COMCAST CORPORATION

                             1987 STOCK OPTION PLAN

             (As Amended and Restated, Effective December 15, 1998)


     1.  Purpose.   COMCAST   CORPORATION,   a  Pennsylvania   corporation  (the
"Company"),  adopts the Comcast  Corporation  1987 Stock  Option Plan  effective
January 5, 1987 (the "Plan"). The Plan is intended as an additional incentive to
employees  and  non-employee  members of the Board of  Directors  (together  the
"Optionees")  to enter  into or  remain  in the  employ  of the  Company  or any
Affiliate  (as  defined  below)  or to serve on the  Board of  Directors  of the
Company or any  Affiliate and to devote  themselves to the Company's  success by
providing  them with an  opportunity  to acquire or increase  their  proprietary
interest in the Company through receipt of rights (the "Options") to acquire the
Company's  Class A Special Common Stock,  par value,  $1.00 per share (except as
otherwise provided in Section 12, the "Common Stock"). Each Option granted under
the Plan to an  employee  of the  Company or an  Affiliate  is intended to be an
incentive  stock  option  ("ISO")  within the  meaning of Section  422(b) of the
Internal  Revenue Code of 1986,  as amended (the "Code") for federal  income tax
purposes, except to the extent any such ISO grant would exceed the limitation of
subsection 6(a) and except for any Option specifically designated at the time of
grant as not being an ISO. No Option  granted to a person who is not an employee
of the  Company  or any  Affiliate  on the  date of grant  shall be an ISO.  For
purposes  of the Plan,  except as  otherwise  provided  in Section  14, the term
"Affiliate"  shall  mean  a  corporation  which  is a  parent  corporation  or a
subsidiary corporation with respect to the Company within the meaning of Section
424(e) or (f) of the Code.

     2.  Administration.  The Plan shall be administered by the  Subcommittee on
Performance  Based  Compensation  of the  Compensation  Committee  or any  other
committee or  subcommittee  designated by the Board of Directors of the Company,
provided  it is  composed  of two or more  non-employee  members of the Board of
Directors  each of whom is an "outside  director"  within the meaning of Section
162(m)(4)(C)  of the Code and applicable  Treasury  Regulations  thereunder (the
"Committee").  Notwithstanding the foregoing, in the case non-employee directors
who are granted  Options in  accordance  with the  provisions  of Section 8, the
directors  to whom such  Options  will be granted,  the timing of grants of such
Options,  the Option Price (as such term is defined in subsection  6(b)) of such
Options  and the number of Option  Shares (as such term is defined in Section 4)
included in such Options  shall be as  specifically  set forth in Section 8. 

          (a)  Meetings.  The  Committee  shall hold  meetings at such times and
places as it may  determine.  Acts  approved  at a meeting by a majority  of the
members of the Committee or acts approved in writing by the unanimous consent of
the members of the Committee shall be the valid acts of the Committee.


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          (b) Grants.  Except with  respect to options  granted to  non-employee
directors  pursuant to Section 8, the  Committee  shall from time to time at its
discretion  direct the  Company to grant  Options  pursuant  to the terms of the
Plan. The Committee  shall have plenary  authority to determine the Optionees to
whom and the  times at which  Options  shall be  granted,  the  number of Option
Shares (as defined in Section 4) to be granted and the price and other terms and
conditions thereof,  including a specification with respect to whether an Option
is intended to be an ISO,  subject,  however,  to the express  provisions of the
Plan.  In making such  determinations  the  Committee  may take into account the
nature of the Optionee's services and  responsibilities,  the Optionee's present
and potential contribution to the Company's success and such other factors as it
may  deem  relevant.   Notwithstanding  the  foregoing,  grants  of  Options  to
non-employee  directors  shall  be  made  in  accordance  with  Section  8.  The
interpretation and construction by the Committee of any provision of the Plan or
of any Option granted under it shall be final, binding and conclusive.

