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  NEITHER THE SECURITY EVIDENCED BY THIS NOTE NOR THE SECURITIES ISSUABLE UPON
  CONVERSION HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
    OR THE SECURITIES LAWS OF ANY STATE, AND SUCH SECURITIES MAY NOT BE SOLD,
   PLEDGED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF REGISTRATION THEREUNDER
      OR AN EXEMPTION THEREFROM, UNLESS AN OPINION OF COUNSEL IS FURNISHED
      REASONABLY SATISFACTORY IN FORM AND SUBSTANCE TO THE COMPANY STATING
                    THAT AN EXEMPTION FROM THE REGISTRATION
            REQUIREMENTS OF APPLICABLE SECURITIES LAWS IS AVAILABLE.


                                 GLOBESPAN, INC.

                    SUBORDINATED CONVERTIBLE PROMISSORY NOTE


$90,000,000                                                    February 24, 2000
                                                            Red Bank, New Jersey


          FOR VALUE RECEIVED, GlobeSpan, Inc., a Delaware corporation
("Company"), promises to pay to PairGain Technologies, Inc. ("Holder"), or its
assigns, the principal sum of Ninety Million Dollars ($90,000,000.00), or such
lesser amount as shall equal the outstanding principal amount hereof, together
with interest from the date of this subordinated convertible promissory note
(this "Note") on the unpaid principal balance calculated in accordance with
Section 2 hereof. All unpaid principal, together with any then unpaid and
accrued interest and other amounts payable hereunder, shall be due and payable
on the earlier of (i) the seventh anniversary of the date of this Note, or (ii)
when, upon or after the occurrence of an Event of Default (as defined below),
such amounts are declared due and payable by Holder or made automatically due
and payable in accordance with the terms hereof. This Note is issued pursuant to
the Asset Purchase Agreement (as defined below).

          The following is a statement of the rights of Holder and the
conditions to which this Note is subject, and to which Holder, by the acceptance
of this Note, agrees:

          1. Definitions. As used in this Note, the following capitalized terms
have the following meanings:

               (a) "Asset Purchase Agreement" shall mean the Asset Purchase
Agreement dated January 21, 2000, between the Company and the Holder.

               (b) "Business Day" shall mean any day other than a Saturday,
Sunday or a legal holiday under the laws of the State of New York.

               (c) "Common Stock" shall mean the shares of common stock, par
value $0.001, of Company.

               (d) "Event of Default" has the meaning given in Section 4 hereof.


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               (e) "Holder" shall mean the Person specified in the introductory
paragraph of this Note or any Person who shall at the time be the holder of this
Note.

               (f) "Liquidity Event" shall mean (i) any consolidation or merger
of Company with or into any Person, or any other corporate reorganizations in
which Company shall not be the continuing or surviving entity of such
consolidation, merger or reorganization or any transaction or series of related
transactions by Company in which in excess of 50% of Company's voting power is
transferred; (ii) a sale of Company assets in one or a series of related
transactions where the aggregate gross proceeds to the Company are in excess of
$30,000,000; or (iii) a sale of debt or equity securities of the Company, where
the aggregate gross proceeds to the Company are in excess of $30,000,000.

               (g) "Obligations" shall mean and include all loans, advances,
debts, liabilities and obligations, howsoever arising, owed by Company to Holder
of every kind and description (whether or not evidenced by any note or
instrument and whether or not for the payment of money), now existing or
hereafter arising under or pursuant to the terms hereof, including, all
interest, fees, charges, expenses, attorneys' fees and costs and accountants'
fees and costs chargeable to and payable by Company hereunder and thereunder, in
each case, whether direct or indirect, absolute or contingent, due or to become
due, and whether or not arising after the commencement of a proceeding under
Title 11 of the United States Code (11 U. S. C. Section 101 et seq.), as amended
from time to time (including post-petition interest) and whether or not allowed
or allowable as a claim in any such proceeding.

               (h) "Person" shall mean and include an individual, a partnership,
a corporation (including a business trust), a joint stock company, a limited
liability company, an unincorporated association, a joint venture or other
entity or a governmental authority.

               (i) "Registration Rights Agreement" shall mean that certain
Registration Rights Agreement of even date herewith, between the Company and the
Holder.

