Document:

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                                                                    Exhibit 4.15

                 Permanent Global Registered Fixed Rate Security

            THESE NOTES ARE A GLOBAL SECURITY WITHIN THE MEANING OF THE
INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY
OR A NOMINEE THEREOF. UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR
NOTES IN CERTIFICATED FORM, THESE NOTES MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE
BY THE DEPOSITARY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO A NOMINEE OF
DTC OR BY DTC OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH
SUCCESSOR DEPOSITARY. UNLESS THESE NOTES ARE PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC TO AT&T CORP. OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE OR PAYMENT, AND ANY NOTE ISSUED IS REGISTERED IN THE NAME OF CEDE &
CO., OR IN SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC
(AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED
BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                   AT&T CORP.

                       $3,000,000,000 6.50% Notes due 2029

REGISTERED                                               CUSIP NO. 001957 BJ 7
No. _____

            AT&T Corp., a New York corporation (herein referred to as the
"Company"), for value received, hereby promises to pay to CEDE & CO. or
registered assigns the principal sum of THREE BILLION DOLLARS on March 15, 2029
(the "Maturity Date"), and to pay interest semiannually on March 15 and
September 15 (each, an "Interest Payment Date"), commencing March 15, 2003, on
said principal sum at the rate per annum specified in these Notes, from
________, 2002 (the "Original Issue Date") until the principal thereof is paid
or made available for payment.
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            Reference is hereby made to the further provisions of this global
security (the "Global Security") set forth on the reverse hereof, which further
provisions shall for all purposes have the same effect as if set forth in this
place.

            This Global Security shall not be valid or become obligatory for any
purpose until the certificate of authentication hereon shall have been executed
by the Trustee under the Indenture referred to herein.

            IN WITNESS WHEREOF, the Company has caused this Global Security to
be duly executed under its corporate seal.

Dated:  _________, 2002

TRUSTEE'S CERTIFICATE OF AUTHENTICATION      AT&T CORP.

This is one of the Securities described      By: ____________________________
in the within-mentioned Indenture.               Vice President and Treasurer

THE BANK OF NEW YORK,                        ATTEST:
             As Trustee

By:_______________________________           ________________________________
         Authorized Signatory                       Assistant Secretary

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                                REVERSE OF NOTES

            Payment of the principal of, and interest on, this Global Security
will be made in immediately available funds at the office or agency of the
Trustee maintained for that purpose in the Borough of Manhattan, The City of New
York, State of New York, in such coin or currency of the United States of
America as at the time of payment shall be legal tender for payment of public
and private debts; provided, however, that at the option of the Company payment
of interest on any Notes other than interest due at the Maturity Date may be
made by check mailed to the address of the person entitled thereto as such
address shall appear in the Note register. Interest will be paid to persons in
whose names the Notes are registered at the close of business on the March 1 or
September 1, as the case may be, prior to any Interest Payment Date.

            These Notes are one of a duly authorized issue of securities of the
Company, issued and to be issued under and pursuant to an indenture dated as of
September 7, 1990 as amended by the First Supplemental Indenture dated as of
October 30, 1992 and the Second Supplemental Indenture dated as of _________,
2002 (herein referred to as the "Indenture"), duly executed and delivered by the
Company to The Bank of New York, as trustee (herein referred to as the
"Trustee"), to which Indenture and all indentures supplemental thereto reference
is hereby made for description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Company and
the Holder (the words "Holders" or "Holder" meaning the registered holders or
registered holder) of these Notes.

            In case an Event of Default with respect to the Notes, as defined in
the Indenture, shall have occurred and be continuing, the principal hereof may
be declared, and upon such

                                      -3-
<PAGE>
declaration shall become due and payable in the manner, with the effect and
subject to the conditions provided in the Indenture.

            The Indenture permits, with certain exceptions as therein provided,
the amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Notes to be affected under the
Indenture at any time by the Company and the Trustee with the consent of the
Holders of a majority in principal amount of the outstanding Notes. The
Indenture also contains provisions permitting the Holders of not less than a
majority in principal amount of the outstanding Notes, on behalf of the Holders
of all Notes, to waive compliance by the Company with certain provisions of the
Indenture. The Indenture also provides that the Holders of not less than a
majority in principal amount of the outstanding notes may waive certain past
defaults and their consequences on behalf of the Holders of all Notes. Any such
consent or waiver by the Holder of any Note shall be conclusive and binding upon
such Holder and upon all future Holders of such Note and of any Note issued upon
registration of transfer hereof or in exchange herefor or in lieu hereof whether
or not notation of such consent or waiver is made upon these Notes.

            The Indenture also provides that the Covered Transactions (as
defined in the Indenture), individually or together, (a) will not result in a
consolidation, merger, sale, conveyance or other transfer of property of the
Company (including stock of subsidiaries) as an entirety or substantially as an
entirety for purposes of Section 5.01 of the Indenture or any other provision of
the Indenture or these Notes, and (b) will not violate Sections 5.01, 5.02, or
5.03 of the Indenture or any other provision of the Indenture or these Notes,
regardless of whether any person assumes any of the indebtedness outstanding
under the Indenture or any other obligation under the Indenture or these Notes.