          (c)  Exculpation.  No  member  of the  Board  of  Directors  or of the
Committee shall be personally liable for monetary damages as such for any action
taken or any failure to take any action in connection with the administration of
the Plan or the  granting of Options  under it unless (i) the director or member
of the  Committee has breached or failed to perform the duties of his office and
(ii)  the  breach  or  failure  to  perform  constitutes  self-dealing,  willful
misconduct  or  recklessness;  provided,  however,  that the  provisions of this
subsection 2(c) shall not apply to the responsibility or liability of a director
or a member of the Committee pursuant to any criminal statute.

          (d)  Indemnification.  Each member of the Board of Directors or of the
Committee  shall be entitled  without  further act on his part to indemnity from
the Company to the fullest  extent  provided by applicable law and the Company's
by-laws in connection with or arising out of any action, suit or proceeding with
respect to the administration of the Plan or the granting of Options under it in
which he may be  involved  by reason of his being or having been a member of the
Board of  Directors  or the  Committee,  whether or not he  continues to be such
member  of the  Board  or the  Committee  at the  time  of the  action,  suit or
proceeding.

     3.  Eligibility.  All employees of the Company or its  Affiliates  (who may
also be directors of the Company or its Affiliates) shall be eligible to receive
ISOs hereunder.  All Optionees  shall be eligible to receive Options  hereunder.
The Committee,  in its sole  discretion,  shall determine  whether an individual
qualifies  as an employee or as an  Optionee.  An Optionee may receive more than
one Option,  but only on the terms and subject to the  restrictions of the Plan,
provided, however, that non-employee directors may receive Options only pursuant
to Section 8.

     4. Option  Shares.  The  aggregate  maximum  number of shares of the Common
Stock  for which  Options  may be issued  under the Plan is  19,500,000  shares,
adjusted as provided in Section 9 (the "Option Shares").  Option Shares shall be
issued from authorized and unissued

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Common Stock or Common  Stock held in or hereafter  acquired for the treasury of
the Company. If any outstanding Option granted under the Plan expires, lapses or
is terminated  for any reason,  the Option Shares  allocable to the  unexercised
portion of such Option may again by the subject of an Option granted pursuant to
the Plan. The maximum number of shares of the Common Stock for which Options may
be issued  to any  single  employee  of the  Company  or its  Affiliates  in any
calendar year,  adjusted as provided in Section 9, shall be, in 1994,  2,300,000
shares, and thereafter 500,000 shares.

     5. Term of Plan. The Plan is effective as of January 5, 1987. No Option may
be granted under the Plan after January 4, 1997.

     6. Terms and Conditions of Options.  Options  granted  pursuant to the Plan
shall be evidenced by written documents (the "Option Documents") in such form as
the Committee  shall from time to time  approve,  which Option  Documents  shall
comply with and be subject to the following  terms and conditions and such other
terms and conditions  which the Committee  shall from time to time require which
are not inconsistent with the terms of the Plan. However, the provisions of this
Section 6 shall not be applicable to Options granted to non-employee  directors,
except as otherwise provided in subsection 8(c).

          (a) Number of Option  Shares.  Each  Option  Document  shall state the
number of  Option  Shares to which it  pertains.  Notwithstanding  that any such
Option is intended to be an ISO,  such option  shall not be an ISO to the extent
that it would not be so treated under the rules  contained in Section  422(d) of
the Code,  and the  Regulations  thereunder  (dealing  with the  annual  vesting
limit).

          (b) Option Price.  Each Option Document shall state the price at which
Option  Shares may be purchased  (the "Option  Price"),  which shall be at least
100% of the fair  market  value of the  Common  Stock at the time the  Option is
granted as determined by the  Committee;  provided,  however,  that if an ISO is
granted to an Optionee who then owns,  directly or by attribution  under Section
424(d)  of the  Code,  shares  possessing  more  than ten  percent  of the total
combined  voting  power of all classes of stock of the Company or an  Affiliate,
then the Option  Price  shall be at least 110% of the fair  market  value of the
Option Shares at the time the Option is granted.

