Document:

FIXED RATE SENIOR NOTE

REGISTERED                                                     REGISTERED
No. FXR                                                        $
                                                               CUSIP: 61744Y736

     Unless this certificate is presented by an authorized representative of
The Depository Trust Company (55 Water Street, New York, New York) to the
issuer or its agent for registration of transfer, exchange or payment, and any
certificate issued is registered in the name of Cede & Co. or such other name
as requested by an authorized representative of The Depository Trust Company
and any payment is made to Cede & Co., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF
FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL since the registered
owner hereof, Cede & Co., has an interest herein.

                                      A-1
<PAGE>

                        MORGAN STANLEY DEAN WITTER & CO.
                    SENIOR GLOBAL MEDIUM-TERM NOTE, SERIES C
                                  (Fixed Rate)

                   CONVERTIBLE NOTE PERFORMANCE EQUITY-LINKED
         REDEMPTION QUARTERLY-PAY SECURITIES ("CONVERTIBLE NOTE PERQS")

                  CONVERTIBLE NOTE PERQS DUE OCTOBER 31, 2001
                            MANDATORILY EXCHANGEABLE
              FOR 7% CONVERTIBLE SUBORDINATED DEBENTURES DUE 2005
                                OF SEPRACOR INC.

<TABLE>
<S>                        <C>                   <C>                        <C>
ORIGINAL ISSUE DATE:       INITIAL REDEMPTION    INTEREST RATE: See         MATURITY DATE:
              , 2000         DATE: N/A             "Interest Payments"        October 31, 2001;
                                                    below                     provided that if
                                                                              on the Determination
                                                                              Date Final Parity is
                                                                              greater than the
                                                                              Maximum Parity Amount
                                                                              and the Final Note
                                                                              Price not determined
                                                                              on the Determination
                                                                              Date, as provided under
                                                                              "--Final Note Price"
                                                                              below, the Maturity
                                                                              Date shall be the second
                                                                              Trading Day following
                                                                              the day on which the
                                                                              Calculation Agent
                                                                              determines the Final
                                                                              Note Price.

INTEREST ACCRUAL DATE:     INITIAL REDEMPTION    INTEREST PAYMENT           OPTIONAL REPAYMENT
              , 2000         PERCENTAGE: N/A       DATES: See "Interest       DATE(S): N/A
                                                   Payments" below

SPECIFIED CURRENCY:        ANNUAL REDEMPTION     INTEREST PAYMENT           APPLICABILITY OF
  U.S. Dollars               PERCENTAGE            PERIOD: See "Interest      MODIFIED PAYMENT UPON
                             REDUCTION: N/A        Payments" below            ACCELERATION: N/A

IF SPECIFIED                                     APPLICABILITY OF           If yes, state Issue
  CURRENCY OTHER                                   ANNUAL INTEREST            Price: N/A
  THAN U.S. DOLLARS,                               PAYMENTS: N/A
  OPTION TO ELECT
  PAYMENT IN U.S.
  DOLLARS: N/A

EXCHANGE RATE                                                               ORIGINAL YIELD TO
   AGENT: N/A                                                                 MATURITY: N/A

OTHER PROVISIONS:
  (See below)
</TABLE>

Denominations and
Principal Amount................. $              and integral multiples thereof

Interest Payments................ The Issuer shall pay a "Supplemental Coupon"
                                  at the rate of 10% per annum on each
                                  $________ principal amount of this
                                  Convertible Note PERQS on each Supplemental
                                  Coupon Interest Payment Date (equivalent to
                                  $____ per year per Convertible Note

                                      A-2
<PAGE>

                                  PERQS. The Supplemental Coupon Interest
                                  Payment Dates are January 31, 2001, April 30,
                                  2001, July 31, 2001 and October 31, 2001.

                                  The Issuer shall also pay an "Underlying
                                  Coupon" on each $________ principal amount of
                                  this Convertible Note PERQS shall be paid on
                                  each Underlying Coupon Interest Payment Date
                                  at a rate equal to the amount of interest, if
                                  any, paid by Sepracor (as defined below) on
                                  one Sepracor Note (as defined below) since
                                  the preceding Underlying Coupon Interest
                                  Payment Date (or since the Original Issue
                                  Date, as applicable) multiplied by the
                                  Exchange Ratio (subject to the terms
                                  described under "Discontinuance of Underlying
                                  Coupon Payments" below). The Underlying
                                  Coupon Interest Payment Dates are December
                                  30, 2000 and June 30, 2001.

Sepracor Notes................... 7% Convertible Subordinated Debentures due
                                  2005 of Sepracor Inc., or any successor
                                  security (CUSIP 817315AH7). The Sepracor
                                  Notes are convertible into Sepracor Stock.

Sepracor Stock................... The common stock, par value $0.10 per share,
                                  of Sepracor Inc., a Delaware corporation, or
                                  any successor entity ("Sepracor").

Exchange at Maturity............. At maturity, upon delivery of this
                                  Convertible Note PERQS to the Trustee, each
                                  $____ principal amount of this Convertible
                                  Note PERQS shall be applied by the Issuer as
                                  payment for a number of Sepracor Notes equal
                                  to the Exchange Ratio.

                                  The number of Sepracor Notes to be delivered
                                  at maturity shall be subject to any
                                  applicable adjustments to the Merger
                                  Consideration Value, as defined in "Certain
                                  Events Affecting the Sepracor Notes -- Merger
                                  or Other Corporate Events" below, to be
                                  delivered instead of, or in addition to, such
                                  Sepracor Notes as a result of any corporate
                                  event described under "Certain Events
                                  Affecting the Sepracor Notes -- Merger or
                                  Other Corporate Events" below, in each case,
                                  required to be made prior to the close of
                                  business on the second Trading Day
                                  immediately prior to maturity.

                                      A-3
<PAGE>

                                  All calculations with respect to the Exchange
                                  Ratio for the Convertible Note PERQS shall be
                                  rounded to the nearest one hundred-thousandth
                                  of a percentage point, with five
                                  one-millionths of a percentage point rounded
                                  upwards (e.g., 9.876545% (or .09876545 would
                                  be rounded to 9.87655% (or .0987655)); and
                                  all dollar amounts used in or resulting from
                                  such calculations shall be rounded to the
                                  nearest cent with one-half cent being rounded
                                  upwards.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to, (i) provide written
                                  notice to the Trustee at its New York office
                                  and to the Depositary, on which notice the
                                  Trustee and the Depositary may conclusively
                                  rely, on or prior to 10:30 a.m. on the
                                  Trading Day immediately prior to maturity of
                                  this Convertible Note PERQS, of the amount of
                                  Sepracor Notes (or the amount of Merger
                                  Consideration Value) to be delivered with
                                  respect to each $ principal amount of this
                                  Convertible Notes PERQS (or of any other
                                  securities included in the Merger
                                  Consideration Value, if applicable) allocated
                                  to each $ principal amount of this
                                  Convertible Note PERQS; provided that, if the
                                  maturity date of this Convertible Note PERQS
                                  is accelerated (other than an acceleration as
                                  a result of (i) an event of default described
                                  under "Certain Events Affecting the Sepracor
                                  Notes -- Events of Default" or (ii) a merger
                                  or other corporate event described under
                                  "Certain Events Affecting the Sepracor Notes
                                  -- Merger or Other Corporate Events"), the
                                  Issuer shall give notice of such acceleration
                                  as promptly as possible, and in no case later
                                  than two Business Days following such deemed
                                  maturity date, (i) to the holder of this
                                  Convertible Note PERQS by mailing notice of
                                  such acceleration by first class mail,
                                  postage prepaid and (ii) to the Trustee and
                                  the Depositary by telephone or facsimile
                                  confirmed by mailing such notice to the
                                  Trustee at its New York office and to the
                                  Depositary by first class mail, postage
                                  prepaid. Any notice that is mailed in the
                                  manner herein provided shall be conclusively
                                  presumed to have been duly given, whether or
                                  not the holder of this Convertible Note PERQS
                                  receives the notice.

