures of, or on behalf of, and the respective acknowledgments of, each of
the parties hereto. Any signature or acknowledgment page to any counterpart may
be detached from such counterpart without impairing the legal effect of the
signatures or acknowledgments thereon and thereafter attached to another
counterpart identical thereto except having attached to it additional signature
or acknowledgment pages.

     11.  AMENDMENT. This Agreement may not be modified orally or in any manner
other than by an agreement, in writing, signed by the parties hereto or their
respective successors in interest.

     12.  SUCCESSORS. This Agreement shall inure to the benefit of and be
binding upon the parties hereto, their successors and assigns.

     13.  REMEDIES CUMULATIVE. All remedies provided for herein are cumulative
and shall be in addition to, but not in lieu of, any and all other rights and
remedies provided by law and by any and all other agreements between Beneficiary
and either Lessor or Lessee.

     14.  FURTHER ASSURANCES. At the request of Beneficiary, Lessor and Lessee
shall execute, acknowledge, and deliver such other documents and/or instruments
as may be reasonably required by Beneficiary in order to effectuate the intent
and purpose of this Agreement; provided, however, that no such document or
instrument shall modify the rights and obligations of Lessor and Lessee as
provided herein.

     15.  ATTORNEYS' FEE. The prevailing party in any action brought against
the other parties hereto to enforce any rights, obligations or duties under this
Agreement shall be entitled to recover from the nonperforming party the
prevailing party's reasonable costs and expenses (including attorneys' fees)
incurred in connection with the enforcement hereof

     16.  TERMINATION. This Agreement shall be of no further force and effect
and shall become null and void upon the recording in the applicable records of
Beneficiary's written release of the lien of the Deed of Trust.

     17.  NO ORAL AGREEMENTS. THIS AGREEMENT EMBODIES THE FINAL, ENTIRE
AGREEMENT OF THE PARTIES HERETO AND SUPERSEDES ANY AND ALL PRIOR COMMITMENTS,
AGREEMENTS, REPRESENTATIONS, AND UNDERSTANDINGS, WHETHER WRITTEN OR ORAL,
RELATING TO THE SUBJECT MATTER HEREOF. THIS AGREEMENT IS INTENDED BY THE PARTIES
HERETO AS A FINAL AND COMPLETE EXPRESSION OF THE TERMS OF THIS AGREEMENT AND NO
COURSE OF DEALING BETWEEN THE PARTIES HERETO, NO COURSE OF PERFORMANCE, NO TRADE
PRACTICES, AND NO EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OR OTHER EXTRINSIC EVIDENCE OF ANY NATURE SHALL BE
USED TO CONTRADICT, VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS AGREEMENT. THERE
ARE NO ORAL AGREEMENTS BETWEEN THE PARTIES HERETO.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

                              BENEFICIARY:

                              COMERICA BANK-TEXAS,
                              a state banking association


                              By: /s/ Sherry R. Layne
                              Name:  Sherry R. Layne
                              Title:  Vice President


                                                                          page 5

<PAGE>


                              LESSOR:

                              STRATUS 7000 WEST JOINT VENTURE,
                              a Texas joint venture

                              By:   Stratus 7000 West, Ltd.,
                                    a Texas limited partnership,
                                    Joint Venturer

                                    By:   STRS L.L.C.,
                                          a Delaware limited liability company,
                                          Its General Partner

                                          By:   Stratus Properties, Inc.,
                                                a Delaware corporation,
                                                Its Sole Member


                                            By: /s/ William H. Armstrong, III
                                            Name:  William H. Armstrong, III
                                            Title: President and Chief Executive
                                                   Officer


                              By:   OLY LANTANA, L.P., a Texas limited
                                    partnership, Joint Venturer

                                    By:   OLY LANTANA, L.P., a Texas limited
                                          liability company, its General Partner


                                            By: /s/ Hal R. Hall
                                            Name:  Hal R. Hall
                                            Title:______________________________


                              LESSEE:

                              SILICON LABORATORIES, INC.
                              a Delaware corporation


                              By: /s/ Navdeep S. Sooch
                              Name:  Navdeep S. Sooch
                              Title:  Chairman & CEO

STATE OF TEXAS

COUNTY OF DALLAS

    This instrument was ACKNOWLEDGED before me on the 4th day of November 1999
by Shery R. Layne, the Vice President of COMERICA BANK-TEXAS, a state banking
association, on behalf of said association.