          (c) Medium of Payment.  An Optionee shall pay for Option Shares (i) in
cash, (ii) by certified check payable to the order of the company, or (iii) by a
combination  of the  foregoing.  In addition,  the  Committee  may provide in an
Option  Document  that  payment  may be made all or in part in  Other  Available
Shares held by the Optionee (a) in the case of payment for ISOs  outstanding  as
of March 28, 1990, for more than one year, or (b) in the case of payment for all
other Options (unless otherwise  provided in an Option Document),  for more than
six months or such shorter period of time as shall not, in the Committee's  sole
discretion,  have an  adverse  effect  on the  Company's  financial  statements;
provided, however, that Option Shares may not be

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paid for in  shares of Class A Common  Stock if such  method  of  payment  would
result in liability  under Section 16(b) of the Securities  Exchange Act of 1934
to an Optionee.  Except as otherwise  provided by the  Committee,  if payment is
made in whole or in part in shares of the Common  Stock or Class A Common  Stock
of the Company,  then the  Optionee  shall  deliver to the Company  certificates
registered in the name of such Optionee  representing  shares of Common Stock or
Class A Common Stock legally and  beneficially  owned by such Optionee,  free of
all liens,  claims and encumbrances of every kind and having a fair market value
on the date of delivery  that is not greater than the Option Price of the Option
Shares with  respect to which such  Option is to be  exercised,  accompanied  by
stock  powers  duly  endorsed  in  blank  by the  record  holder  of the  shares
represented by such certificates.  Notwithstanding the foregoing, the Committee,
in its sole  discretion,  may refuse to accept shares of Common Stock or Class A
Common Stock in payment of the Option  Price.  In that event,  any  certificates
representing shares of Common Stock or Class A Common Stock which were delivered
to the Company  shall be returned to the Optionee  with notice of the refusal of
the  Committee  to accept  such  shares in  payment  of the  Option  Price.  The
Committee may impose such  limitations and  prohibitions on the use of shares of
the  Common  Stock or Class A Common  Stock to  exercise  an  Option as it deems
appropriate.

          (d) Termination of Options.  No Option shall be exercisable  after the
first to occur of the following:

               (i)  Expiration  of the  Option  term  specified  in  the  Option
Document,  which for an ISO,  shall not  exceed  (A) ten years  from the date of
grant,  or (B) five years from the date of grant if the  Optionee on the date of
grant owns,  directly or by attribution under Section 424(d) of the Code, shares
possessing  more than ten  percent  of the total  combined  voting  power of all
classes  of stock of the  Company  or of an  Affiliate,  and which for any other
Option shall not exceed ten years and six months from the date of grant;

               (ii)  Expiration  of three  months  from the date the  Optionee's
employment  with the Company or its  Affiliates  terminates for any reason other
than  disability   (within  the  meaning  of  Section   22(e)(3)  of  the  Code)
("Disability"),  death or as  specified  in  subsection  6(d)(iv)  or (v) below,
provided,  however, that the Committee may specify in an Option Document that an
Option  may be  exercisable  during  a  longer  period  following  the  date the
Optionee's  employment with the Company or its Affiliates so terminates,  but in
no event later than the  expiration of the Option Term  specified in such Option
Document;

               (iii)  Expiration  of one  year  from  the  date  the  Optionee's
employment  with the  Company  or its  Affiliates  terminates  by  reason of the
Optionee's Disability or death;

               (iv) The date set by the  Committee  pursuant  to  Section  13 in
connection with a Terminating Event; or

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               (v) A finding by the Committee,  after full  consideration of the
facts  presented  on  behalf  of both the  Company  and the  Optionee,  that the
Optionee has breached his employment  contract with the Company or an Affiliate,
or has been engaged in any sort of  disloyalty  to the Company or an  Affiliate,
including,  without  limitation,  fraud,  embezzlement,  theft,  commission of a
felony or proven  dishonesty  in the course of his  employment  or has disclosed
trade  secrets of the Company or an  Affiliate.  In such  event,  in addition to
immediate  termination of the Option, the Optionee,  upon a determination by the
Committee  shall  automatically  forfeit all Option Shares for which the Company
has not yet delivered the share  certificates  upon refund by the Company of the
Option Price.