                                      -4-
<PAGE>
            The Indenture contains provisions setting forth certain conditions
to the institution of proceedings by Holders of Securities with respect to the
Indenture or for any remedy under the Indenture.

            No reference herein to the Indenture and no provision of these Notes
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay the principal of and interest on these
Notes at the place, at the respective times, at the rate and in the coin or
currency herein prescribed.

            The Notes are issuable as registered Notes without coupons in
denominations of U.S. $1,000 or any amount in excess thereof which is a multiple
of U.S.$1,000 at the office or agency of the Company referred to above and in
the manner and subject to the limitations provided in the Indenture. Notes may
be exchanged without service charge for like aggregate principal amount of Notes
having the same maturity, interest rate, redemption provisions, repayment
provisions, and Original Issue Date of other authorized denominations.

            The initial interest rate per annum on the principal sum of these
Notes is 6.50%. At the Effective Time (as defined in the Merger Agreement), the
interest rate per annum on the principal sum of these Notes will be increased to
____% and the Maturity Date of these Notes will be changed to March 15, 20__. If
the Merger Agreement is terminated and the Mergers (as defined therein) are
abandoned at any time prior to the Effective Time, the interest rate per annum
on the principal sum of these Notes shall remain at 6.50% and the Maturity Date
will remain as March 15, 2029.

            These Notes have been exchanged for 6.50% Notes Due 2029 (the
"Prior Notes"). Interest accrued and unpaid on the Prior Notes through but not
including the date of such exchange will be paid, without interest, on the first
Interest Payment Date hereunder.

                                      -5-
<PAGE>
                  "MERGER AGREEMENT" means the Agreement and Plan of Merger by
and among the Company, AT&T Broadband Corp., Comcast Corporation, AT&T Broadband
Acquisition Corp., Comcast Acquisition Corp. and AT&T Comcast Corporation, dated
as of December 19, 2001, as it may be amended, supplemented or otherwise
modified from time to time, whether prior to or after the date hereof.

            The Company will, subject to the exceptions and limitations set
forth below, pay as additional interest on these Notes such additional amounts
as are necessary so that the net payment by the Company or a paying agent of the
principal of and interest on these Notes to a person that is not a United States
Holder, after deduction for any present or future tax, assessment or
governmental charge of the United States or a political subdivision or taxing
authority thereof or therein, imposed by withholding with respect to the
payment, will not be less than the amount that would have been payable in
respect of these Notes had no such withholding or deduction been required.

            The Company's obligation to pay additional amounts shall not apply:

                  (1) to a tax, assessment or governmental charge that is
      imposed or withheld solely because the Holder, or a fiduciary, settlor,
      beneficiary, member or shareholder of the Holder if the Holder is an
      estate, trust, partnership or corporation, or a person holding a power
      over an estate or trust administered by a fiduciary Holder:

                        (a) is or was present or engaged in trade or business in
            the United States or has or had a permanent establishment in the
            United States;

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                        (b) has a current or former relationship with the United
            States, including a relationship as a citizen or resident thereof;

                        (c) is or has been a foreign or domestic personal
            holding company, a passive foreign investment company or a
            controlled foreign corporation with respect to the United States or
            a corporation that has accumulated earnings to avoid United States
            federal income tax; or

                        (d) is or was a "10-percent shareholder" of the Company
            as defined in section 871(h)(3) of the United States Internal
            Revenue Code or any successor provision;

                  (2) to any Holder that is not the sole beneficial owner of
      these Notes, or a portion thereof, or that is a fiduciary or partnership,
      but only to the extent that the beneficial owner, a beneficiary or settlor
      with respect to the fiduciary, or a member of the partnership would not
      have been entitled to the payment of an additional amount had such
      beneficial owner, beneficiary, settlor or member received directly its
      beneficial or distributive share of the payment;

                  (3) to a tax, assessment or governmental charge that is
      imposed or withheld solely because the Holder or any other person failed
      to comply with certification, identification or information reporting
      requirements concerning the nationality, residence, identity or connection
      with the United States of the Holder or beneficial owner of such Notes, if
      compliance is required by statute, by regulation of the United States
      Treasury Department or by an applicable income tax treaty to which the

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      United States is a party as a precondition to exemption from such tax,
      assessment or other governmental charge;

                  (4) to a tax, assessment or governmental charge that is
      imposed other than by withholding by the Company or an exchange agent from
      the payment;

                  (5) to a tax, assessment or governmental charge that is
      imposed or withheld solely because of a change in law, regulation, or
      administrative or judicial interpretation that becomes effective more than
      15 days after the payment becomes due or is duly provided for, whichever
      occurs later;

                  (6) to an estate, inheritance, gift, sales, excise, transfer,
      wealth or personal property tax or a similar tax, assessment or
      governmental charge;

                  (7) to any tax, assessment or other governmental charge any
      paying agent must withhold from any payment of principal of or interest on
      such Notes, if such payment can be made without such withholding by any
      other paying agent; or

                  (8)   in the case of any combination of the above items.