[SEAL]                                          /s/ Kristine K. Finn
                                               -------------------------------
                                               Notary Public, State of Texas
My Commission Expires:
                                               _______________________________
______________________                         Printed Name of Notary Public


                                                                          Page 6

<PAGE>

STATE OF TEXAS      Section
                    Section
COUNTY OF TRAVIS    Section
         --------

     The foregoing instrument was ACKNOWLEDGED before me this 29th day of
October, 1999, by William H. Armstrong, III, the President and Chief Executive
Officer of STRATUS PROPERTIES, INC., a Delaware corporation and the Sole Member
of STRS L.L.C., a Delaware limited liability company and the General Partner of
STRATUS 7000 WEST, LTD., a Texas limited partnership and Operating Partner of
STRATUS 7000 WEST JOINT VENTURE, a Texas joint venture, on behalf of each of
said entities.


[SEAL]                                   /s/ Mary Bradley
                                       ----------------------------------------
                                       Notary Public, State of Texas
My Commission Expires:
                                         MARY BRADLEY
                                       ----------------------------------------
Jan. 16, 2002                          (Printed Name of Notary Public)
-----------------


STATE OF TEXAS      Section
                    Section
COUNTY OF DALLAS    Section
         --------

     The foregoing instrument was ACKNOWLEDGED before me this 2 day of
November, 1999, by Hal Hall, the Vice President of OLY Lantana, G.P., L.L.C.,
general partner of OLY Lantana, L.P, a Texas limited partnership, Joint
Venturer, of STRATUS 7000 WEST JOINT VENTURE, on behalf of said entities.

[SEAL]                                   /s/ Kerry A. Nunn
                                       ----------------------------------------
                                       Notary Public, State of Texas
My Commission Expires:
                                         Kerry A. Nunn
                                       ----------------------------------------
October 6, 2002                        (Printed Name of Notary Public)
-----------------


                                                                         Page 7
<PAGE>

STATE OF TEXAS      Section
                    Section
COUNTY OF TRAVIS    Section
         --------

     This instrument was ACKNOWLEDGED before me on the 29th day of October,
1999, by NAVDEEP S. SOOCH, the Chairman and CEO of SILICON LABORATORIES, INC.,
a DELAWARE Corporation on behalf of corporation.


[SEAL]                                   /s/ Lynette L. Herr
                                       ----------------------------------------
                                       Notary Public, State of Texas
My Commission Expires:
                                         Lynette L. Herr
                                       ----------------------------------------
April 27, 2002                         Printed Name of Notary Public
-----------------


EXHIBIT LIST

Exhibit A - Legal Description


                                                                         Page 8
<PAGE>

                                  EXHIBIT I

                     LETTER OF CREDIT PRO FORMA WORDING

                               PAGE ONE OF TWO

               (FOR LETTER OF CREDIT ISSUED BY IMPERIAL BANK)

APPLICANT:

BENEFICIARY:

AMOUNT:


EXPIRY DATE AND PLACE FOR PRESENTATION OF DOCUMENTS: [need date] IMPERIAL BANK
INTERNATIONAL DIVISION, 2015 MANHATTAN BEACH BLVD., 2ND FLR., REDONDO BEACH,
CA 90278

CREDIT IS AVAILABLE WITH IMPERIAL BANK INTERNATIONAL DIVISION AGAINST PAYMENT
OF DRAFTS DRAWN AT SIGHT ON IMPERIAL BANK INTERNATIONAL DIVISION, 2015 MANHATTAN
BEACH BLVD., 2ND FLR., REDONDO BEACH, CA 90278

DOCUMENTS REQUIRED:

1. THE ORIGINAL OF THIS STANDBY LETTER OF CREDIT AND AMENDMENT(S) IF ANY.

2. BENEFICIARY'S STATEMENT PURPORTEDLY SIGNED BY AN AUTHORIZED OFFICER
CERTIFYING THAT [APPLICANT' NAME] IS IN DEFAULT OR THAT AN EVENT OF DEFAULT HAS
OCCURRED UNDER ONE OR MORE OF THE TERMS OF THAT CERTAIN LEASE AGREEMENT DATED
[GIVE DATE] THAT EXISTS BETWEEN [APPLICANT'S NAME] AND [BENEFICIARY'S NAME] AND
THAT ANY APPLICABLE CURE PERIOD HAS LAPSED WITHOUT REMEDY.

SPECIAL CONDITIONS:

ALL INFORMATION REQUIRED UNDER DOCUMENT REQUIREMENT NO. 2 WHETHER INDICATED BY
BLANKS, BRACKETS OR OTHERWISE, MUST BE COMPLETED AT THE TIME OF DRAWING.