          (e)  Transfers.  This  subsection  6(e)  shall  not  apply to  Options
described in Section 6.1.

               (i) In General.  Except as provided in  subsection  6(e)(ii),  no
Option granted under the Plan may be transferred,  except by will or by the laws
of descent and distribution. During the lifetime of the person to whom an Option
is granted, such Option may be exercised only by him.

               (ii) Transferable  Options. The Committee may, in its discretion,
at the time of grant of an Option that is not an ISO (an "NQO") or by  amendment
of an Option  Document for an ISO or an NQO,  provide that Options granted to or
held by an  Optionee  may be  transferred,  in whole or in part,  to one or more
transferees and exercised by any such transferee;  provided further that (A) any
such transfer is without  consideration  and (B) each  transferee is a member of
such Optionee's Immediate Family (as hereinafter defined);  and provided further
that any ISO granted  pursuant to an Option  Document which is amended to permit
transfers during the lifetime of the Optionee shall,  upon the  effectiveness of
such amendment,  be treated thereafter as an NQO. No transfer of an Option shall
be effective unless the Committee is notified of the terms and conditions of the
transfer  and the  Committee  determines  that the  transfer  complies  with the
requirements  for transfers of Options  under the Plan and the Option  Document.
Any person to whom an Option has been  transferred may exercise any Options only
in accordance  with the  provisions of  subsections  6(c),  6(d),  6(f) and this
subsection  6(e).  For purposes of this  subsection  6(e),  the term  "Immediate
Family" shall mean an Optionee's  spouse and lineal  descendants,  any trust all
beneficiaries  of which are any of such persons and any partnership all partners
of which are any of such persons.

          (f) Other  Provisions.  The Option  Documents shall contain such other
provisions  including,  without  limitation,  additional  restrictions  upon the
exercise of the Option or additional limitations upon the term of the Option, as
the Committee shall deem advisable.

          (g)  Amendment.  The  Committee  shall have the right to amend  Option
Documents issued to an Optionee subject to his consent,  except that the consent
of the Optionee  shall not be required for any amendment  made under  subsection
6(d)(iv).

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          (h) Exercisability. To the extent that the grant of an Option would be
subject to  Section  16(b) of the  Securities  Exchange  Act of 1934  unless the
requirements for exemption therefrom in Rule 16b-3(c)(1), under such Act, or any
successor  provision,  are met,  the Option  Documents  shall  provide that such
Option is not  exercisable  until not less than six months have elapsed from the
date of grant.

     6.1 Certain  Options  Awarded to Ralph J.  Roberts.  With  respect to those
Options  awarded to Ralph J.  Roberts on January 8, 1992  (options  to  purchase
249,441 shares of Class A Special Common Stock at $16.25 per share), and January
6, 1993 (options to purchase  249,545  shares of Class A Special Common Stock at
$18.125  per  share),  and  notwithstanding  subsection  6(e) of this Plan,  the
Committee  may,  in its  discretion,  amend such  Options  to provide  that such
Options may be transferred by Mr.  Roberts,  in whole or in part, to one or more
transferees  and  exercised by any such  transferee,  provided that (i) any such
transfer is without  consideration,  and (ii) each transferee is a member of Mr.
Roberts'  Immediate Family.  "Immediate  Family" shall mean Mr. Roberts' spouse,
children,  grandchildren, any trust all beneficiaries of which are such persons,
and any  partnership  all partners of which are such  persons.  In the event the
Committee so amends such Options,  the  Committee  shall include in such amended
Options such further provisions as it determines are necessary or appropriate at
the time of such amendment to permit the Company to deduct compensation expenses
recognized  upon  exercise  of such  options  for  federal  or state  income tax
purposes.