            These Notes are subject in all cases to any tax, fiscal or other law
or regulation or administrative or judicial interpretation applicable. Except as
specifically provided, the Company does not have to make any payment with
respect to any tax, assessment or governmental charge imposed by any government
or a political subdivision or taxing authority.

            "UNITED STATES HOLDER" means a beneficial owner that is for United
States federal income tax purposes: (a) a citizen or resident of the United
States, (b) a corporation, partnership

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or other entity created or organized in or under the laws of the United States
or of any political subdivision thereof, (c) an estate or trust the income of
which is subject to United States federal income taxation regardless of its
source or (d) any other person whose income from these Notes is effectively
connected with the conduct of a United States trade or business.

            If (a) the Company becomes or will become obligated to pay
additional amounts as described above under as a result of any change in, or
amendment to, the laws (or any regulations or rulings promulgated thereunder) of
the United States (or any political subdivision or taxing authority thereof or
therein), or any change in, or amendments to, any official position regarding
the application or interpretation of such laws, regulations or rulings, which
change or amendment is announced or becomes effective on or after March 23,
1999, or (b) a taxing authority of the United States takes an action on or after
March 23, 1999, whether or not with respect to the Company or any of its
affiliates, that results in a substantial probability that the Company will or
may be required to pay such additional amounts, then the Company may, at its
option, redeem, as a whole, but not in part, these Notes on any interest payment
date on not less than 30 nor more than 60 calendar days' prior notice, at a
redemption price equal to 100% of their principal amount, together with interest
accrued thereon to the date fixed for redemption; provided that the Company
determines, in its business judgment, that the obligation to pay such additional
amounts cannot be avoided by the use of reasonable measures available to it, not
including substitution of the obligor under such Notes. No redemption pursuant
to (b) above may be made unless the Company shall have received an opinion if
independent counsel to the effect that an act taken by a taxing authority of the
United States results in a substantial probability that the Company will or may
be required to pay the additional amounts described above and the Company shall
have delivered to the trustee a certificate, signed by a duly

                                      -9-
<PAGE>
authorized officer stating, that based on such opinion the Company is entitled
to redeem the Notes pursuant to their terms.

            These Notes may be redeemed at the option of the Company at any time
or from time to time, as a whole or in part. Upon such redemption (a "Redemption
Date"), the Company will pay the Holder hereof the greater of: (1)
$3,000,000,000 and (2) the sum of the present value of the Remaining Scheduled
Payments discounted, on a semiannual basis (assuming a 360-day year consisting
of twelve 30-day months), at a rate equal to the sum of the Treasury Rate and 10
basis points. Accrued interest will be payable to the Redemption Date. On and
after the Redemption Date, interest will cease to accrue on these Notes or any
portion of the Notes called for redemption (unless the Company defaults in the
payments of the redemption price and accrued interest). On or before the
Redemption Date, the Company will deposit with a paying agent (or the Trustee)
money sufficient to pay the redemption price of and accrued interest on these
Notes. Notice of redemption shall be mailed to the registered holders of these
Notes at their last registered address not less than 30 nor more than 90 days
prior to the Redemption Date, all as provided in the Indenture. In the event of
redemption of these Notes 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 presentation and cancellation hereof.

            "TREASURY RATE" means, with respect to a Redemption Date, the rate
per annum equal to the semiannual equivalent yield to maturity of the comparable
Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as
a percentage of its principal amount) equal to the Comparable Treasury price for
such Redemption Date.

                                      -10-
<PAGE>
            "COMPARABLE TREASURY ISSUE" means the United States Treasury
security selected by an Independent Investment Banker as having a maturity
comparable to the remaining term of these Notes to be redeemed that would be
utilized, at the time of selection and in accordance with customary financial
practice, in pricing new issues of corporate debt securities of comparable
maturity to the remaining term of these Notes. "Independent Investment Banker"
means one of the Reference Treasury Dealers appointed by the Company.

            "COMPARABLE TREASURY PRICE" means, with respect to a Redemption
Date, (1) the aver of the Reference Treasury Dealer Quotations for such
Redemption Date after excluding the highest and lowest of such Reference
Treasury Dealer Quotations, or (2) if the Trustee obtains fewer than five such
Reference Treasury Dealer Quotations, the average of all such quotations.
"Reference Treasury Dealer Quotations" means, with respect to each Reference
Treasury Dealer and any Redemption Date, the average, as determined by the
Trustee, of the bid and asked prices for the Comparable Treasury Issue
(expressed in each case as a percentage of its principal amount) quoted in
writing to the Trustee by such Reference Treasury Dealer at 3:30 p.m., New York
City time, on the third business day preceding such Redemption Date.

