EXHIBIT 8.1

               [FORM OF OPINION OF DAVIS POLK & WARDWELL REGARDING
                    MATERIAL FEDERAL INCOME TAX CONSEQUENCES]

                                  212-450-4000


                    FORM OF OPINION OF DAVIS POLK & WARDWELL

                                          __________, 2002

Comcast Corporation
1500 Market Street
Philadelphia, Pennsylvania 19102

Ladies and Gentlemen:

     We have acted as counsel to Comcast Corporation, a Pennsylvania corporation
("COMCAST"), in connection with (i) the proposed Mergers, as defined and
described in the Agreement and Plan of Merger dated as of December 19, 2001 (the
"MERGER AGREEMENT") among AT&T Corp., a New York corporation ("AT&T"), AT&T
Broadband Corp, a Delaware corporation and a wholly owned subsidiary of AT&T,
Comcast, AT&T Comcast Corporation, a Pennsylvania corporation ("PARENT"), AT&T
Broadband Acquisition Corp., a Delaware corporation and a wholly owned
subsidiary of Parent and Comcast Acquisition Corp., a Pennsylvania corporation
and a wholly owned subsidiary of Parent and (ii) the preparation and filing of
the related Registration Statement on Form S-4 (the "REGISTRATION STATEMENT"),
which includes the Joint Proxy Statement/Prospectus (the "JOINT PROXY
STATEMENT/PROSPECTUS"), filed with the Securities and Exchange Commission (the
"COMMISSION") under the Securities Act of 1933, as amended (the "Securities
Act") and the Securities Exchange Act of 1934, as amended.

     We have reviewed the Merger Agreement, the Joint Proxy
Statement/Prospectus, the representation letters of Parent, Comcast and AT&T to
us dated ______, 2002 and delivered to us for purposes of our opinion (the
"REPRESENTATION LETTERS") and such other documents as we have deemed necessary
or appropriate for purposes of our opinion. For purposes of this opinion we have
assumed that (i) in all respects relevant to this opinion, the Mergers will be
consummated in the manner described in the Merger Agreement and the Joint Proxy
Statement/Prospectus and none of the terms or conditions contained therein have
been or will be modified in any respect relevant to this opinion and (ii) the
representations made to us in the Representation Letters are accurate and
complete. The opinion expressed herein is based upon existing statutory,
regulatory and judicial authority and administrative rulings, any of which may
be changed at any time with retroactive effect. In addition, our opinion is
based solely on the documents that we have examined and the statements contained
in the Representation Letters, which we have assumed will be true as of the
effective time of the Mergers. Our opinion cannot be relied upon if any of the
facts pertinent to the U.S. federal income tax treatment of the Mergers stated
in such documents or in such additional information is, or later becomes,
inaccurate, or if any of the statements contained in the Representation Letters
are, or later become, inaccurate.

     On the basis of the foregoing, we are of the opinion that the discussion
set forth under the caption "Material Federal Income Tax Consequences - Material
Federal Income Tax Consequences of the Mergers" in the Joint Proxy
Statement/Prospectus accurately describes in all material respects the material
United States federal income tax consequences of the Mergers, subject to the
qualifications set forth in such discussion.

     In accordance with the requirements of Item 601(b)(23) of Regulation S-K
under the Securities Act, we hereby consent to the discussion of this opinion in
the Joint Proxy Statement/Prospectus, to the filing of this opinion as an
exhibit to the Registration Statement and to the reference to our firm under the
headings "Material Federal Income Tax Consequences - Material Federal Income Tax
Consequences of the Mergers" and "Legal Matters" in the Joint Proxy

Statement/Prospectus. In giving such consent, we do not thereby admit that we
are in the category of persons whose consent is required under Section 7 of the
Securities Act or the rules and regulations of the Commission thereunder.

     This opinion is being provided to you solely in connection with the
Registration Statement and may not be relied upon, circulated, quoted or
otherwise referred to for any other purpose.

                                            Very truly yours,