               (j) "Senior Indebtedness" shall mean, unless expressly
subordinated to or made on a parity with the amounts due under this Note, the
principal of (and premium, if any), unpaid interest on and amounts reimbursable,
fees, expenses, costs of enforcement and other amounts due in connection with,
(i) indebtedness of Company, to banks, commercial finance lenders, insurance
companies, leasing or equipment financing institutions or other lending
institutions regularly engaged in the business of lending money (excluding
venture capital, investment banking or similar institutions which sometimes
engage in lending activities but which are primarily engaged in investments in
equity securities), which is for money borrowed, or purchase or leasing of
equipment in the case of lease or other equipment financing, whether or not
secured, and (ii) any such indebtedness or any debentures, notes or other
evidence of indebtedness issued in exchange for such Senior Indebtedness, or any
indebtedness arising from the satisfaction of such Senior Indebtedness by a
guarantor.

               (k) "Subsidiary" shall mean (a) any corporation of which more
than 50% of the issued and outstanding equity securities having ordinary voting

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power to elect a majority of the Board of Directors of such corporation is at
the time directly or indirectly owned or controlled by Company, (b) any
partnership, joint venture, or other association of which more than 50% of the
equity interest having the power to vote, direct or control the management of
such partnership, joint venture or other association is at the time directly or
indirectly owned and controlled by Company, (c) any other entity included in the
financial statements of Company on a consolidated basis.

          2. Interest. The interest rate to be applied to the unpaid principal
balance of this Note shall be five percent (5%) per annum (calculated on the
basis of a 360-day year consisting of twelve 30-day months). Interest shall
accrue and shall not be payable until the final maturity of the Note or its
earlier prepayment or conversion. If this Note or a portion hereof is called for
prepayment or conversion as provided herein, this Note or such portion shall
cease to bear interest on and after the date fixed for such prepayment or
conversion.

          3. Prepayment. At any time (i) on or prior to August 24, 2000, upon
fifteen days prior written notice to Holder, or (ii) after August 24, 2000,
concurrently with the consummation of a Liquidity Event, provided that Company
has given Holder not less than ten Business Days prior written notice of the
consummation of such Liquidity Event, Company may (subject to the limitations
set forth below in this Section 3), at its option, prepay, without penalty or
premium, this Note in whole or in part, from time to time, unless Holder elects
to convert this Note in accordance with section 7 of this Note; provided that
any such prepayment will be applied first to interest accrued on this Note to
the date of prepayment and second, if the amount of prepayment exceeds the
amount of all such expenses and accrued interest to the date of prepayment, to
the payment of principal of this Note. Any notice of prepayment given by the
Company under this Section 3 in connection with a Liquidity Event, shall include
the aggregate gross proceeds that the Company will receive in connection with
such Liquidity Event (the "Liquidity Proceeds") together with the amount under
this Note that the Company intends to prepay concurrently with the consummation
of such Liquidity Event (the "Prepayment Amount"); provided, that, in no event
shall the Prepayment Amount exceed the Liquidity Proceeds; provided, further,
that in the event such Liquidity Event is a sale of equity securities of the
Company pursuant to a registered offering under the Securities Act of 1933, as
amended, in which the Holder would be entitled to participate pursuant to the
terms of the Registration Rights Agreement, then in no event shall the
Prepayment Amount exceed the aggregate net proceeds that the Holder would have
received had the Holder elected to participate in such offering. In addition,
notice of prepayment or other notices shall be given by registered or certified
mail to the person in whose name this Note is registered at its address
designated on the register maintained by the Company on the date of making such
notice of prepayment or other notice.

          4. Events of Default. The occurrence of any of the following shall
constitute an "Event of Default" under this Note:

               (a) FAILURE TO PAY. Company shall fail to pay (i) when due any
principal payment on the due date hereunder or (ii) any interest or other
payment required under the terms of this Note on the date due and such payment
shall not have been made within five (5) Business Days of Company's receipt of
Holder's written notice to Company of such failure to pay; or
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               (b) VOLUNTARY BANKRUPTCY OR INSOLVENCY PROCEEDINGS. Company or
any of its Subsidiaries shall (i) apply for or consent to the appointment of a
receiver, trustee, liquidator or custodian of itself or of all or a substantial
part of its property, (ii) be unable, or admit in writing its inability, to pay
its debts generally as they mature, (iii) make a general assignment for the
benefit of its or any of its creditors, (iv) be dissolved or liquidated, (v)
become insolvent (as such term may be defined or interpreted under any
applicable statute), (vi) commence a voluntary case or other proceeding seeking
liquidation, reorganization or other relief with respect to itself or its debts
under any bankruptcy, insolvency or other similar law now or hereafter in effect
or consent to any such relief or to the appointment of or taking possession of
its property by any official in an involuntary case or other proceeding
commenced against it, or (vii) take any action for the purpose of effecting any
of the foregoing; or