            "REFERENCE TREASURY DEALER" means each of Merrill Lynch, Pierce,
Fenner & Smith Incorporated, Salomon Smith Barney Inc., Deutsche Bank Securities
Inc., Banc One Capital Markets Inc., Lehman Brothers Inc., J.P. Morgan
Securities Inc. and Banc of America Securities LLC and their respective
successors. If any of the foregoing ceases to be a primary U.S. Government
securities dealer (a "Primary Treasury Dealer"), the Company will substitute
another nationally recognized investment banking firm that is a Primary Treasury
Dealer.

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<PAGE>
            "REMAINING SCHEDULED PAYMENTS" means the remaining scheduled
payments of principal and interest on these Notes that would be due after the
related Redemption Date but for such redemption. If such Redemption Date is not
an Interest Payment Date, the amount of the next succeeding scheduled interest
payment on these Notes will be reduced by the amount of interest accrued on
these Notes to such Redemption Date.

            These Notes are not subject to repayment at the option of the
Holder.

            Upon due presentment for registration of transfer of these Notes at
the above-mentioned office or agency of the Trustee, a new Global Security or
Notes of authorized denominations, for a like aggregate principal amount will be
issued to the transferee as provided in the Indenture. No service charge shall
be made for any such transfer, but the Company may require payment of a sum
sufficient to cover any tax or other governmental charge that may be imposed in
relation thereto.

            The Company, the Trustee, and any agent of the Company and the
Trustee may deem and treat the Holder hereof as the absolute owner hereof
(whether or not this Global Security shall be overdue and notwithstanding any
notation of ownership or other writing hereon) for the purpose of receiving
payment of or on account of the principal hereof and subject to the provisions
above, of premium or interest thereon, and for all other purposes and neither
the Company nor the Trustee nor any such agent shall be affected by any notice
to the contrary.

            No recourse shall be had for the payment of the principal of, or the
interest on, this Global Security or for any claims based hereon, or otherwise
in respect hereof, or based on or with respect of the Indenture or any indenture
supplemental therein against any incorporator, shareholder, officer or director
as such, past, present or future, of the Company or of any

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successor corporation, either directly or through the Company or of 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 Global Security shall be deemed to be a contract made under the
laws of the State of New York and for all purposes shall be governed by and
construed in accordance with the laws of said State.

            All terms used in this Global Security which are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                                      -13-
<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 -                         (Cust)                     (Minor)
                    ------------------------      ---------------------
Under Uniform Gifts to Minor Act                            (State)
                                 ---------------------------

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

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

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

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

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the within Notes and all rights thereunder, hereby irrevocably constituting and
appointing such person attorney to transfer such Note on the books of the
Company, 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 Notes in every particular
            without alteration or enlargement or any change whatsoever.

                                      -14-<PAGE>

                                                                    Exhibit 4.16

              Medium Term Global Registered Floating Rate Security

                  THESE NOTES ARE A GLOBAL SECURITY WITHIN THE MEANING OF THE
INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY
OR A NOMINEE THEREOF. UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR
NOTES IN CERTIFICATED FORM, THESE NOTES MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE
BY THE DEPOSITARY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO A NOMINEE OF
DTC OR BY DTC OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH
SUCCESSOR DEPOSITARY. UNLESS THESE NOTES ARE PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC TO AT&T CORP. OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE OR PAYMENT, AND ANY NOTE ISSUED IS REGISTERED IN THE NAME OF CEDE &
CO., OR IN SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC
(AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED
BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                   AT&T CORP.

          $10,563,000 Floating Rate Medium Term Note, Series A Due 2054

REGISTERED

No. FLR-_____________                     CUSIP NO. 001957 BK 4

                  AT&T Corp., a New York corporation (herein referred to as the
"Company"), for value received, hereby promises to pay to CEDE & CO. or
registered assigns the principal sum of TEN MILLION FIVE HUNDRED AND SIXTY-THREE
THOUSAND DOLLARS on December 28, 2054 (the "Maturity Date"), and to pay interest
semiannually on June 28 and December 28 (each, an "Interest Payment Date"),
commencing December 28, 2002, on said principal sum at the rate per annum
specified in these Notes, from ________, 2002 (the "Original Issue Date") until
the principal thereof is paid or made available for payment.
<PAGE>
                  Reference is hereby made to the further provisions of this
global security (the "Global Security") set forth on the reverse hereof, which
further provisions shall for all purposes have the same effect as if set forth
in this place.

                  This Global Security shall not be valid or become obligatory
for any purpose until the certificate of authentication hereon shall have been
executed by the Trustee under the Indenture referred to herein.

                  IN WITNESS WHEREOF, the Company has caused this Global
Security to be duly executed under its corporate seal.

Dated:  _________, 2002

TRUSTEE'S CERTIFICATE OF                    AT&T CORP.
    AUTHENTICATION

This is one of the Securities described     By:
                                               --------------------------------
in the within-mentioned Indenture.               Vice President and Treasurer

THE BANK OF NEW YORK,                       ATTEST:
              As Trustee

By:
   ------------------------------------     -----------------------------------
          Authorized Signatory                      Assistant Secretary

                                      -2-
<PAGE>
                                REVERSE OF NOTES

                  Payment of the principal of, and interest on, this Global
Security will be made in immediately available funds at the office or agency of
the Trustee maintained for that purpose in the Borough of Manhattan, The City of
New York, State of New York, in such coin or currency of the United States of
America as at the time of payment shall be legal tender for payment of public
and private debts; provided, however, that at the option of the Company payment
of interest on any Notes other than interest due at the Maturity Date may be
made by check mailed to the address of the person entitled thereto as such
address shall appear in the Note register. Interest will be paid to persons in
whose names the Notes are registered at the close of business on the June 13 or
December 13, as the case may be, prior to any Interest Payment Date.