                                      A-4
<PAGE>

                                  In addition, if the Maturity Date of this
                                  Convertible Note PERQS is extended, the
                                  Issuer shall provide notice immediately, by
                                  telephone or facsimile confirmed by mailing
                                  such notice by first class mail, postage
                                  prepaid to the Trustee and the Depositary, on
                                  which notice the Trustee and Depositary may
                                  conclusively rely, that (i) the Maturity Date
                                  has been deferred and (ii) the Issuer will
                                  specify by the same means the new Maturity
                                  Date as soon as practicable following the
                                  determination of the Final Note Price.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to, deliver any such
                                  Sepracor Notes and cash in respect of
                                  interest and any fractional Sepracor Notes
                                  and cash otherwise due upon any acceleration
                                  described above to the Trustee for delivery
                                  to the holder. The Calculation Agent shall
                                  determine the Exchange Ratio applicable at
                                  the maturity of this Convertible Note PERQS.
                                  References to payment "per Convertible Note
                                  PERQS" refer to each $ principal amount of
                                  this Convertible Note PERQS.

                                  If this Convertible Note PERQS is not
                                  surrendered for exchange at maturity, it
                                  shall be deemed to be no longer Outstanding
                                  under, and as defined in, the Senior
                                  Indenture (as defined on the reverse hereof),
                                  except with respect to the holder's right to
                                  receive the Sepracor Notes due at maturity.

No Fractional Sepracor Notes..... Upon delivery of this Convertible Note PERQS
                                  to the Trustee at maturity (including as a
                                  result of acceleration under the terms of the
                                  senior indenture or this Convertible Note
                                  PERQS), the Issuer shall deliver the
                                  aggregate number of Sepracor Notes due in
                                  respect of all such Convertible Note PERQS,
                                  as described above, but the Issuer shall pay
                                  cash in lieu of delivering any fractional
                                  Sepracor Note in an amount equal to the
                                  corresponding fractional Final Note Price of
                                  such fraction of a Sepracor Note as
                                  determined by the Calculation Agent as of the
                                  Determination Date (or, in the event of an
                                  acceleration, any other date on which Final
                                  Parity is determined).

                                      A-5
<PAGE>

Exchange Ratio................... If Final Parity is less than or equal to the
                                  Maximum Parity Amount, the Exchange Ratio
                                  shall be 0.5. If Final Parity is greater than
                                  the Maximum Parity Amount, the Exchange Ratio
                                  shall be 0.5 minus the Parity Excess
                                  Fraction.

Final Parity..................... Parity on the Determination Date

Parity........................... Parity on any date means the aggregate Market
                                  Price of the number of shares of Sepracor
                                  Stock into which one Sepracor Note would be
                                  convertible on such date, as determined by
                                  the Calculation Agent.

Maximum Parity Amount............ $          , equal to      % of Initial Parity

Initial Parity................... $          , which is Parity on the Pricing
                                  Date, as determined by the Calculation Agent

Parity Excess Fraction........... The Parity Excess Fraction is equal to 0.5
                                  times a fraction, the numerator of which
                                  shall be Final Parity minus the Maximum
                                  Parity Amount and the denominator of which
                                  shall be the Final Note Price.

Final Note Price................. The Final Note Price shall be the highest bid
                                  price for Sepracor Notes, plus accrued but
                                  unpaid interest, obtained from as many
                                  dealers or other institutional purchasers in
                                  the Sepracor Notes (which may include MS &
                                  Co. or any of the Issuer's other subsidiaries
                                  or affiliates), but not exceeding three, as
                                  shall make such bid prices available to the
                                  Calculation Agent on the Determination Date;
                                  provided that such bid prices shall be for a
                                  number of Sepracor Notes, as determined by
                                  the Calculation Agent, approximately equal in
                                  value to the Parity Excess Fraction
                                  multiplied by the aggregate principal amount
                                  of Convertible Note PERQS then outstanding;
                                  provided further that if the Calculation
                                  Agent is unable to obtain at least two such
                                  bid prices on the Determination Date, the
                                  Final Note Price shall be determined on the
                                  next succeeding Trading Day on which the
                                  Calculation Agent is able to obtain at least
                                  two such bid prices; provided further that if
                                  the

                                      A-6
<PAGE>

                                  Calculation Agent has not been able to obtain
                                  two such bid prices by the fifth Trading Day
                                  following the Determination Date, then the
                                  Calculation Agent shall determine the Final
                                  Note Price on such day in good faith using
                                  its reasonable judgment.

Determination Date............... October 26, 2001, or if such day is not a
                                  Trading Day or if there is a Market
                                  Disruption Event on such day, the
                                  Determination Date shall be the immediately
                                  succeeding Trading Day during which no Market
                                  Disruption Event shall have occurred;
                                  provided that the Determination Date shall be
                                  no later than the second scheduled Trading
                                  Day preceding the scheduled Maturity Date,
                                  notwithstanding the occurrence of a Market
                                  Disruption Event on such second scheduled
                                  Trading Day. See also "-Final Parity" above.

Market Price..................... If Sepracor Stock (or any other security for
                                  which a Market Price must be determined) is
                                  listed on a national securities exchange, is
                                  a security of the Nasdaq National Market or
                                  is included in the OTC Bulletin Board Service
                                  (the "OTC Bulletin Board") operated by the
                                  National Association of Securities Dealers,
                                  Inc. (the "NASD"), the Market Price for one
                                  share of Sepracor Stock (or one unit of any
                                  such other security) on any Trading Day means
                                  (i) the last reported sale price, regular
                                  way, of the principal trading session on such
                                  day on the principal United States securities
                                  exchange registered under the Securities
                                  Exchange Act of 1934, as amended (the
                                  "Exchange Act"), on which Sepracor Stock (or
                                  such other security) is listed or admitted to
                                  trading or (ii) if not listed or admitted to
                                  trading on any such securities exchange or if
                                  such last reported sale price is not
                                  obtainable (even if Sepracor Stock (or any
                                  such other security) is listed or admitted to
                                  trading on such securities exchange), the
                                  last reported sale price of the principal
                                  trading session on the over-the-counter
                                  market as reported on the Nasdaq National
                                  Market or OTC Bulletin Board on such day. If
                                  the last reported sale price is not available
                                  pursuant to clause (i) or (ii) of the
                                  preceding sentence because of a Market
                                  Disruption Event or otherwise, the Market
                                  Price for any Trading Day shall be the mean,
                                  as determined by the Calculation Agent, of

                                      A-7
<PAGE>

                                  the bid prices for Sepracor Stock (or any
                                  such other security) obtained from as many
                                  dealers in such security (which may include
                                  MS & Co. or any of its affiliates), but not
                                  exceeding three, as shall make such bid
                                  prices available to the Calculation Agent.
                                  The term "securities traded on the Nasdaq
                                  National Market" shall include a security
                                  included in any successor to such system and
                                  the term "OTC Bulletin Board Service" shall
                                  include any successor service thereto.

Trading Day...................... A day on which trading is generally conducted
                                  on the New York Stock Exchange ("NYSE"), the
                                  American Stock Exchange LLC, the Nasdaq
                                  National Market, the Chicago Mercantile
                                  Exchange and the Chicago Board of Options
                                  Exchange and in the over-the-counter market
                                  for equity securities in the United States,
                                  as determined by the Calculation Agent.

Business Day..................... Any day other than a Saturday or Sunday, that
                                  is neither a legal holiday nor a day on which
                                  banking institutions are authorized or
                                  required by law or regulation to close in The
                                  City of New York.

Optional Redemption.............. The Issuer shall not redeem this Convertible
                                  Note PERQS prior to the Maturity Date, and
                                  this Convertible Note PERQS shall not be
                                  exchangeable by the holder prior to the
                                  Maturity Date.

Discontinuance of Underlying
Coupon Payments.................. If there is a default by Sepracor with
                                  respect to the payment of interest on the
                                  Sepracor Notes, the Issuer shall discontinue
                                  payments of the Underlying Coupon on this
                                  Convertible Note PERQS and the Issuer shall
                                  have the right to accelerate the maturity of
                                  this Convertible Note PERQS, as described
                                  under "Certain Events Affecting the Sepracor
                                  Notes." If the Issuer does not accelerate the
                                  maturity of this Convertible Note PERQS, the
                                  Issuer shall resume payments of the
                                  Underlying Coupon if, when and to the extent
                                  that such default is cured by Sepracor prior
                                  to the earlier of the Determination Date and
                                  the Early Determination Date (as defined
                                  under "Certain Events Affecting the Sepracor
                                  Notes" below). Upon a cure by Sepracor of any
                                  such default, the Issuer shall promptly, but
                                  in no

                                      A-8
<PAGE>

                                  event later than two Business Days following
                                  the date on which holders of the Sepracor
                                  Notes receive a payment of delinquent
                                  interest with respect to the Sepracor Notes,
                                  pay to each holder an amount per each $______
                                  principal amount of this Convertible Note
                                  PERQS equal to the amount of delinquent
                                  interest paid by Sepracor to the holders of a
                                  Sepracor Note multiplied by the Exchange
                                  Ratio. Payment of the Underlying Coupon on
                                  this Convertible Note PERQS shall thereafter
                                  be paid on the next applicable succeeding
                                  Interest Payment Date, as described under
                                  "Interest Payments" above, subject to the
                                  conditions set forth in this paragraph.