               (c) INVOLUNTARY BANKRUPTCY OR INSOLVENCY PROCEEDINGS. Proceedings
for the appointment of a receiver, trustee, liquidator or custodian of Company
or any of its Subsidiaries or of all or a substantial part of the property
thereof, or an involuntary case or other proceedings seeking liquidation,
reorganization or other relief with respect to Company or any of its
Subsidiaries or the debts thereof under any bankruptcy, insolvency or other
similar law now or hereafter in effect shall be commenced and an order for
relief entered or such proceeding shall not be dismissed or discharged within
thirty (30) days of commencement.

          5. Rights of Holder upon Default. Upon the occurrence or existence of
any Event of Default (other than an Event of Default referred to in Sections
4(b) and 4(c)) and at any time thereafter during the continuance of such Event
of Default, Holder may, by written notice to Company, declare all outstanding
Obligations payable by Company hereunder to be immediately due and payable
without presentment, demand, protest or any other notice of any kind, all of
which are hereby expressly waived, anything contained herein to the contrary
notwithstanding. Upon the occurrence or existence of any Event of Default
described in Sections 4(b) and 4(c), immediately and without notice, all
outstanding Obligations payable by Company hereunder shall automatically become
immediately due and payable, without presentment, demand, protest or any other
notice of any kind, all of which are hereby expressly waived, anything contained
herein to the contrary notwithstanding. At any time after any declaration of
acceleration as to this Note has been made as provided in this Section 5, the
Holder may, by notice to the Company, rescind such declaration and its
consequences, if (i) the Company has paid all overdue installments of interest
on this Note and all principal that has become due otherwise than by such
declaration of acceleration and (ii) all other defaults and Events of Default
(other than nonpayments of principal and interest that have become due solely by
reason of acceleration) shall have been remedied or cured or shall have been
waived pursuant to this paragraph; provided, however, that no such recission
shall extend to or affect any subsequent default or Event of Default or impair
any right consequent thereon. In addition to the foregoing remedies, upon the
occurrence or existence of any Event of Default, Holder may exercise any other
right power or remedy permitted to it by law, either by suit in equity or by
action at law, or both.


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          6. Subordination.

               (a) SUBORDINATION. The indebtedness evidenced by this Note is
hereby expressly subordinated, to the extent and in the manner hereinafter set
forth, in right of payment to the prior payment in full of all of Company's
Senior Indebtedness.

               (b) FURTHER ASSURANCES. By acceptance of this Note, Holder agrees
to execute and deliver customary forms of subordination agreements requested
from time to time by holders of Senior Indebtedness, and as a condition to
Holder's rights hereunder, Company may require that Holder execute such forms of
subordination agreements; provided that such forms shall not impose on Holder
terms less favorable than those provided herein.

               (c) OTHER INDEBTEDNESS. No indebtedness which does not constitute
Senior Indebtedness shall be senior in any respect to the indebtedness
represented by this Note.

               (d) NO IMPAIRMENT. Subject to the rights, if any, of the holders
of Senior Indebtedness, under subordination agreements entered into between
Holder and holders of Senior Indebtedness, to receive cash, securities or other
properties otherwise payable or deliverable to Holder, nothing contained in this
Section 6 shall impair, as between Company and Holder, the obligation of
Company, subject to the terms and conditions hereof, to pay to Holder the
principal hereof and interest hereon as and when the same become due and
payable, or shall prevent Holder, upon default hereunder, from exercising all
rights, powers and remedies otherwise provided herein or by applicable law.

          7. Conversion.

               (a) VOLUNTARY CONVERSION. On or after August 24, 2000, Holder has
the right, at Holder's option, at any time prior to payment in full of this
Note, to convert this Note, in whole or in part, at the office of the Company or
any transfer agent into the number of shares of Common Stock of the Company
which is equal to the quotient obtained by dividing (A) the outstanding
principal unpaid amount of this Note (or a portion thereof) which the Holder
elects to convert, by (B) the Note Conversion Price, immediately in effect prior
to the time of such conversion. The "Note Conversion Price" shall be $92.49 (as
adjusted from time to time as provided below).