     7. Exercise.  No Option shall be deemed to have been exercised prior to the
receipt by the Company of written notice of such exercise and of payment in full
of the Option  Price for the Option  Shares to be  purchased.  Each such  notice
shall  specify the number of Option Shares to be purchased and shall (unless the
Option  Shares  are  covered  by a  then  current  registration  statement  or a
Notification  under  Regulation A under the Securities Act of 1933 (the "Act")),
contain the Optionee's  acknowledgment in form and substance satisfactory to the
Company that (2) such Option Shares are being  purchased for  investment and not
for  distribution  or resale (other than a distribution  or resale which, in the
opinion of counsel  satisfactory to the Company,  may be made without  violating
the  registration  provisions of the Act), (b) the Optionee has been advised and
understands  that (i) the Option Shares have not be registered under the Act and
are "restricted securities" within the meaning of Rule 144 under the Act and are
subject to  restrictions on transfer and (ii) the Company is under no obligation
to register  the Option  Shares  under the Act or to take any action which would
make  available to the Optionee any exemption  from such  registration,  and (c)
such Option Shares may not be transferred without compliance with all applicable
federal and state securities laws. Notwithstanding the above, should the Company
be advised by counsel  that  issuance  of shares  should be delayed  pending (A)
registration  under  federal or state  securities  laws or (B) the receipt of an
opinion that an appropriate  exemption  therefrom is available,  the Company may
defer exercise of any Option granted hereunder until either such event in (A) or
(B) has occurred.


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     8.  Special  Provisions  Relating  to Grants  of  Options  to  Non-employee
Directors.  Options granted pursuant to the Plan to non-employee directors shall
be granted,  without any further action by the Committee, in accordance with the
terms and  conditions set forth in this Section 8. Options  granted  pursuant to
this  Section  8 shall be  evidenced  by  Option  Documents  in such form as the
Committee shall from time to time approve,  which Option  Documents shall comply
with and be subject to the following  terms and  conditions and such other terms
and  conditions as the  Committee  shall from time to time require which are not
inconsistent with the terms of the Plan.

          (a)  Timing  of  Grants;   Number  of  Shares   Subject  of   Options;
Exercisability of Options;  Option Price.  Each  non-employee  director shall be
granted,  commencing on February 1, 1995 and on each successive  February 1 (the
"Grant  Date")  thereafter,  an Option to purchase  five  thousand  four hundred
(5,400) shares of Common Stock. Notwithstanding anything herein to the contrary,
each newly  elected  non-employee  director who is first elected to the Board of
Directors after February 1, 1994 shall (i) be granted an Option to purchase nine
thousand  (9,000) shares of Common Stock on the date on which such  non-employee
director is elected to the Board of Directors (the "Election Date") and (ii) not
be entitled to the grant of an Option  hereunder  on the Grant Date  immediately
following  the  non-employee  director's  Election Date if such Election Date is
within  ninety (90) days of the Grant Date.  No such Option shall be an ISO, and
each such Option  shall first  become  exercisable  six months after the date of
grant and shall then be exercisable  in its entirety.  The Option Price shall be
equal  to 100% of the fair  market  value  of the  Common  Stock on the date the
Option is granted.

          (b) Termination of Options Granted Pursuant to Section 8.

               (i) All  options  granted  pursuant  to this  Section  8 shall be
exercisable until the first to occur of the following:

                    (A) Expiration of five (5) years from the date of grant;

                    (B)  Expiration  of  ninety  (90)  days  from  the  date the
          Optionee's  service  as a  non-employee  director  terminates  for any
          reason other than  Disability  or death or as  otherwise  specified in
          subsection 8(b)(i)(D) below;

                    (C)  Expiration of one (1) year from the date the Optionee's
          service with Company as a non-employee  director terminates due to the
          Optionee's Disability or death; or

                    (D) The date the Optionee's  directorship is terminated,  if
          the  directorship  is  terminated  on account of (1) any act of fraud,
          intentional  misrepresentation,  embezzlement or theft, (2) commission
          of a felony or (3) disclosure of

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          trade  secrets  of the  Company or an  Affiliate.  In such  event,  in
          addition to the  immediate  termination  of the Option,  the  Optionee
          shall  automatically  forfeit all Option  Shares for which the Company
          has not yet  delivered  the  share  certificates  upon  refund  by the
          Company of the Option Price.