                  These Notes are one of a duly authorized issue of securities
of the Company, issued and to be issued under and pursuant to an indenture dated
as of September 7, 1990 as amended by the First Supplemental Indenture dated as
of October 30, 1992 and the Second Supplemental Indenture dated as of _________,
2002 (herein referred to as the "Indenture"), duly executed and delivered by the
Company to The Bank of New York, as trustee (herein referred to as the
"Trustee"), to which Indenture and all indentures supplemental thereto reference
is hereby made for description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Company and
the Holder (the words "Holders" or "Holder" meaning the registered holders or
registered holder) of these Notes.

                  In case an Event of Default with respect to the Notes, as
defined in the Indenture, shall have occurred and be continuing, the principal
hereof may be declared, and upon such declaration shall become due and payable
in the manner, with the effect and subject to the conditions provided in the
Indenture.

                                      -3-
<PAGE>
                  The Indenture permits, with certain exceptions as therein
provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Notes to be
affected under the Indenture at any time by the Company and the Trustee with the
consent of the Holders of a majority in principal amount of the outstanding
Notes. The Indenture also contains provisions permitting the Holders of not less
than a majority in principal amount of the outstanding Notes, on behalf of the
Holders of all Notes, to waive compliance by the Company with certain provisions
of the Indenture. The Indenture also provides that the Holders of not less than
a majority in principal amount of the outstanding notes may waive certain past
defaults and their consequences on behalf of the Holders of all Notes. Any such
consent or waiver by the Holder of any Note shall be conclusive and binding upon
such Holder and upon all future Holders of such Note and of any Note issued upon
registration of transfer hereof or in exchange herefor or in lieu hereof whether
or not notation of such consent or waiver is made upon these Notes.

                  The Indenture also provides that the Covered Transactions (as
defined in the Indenture), individually or together, (a) will not result in a
consolidation, merger, sale, conveyance or other transfer of property of the
Company (including stock of subsidiaries) as an entirety or substantially as an
entirety for purposes of Section 5.01 of the Indenture or any other provision of
the Indenture or these Notes, and (b) will not violate Sections 5.01, 5.02, or
5.03 of the Indenture or any other provision of the Indenture or these Notes,
regardless of whether any person assumes any of the indebtedness outstanding
under the Indenture or any other obligation under the Indenture or these Notes.

                                      -4-
<PAGE>
                  The Indenture contains provisions setting forth certain
conditions to the institution of proceedings by Holders of Securities with
respect to the Indenture or for any remedy under the Indenture.

                  No reference herein to the Indenture and no provision of these
Notes or of the Indenture shall alter or impair the obligation of the Company,
which is absolute and unconditional, to pay the principal of and interest on
these Notes at the place, at the respective times, at the rate and in the coin
or currency herein prescribed.

                  The Notes are issuable as registered Notes without coupons.
The Notes are issuable only in denominations of U.S. $25,000 or any amount in
excess thereof which is an integral multiple of U.S. $1,000. Notes may be
exchanged without a service charge for a like aggregate principal amount of
Notes of other authorized denominations having the same maturity, interest rate,
optional redemption provisions and original issue date.

                  Initially, these Notes will bear interest at the interest rate
calculated with reference to the Commercial Paper Rate and the Old Spread
described below. At the Effective Time (as defined in the Merger Agreement),
these Notes will bear interest at the interest rate calculated with reference to
the Commercial Paper Rate and the New Spread described below. If the Merger
Agreement is terminated and the Mergers (as defined therein) are abandoned at
any time prior to the Effective Time, these Notes will bear interest at the
interest rate calculated with reference to the Commercial Paper Rate and the Old
Spread.

                  "MERGER AGREEMENT" means the Agreement and Plan of Merger by
and among the Company, AT&T Broadband Corp., Comcast Corporation, AT&T Broadband
Acquisition Corp., Comcast Acquisition Corp. and AT&T Comcast Corporation, dated
as of December 19,

                                      -5-
<PAGE>
2001, as it may be amended, supplemented or otherwise modified from time to
time, whether prior to or after the date hereof.

                  The rate of interest on each of these Notes will be reset
monthly commencing the 28th calendar day of the first month occurring after the
Original Issue Date and at the Effective Time (as defined in the Merger
Agreement) (such period being the "Interest Reset Period" for these Notes and
the first date of each Interest Reset Period being an "Interest Reset Date");
provided, however, that the interest rate in effect from the date of issue to
the first Interest Reset Date (the "Initial Interest Reset Date") with respect
to these Notes will be calculated with reference to the Commercial Paper Rate
and the Old Spread.