                                  A discontinuance of payments of the
                                  Underlying Coupon, whether or not resumed,
                                  pursuant to the immediately preceding
                                  paragraph shall not constitute a default
                                  under the Senior Indenture for this
                                  Convertible Note PERQS.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to, provide written notice
                                  to the Trustee at its New York office, on
                                  which notice the Trustee can conclusively
                                  rely, and to the holders (i) no later than
                                  10:00 a.m. on the Business Day next
                                  succeeding an interest payment date for the
                                  Sepracor Notes of any default by Sepracor in
                                  the payment of interest on the Sepracor Notes
                                  and (ii) no later than 10:00 a.m. on the
                                  Business Day next succeeding any payment of
                                  interest on the Sepracor Notes by Sepracor to
                                  cure any such default of the amount of
                                  interest to be delivered per Convertible Note
                                  PERQS.

Certain Events Affecting
the Sepracor Notes............... Events of Default
                                  If, on any date prior to the Maturity Date,
                                  the Issuer becomes aware of an event of
                                  default with respect to the Sepracor Notes
                                  (such date, the "Default Notice Date"), the
                                  Issuer shall have the right, but not the
                                  obligation on the Default Notice Date and on
                                  any succeeding Trading Day (to and including
                                  the scheduled Trading Day immediately
                                  preceding the Determination Date) on which
                                  such event of default is continuing, to (i)
                                  deliver to the Trustee and the holders of
                                  this Convertible Note

                                      A-9
<PAGE>

                                  PERQS notice of such event of default (such
                                  date, the "Acceleration Notice Date") and
                                  (ii) accelerate the maturity of this
                                  Convertible Note PERQS and distribute, in
                                  exchange for each Convertible Note PERQS,
                                  Sepracor Notes at the Exchange Ratio,
                                  calculated as if the Acceleration Notice Date
                                  were the Determination Date (the "Early
                                  Determination Date"), plus (a) any accrued
                                  and unpaid Supplemental Coupons to such Early
                                  Determination Date and (b) the present value
                                  of any future Supplemental Coupons calculated
                                  based on the interpolated U.S. dollar zero
                                  swap rate, as determined by the Calculation
                                  Agent (such distribution, an "Early
                                  Distribution"); provided that if the
                                  Acceleration Notice Date is not a Trading Day
                                  or if there is a Market Disruption Event on
                                  such date, the Early Determination Date shall
                                  be the next succeeding Trading Day during
                                  which no Market Disruption Event shall have
                                  occurred; provided further that if it is
                                  necessary to determine a Final Note Price and
                                  two bid prices (as described under "Final
                                  Note Price") are not available on such day,
                                  the Calculation Agent shall determine the
                                  Final Note Price in good faith using its
                                  reasonable judgment. The Issuer shall make
                                  any such Early Distribution on the second
                                  Business Day next succeeding the Early
                                  Determination Date (the "Early Distribution
                                  Date"). If the Early Distribution Date falls
                                  after a record date for the payment of
                                  interest on the Sepracor Notes and prior to
                                  the immediately succeeding interest payment
                                  date, the Issuer shall not pay any accrued
                                  but unpaid Underlying Coupon on the Early
                                  Distribution Date; provided that the Issuer
                                  shall deliver, with the Sepracor Notes
                                  delivered on the Early Distribution Date,
                                  due-bills or other instruments with respect
                                  to such Sepracor Notes evidencing the
                                  transfer of title to any such interest
                                  payments.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to (i) provide written
                                  notice to the Trustee at its New York office,
                                  on which notice the Trustee can conclusively
                                  rely, and to the holders of this Convertible
                                  Note PERQS on or prior to 10:30 a.m. on the
                                  Business Day immediately preceding the Early
                                  Distribution Date (A) of the number of
                                  Sepracor Notes (and the amount of any cash in
                                  respect of interest or fractional Sepracor
                                  Notes) to be delivered per Convertible Note
                                  PERQS

                                      A-10
<PAGE>

                                  and (B) that such distribution is pursuant to
                                  a decision to accelerate this Convertible
                                  Note PERQS as a result of an event of default
                                  with respect to the Sepracor Notes and (ii)
                                  deliver on the Early Distribution Date the
                                  Early Distribution to the Trustee for
                                  delivery to the holders against delivery of
                                  this Convertible Note PERQS to the Trustee.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to, deliver any such
                                  Sepracor Notes and cash in respect of the
                                  Supplemental Coupon payable and any
                                  fractional Sepracor Notes and cash otherwise
                                  due upon an acceleration for an event of
                                  default with respect to the Sepracor Notes
                                  described above to the Trustee for delivery
                                  to the holder.

                                  If a "Fundamental Change," as described
                                  below, occurs as a result of a liquidation or
                                  other similar event that also constitutes an
                                  event of default, any acceleration of this
                                  Convertible Note PERQS shall be made in
                                  accordance with the procedures described
                                  above, rather than in accordance with
                                  procedures related to mergers or other
                                  corporate events described below.

                                  Mergers or Other Corporate Events
                                  If, as a result of a merger or other
                                  corporate event affecting Sepracor, the
                                  Sepracor Notes become convertible solely into
                                  equity securities other than Sepracor Stock,
                                  Parity shall be determined, and the Exchange
                                  Ratio shall be calculated, by reference to
                                  the Market Price of such other equity
                                  securities (unless such merger or other event
                                  constitutes a Fundamental Change, as defined
                                  below). The terms of this Convertible Note
                                  PERQS shall not otherwise change.

                                  If, as the result of such an event, the
                                  Sepracor Notes become convertible into (i)
                                  equity securities other than Sepracor Stock
                                  and (ii) cash or other property other than
                                  equity securities ("Other Merger
                                  Consideration"), then the Calculation Agent
                                  shall determine the total value (the "Merger
                                  Consideration Value") of such equity
                                  securities and such Other Merger
                                  Consideration on the date holders of Sepracor
                                  Stock receive such merger consideration (the
                                  "Merger Valuation Date"); provided

                                      A-11
<PAGE>

                                  that if such day is not a Trading Day, the
                                  Merger Valuation Date shall be the next
                                  succeeding Trading Day. The Calculation Agent
                                  shall make such determination by reference to
                                  (a) the Market Price of such securities, (b)
                                  the amount of such cash and (c) the fair
                                  market value, as determined by the
                                  Calculation Agent, of any such other
                                  property.

                                  If the value of the Other Merger
                                  Consideration on the Merger Valuation Date is
                                  less than or equal to 1% of the Merger
                                  Consideration Value, Parity shall be
                                  determined, and the Exchange Ratio shall be
                                  calculated, by reference to the Market Price
                                  of such equity securities and the value of
                                  the Other Merger Consideration (unless such
                                  merger or other event constitutes a
                                  Fundamental Change, as defined below). The
                                  terms of this Convertible Note PERQS shall
                                  not otherwise change.

                                  If (i) the value of the Other Merger
                                  Consideration on the Merger Valuation Date is
                                  greater than 1% of the Merger Consideration
                                  Value or (ii) such merger or other event
                                  constitutes a "Fundamental Change" under the
                                  terms of the Sepracor Notes, the Issuer shall
                                  accelerate the Convertible Note PERQS. A
                                  "Fundamental Change" with respect to the
                                  Sepracor Notes means an event which results
                                  in all or substantially all of the shares of
                                  common stock of Sepracor being exchanged for
                                  consideration which is not all or
                                  substantially all common stock which is
                                  listed on a national securities exchange or
                                  automated quotation system.