               (b) MECHANICS OF CONVERSION. This Note is convertible by
surrendering the original Note, duly endorsed, at the office of the Company or
of any transfer agent for the shares of Common Stock and giving written notice
to Company at such office that Holder elects to convert the same. Thereupon, the
Company shall, as soon as practicable thereafter, issue and deliver at such
office to Holder a certificate or certificates for the number of shares of
Common Stock to which Holder is entitled together with a check in an amount
equal to the amount of accrued but unpaid interest on the principal amount of
the Note which is being converted, and, if the Holder elects to convert less
than the entire unpaid amount of this Note, then the Company shall, at the same
time it issues and delivers the Common Stock certificate or certificates, issue
and deliver at such office to Holder a new promissory note, in substantially the
form hereof, representing the remaining amounts owing hereunder. Such conversion
shall be deemed to have been made immediately prior to the close of business on
the date of such surrender of the certificate or certificates representing the
shares to be converted, and the person entitled to receive the shares of Common
Stock issuable upon such conversion shall be treated for all purposes as the
record holder of such shares of Common Stock on such date.
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               (c) ADJUSTMENT FOR STOCK SPLITS AND COMBINATIONS. If the Company
at any time or from time to time after the date of this Note (the "Effective
Date") effects a division of the outstanding shares of Common Stock, then the
Note Conversion Price shall be proportionately decreased and, conversely, if
this Company at any time, or from time to time, after the Effective Date
combines the outstanding shares of Common Stock, then the Note Conversion Price
shall be proportionately increased. Any adjustment under this Section 7(c) shall
be effective on the close of business on the date such division or combination
becomes effective.

               (d) ADJUSTMENT FOR CERTAIN DIVIDENDS AND DISTRIBUTIONS. If the
Company at any time or from time to time after the Effective Date pays or fixes
a record date for the determination of holders of shares of Common Stock
entitled to receive a dividend or other distribution in the form of shares of
Common Stock, or rights or options for the purchase of, or securities
convertible into, Common Stock, then in each such event the Note Conversion
Price shall be decreased, as of the time of such payment or, in the event a
record date is fixed, as of the close of business of such record date, by
multiplying the Note Conversion Price by a fraction (i) the numerator of which
shall be the total number of shares of Common Stock outstanding immediately
prior to the time of such payment or the close of business on such record date,
as the case may be, and (ii) the denominator of which shall be the sum of (A)
the total number of shares of Common Stock outstanding immediately prior to the
time of such payment or the close of business on such record date, as the case
may be, plus (B) the number of shares of Common Stock issuable in payment of
such dividend or distribution or upon exercise of such option or right of
conversion; PROVIDED, HOWEVER, that if a record date is fixed and such dividend
is not fully paid or such other distribution is not fully made on the date fixed
therefor, then the Note Conversion Price shall not be decreased as of the close
of business on such record date as hereinabove provided as to the portion not
fully paid or distributed and thereafter the Note Conversion Price shall be
decreased pursuant to this Section 7(d) as of the date or dates of actual
payment of such dividend or distribution.

               (e) ADJUSTMENTS FOR OTHER DIVIDENDS AND DISTRIBUTIONS. If the
Company at any time or from time to time after the Effective Date pays, or fixes
a record date for the determination of holders of shares of Common Stock
entitled to receive, a dividend or other distribution in the form of securities
of the Company other than shares of Common Stock or rights or options for the
purchase of, or securities convertible into, Common Stock, then in each such
event provision shall be made so that the Holder shall receive upon conversion
of this Note, in addition to the number of shares of Common Stock receivable
thereupon, the amount of securities of the Company which it would have received
had this Note been converted into shares of Common Stock on the date one day
before such event (adjusted to account for any additional accrued but unpaid
interest and other fees due under this Note) and had Holder thereafter, from the
date of such event to and including the actual date of conversion of this Note,
retained such securities, subject to all other adjustments called for during
such period under this Section 7 with respect to the rights of the Holder.
<PAGE>

               (f) ADJUSTMENT FOR RECLASSIFICATION, EXCHANGE AND SUBSTITUTION.
If at any time or from time to time after the Effective Date the number of
shares of Common Stock issuable upon conversion of this Note, is changed into
the same or a different number of shares of any other class or classes of stock
or other securities, whether by recapitalization, reclassification or otherwise
(other than a recapitalization, division or combination of shares or a stock
dividend, or a reorganization, merger, consolidation or sale of assets provided
for elsewhere in this Section 7), then in any such event the Holder shall have
the right thereafter to convert this Note into the same kind and amount of stock
and other securities receivable upon such recapitalization, reclassification or
other change, as the maximum number of shares of Common Stock into which this
Note, could have been converted immediately prior to such recapitalization
(adjusted to account for any additional accrued but unpaid interest and other
fees due under this Note), reclassification or change, all subject to further
adjustment as provided herein.