                  If any Interest Reset Date for any of these Notes would
otherwise be a day that is not a business day, such Interest Reset Date will be
postponed to the next succeeding business day.

                  For purposes of this section "Spread" refers to the Old Spread
until the Effective Time (as defined in the Merger Agreement) and to the New
Spread thereafter. The interest rate on each of these Notes will be calculated
by reference to the Commercial Paper Rate plus or minus the Spread. Interest
payments on these Notes will be the amount of interest accrued from, and
including, the date of issue or the last date to which interest has been paid
to, but excluding, the Interest Payment Date or date of maturity, as the case
may be; provided that if the maturity date that would otherwise fall on a day
that is not a business day is postponed or changed as described above, the
interest payable on such date shall accrue to, but exclude, the date that would
have been the maturity date had it been a business day.

                                      -6-
<PAGE>

                  Accrued interest shall be calculated by multiplying the
principal amount of these Notes by an accrued interest factor. Such accrued
interest factor will be computed by adding the interest factors calculated for
each day in the Interest Reset Period or from the last date from which accrued
interest is being calculated. The interest factor for each such day is computed
by dividing the interest rate applicable to such day by 360. The interest rate
applicable to any day that is an Interest Reset Date is the applicable rate as
reset on such date. The interest rate applicable to any other day is the
interest rate for the immediately preceding Interest Reset Date (or, if none,
the Initial Interest Rate, as described below).

                  These Notes have been exchanged for FRN Medium-Term Notes,
Series A Due 2054 (the "Prior Notes"). Interest accrued and unpaid on
the Prior Notes through but not including the date of such exchange will be
paid, without interest, on the first Interest Payment Date hereunder.

                  ___________ will be the calculation agent. Upon the request of
the Holder of any of these Notes, the calculation agent will provide the
interest rate then in effect and, if determined, the interest rate which will
become effective on the next Interest Reset Date.

                  All percentages resulting from any calculation of the rate of
interest on these Notes will be rounded, if necessary, to the nearest
one-hundred-thousandth of a percentage point (.0000001), with five
one-millionths of a percentage point rounded upward, and all dollar amounts used
in or resulting from such calculation on these Notes will be rounded to the
nearest cent (with one-half cent rounded upward).

                  The interest rate for each Interest Reset Date subsequent to
the Initial Interest Reset Date will be determined by the calculation agent as
follows.

                  The "CALCULATION DATE" pertaining to any Commercial Paper
Interest Determination Date will be the earlier of, either (i) the tenth
calendar day after such date, or, if

                                      -7-
<PAGE>
such tenth day is not a business day, the next succeeding business day, or (ii)
the business day preceding the applicable Interest Payment Date or date of
maturity, as the case may be.

                  The "COMMERCIAL PAPER RATE" for each Interest Reset Date will
be determined on the Calculation Date by the calculation agent as of the second
business day prior to such Interest Reset Date (a "Commercial Paper Interest
Determination Date") and shall be the Money Market Yield (as defined below) on
such Commercial Paper Interest Determination Date of the rate for commercial
paper having a 30-day maturity, as such rate shall be published by the Board of
Governors of the Federal Reserve System in "Statistical Release H.15(519),
Selected Interest Rates" ("H.15(519)"), or any successor publication, under the
heading "Commercial Paper." In the event that such rate is not published prior
to 9:00 A.M., New York City time, on the Calculation Date, then the Commercial
Paper Rate shall be the Money Market Yield on such Commercial Paper Interest
Determination Date of the rate for commercial paper having a 30-day maturity as
published by the Federal Reserve Bank of New York in its daily statistical
release "Composite 3:30 P.M. Quotations for U.S. Government Securities"
("Composite Quotations") under the heading "Commercial Paper." If by 3:00 P.M.,
New York City time, on such Calculation Date such rate is not yet published in
either H.15(519) (or any successor publication) or Composite Quotations, then
the Commercial Paper Rate shall be the Money Market Yield of the arithmetic mean
of the offered rates as of 11:00 A.M., New York City time, on such Commercial
Paper Interest Determination Date of three leading dealers of commercial paper
in The City of New York selected by the calculation agent for commercial paper
having a 30-day maturity, placed for an industrial issuer whose bond rating is
AA, or the equivalent, from a nationally recognized rating agency; provided,
however, that if the dealers selected as aforesaid by the calculation agent are
not quoting offered rates as mentioned in this sentence, the rate of

                                      -8-
<PAGE>
interest in effect for the applicable period will be the rate of interest in
effect on such Commercial Paper Interest Determination Date.

                  "MONEY MARKET YIELD" shall be a yield calculated in accordance
with the following formula:

                                            D x 360
                    Money Market Yield = ------------- x 100
                                         360 - (D x M)

where "D" refers to the applicable per annum rate for commercial paper quoted on
a bank discount basis and expressed as a decimal, and "M" refers to the actual
number of days in the period for which interest is being calculated.