                                  If, as a result of a merger or other
                                  corporate event affecting Sepracor, the
                                  Sepracor Notes become convertible solely into
                                  Other Merger Consideration, the Issuer shall
                                  accelerate this Convertible Note PERQS.

                                  Acceleration Upon a Merger or Other Corporate
                                  Event
                                  If the Issuer accelerates this Convertible
                                  Note PERQS as a result of a situation
                                  described in either of the two immediately
                                  preceding paragraphs, (i) Parity shall be
                                  determined, and the Exchange Ratio shall be
                                  calculated, by reference to the Merger
                                  Consideration Value and (ii)

                                      A-12
<PAGE>

                                  the Issuer shall distribute, in exchange for
                                  each Convertible Note PERQS, Sepracor Notes
                                  at the Exchange Ratio, calculated as if the
                                  Merger Valuation Date were the Determination
                                  Date, plus any accrued and unpaid
                                  Supplemental Coupon to such Merger Valuation
                                  Date (such distribution, an "Merger
                                  Distribution"). The Issuer shall make any
                                  such Merger Distribution on the second
                                  Business Day next succeeding the Merger
                                  Valuation Date (the "Merger Distribution
                                  Date"). If the Merger Distribution Date falls
                                  after a record date for the payment of
                                  interest on the Sepracor Notes and prior to
                                  the immediately succeeding interest payment
                                  date, the Issuer shall not pay any accrued
                                  but unpaid Underlying Coupon on the Merger
                                  Distribution Date.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to (i) provide written
                                  notice to the Trustee at its New York office,
                                  on which notice the Trustee can conclusively
                                  rely, and to the holders of this Convertible
                                  Note PERQS on or prior to 10:30 a.m. on the
                                  Business Day immediately preceding the Merger
                                  Distribution Date (A) of the number of
                                  Sepracor Notes (and the amount of any cash)
                                  to be delivered per Convertible Note PERQS
                                  and (B) that such distribution is pursuant to
                                  an acceleration of this Convertible Note
                                  PERQS as a result of a merger or other
                                  corporate event with respect to Sepracor and
                                  (ii) deliver on the Merger Distribution Date
                                  the Merger Distribution to the Trustee for
                                  delivery to the holders against delivery of
                                  this Convertible Note PERQS to the Trustee.

                                  The Issuer shall, or shall cause the
                                  Calculation Agent to, deliver any such
                                  Sepracor Notes and cash in respect of any
                                  accrued but unpaid Supplemental Coupon
                                  interest and any fractional Sepracor Notes
                                  and cash otherwise due upon an acceleration
                                  occurring as a result of a merger or other
                                  corporate event described under "Certain
                                  Events Affecting the Sepracor Notes -- Merger
                                  or Other Corporate Events" to the Trustee for
                                  delivery to the holder.

                                  The holder shall not be entitled to tender or
                                  exchange Sepracor Stock or the Sepracor Notes
                                  in any tender or

                                      A-13
<PAGE>

                                  exchange offer by Sepracor or any third
                                  party, nor shall the holder be entitled to
                                  respond to any consent solicitation made to
                                  holders of the Sepracor Notes or have any
                                  other rights, including, without limitation,
                                  voting rights with respect to the Sepracor
                                  Notes or Sepracor Stock, until such time as
                                  the Issuer delivers the Sepracor Notes to the
                                  holder at maturity or Sepracor delivers
                                  Sepracor Stock to the holder upon conversion
                                  of the holder's Sepracor Notes, as
                                  applicable.

Calculation Agent................ Morgan Stanley & Co. Incorporated and its
                                  successors ("MS & Co.")

Market Disruption Event.......... "Market Disruption Event" means, with respect
                                  to Sepracor Stock (and any other security
                                  that may be included as Exchange Property):

                                  (i) a suspension, absence or material
                                  limitation of trading of Sepracor Stock (or
                                  any such security) on the primary market for
                                  Sepracor Stock (or any such security) for
                                  more than two hours of trading or during the
                                  one-half hour period preceding the close of
                                  trading in such market; or a breakdown or
                                  failure in the price and trade reporting
                                  systems of the primary market for Sepracor
                                  Stock (or any such security) as a result of
                                  which the reported trading prices for
                                  Sepracor Stock (or any such security) during
                                  the last one-half hour preceding the closing
                                  of trading in such market are materially
                                  inaccurate; or the suspension or material
                                  limitation on the primary market for trading
                                  in options contracts related to Sepracor
                                  Stock (or any such security), if available,
                                  during the one-half hour period preceding the
                                  close of trading in the applicable market, in
                                  each case as determined by the Calculation
                                  Agent in its sole discretion; and

                                  (ii) a determination by the Calculation Agent
                                  in its sole discretion that the event
                                  described in clause (i) above materially
                                  interfered with the ability of the Issuer or
                                  any of its affiliates to unwind all or a
                                  material portion of the hedge with respect to
                                  the Convertible Note PERQS due October 31,
                                  2001 (Mandatorily Exchangeable For 7%
                                  Convertible Subordinated Notes of Sepracor
                                  Inc.).

                                      A-14
<PAGE>

                                  For purposes of determining whether a Market
                                  Disruption Event has occurred: (1) a
                                  limitation on the hours or number of days of
                                  trading shall not constitute a Market
                                  Disruption Event if it results from an
                                  announced change in the regular business
                                  hours of the relevant exchange, (2) a
                                  decision to permanently discontinue trading
                                  in the relevant option contract shall not
                                  constitute a Market Disruption Event, (3)
                                  limitations pursuant to any applicable rule
                                  or regulation enacted or promulgated by the
                                  National Association of Securities Dealers
                                  (or any other self-regulatory organization
                                  with jurisdiction over the Nasdaq National
                                  Market) on trading during significant market
                                  fluctuations shall constitute a suspension,
                                  absence or material limitation of trading,
                                  (4) a suspension of trading in an options
                                  contract on Sepracor Stock (or any such
                                  security) by the primary securities market
                                  trading in such options, if available, by
                                  reason of (x) a price change exceeding limits
                                  set by such securities exchange or market,
                                  (y) an imbalance of orders relating to such
                                  contracts or (z) a disparity in bid and ask
                                  quotes relating to such contracts shall
                                  constitute a suspension, absence or material
                                  limitation of trading in options contracts
                                  related to Sepracor Stock (or any such
                                  security) and (5) a suspension, absence or
                                  material limitation of trading on the primary
                                  securities market on which options contracts
                                  related to Sepracor Stock are traded shall
                                  not include any time when such securities
                                  market is itself closed for trading under
                                  ordinary circumstances.

Alternative Determination Date
in case of an Event of Default
with respect to this Convertible
Note PERQS....................... In case an Event of Default with respect to
                                  any Convertible Note PERQS shall have
                                  occurred and be continuing, the number of
                                  Sepracor Notes for which each Convertible
                                  Note PERQS shall be exchangeable upon any
                                  acceleration of this Convertible Note PERQS
                                  shall be determined by the Calculation Agent
                                  as though the Determination Date were the
                                  date of acceleration. See "Exchange at
                                  Maturity" above. In addition, an amount equal
                                  to any accrued but unpaid Supplemental Coupon
                                  to but not including such date of
                                  acceleration shall be due and payable. If the
                                  date of acceleration falls after a record
                                  date for the payment of interest on the

                                      A-15
<PAGE>

                                  Sepracor Notes and prior to the immediately
                                  succeeding interest payment date, the Issuer
                                  shall not pay any accrued but unpaid
                                  Underlying Coupon on the date of
                                  acceleration.

United States Federal Income
Tax Purposes..................... The Issuer, by its sale of this Convertible
                                  Note PERQS, and the holders of this
                                  Convertible Note PERQS (and any successor
                                  holder of this PERQS), by its respective
                                  purchase thereof, agree (in the absence of an
                                  administrative determination or judicial
                                  ruling to the contrary) to characterize this
                                  Convertible Note PERQS for all tax purposes
                                  as an investment unit consisting of (i) a
                                  contract (the "Forward Contract") that
                                  requires the holder of this Convertible Note
                                  PERQS to purchase, and the Issuer to sell,
                                  for an amount equal to $ (the "Forward
                                  Price"), the Sepracor Notes at maturity (or,
                                  alternatively, upon an earlier redemption of
                                  this Convertible Note PERQS), and (ii) a
                                  deposit with the Issuer of a fixed amount of
                                  cash, equal to the Issue Price, to secure the
                                  holder's obligation to purchase the Sepracor
                                  Notes (the "Deposit").