               (g) REORGANIZATIONS, MERGERS, CONSOLIDATIONS OR SALES OF ASSETS.
If at any time or from time to time after the Effective Date there is a capital
reorganization of the Common Stock (other than a recapitalization, division,
combination, reclassification or exchange of shares provided for elsewhere in
this Section 7) or a merger or consolidation of this Company into or with
another corporation or the sale of all or substantially all of its assets to
another corporation in such a way (including, without limitation, by way of
consolidation or merger) that holders of Common Stock shall be entitled to
receive stock, securities or assets with respect to or in exchange for Common
Stock, then, unless this Note is converted prior thereto or prepaid upon
consummation thereof as provided in Section 3 above, as a part of such capital
reorganization, merger or ,consolidation, or sale, provision shall be made so
that the Holder shall thereafter receive upon conversion hereof the number of
shares of stock or other securities or property of this Company, or of the
successor corporation resulting from such capital reorganization, merger, or
consolidation or sale, to which a holder of the number of shares of Common Stock
into which this Note would have been entitled on such capital reorganization,
merger, consolidation or sale (adjusted to account for any additional accrued
but unpaid interest due under this Note). In any such case, appropriate
adjustment shall be made in the application of the provisions of this Section 7
with respect to the rights of the Holder after such capital reorganization,
merger, consolidation, or sale. The provisions of this Section 7 (including
adjustment of the Note Conversion Price and the number of shares into which this
Note may be converted) shall be applicable after that event and be as nearly
equivalent to such Note Conversion Prices and number of shares as may be
practicable.

               (h) FRACTIONAL SHARES; EFFECT OF CONVERSION. The Company may, but
shall not be obligated to, issue any fractional shares upon conversion of this
Note. In the event that Company elects not to issue fractional shares, Company
shall round the number of shares to the nearest whole share of each type of
Common Stock, provided that if such rounding would result in Holder receiving
less than 99.9% of the amount of such Common Stock to which it is entitled,
pursuant to this Section 7, such fraction shall be rounded up to the next whole
share of Common Stock.

               (i) RESERVATION OF STOCK ISSUABLE UPON CONVERSION. The Company
shall at all times reserve and keep available out of its authorized but unissued

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                                     [copy]


shares of Common Stock or treasury stock, solely for the purpose of effecting
the conversion of this Note, such number of shares of Common Stock as shall from
time to time be sufficient to effect the conversion of this Note.

          8. Successors and Assigns. Subject to the restrictions on transfer
described in Section 9 below, the rights and obligations of Company and Holder
of this Note shall be binding upon and benefit the successors, assigns, heirs,
administrators and transferees of the parties.

          9. Assignment by Company. Neither this Note nor any of the rights,
interests or obligations hereunder may be assigned, by operation of law or
otherwise, in whole or in part, by Company without the prior written consent of
Holder.

          10. Waiver. Company hereby waives presentment, demand, or protest and
any notice of any kind in connection with the delivery, acceptance, performance,
default, acceleration, or collection of this Note.

          11. Notices. Any notice, request or other communication required or
permitted hereunder shall be in writing and shall be deemed to have been duly
given if personally delivered or mailed by recognized overnight courier or
personal delivery at the respective addresses of the parties as set forth in the
Asset Purchase Agreement or on the register maintained by Company. Any party
hereto may by notice so given change its address for future notice hereunder.
Notice shall conclusively be deemed to have been given when received.

          12. Payment. Payments made hereunder shall be made in lawful tender of
the United States.

          13. Expenses. If action is instituted to collect any amounts owing
under this Note, Company promises to pay all costs and expenses, including,
without limitation, reasonable attorneys' fees and costs, incurred in connection
with such action.

          14. Governing Law. This Note and all actions arising out of or in
connection with this Note shall be governed by and construed in accordance with
the laws of the State of New York, without regard to the conflicts of law
provisions of the State of New York, or of any other state.

          IN WITNESS WHEREOF, Company has caused this Note to be issued as of
the date first written above.

GLOBESPAN, INC.,
a Delaware corporation



By:/s/Armando Geday [copy]
   Armando Geday, President and Chief
   Executive Officer