          (c)  Applicability  of  Certain  Provisions  of  Section 6 to  Options
Granted  Pursuant to Section 8. The  following  provisions of Section 6 shall be
applicable  to Options  granted  pursuant  to this  Section 8:  Subsection  6(a)
(provided  that no Option  granted  pursuant to this Section 8 shall be an ISO);
subsection  6(c) (provided  that Option  Documents  relating to options  granted
pursuant to this  Section 8 shall  provide  that payment may be made in whole or
part in shares of Common  Stock or Class A Common Stock held by the Optionee for
more than six months,  subject to the limitation on payment in shares of Class A
Common Stock set forth in subsection 6(c) if such method of payment would result
in  liability  under  Section  16(b) of the  Securities  Exchange  Act of 1934);
subsection 6(e); subsection 6(g); and subsection 6(h).

     9. Adjustments on Changes in Capitalization. The aggregate number of shares
and class of shares as to which Options may be granted hereunder,  the number of
shares covered by each outstanding Option, and the Option Price thereof shall be
appropriately  adjusted  in  the  event  of  a  stock  dividend,   stock  split,
recapitalization  or  other  change  in  the  number  or  class  of  issued  and
outstanding  equity  securities of the Company  resulting  from a subdivision or
consolidation of the Common Stock and/or other outstanding  equity security or a
recapitalization  or other  capital  adjustment  (not  including the issuance of
Common Stock on the  conversion  of other  securities  of the Company  which are
convertible  into Common  Stock)  affecting  the Common  Stock which is effected
without  receipt of  consideration  by the  Company.  The  Committee  shall have
authority to  determine  the  adjustments  to be made under this Section and any
such  determination  by the Committee  shall be final,  binding and  conclusive;
provided,  however,  that no adjustment shall be made which will cause an ISO to
lose its status as such without the consent of the  Optionee  and no  adjustment
shall be made to the number of shares set forth in subsection 8(a).  However, an
Option granted pursuant to subsection 8(a).  However, an Option granted pursuant
to  subsection  8(a) shall be  subject  to  adjustment  in  accordance  with the
provisions of this Section 9 after the date of grant.

     10.  Amendment of the Plan.  The Board or the  Committee may amend the Plan
from time to time in such manner as it may deem advisable. Nevertheless, neither
the Board nor the Committee  may,  without  within twelve months before or after
such action  obtaining  approval by such vote of shareholders as may be required
by  Pennsylvania  law for any action  requiring  shareholder  approval,  or by a
majority of votes cast at a duly held shareholders'  meeting at which a majority
of all voting stock is present and voting on such amendment, either in person or
in proxy (but not, in any event,  less than the vote  required  pursuant to Rule
16b-3(b)  under  the  Securities  Exchange  Act of  1934),  change  the class of
individuals  eligible to receive an ISO, extend the expiration date of the Plan,
decrease the minimum  Option Price of an ISO granted  under the Plan or increase
the maximum number of shares as to which Options may be granted,

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except as provided in Section 9 hereof. In addition, the provisions of Section 8
that determine (i) which directors shall be granted Options  pursuant to Section
8; (ii) the  number of Option  Shares  subject to Options  granted  pursuant  to
Section 8; (iii) the Option Price of Option  Shares  subject to Options  granted
pursuant  to Section 8; and (iv) the  timing of grants of  Options  pursuant  to
Section 8 shall not be amended  more than once every six  months,  other than to
comport with changes in the Code or the Employee  Retirement Income Security Act
of 1974, as amended, if applicable.

     11. Continued Employment. The grant of an Option pursuant to the Plan shall
not be construed to imply or to constitute evidence of any agreement, express or
implied,  on the part of the Company or any  Affiliate to retain the Optionee in
the employ of the Company or an Affiliate or as a member of the Company's  Board
of Directors or in any other capacity.