                                      A-16
<PAGE>

     Morgan Stanley Dean Witter & Co., a Delaware corporation (together with
its successors and assigns, the "Issuer"), for value received, hereby promises
to pay to CEDE & CO., or registered assignees, the amount of Sepracor
Notes (or other Exchange Property), as determined in accordance with the
provisions set forth under "Exchange at Maturity" above, due with respect to
the principal sum of U.S.$          (UNITED STATES DOLLARS                  )
on the Maturity Date specified above (except to the extent redeemed or repaid
prior to maturity) and to pay interest thereon at the Interest Rate per annum
specified above, from and including the Interest Accrual Date specified above
until the principal hereof is paid or duly made available for payment weekly,
monthly, quarterly, semiannually or annually in arrears as specified above as
the Interest Payment Period on each Interest Payment Date (as specified above),
commencing on the Interest Payment Date next succeeding the Interest Accrual
Date specified above, and at maturity (or on any redemption or repayment date);
provided, however, that if the Interest Accrual Date occurs between a Record
Date, as defined below, and the next succeeding Interest Payment Date, interest
payments will commence on the second Interest Payment Date succeeding the
Interest Accrual Date to the registered holder of this Note on the Record Date
with respect to such second Interest Payment Date; and provided, further, that
if this Note is subject to "Annual Interest Payments," interest payments shall
be made annually in arrears and the term "Interest Payment Date" shall be
deemed to mean the first day of March in each year.

     Interest on this Note will accrue from and including the most recent date
to which interest has been paid or duly provided for, or, if no interest has
been paid or duly provided for, from and including the Interest Accrual Date,
until, but excluding the date the principal hereof has been paid or duly made
available for payment. The interest so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, subject to certain exceptions
described herein, be paid to the person in whose name this Note (or one or more
predecessor Notes) is registered at the close of business on the date 15
calendar days prior to such Interest Payment Date (whether or not a Business
Day (as defined below)) (each such date a "Record Date"); provided, however,
that interest payable at maturity (or any redemption or repayment date) will be
payable to the person to whom the principal hereof shall be payable. As used
herein, "Business Day" means any day, other than a Saturday or Sunday, (a) that
is neither a legal holiday nor a day on which banking institutions are
authorized or required by law or regulation to close (x) in The City of New
York or (y) if this Note is denominated in a Specified Currency other than U.S.
dollars, Australian dollars or euro, in the principal financial center of the
country of the Specified Currency, or (z) if this Note is denominated in
Australian dollars, in Sydney and (b) if this Note is denominated in euro, that
is also a day on which the Trans-European Automated Real-time Gross Settlement
Express Transfer System ("TARGET") is operating (a "TARGET Settlement Day").

     Payment of the principal of this Note, any premium and the interest due at
maturity (or any redemption or repayment date), unless this Note is denominated
in a Specified Currency other than U.S. dollars and is to be paid in whole or
in part in such Specified Currency, will be made in immediately available funds
upon surrender of this Note at the office or agency of the Paying Agent, as
defined on the reverse hereof, maintained for that purpose in the Borough of
Manhattan, The City of New York, or at such other paying agency as the Issuer
may determine, in U.S. dollars. U.S. dollar payments of interest, other than
interest due at maturity or on any date of redemption or

                                      A-17
<PAGE>

repayment, will be made by U.S. dollar check mailed to the address of the
person entitled thereto as such address shall appear in the Note register. A
holder of U.S. $10,000,000 (or the equivalent in a Specified Currency) or more
in aggregate principal amount of Notes having the same Interest Payment Date,
the interest on which is payable in U.S. dollars, shall be entitled to receive
payments of interest, other than interest due at maturity or on any date of
redemption or repayment, by wire transfer of immediately available funds if
appropriate wire transfer instructions have been received by the Paying Agent
in writing not less than 15 calendar days prior to the applicable Interest
Payment Date.

     If this Note is denominated in a Specified Currency other than U.S.
dollars, and the holder does not elect (in whole or in part) to receive payment
in U.S. dollars pursuant to the next succeeding paragraph, payments of
interest, principal or any premium with regard to this Note will be made by
wire transfer of immediately available funds to an account maintained by the
holder hereof with a bank located outside the United States if appropriate wire
transfer instructions have been received by the Paying Agent in writing, with
respect to payments of interest, on or prior to the fifth Business Day after
the applicable Record Date and, with respect to payments of principal or any
premium, at least ten Business Days prior to the Maturity Date or any
redemption or repayment date, as the case may be; provided that, if payment of
interest, principal or any premium with regard to this Note is payable in euro,
the account must be a euro account in a country for which the euro is the
lawful currency, provided, further, that if such wire transfer instructions are
not received, such payments will be made by check payable in such Specified
Currency mailed to the address of the person entitled thereto as such address
shall appear in the Note register; and provided, further, that payment of the
principal of this Note, any premium and the interest due at maturity (or on any
redemption or repayment date) will be made upon surrender of this Note at the
office or agency referred to in the preceding paragraph.

     If so indicated on the face hereof, the holder of this Note, if
denominated in a Specified Currency other than U.S. dollars, may elect to
receive all or a portion of payments on this Note in U.S. dollars by
transmitting a written request to the Paying Agent, on or prior to the fifth
Business Day after such Record Date or at least ten Business Days prior to the
Maturity Date or any redemption or repayment date, as the case may be. Such
election shall remain in effect unless such request is revoked by written
notice to the Paying Agent as to all or a portion of payments on this Note at
least five Business Days prior to such Record Date, for payments of interest,
or at least ten days prior to the Maturity Date or any redemption or repayment
date, for payments of principal, as the case may be.

     If the holder elects to receive all or a portion of payments of principal
of and any premium and interest on this Note, if denominated in a Specified
Currency other than U.S. dollars, in U.S. dollars, the Exchange Rate Agent (as
defined on the reverse hereof) will convert such payments into U.S. dollars. In
the event of such an election, payment in respect of this Note will be based
upon the exchange rate as determined by the Exchange Rate Agent based on the
highest bid quotation in The City of New York received by such Exchange Rate
Agent at approximately 11:00 a.m., New York City time, on the second Business
Day preceding the applicable payment date from three recognized foreign
exchange dealers (one of which may be the Exchange Rate Agent unless such

                                      A-18
<PAGE>

Exchange Rate Agent is an affiliate of the Issuer) for the purchase by the
quoting dealer of U.S. dollars for the Specified Currency for settlement on
such payment date in the amount of the Specified Currency payable in the
absence of such an election to such holder and at which the applicable dealer
commits to execute a contract. If such bid quotations are not available, such
payment will be made in the Specified Currency. All currency exchange costs
will be borne by the holder of this Note by deductions from such payments.

     Reference is hereby made to the further provisions of this Note set forth
on the reverse hereof, which further provisions shall for all purposes have the
same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof by manual signature, this Note shall
not be entitled to any benefit under the Senior Indenture, as defined on the
reverse hereof, or be valid or obligatory for any purpose.

                                      A-19
<PAGE>

     IN WITNESS WHEREOF, the Issuer has caused this Note to be duly executed.

DATED:                                  MORGAN STANLEY DEAN WITTER & CO.

                                        By:
                                           -----------------------------------
                                           Name:
                                           Title:

TRUSTEE'S CERTIFICATE
  OF AUTHENTICATION

This is one of the Notes referred
  to in the within-mentioned
  Senior Indenture.

THE CHASE MANHATTAN BANK,
  as Trustee

By:
   ------------------------------
   Authorized Officer

                                      A-20
<PAGE>

                              REVERSE OF SECURITY

     This Note is one of a duly authorized issue of Senior Global Medium-Term
Notes, Series C, having maturities more than nine months from the date of issue
(the "Notes") of the Issuer. The Notes are issuable under an Amended and
Restated Senior Indenture, dated as of May 1, 1999, between the Issuer and The
Chase Manhattan Bank, as Trustee (the "Trustee," which term includes any
successor trustee under the Senior Indenture) (as may be amended or
supplemented from time to time, the "Senior Indenture"), to which Senior
Indenture and all indentures supplemental thereto reference is hereby made for
a statement of the respective rights, limitations of rights, duties and
immunities of the Issuer, the Trustee and holders of the Notes and the terms
upon which the Notes are, and are to be, authenticated and delivered. The
Issuer has appointed The Chase Manhattan Bank at its corporate trust office in
The City of New York as the paying agent (the "Paying Agent," which term
includes any additional or successor Paying Agent appointed by the Issuer) with
respect to the Notes. The terms of individual Notes may vary with respect to
interest rates, interest rate formulas, issue dates, maturity dates, or
otherwise, all as provided in the Senior Indenture. To the extent not
inconsistent herewith, the terms of the Senior Indenture are hereby
incorporated by reference herein.