                  The "OLD SPREAD" to the Commercial Paper Rate is adjusted each
Interest Period based upon the Standard and Poor's (S&P) long-term senior debt
rating of the Company as follows:

<TABLE>
<CAPTION>
AT&T RATING                                                          OLD SPREAD
-----------                                                          ----------
<S>                                                            <C>
AAA.........................................................   -30 basis points
AA+.........................................................   -27 basis points
AA..........................................................   -25 basis points
AA-.........................................................   -23 basis points
A+..........................................................   -21 basis points
A...........................................................   -19 basis points
A-..........................................................   -17 basis points
BBB+........................................................   -15 basis points
BBB.........................................................   -13 basis points
BBB-........................................................   -11 basis points
Below BBB...................................................   +35 basis points
</TABLE>

                  The "New Spread" to the Commercial Paper Rate is adjusted each
Interest Period based upon the Standard and Poor's (S&P) long-term senior debt
rating of the Company as follows:

                                      -9-
<PAGE>

<TABLE>
<CAPTION>
AT&T RATING                                                          NEW SPREAD
-----------                                                          ----------
<S>                                                            <C>
AAA.........................................................   ___ basis points
AA+.........................................................   ___ basis points
AA..........................................................   ___ basis points
AA- ........................................................   ___ basis points
AA..........................................................   ___ basis points
A+..........................................................   ___ basis points
A- .........................................................   ___ basis points
BBB+........................................................   ___ basis points
BBB.........................................................   ___ basis points
BBB- .......................................................   ___ basis points
Below BBB...................................................   ___ basis points
</TABLE>

                  If S&P ceases to exist, then the calculation agent and the
Company shall mutually select a nationally recognized securities ratings agency,
with preference, if possible, given to one contemporaneously assigning the same
rating to the Company as that of S&P at the time of S&P's cessation, to act as a
substitute rating agency, and mutually make any necessary adjustments to provide
for an equivalent ratings scale.

                  Interest payments will include the amount of interest accrued
from and including the most recent Interest Payment Date to which interest has
been paid (or from and including the original issue date if no interest has been
paid on these Notes) to, but excluding the applicable Interest Payment Date.

                  The Aggregate Interest Amount shall be the sum of (i) the
Interest Amount calculated for such Interest Period, (ii) the Aggregate
Carry-over Interest Amount in respect of such Interest Period and (iii) the
Compounding Amount. If the Interest Reset Date is an Interest Payment Date, then
the Aggregate Interest Amount will be the Interest Payment Amount payable on
such Interest Payment Date. If the Interest Reset Date is not an Interest
Payment Date, then such amount shall be deemed to be the Aggregate Carry-over
Interest Amount for the next

                                      -10-
<PAGE>
succeeding Interest Period and no payment shall be made on that date. Interest
Amount means with respect to each Interest Period, the product of the Principal
Amount and an accrued Interest Factor. This accrued Interest Factor will be
computed by adding the Interest Factors calculated for each day in the Interest
Period. The Interest Factor for the Notes for each such day will be computed by
dividing the Interest Rate applicable to such day by 360.

                  "INTEREST PERIOD" means each of the following periods: (i)
from and including the original issue date to but excluding the Initial Reset
Date and (ii) from and including each Interest Reset Date (other than the
maturity date) to but excluding the next Interest Reset Date. Aggregate
Carry-over Interest Amount shall be zero with respect to each interest period
immediately succeeding an Interest Payment Date and with respect to each of the
succeeding Interest Periods, means the amount calculated as provided above.
Aggregate Interest Amount means the amount calculated as provided above.
Compounding Amount means the amount which is the product of (i) the accrued
Interest Factor for any relevant Interest Period and (ii) the Aggregate
Carry-over Interest Amount for such Interest Period.

                  The calculation agent shall calculate the interest rate on
these Notes on or before each Calculation Date. The interest rate on these Notes
will in no event be higher than the maximum rate permitted by New York law as
the same may be modified by United States law of general applicability.

                  The calculation agent will, upon the request of the Holder of
these Notes, provide to such Holder the interest rate hereon then in effect and,
if determined, the interest rate which will become effective as a result of a
determination rate with respect to the most recent Interest Determination Date.

                                      -11-
<PAGE>
                  These Notes are not redeemable prior to December 28, 2009. On
or after such date, these Notes are redeemable (the "Redemption Date") prior to
the Maturity Date at the option of the Company on December 28, 2029 and December
28th ever year thereafter with not less than 30 calendar days notice, at the
prices set forth below (expressed as a percentage of the principal amount). On
and after the Redemption Date, interest will cease to accrue on these Notes or
any portion of the Notes called for redemption (unless the Company defaults in
the payments of the redemption price and accrued interest). On or before the
Redemption Date, the Company will deposit with a paying agent (or the Trustee)
money sufficient to pay the redemption price of and accrued interest on these
Notes. Notice of redemption shall be mailed to the registered holders of these
Notes at their last registered address not less than 30 days prior to the
Redemption Date, all as provided in the Indenture. In the event of redemption of
these Notes 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
presentation and cancellation hereof.