     12. Withholding of Taxes.

          (a)  Whenever  the  Company  proposes  or is  required  to  deliver or
transfer Option Shares in connection with the exercise of an Option, the Company
shall have the right to (i)  require  the  recipient  to remit to the Company an
amount  sufficient to satisfy any federal,  state and/or local  withholding  tax
requirements   prior  to  the  delivery  or  transfer  of  any   certificate  or
certificates  for such Option  Shares or (ii) take any action  whatever  that it
deems  necessary to protect its interests with respect to tax  liabilities.  The
Company's  obligation to make any delivery or transfer of Option Shares shall be
conditioned on the recipient's compliance,  to the Company's satisfaction,  with
any withholding requirement.

          (b)  Except as  otherwise  provided  in this  Section  12(b),  any tax
liabilities incurred in connection with the exercise of an Option under the Plan
other than an ISO shall be satisfied by the  Company's  withholding a portion of
the Option Shares  underlying  the Option  exercised  having a fair market value
approximately  equal to the minimum  amount of taxes  required to be withheld by
the Company under applicable law, unless  otherwise  determined by the Committee
with respect to any participant.  Notwithstanding  the foregoing,  the Committee
may permit an Optionee to elect one or both of the following:  (i) to have taxes
withheld in excess of the minimum amount  required to be withheld by the Company
under  applicable  law;  provided that the Optionee  certifies in writing to the
Company that the  Optionee  owns a number of Other  Available  Shares that is at
least equal to the number to be  withheld  by the  Company for the  then-current
exercise on account of withheld taxes in excess of such minimum amount, and (ii)
to pay to the Company in cash all or a portion of the taxes to be withheld  upon
the exercise of an Option.  In all cases,  the Option  Shares so withheld by the
Company  shall have a fair market value that does not exceed the amount of taxes
to be withheld  minus the cash payment,  if any, made by the Optionee.  The fair
market value of such shares shall be determined  based on the last reported sale
price of a share of Common Stock on the  principal  exchange on which the Common
Stock is listed or, if not so listed,  on the  Nasdaq  Stock  Market on the last
trading  day prior to the date on which the Option is  exercised.  Any  election
pursuant to this Section 12(b) must be in

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<PAGE>

writing  made prior to the date  specified  by the  Committee,  and in any event
prior to the date the amount of tax to be  withheld  or paid is  determined.  An
election  pursuant to this  Section  may be made only by an Optionee  or, in the
event of the Optionee's death, by the Optionee's legal representative. No shares
withheld pursuant to this Section 12(b) shall be available for subsequent grants
under the Plan. The Committee may add such other  requirements  and  limitations
regarding elections pursuant to this Section 12(b) as it deems appropriate.

     13. Terminating Events.

          (a) The Sponsor shall give Optionees at least thirty (30) days' notice
(or, if not practicable,  such shorter notice as may be reasonably  practicable)
prior to the anticipated date of the consummation of a Terminating  Event.  Upon
receipt of such notice,  and for a period of ten (10) days  thereafter  (or such
shorter  period as the  Board  shall  reasonably  determine  and so  notify  the
Optionees),  each  Optionee  shall be  permitted  to exercise  the Option to the
extent the Option are then  exercisable;  provided  that,  the  Sponsor  may, by
similar notice,  require the Optionee to exercise the Option,  to the extent the
Option is then  exercisable,  or to forfeit the Option (or portion  thereof,  as
applicable).  The  Committee  may,  in its  discretion,  provide  that  upon the
Optionee's  receipt  of the notice of a  Terminating  Event  under this  Section
13(a),  the entire number of Shares covered by Options shall become  immediately
exercisable. Upon the close of the period described in this Section 13(a) during
which an Option may be exercised in connection  with a Terminating  Event,  such
Option (including such portion thereof that is not exercisable)  shall terminate
to the extent that such Option have not theretofore been exercised.

          (b) Notwithstanding  Section 13(a), in the event the Terminating Event
is not  consummated,  the Option shall be deemed not to have been  exercised and
shall be exercisable  thereafter to the extent it would have been exercisable if
no such notice had been given.