     Unless otherwise indicated on the face hereof, this Note will not be
subject to any sinking fund and, unless otherwise provided on the face hereof
in accordance with the provisions of the following two paragraphs, will not be
redeemable or subject to repayment at the option of the holder prior to
maturity.

     If so indicated on the face hereof, this Note may be redeemed in whole or
in part at the option of the Issuer on or after the Initial Redemption Date
specified on the face hereof on the terms set forth on the face hereof,
together with interest accrued and unpaid hereon to the date of redemption. If
this Note is subject to "Annual Redemption Percentage Reduction," the Initial
Redemption Percentage indicated on the face hereof will be reduced on each
anniversary of the Initial Redemption Date by the Annual Redemption Percentage
Reduction specified on the face hereof until the redemption price of this Note
is 100% of the principal amount hereof, together with interest accrued and
unpaid hereon to the date of redemption. Notice of redemption shall be mailed
to the registered holders of the Notes designated for redemption at their
addresses as the same shall appear on the Note register not less than 30 nor
more than 60 days prior to the date fixed for redemption or within the
Redemption Notice Period specified on the face hereof, subject to all the
conditions and provisions of the Senior Indenture. In the event of redemption
of this Note in part only, a new Note or Notes for the amount of the unredeemed
portion hereof shall be issued in the name of the holder hereof upon the
cancellation hereof.

     If so indicated on the face of this Note, this Note will be subject to
repayment at the option of the holder on the Optional Repayment Date or Dates
specified on the face hereof on the terms set forth herein. On any Optional
Repayment Date, this Note will be repayable in whole or in part in increments
of $1,000 or, if this Note is denominated in a Specified Currency other than
U.S. dollars, in increments of 1,000 units of such Specified Currency (provided
that any remaining principal amount hereof shall not be less than the minimum
authorized denomination hereof) at the option of the holder hereof at a price
equal to 100% of the principal amount to be repaid, together with interest

                                      A-21
<PAGE>

accrued and unpaid hereon to the date of repayment. For this Note to be repaid
at the option of the holder hereof, the Paying Agent must receive at its
corporate trust office in the Borough of Manhattan, The City of New York, at
least 15 but not more than 30 days prior to the date of repayment, (i) this
Note with the form entitled "Option to Elect Repayment" below duly completed or
(ii) a telegram, telex, facsimile transmission or a letter from a member of a
national securities exchange or the National Association of Securities Dealers,
Inc. or a commercial bank or a trust company in the United States setting forth
the name of the holder of this Note, the principal amount hereof, the
certificate number of this Note or a description of this Note's tenor and
terms, the principal amount hereof to be repaid, a statement that the option to
elect repayment is being exercised thereby and a guarantee that this Note,
together with the form entitled "Option to Elect Repayment" duly completed,
will be received by the Paying Agent not later than the fifth Business Day
after the date of such telegram, telex, facsimile transmission or letter;
provided, that such telegram, telex, facsimile transmission or letter shall
only be effective if this Note and form duly completed are received by the
Paying Agent by such fifth Business Day. Exercise of such repayment option by
the holder hereof shall be irrevocable. In the event of repayment of this Note
in part only, a new Note or Notes for the amount of the unpaid portion hereof
shall be issued in the name of the holder hereof upon the cancellation hereof.

     Interest payments on this Note will include interest accrued to but
excluding the Interest Payment Dates or the Maturity Date (or any earlier
redemption or repayment date), as the case may be. Unless otherwise provided on
the face hereof, interest payments for this Note will be computed and paid on
the basis of a 360-day year of twelve 30-day months.

     In the case where the Interest Payment Date or the Maturity Date (or any
redemption or repayment date) does not fall on a Business Day, payment of
interest, premium, if any, or principal otherwise payable on such date need not
be made on such date, but may be made on the next succeeding Business Day with
the same force and effect as if made on the Interest Payment Date or on the
Maturity Date (or any redemption or repayment date), and no interest on such
payment shall accrue for the period from and after the Interest Payment Date or
the Maturity Date (or any redemption or repayment date) to such next succeeding
Business Day.

     This Note and all the obligations of the Issuer hereunder are direct,
unsecured obligations of the Issuer and rank without preference or priority
among themselves and pari passu with all other existing and future unsecured
and unsubordinated indebtedness of the Issuer, subject to certain statutory
exceptions in the event of liquidation upon insolvency.

     This Note, and any Note or Notes issued upon transfer or exchange hereof,
is issuable only in fully registered form, without coupons, and, if denominated
in U.S. dollars, is issuable only in denominations of U.S. $1,000 and any
integral multiple of U.S. $1,000 in excess thereof. If this Note is denominated
in a Specified Currency other than U.S. dollars, then, unless a higher minimum
denomination is required by applicable law, it is issuable only in
denominations of the equivalent of U.S. $1,000 (rounded to an integral multiple
of 1,000 units of such Specified Currency), or any amount in excess thereof
which is an integral multiple of 1,000 units of such Specified Currency, as
determined by reference to the noon dollar buying rate in The City of New York
for cable

                                      A-22
<PAGE>

transfers of such Specified Currency published by the Federal Reserve Bank of
New York (the "Market Exchange Rate") on the Business Day immediately preceding
the date of issuance.

     The Trustee has been appointed registrar for the Notes, and the Trustee
will maintain at its office in The City of New York a register for the
registration and transfer of Notes. This Note may be transferred at the
aforesaid office of the Trustee by surrendering this Note for cancellation,
accompanied by a written instrument of transfer in form satisfactory to the
Trustee and duly executed by the registered holder hereof in person or by the
holder's attorney duly authorized in writing, and thereupon the Trustee shall
issue in the name of the transferee or transferees, in exchange herefor, a new
Note or Notes having identical terms and provisions and having a like aggregate
principal amount in authorized denominations, subject to the terms and
conditions set forth herein; provided, however, that the Trustee will not be
required (i) to register the transfer of or exchange any Note that has been
called for redemption in whole or in part, except the unredeemed portion of
Notes being redeemed in part, (ii) to register the transfer of or exchange any
Note if the holder thereof has exercised his right, if any, to require the
Issuer to repurchase such Note in whole or in part, except the portion of such
Note not required to be repurchased, or (iii) to register the transfer of or
exchange Notes to the extent and during the period so provided in the Senior
Indenture with respect to the redemption of Notes. Notes are exchangeable at
said office for other Notes of other authorized denominations of equal
aggregate principal amount having identical terms and provisions. All such
exchanges and transfers of Notes will be free of charge, but the Issuer may
require payment of a sum sufficient to cover any tax or other governmental
charge in connection therewith. All Notes surrendered for exchange shall be
accompanied by a written instrument of transfer in form satisfactory to the
Trustee and executed by the registered holder in person or by the holder's
attorney duly authorized in writing. The date of registration of any Note
delivered upon any exchange or transfer of Notes shall be such that no gain or
loss of interest results from such exchange or transfer.

     In case this Note shall at any time become mutilated, defaced or be
destroyed, lost or stolen and this Note or evidence of the loss, theft or
destruction thereof (together with the indemnity hereinafter referred to and
such other documents or proof as may be required in the premises) shall be
delivered to the Trustee, the Issuer in its discretion may execute a new Note
of like tenor in exchange for this Note, but, if this Note is destroyed, lost
or stolen, only upon receipt of evidence satisfactory to the Trustee and the
Issuer that this Note was destroyed or lost or stolen and, if required, upon
receipt also of indemnity satisfactory to each of them. All expenses and
reasonable charges associated with procuring such indemnity and with the
preparation, authentication and delivery of a new Note shall be borne by the
owner of the Note mutilated, defaced, destroyed, lost or stolen.