ALL SIGNATURES MUST BE MANUALLY EXECUTED IN ORIGINALS.

PARTIAL DRAWINGS MAY BE MADE UNDER THIS LETTER OF CREDIT, PROVIDED, HOWEVER,
THAT EACH SUCH DEMAND THAT IS PAID BY US SHALL REDUCE THE AMOUNT AVAILABLE UNDER
THIS LETTER OF CREDIT.

IT IS A CONDITION OF THIS STANDBY LETTER OF CREDIT THAT IT SHALL BE DEEMED
AUTOMATICALLY EXTENDED WITHOUT AMENDMENT FOR ONE YEAR PERIODS FROM THE PRESENT
EXPIRATION DATE HEREOF, UNLESS THIRTY (30) DAYS PRIOR TO ANY SUCH DATE, WE SHALL
NOTIFY YOU IN WRITING BY CERTIFIED MAIL OR COURIER SERVICE AT THE ABOVE LISTED
ADDRESS THAT WE ELECT NOT TO CONSIDER THIS IRREVOCABLE LETTER OF CREDIT RENEWED
FOR ANY SUCH ADDITIONAL PERIOD. UPON RECEIPT BY YOU OF SUCH NOTICE, YOU MAY DRAW
HEREUNDER BY MEANS OF YOUR DRAFT(S) ON US AT SIGHT ACCOMPANIED BY YOUR ORIGINAL
SIGNED STATEMENT WORDED AS FOLLOWS: [beneficiary] HAS RECEIVED NOTICE FROM
IMPERIAL BANK THAT THE EXPIRATION DATE OF LETTER OF CREDIT NO. [INSERT L/C NO.]
WILL NOT BE EXTENDED FOR AN ADDITIONAL PERIOD. AS OF THE DATE OF THIS DRAWING,
[beneficiary] HAS NOT RECEIVED A SUBSTITUTE LETTER OF CREDIT OR OTHER INSTRUMENT
ACCEPTABLE TO [beneficiary] AS SUBSTITUTE FOR IMPERIAL BANK LETTER OF CREDIT NO.
[INSERT L/C NO.].

NOTWITHSTANDING THE ABOVE, THE FINAL EXPIRATION DATE SHALL BE MMDDYY.

ALL DRAFTS AND DOCUMENTS REQUIRED UNDER THIS LETTER OF CREDIT MUST BE MARKED:
"DRAWN UNDER IMPERIAL BANK LETTER OF CREDIT NO. [INSERT L/C NO.]"

ALL DOCUMENTS ARE TO BE DISPATCHED IN ONE LOT BY COURIER SERVICE TO IMPERIAL
BANK INTERNATIONAL DIVISION, 2015 MANHATTAN BEACH BLVD., 2ND FLR., REDONDO
BEACH, CA 90278


                                     G-4
<PAGE>

                                  EXHIBIT I

                      LETTER OF CREDIT PRO FORMA WORDING

                               PAGE TWO OF TWO

THIS LETTER OF CREDIT SETS FORTH IN FULL THE TERMS OF OUR UNDERTAKING AND SUCH
UNDERTAKING SHALL NOT BE IN ANY WAY MODIFIED, AMENDED OR AMPLIFIED BY REFERENCE
TO ANY DOCUMENT, INSTRUMENT OR AGREEMENT REFERRED TO HEREIN OR IN WHICH THIS
LETTER OF CREDIT IS REFERRED TO OR TO WHICH THIS LETTER OF CREDIT RELATES, AND
ANY SUCH REFERENCE SHALL NOT BE DEEMED TO INCORPORATE HEREIN BY REFERENCE ANY
DOCUMENT, INSTRUMENT OR AGREEMENT.

WE HEREBY ENGAGE WITH YOU THAT ALL DRAFTS DRAWN UNDER AND IN COMPLIANCE WITH THE
TERMS OF THIS CREDIT WILL BE DULY HONORED IF DRAWN AND PRESENTED FOR PAYMENT AT
THIS OFFICE ON OR BEFORE THE EXPIRATION DATE OF THIS CREDIT.

EXCEPT SO FAR AS OTHERWISE EXPRESSLY STATED, THIS CREDIT IS SUBJECT TO THE
"UNIFORM CUSTOMS AND PRACTICE FOR DOCUMENTARY CREDITS" (1993 REVISION)
INTERNATIONAL CHAMBER OF COMMERCE (PUBLICATION NO. 500).