                  If redeemed on December 28th:

<TABLE>
<CAPTION>
YEAR                                                                  PERCENTAGE
----                                                                  ----------
<S>                                                                   <C>
2009 through 2013................................................     110.000%
2014 through 2018................................................     108.000%
2019 through 2023................................................     107.000%
2024 through 2028................................................     106.000%
2029 through 2035................................................     105.500%
2036.............................................................     105.000%
2037.............................................................     104.375%
2038.............................................................     103.750%
2039.............................................................     103.125%
2040.............................................................     102.500%
2041.............................................................     101.875%
2042.............................................................     101.250%
2043.............................................................     100.625%
2044 through 2054 ...............................................     100.000%
</TABLE>

                                      -12-
<PAGE>
                  These Notes are repayable at the option of the Holders on
December 28, 2005 and on each December 28th every third year thereafter with not
less than 30 calendar days notice, at the following redemption prices (expressed
as a percentage of the principal amount) plus interest accrued from, and
including, the last date to which interest has been paid to but excluding the
applicable optional repayment date:

                  If repaid on December 28th:

<TABLE>
<CAPTION>
YEAR                                                                  PERCENTAGE
<S>                                                                   <C>
2005..............................................................    99.40%
2008..............................................................    99.52%
2011..............................................................    99.64%
2014..............................................................    99.78%
2017..............................................................    99.92%
2020..............................................................    100.00%
2023..............................................................    100.00%
2026..............................................................    100.00%
2029..............................................................    100.00%
2032..............................................................    100.00%
2035..............................................................    100.00%
2038..............................................................    100.00%
2041..............................................................    100.00%
2044..............................................................    100.00%
2047..............................................................    100.00%
2050..............................................................    100.00%
2053..............................................................    100.00%
</TABLE>

                  These Notes are repayable at the option of the Holders upon
the occurrence and continuance of any Event of Default specified in the
Indenture at the next Interest Payment Date at 100.00% of principal amount plus
interest accrued from, and including, the last date to which interest has been
paid to, but excluding, the Interest Payment Date for repayment.

                  In order for the repayment option applicable to these Notes to
be exercised, the Trustee must receive at least 30 days but no more than 45 days
prior to the repayment date (i) the Notes with the form entitled "Option to
Elect Repayment" on the reverse of the Notes duly

                                      -13-
<PAGE>
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 trust company in the United
States setting forth the name of the Holder of the Notes, the principal amount
of the Notes, the principal amount of the Notes to be repaid, the certificate
number or a description of the tenor and terms of the Notes, and containing a
statement that the option to elect repayment is being exercised thereby and a
guarantee that the Notes to be repaid with the form entitled "Option to Elect
Repayment" on the reverse of the Notes duly completed will be received by the
trustee not later than five business days after the date of such telegram,
telex, facsimile transmission or letter and such Note and form duly completed
are received by the trustee by such fifth business day. The repayment option may
be exercised by the Holder of these Notes for less than the entire principal
amount of the Notes, provided that the principal amount of these Notes remaining
outstanding after repayment is an authorized denomination.

                  Upon due presentment for registration of transfer of these
Notes at the above-mentioned office or agency of the Trustee, a new Global
Security or Notes of authorized denominations for a like aggregate principal
amount will be issued to the transferee as provided in the Indenture. No service
charge shall be made for any such transfer, but the Company may require payment
of a sum sufficient to cover any tax or other governmental charge that may be
imposed in relation thereto.

                  The Company, the Trustee, and any agent of the Company and the
Trustee may deem and treat the Holder hereof as the absolute owner hereof
(whether or not this Global Security shall be overdue and notwithstanding any
notation of ownership or other writing hereon) for the purpose of receiving
payment of or on account of the principal hereof and subject

                                      -14-
<PAGE>
to the provisions above, of premium or interest thereon, and for all other
purposes and neither the Company nor the Trustee nor any such agent shall be
affected by any notice to the contrary.

                  No recourse shall be had for the payment of the principal of,
or the interest on, this Global Security or for any claims based hereon, or
otherwise in respect hereof, or based on or with respect of the Indenture or any
indenture supplemental therein against any incorporator, shareholder, officer or
director as such, past, present or future, of the Company or of any successor
corporation, either directly or through the Company or of 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 Global Security shall be deemed to be a contract made
under the laws of the State of New York and for all purposes shall be governed
by and construed in accordance with the laws of said State.

                  All terms used in this Global Security which are defined in
the Indenture shall have the meanings assigned to them in the Indenture.

                                      -15-
<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
                                      ----------           ---------------------
                                      (Cust)               (Minor)

                  Under Uniform Gifts to Minor Act
                                                   -----------------------------
                                                   (State)

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

                  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
Company, with full power of substitution in the premises.

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

                                      -16-
<PAGE>
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.

                                      -17-
<PAGE>
                            OPTION TO ELECT REPAYMENT

The undersigned hereby irrevocably request(s) and instruct(s) the Company 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 shall be in authorized increments) 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):

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

Date:
     --------------------------     -------------------------------------------

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

                                      -18-

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