     The Senior Indenture provides that (a) if an Event of Default (as defined
in the Senior Indenture) due to the default in payment of principal of,
premium, if any, or interest on, any series of debt securities issued under the
Senior Indenture, including the series of Senior Medium-Term Notes of which
this Note forms a part, or due to the default in the performance or breach of
any other covenant or warranty of the Issuer applicable to the debt securities
of such series but not applicable to all outstanding debt securities issued
under the Senior Indenture shall have occurred

                                      A-23
<PAGE>

and be continuing, either the Trustee or the holders of not less than 25% in
principal amount of the debt securities of each affected series (voting as a
single class) may then declare the principal of all debt securities of all such
series and interest accrued thereon to be due and payable immediately and (b)
if an Event of Default due to a default in the performance of any other of the
covenants or agreements in the Senior Indenture applicable to all outstanding
debt securities issued thereunder, including this Note, or due to certain
events of bankruptcy or insolvency of the Issuer, shall have occurred and be
continuing, either the Trustee or the holders of not less than 25% in principal
amount of all debt securities issued under the Senior Indenture then
outstanding (treated as one class) may declare the principal of all such debt
securities and interest accrued thereon to be due and payable immediately, but
upon certain conditions such declarations may be annulled and past defaults may
be waived (except a continuing default in payment of principal (or premium, if
any) or interest on such debt securities) by the holders of a majority in
principal amount of the debt securities of all affected series then
outstanding.

     If the face hereof indicates that this Note is subject to "Modified
Payment upon Acceleration," then (i) if the principal hereof is declared to be
due and payable as described in the preceding paragraph, the amount of
principal due and payable with respect to this Note shall be limited to the
aggregate principal amount hereof multiplied by the sum of the Issue Price
specified on the face hereof (expressed as a percentage of the aggregate
principal amount) plus the original issue discount amortized from the Interest
Accrual Date to the date of declaration, which amortization shall be calculated
using the "interest method" (computed in accordance with generally accepted
accounting principles in effect on the date of declaration), (ii) for the
purpose of any vote of securityholders taken pursuant to the Senior Indenture
prior to the acceleration of payment of this Note, the principal amount hereof
shall equal the amount that would be due and payable hereon, calculated as set
forth in clause (i) above, if this Note were declared to be due and payable on
the date of any such vote and (iii) for the purpose of any vote of
securityholders taken pursuant to the Senior Indenture following the
acceleration of payment of this Note, the principal amount hereof shall equal
the amount of principal due and payable with respect to this Note, calculated
as set forth in clause (i) above.

     The Senior Indenture permits the Issuer and the Trustee, with the consent
of the holders of not less than a majority in aggregate principal amount of the
debt securities of all series issued under the Senior Indenture then
outstanding and affected (voting as one class), to execute supplemental
indentures adding any provisions to or changing in any manner the rights of the
holders of each series so affected; provided that the Issuer and the Trustee
may not, without the consent of the holder of each outstanding debt security
affected thereby, (a) extend the final maturity of any such debt security, or
reduce the principal amount thereof, or reduce the rate or extend the time of
payment of interest thereon, or reduce any amount payable on redemption or
repayment thereof, or change the currency of payment thereof, or modify or
amend the provisions for conversion of any currency into any other currency, or
modify or amend the provisions for conversion or exchange of the debt security
for securities of the Issuer or other entities (other than as provided in the
antidilution provisions or other similar adjustment provisions of the debt
securities or otherwise in accordance with the terms thereof), or impair or
affect the rights of any holder to institute suit for the payment thereof
without the consent of the holder of each debt security so affected or (b)
reduce the aforesaid

                                      A-24
<PAGE>

percentage in principal amount of debt securities the consent of the holders of
which is required for any such supplemental indenture.

     Except as set forth below, if the principal of, premium, if any, or
interest on, this Note is payable in a Specified Currency other than U.S.
dollars and such Specified Currency is not available to the Issuer for making
payments hereon due to the imposition of exchange controls or other
circumstances beyond the control of the Issuer or is no longer used by the
government of the country issuing such currency or for the settlement of
transactions by public institutions within the international banking community,
then the Issuer will be entitled to satisfy its obligations to the holder of
this Note by making such payments in U.S. dollars on the basis of the Market
Exchange Rate on the date of such payment or, if the Market Exchange Rate is
not available on such date, as of the most recent practicable date; provided,
however, that if the euro has been substituted for such Specified Currency, the
Issuer may at its option (or shall, if so required by applicable law) without
the consent of the holder of this Note effect the payment of principal of,
premium, if any, or interest on, any Note denominated in such Specified
Currency in euro in lieu of such Specified Currency in conformity with legally
applicable measures taken pursuant to, or by virtue of, the treaty establishing
the European Community (the "EC"), as amended by the treaty on European Union
(as so amended, the "Treaty"). Any payment made under such circumstances in
U.S. dollars or euro where the required payment is in an unavailable Specified
Currency will not constitute an Event of Default. If such Market Exchange Rate
is not then available to the Issuer or is not published for a particular
Specified Currency, the Market Exchange Rate will be based on the highest bid
quotation in The City of New York received by the Exchange Rate Agent at
approximately 11:00 a.m., New York City time, on the second Business Day
preceding the date of such payment from three recognized foreign exchange
dealers (the "Exchange Dealers") for the purchase by the quoting Exchange
Dealer of the Specified Currency for U.S. dollars for settlement on the payment
date, in the aggregate amount of the Specified Currency payable to those
holders or beneficial owners of Notes and at which the applicable Exchange
Dealer commits to execute a contract. One of the Exchange Dealers providing
quotations may be the Exchange Rate Agent unless the Exchange Rate Agent is an
affiliate of the Issuer. If those bid quotations are not available, the
Exchange Rate Agent shall determine the market exchange rate at its sole
discretion.

     The "Exchange Rate Agent" shall be Morgan Stanley & Co. Incorporated,
unless otherwise indicated on the face hereof.

     All determinations referred to above made by, or on behalf of, the Issuer
or by, or on behalf of, the Exchange Rate Agent shall be at such entity's sole
discretion and shall, in the absence of manifest error, be conclusive for all
purposes and binding on holders of Notes and coupons.

     So long as this Note shall be outstanding, the Issuer will cause to be
maintained an office or agency for the payment of the principal of and premium,
if any, and interest on this Note as herein provided in the Borough of
Manhattan, The City of New York, and an office or agency in said Borough of
Manhattan for the registration, transfer and exchange as aforesaid of the
Notes. The Issuer may designate other agencies for the payment of said
principal, premium and interest at such place or places (subject to applicable
laws and regulations) as the Issuer may decide. So long as

                                      A-25
<PAGE>

there shall be such an agency, the Issuer shall keep the Trustee advised of the
names and locations of such agencies, if any are so designated.

     With respect to moneys paid by the Issuer and held by the Trustee or any
Paying Agent for payment of the principal of or interest or premium, if any, on
any Notes that remain unclaimed at the end of two years after such principal,
interest or premium shall have become due and payable (whether at maturity or
upon call for redemption or otherwise), (i) the Trustee or such Paying Agent
shall notify the holders of such Notes that such moneys shall be repaid to the
Issuer and any person claiming such moneys shall thereafter look only to the
Issuer for payment thereof and (ii) such moneys shall be so repaid to the
Issuer. Upon such repayment all liability of the Trustee or such Paying Agent
with respect to such moneys shall thereupon cease, without, however, limiting
in any way any obligation that the Issuer may have to pay the principal of or
interest or premium, if any, on this Note as the same shall become due.

     No provision of this Note or of the Senior Indenture shall alter or impair
the obligation of the Issuer, which is absolute and unconditional, to pay the
principal of, premium, if any, and interest on this Note at the time, place,
and rate, and in the coin or currency, herein prescribed unless otherwise
agreed between the Issuer and the registered holder of this Note.

     Prior to due presentment of this Note for registration of transfer, the
Issuer, the Trustee and any agent of the Issuer or the Trustee may treat the
holder in whose name this Note is registered as the owner hereof for all
purposes, whether or not this Note be overdue, and none of the Issuer, the
Trustee or any such agent shall be affected by notice to the contrary.