                                     G-4
<PAGE>

                                  EXHIBIT J

                            CONFIDENTIAL AGREEMENT

                    DISCLOSURE OF CONFIDENTIAL INFORMATION

This agreement, effective this 27th day of October 1999 by and between Silicon
Laboratories Inc., a corporation organized under the laws of the State of
Delaware, and having its principal place of business at 4635 Boston Lane,
Austin, TX 78735, and Stratus 7000 West Joint Venture, a joint venture organized
under the laws of Texas and having its principal place of business at Stratus
Properties Inc. 98 San Jacinto, Suite 220 Austin, Texas 78701 hereinafter
referred to as the "party" or the "parties." Whereas, the parties desire to
discuss with each other information relating to historical financial
information, financial forecasts, business plans, staffing levels and future
product development activities.

Now, therefore, in consideration of the aforesaid disclosures and further in
consideration of the rights and obligations hereinafter set forth, it is hereby
agreed as follows:

I.   Each party shall hold in confidence any and all confidential information
     disclosed by the other, with regard to the above part numbers and shall
     exercise the same degree of diligence with respect to the dissemination of
     such information as that exercised with respect to their own confidential
     information which they do not want disclosed.

II.  Each party agrees not to disclose to any third party confidential
     information disclosed by the other or to offer for sale or otherwise
     dispose of to any third party devices (or information relating to the
     subject matter) utilizing any of the confidential information (unless
     otherwise authorized in writing).

Information disclosed hereunder shall not be deemed to be confidential if:

          A.   The information was generally available to the public at the time
               of disclosure to the receiving party; or
          B.   The information hereafter becomes generally available to the
               public, except as the result of unauthorized disclosure by the
               receiving party; or
          C.   The party disclosing the information agrees, in writing, that it
               can be disclosed, by the receiving party to a third party; or
          D.   The information is known to the receiving party and documented in
               writing prior to its receipt, is not subject to a non-disclosure
               commitment on the part of the receiving party, and the receiving
               party informs the disclosing party of such facts at the time of
               the disclosure; or
          E.   The information is or becomes available on an unrestricted basis
               to a third party from the disclosing party or from someone acting
               under its control (except that a corporate subsidiary of either
               party shall not be deemed a "third party" hereunder).

In the event the receiving party is obligated to produce such information, as a
result of court order or pursuant to governmental action and the transmitting
party shall have been given notice and an opportunity to appear and object to
such disclosure but is unsuccessful, then the receiving party may produce such
information as is required by the court order or governmental action to such
third party.

III. The disclosing party's confidential information shall be made available
     only to those employees of the receiving party who have a reasonable need
     for such information.

IV.  The parties agree not to utilize any such confidential information received
     under this Agreement in the manufacture of articles sold or offered for
     sale to anyone other than the disclosing party without prior written
     consent of the disclosing party, subject to the same exceptions set forth
     in Paragraph II above.

V.   Any confidential disclosure, if made orally, shall be identified as
     confidential prior to disclosure and shall be promptly confirmed in writing
     by the disclosing party, within 30 days, if the disclosing party wishes to
     keep such information proprietary under this Agreement.

<PAGE>

                                  EXHIBIT J

VI.  Nothing in this Agreement shall be construed to grant to either party any
     right or license under any patent of the other party.

VII. The obligations under paragraphs I, II, III, and IV shall continue for a
     period of one (1) year after the end of term of a Lease Agreement Between
     Stratus 7000 West Joint Venture as Landlord and Silicon Laboratories Inc.
     as Tenant dated OCTOBER 27, 1999.

VIII. It is understood by both parties that such information may relate to
     products that are under development or planned for development. BOTH
     PARTIES UNDERSTAND THAT NO WARRANTIES ARE MADE OR IMPLIED REGARDING THE
     ACCURACY OF THIS INFORMATION. Neither party accepts responsibility for any
     expense, losses, or action incurred or undertaken by the other as a result
     of the receipt of this information. It is further understood by both
     parties that neither party warrants or represents that it will introduce
     any product to which the information is disclosed herein is related.

IX   The adjudication of this agreement shall be governed by the laws of the
     State of Texas.

X.   The existence of this agreement and, the fact that confidential information
     exists and has been disclosed constitutes confidential information and
     shall be treated as such under the terms of this agreement.

By    /s/ Navdeep S. Sooch                   By   /s/ William H. Armstrong, III
      -------------------------                   -----------------------------
      Signature                                   Signature

      -------------------------                   -----------------------------
      Navdeep S. Sooch                            William H. Armstrong, III

      -------------------------                   -----------------------
      Chairman and Chief Executive Officer        President and CEO
      Silicon Laboratories Inc.                   Stratus Properties Inc.,
                                                  a Delaware limited
                                                  liability company