     14. Additional Definitions.

          (a) "Affiliate." For purposes of this Section 14,  "Affiliate"  means,
with respect to any Person, any other Person that, directly or indirectly, is in
control of, is controlled by, or is under common control with, such Person.  For
purposes of this definition, the term "control," including its correlative terms
"controlled  by" and "under  common  control  with,"  mean,  with respect to any
Person, the possession,  directly or indirectly, of the power to direct or cause
the direction of the management and policies of such Person, whether through the
ownership of voting securities, by contract or otherwise.

          (b) "Board" means the board of directors of the Sponsor.


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<PAGE>


          (c)  "Change  of  Control"   means  any   transaction   or  series  of
transactions  as a result of which any Person who was a Third Party  immediately
before  such  transaction  or  series  of  transactions  owns   then-outstanding
securities  of the Sponsor  having more than 50 percent of the voting  power for
the election of directors of the Sponsor.

          (d) "Comcast  Plan" means any  restricted  stock,  stock bonus,  stock
option  or other  compensation  plan,  program  or  arrangement  established  or
maintained  by the Company or an  Affiliate,  including  but not limited to this
Plan,  the Comcast  Corporation  1996 Stock Option Plan and the 1990  Restricted
Stock Plan.

          (e) "Common  Stock." For purposes of the definition of the term "Other
Available Shares" in Section 12(f), "Common Stock" means:

               (i)  the  Sponsor's  Class A Common Stock,  par value,  $1.00 per
                    share; and

               (ii) the Sponsor's Class A Special Common Stock, par value, $1.00
                    per share

          (f) "Other Available Shares" means, as of any date, the excess, if any
of:

               (i)  the total  number of  shares  of  Common  Stock  owned by an
                    Optionee; over

               (ii) the sum of:

                    (x)  the  number of shares  of  Common  Stock  owned by such
                         Optionee for less than six months; plus

                    (y)  the  number of shares  of  Common  Stock  owned by such
                         Optionee  that has,  within the  preceding  six months,
                         been  the  subject  of  a   withholding   certification
                         pursuant to Section  12(b) or any  similar  withholding
                         certification under any other Comcast Plan; plus

                    (z)  the  number of shares  of  Common  Stock  owned by such
                         Optionee  that has,  within the  preceding  six months,
                         been  received in exchange  for Shares  surrendered  as
                         payment,  in full or in part, of the exercise price for
                         an option to purchase any

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<PAGE>

                         securities  of the  Sponsor or an  Affiliate  under any
                         Comcast  Plan,  but only to the extent of the number of
                         Shares surrendered.

For  purposes of Section  6(c),  the number of Other  Available  Shares shall be
determined separately for the Company's Class A Special Common Stock, par value,
$1.00 per share,  and for the Company's Class A Common Stock,  par value,  $1.00
per share.

          (g) "Person" means an individual,  a  corporation,  a partnership,  an
association, a trust or any other entity or organization.

          (h) "Roberts Family." Each of the following is a member of the Roberts
Family:

               (i)  Ralph J. Roberts;

               (ii) a lineal descendant of Ralph J. Roberts; or

               (iii)a trust  established  for the  benefit  of any of  Ralph  J.
                    Roberts  and/or a lineal  descendant or descendants of Ralph
                    J. Roberts.

          (i) "Sponsor" means Comcast Corporation,  a Pennsylvania  corporation,
including any successor thereto by merger, consolidation,  acquisition of all or
substantially all the assets thereof, or otherwise.

          (j) "Terminating Event" means any of the following events:

               (i)  the liquidation of the Sponsor; or

               (ii) a Change of Control.


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          (k) "Third Party" means any Person other than a Company, together with
such Person's Affiliates, provided that the term "Third Party" shall not include
the Sponsor, an Affiliate of the Sponsor or any member or members of the Roberts
Family.

                                 Executed as of the 15th day of December, 1998



                                           COMCAST CORPORATION




                                           BY: /s/ Stanley Wang




                                           ATTEST: /s/ Arthur R. Block

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