     No recourse shall be had for the payment of the principal of, premium, if
any, or the interest on this Note, for any claim based hereon, or otherwise in
respect hereof, or based on or in respect of the Senior Indenture or any
indenture supplemental thereto, against any incorporator, shareholder, officer
or director, as such, past, present or future, of the Issuer or of any
successor corporation, either directly or through the Issuer or any successor
corporation, whether by virtue of any constitution, statute or rule of law or
by the enforcement of any assessment or penalty or otherwise, all such
liability being, by the acceptance hereof and as part of the consideration for
the issue hereof, expressly waived and released.

     This Note shall for all purposes be governed by, and construed in
accordance with, the laws of the State of New York.

     All terms used in this Note which are defined in the Senior Indenture and
not otherwise defined herein shall have the meanings assigned to them in the
Senior Indenture.

                                      A-26
<PAGE>

                                 ABBREVIATIONS

     The following abbreviations, when used in the inscription on the face of
this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

          TEN COM  -  as tenants in common
          TEN ENT  -  as tenants by the entireties
          JT TEN   -  as joint tenants with right of survivorship and not as
                      tenants in common

     UNIF GIFT MIN ACT - _____________________ Custodian ______________________
                                (Minor)                          (Cust)

     Under Uniform Gifts to Minors Act_________________________________________
                                                      (State)

     Additional abbreviations may also be used though not in the above list.

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

                                      A-27
<PAGE>

     FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and
transfer(s) unto

-------------------------------------------
[PLEASE INSERT SOCIAL SECURITY OR OTHER
   IDENTIFYING NUMBER OF ASSIGNEE]

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

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

-------------------------------------------------------------------------------
    [PLEASE PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE]

the within Note and all rights thereunder, hereby irrevocably constituting and
appointing such person attorney to transfer such note on the books of the
Issuer, with full power of substitution in the premises.

Dated:
     ------------------------------------

NOTICE: The signature to this assignment must correspond with the name
        as written upon the face of the within Note in every particular
        without alteration or enlargement or any change whatsoever.

                                      A-28
<PAGE>

                           OPTION TO ELECT REPAYMENT

     The undersigned hereby irrevocably requests and instructs the Issuer to
repay the within Note (or portion thereof specified below) pursuant to its
terms at a price equal to the principal amount thereof, together with interest
to the Optional Repayment Date, to the undersigned at

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

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

-------------------------------------------------------------------------------
        (Please print or typewrite name and address of the undersigned)

     If less than the entire principal amount of the within Note is to be
repaid, specify the portion thereof which the holder elects to have repaid:
_______; and specify the denomination or denominations (which shall not be less
than the minimum authorized denomination) of the Notes to be issued to the
holder for the portion of the within Note not being repaid (in the absence of
any such specification, one such Note will be issued for the portion not being
repaid): _________.

Dated:
      --------------------------------     ------------------------------------
                                           NOTICE: The signature on this Option
                                           to Elect Repayment must correspond
                                           with the name as written upon the
                                           face of the within instrument in
                                           every particular without alteration
                                           or enlargement.

                                      A-29<PAGE>

                                  Exhibit 10.3

                      SECOND AMENDMENT TO COMMERCIAL LEASE

THIS AMENDMENT is dated July 31, 2000, between GBF PARTNERS ("Landlord") and
NEOWARE SYSTEMS, INC. ("Tenant").

                                   BACKGROUND
                                   ----------

         Tenant is the successor by merger to Human Design Systems, Inc.
("HDS"). Landlord and HDS entered into the Commercial Lease, dated August 8,
1994, and amended by Agreement to Amend Lease, dated August 8, 1994, respecting
approximately 21,670 square feet of space in Landlord's building located at 400
Feheley Drive, King of Prussia, Pennsylvania (as so amended, the "Lease").

         Landlord and Tenant now desire to amend the Lease as hereinafter
provided. Capitalized terms used in this Amendment and not otherwise defined
shall have the respective meanings given to such terms in the Lease.

                                    AGREEMENT
                                    ---------

         For valuable consideration and intending to be legally bound hereby,
Landlord and Tenant agree as follows:

         A. The Lease is hereby amended as follows:

                  1. In Section 1.05, the date "September 30, 2000" is deleted
and is replaced by the date "September 30, 2005."

                  2. In Section 1.11, the numeral "25" is deleted and is
replaced by the numeral "28."

                  3. Commencing October 1, 2000, and for the remainder of the
Lease Term, the rental herein reserved shall be payable on the following basis:

                     One Hundred Fifty-One Thousand Six Hundred
                     Ninety Dollars ($151,690.00) per annum from
                     October 1, 2000 to September 30, 2001,
                     payable monthly in advance on the first day
                     of each and every month in equal
                     installments of Twelve Thousand Six Hundred
                     Forty Dollars and Eighty-Three Cents
                     ($12,640.83);

<PAGE>

                     One Hundred Fifty-Five Thousand Four Hundred
                     Eighty-Two Dollars and Twenty-Five Cents
                     ($155,482.25) per annum from October 1, 2001
                     to September 30, 2002, payable monthly in
                     advance on the first day of each and every
                     month in equal installments of Twelve
                     Thousand Nine Hundred Sixty-Five Dollars and
                     Eighty-Five Cents ($12,965.85);

                     One Hundred Fifty-Nine Thousand Three
                     Hundred Sixty-Nine Dollars and Thirty Cents
                     ($159,369.30) per annum from October 1, 2002
                     to September 30, 2003, payable monthly in
                     advance on the first day of each and every
                     month in equal installments of Thirteen
                     Thousand Two Hundred Eighty Dollars and
                     Seventy-Seven Cents ($13,280.77);

                     One Hundred Sixty-Three Thousand Three
                     Hundred Fifty-Three Dollars and Thirty-Five
                     Cents ($163,353.35) per annum from October
                     1, 2003 to September 30, 2004, payable
                     monthly in advance on the first day of each
                     and every month in equal installments of
                     Thirteen Thousand Six Hundred Twelve Dollars
                     and Seventy-Nine Cents ($13,612.79);

                     One Hundred Sixty-Seven Thousand Four
                     Hundred Thirty-Seven Dollars and Twenty
                     Cents ($167,437.20) per annum from October
                     1, 2004 to September 30, 2005, payable
                     monthly in advance on the first day of each
                     and every month in equal installments of
                     Thirteen Thousand Nine Hundred Fifty-Three
                     Dollars and Ten Cents ($13,953.10).

                  4. Section 3.02 is deleted.

                  5. Section 3.03(b) is deleted.

                  6. Furthermore, anything else in the Lease to the contrary
notwithstanding, Landlord and Tenant agree as
follows:

                           a. Landlord hereby affirms its obligation (i) to
maintain and repair, at Landlord's sole cost and expense and without
reimbursement by Tenant, in whole or in part, the roof, building structure and
boiler system servicing the entire Project, and (ii) to keep the Property
watertight and free of leaks.

                           b. The temporary demising wall originally constructed
by Tenant shall be replaced by Tenant, at its sole cost and expense, with a
permanent wall meeting all applicable building code requirements, within one
hundred eighty (180) days after the date of this Amendment. Such wall, together
with all other leasehold improvements made by Tenant to the Property during the
Lease Term and which have been approved by Landlord, but not Tenant's trade
fixtures, equipment and personal property, shall remain part of the Project and
shall not be removed by Tenant upon the expiration or earlier termination of the
Lease Term.

                                       2
<PAGE>

                           c. Tenant's pro rata share, for purposes of
determining Tenant's contribution to Landlord on account of various costs
incurred by Landlord in maintaining, repairing and operating the Project as to
which the Lease provides for Tenant's contribution, shall be fifty percent
(50%). In particular, to the extent Landlord deems it necessary to repave the
front parking lot of the Project, Tenant shall be obligated to reimburse
Landlord for Tenant's pro rata share of the cost thereof. B. As amended by this
Amendment, the Lease is ratified and confirmed, with Landlord and Tenant
agreeing that any conflict between the Lease and this Amendment is to be
resolved in favor of this Amendment, which shall take priority. IN WITNESS
WHEREOF, Landlord and Tenant have executed this Amendment the date first above
written.

                                         NEOWARE SYSTEMS, INC.

                                         By: __________________________________
                                                  Title:

                                         GBF PARTNERS

                                         By: __________________________________
                                             George Shapiro, General Partner

                                         By: __________________________________
                                             Bruce Shapiro, General Partner

                                         By: __________________________________
                                             Fred Shapiro, General Partner

                                       3

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