EXHIBIT 10.4

                                EMC CORPORATION

              1993 STOCK OPTION PLAN, as amended January 22, 1997

1.  PURPOSE.
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    The purpose of the EMC Corporation 1993 Stock Option Plan is to enable EMC
Corporation to provide a special incentive to a limited number of key employees
of the Company and its Subsidiaries, if any, who are in a position to have a
significant effect upon the Company's business and earnings.  In order to
accomplish this purpose, the Plan authorizes the grant to such key employees of
options to purchase Common Stock of the Company.  Increased ownership of Common
Stock will provide such key employees with an additional incentive to take into
account the long-term interests of the Company.

2.  DEFINITIONS.
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    As used herein, the following words or terms have the meanings set forth
below.  The masculine gender is used throughout the Plan but is intended to
apply to members of both sexes.

    2.1  "Board of Directors" means the Board of Directors of the Company.

    2.2  "Code" means the Internal Revenue Code of 1986, as amended from time to
time, or any successor statute.

    2.3  "Committee" means the Committee appointed by the Board of Directors to
administer the Plan or the Board of Directors as a whole if no appointment is
made.

    2.4  "Common Stock" means the Common Stock of the Company.

    2.5  "Company" means EMC Corporation, a corporation established under the
laws of The Commonwealth of Massachusetts.

    2.6  "Fair Market Value" in the case of a share of Common Stock on a
particular day, means the fair market value as determined from time to time by
the Board of Directors or, where appropriate, by the Committee, taking into
account all information which the Board of Directors, or the Committee,
considers relevant.

    2.7  "Incentive Stock Option" means a stock option that satisfies the
requirements of Section 422 of the Code.

    2.8  "Participant" means an individual holding a stock option or stock
options granted to him under the Plan.

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    2.9  "Plan" means the EMC Corporation 1993 Stock Option Plan set forth
herein.

    2.10 "Subsidiary" or "Subsidiaries" means a corporation or corporations
in which the Company owns, directly or indirectly, stock possessing 50 percent
or more of the total combined voting power of all classes of stock.

    2.11 "Ten Percent Stockholder" means any person who, at the time an
option is granted, owns or is deemed to own stock (as determined in accordance
with Sections 422 and 424 of the Code) possessing more than ten percent (10%) of
the total combined voting power of all classes of stock of the Company or its
parent or a subsidiary.

3.  ADMINISTRATION.
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    3.1  The Plan shall be administered by the Committee and, to the extent
provided herein, the Board of Directors.  A majority of the members of the
Committee shall constitute a quorum, and all determinations of the Committee
shall be made by a majority of its members.  Any determination of the Committee
under the Plan may be made without notice or meeting of the Committee by a
writing signed by a majority of the Committee members.

    3.2  Subject to the provisions set forth herein, each of the Committee and
the Board of Directors shall have full authority to determine the provisions of
options to be granted under the Plan. Subject to the provisions set forth
herein, the Committee shall have full authority to interpret the terms of the
Plan and of options granted under the Plan, to adopt, amend and rescind rules
and guidelines for the administration of the Plan and for its own acts and
proceedings and to decide all questions and settle all controversies and
disputes which may arise in connection with the Plan; provided, however, that
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any change to the terms of an option granted hereunder shall be approved by the
Board of Directors to the extent such change would be deemed to be a new option
grant or such terms relate to a subsequent transaction that would not be exempt
from Section 16(b) of the Securities Exchange Act of 1934 in the absence of such
approval.


    3.3  The decision of the Committee or the Board of Directors, as applicable,
on any matter as to which the Committee or the Board of Directors, as
applicable, is given authority under subsection 3.2 shall be final and binding
on all persons concerned.

    3.4  Nothing in the Plan shall be deemed to give any officer or employee, or
his legal representatives or assigns, any right to participate in the Plan,
except to such extent, if any, as the Committee or the Board, as applicable, may
have determined or approved pursuant to the provisions of the Plan.

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4.  SHARES SUBJECT TO THE PLAN.
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    4.1  The maximum number of shares of Common Stock that may be delivered upon
the exercise of options granted under the Plan shall be 14,000,000/*/, subject
to adjustment in accordance with the provisions of Section 8.

    4.2  If any option granted under the Plan terminates without having been
exercised in full (including an option which terminates by agreement between the
Company and the Participant), the number of shares of Common Stock as to which
such option has not been exercised prior to termination shall be available for
future grants within the limits set forth in subsection 4.1.

    4.3  Shares of Common Stock delivered upon the exercise of options shall
consist of shares of authorized and unissued Common Stock, except that the Board
of Directors may from time to time in its discretion determine in any case the
shares to be so delivered shall consist of shares of authorized and issued
Common Stock reacquired by the Company and held in its Treasury.  No fractional
shares of Common Stock shall be delivered upon the exercise of an option.

5.  ELIGIBILITY FOR OPTIONS.
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    Employees eligible to receive options under the Plan shall be those key
employees of the Company and its Subsidiaries, if any, who, in the opinion of
the Committee, are in a position to have a significant effect upon the Company's
business and earnings.  Members of the Board of Directors of the Company or a
Subsidiary who are not employed as regular salaried officers or employees of the
Company or a Subsidiary may not participate in the Plan.

6.  GRANT OF OPTIONS.
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    6.1  From time to time while the Plan is in effect, each of the Committee
and the Board of Directors may, in its absolute discretion, select from among
the persons eligible to receive options (including persons to whom options were
previously granted) those persons to whom options are to be granted.

    6.2  Each of the Committee and the Board of Directors shall, in its absolute
discretion, determine the number of shares of Common Stock to be subject to each
option granted by it under the Plan.

    6.3  No Incentive Stock Option may be granted under the Plan after May 12,
2003, but options theretofore granted may extend beyond that date.



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/*/ Subject to stockholder approval.

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7.  PROVISIONS OF OPTIONS.
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    7.1  Incentive Stock Options or Other Options. Options granted under the
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Plan may be either Incentive Stock Options or options which do not qualify as
Incentive Stock Options, as the Committee or the Board of Directors shall
determine at the time of each grant of options hereunder.

    7.2  Stock Option Certificates or Agreements. Options granted under the Plan
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shall be evidenced by certificates or agreements in such form as the Committee
shall from time to time approve. Such certificates or agreements shall comply
with the terms and conditions of the Plan and may contain such other provisions
not inconsistent with the terms and conditions of the Plan as the Committee
shall deem advisable. In the case of options intended to qualify as Incentive
Stock Options, the certificates or agreements shall contain such provisions
relating to exercise and other matters as are required of incentive stock
options under the Code.

    7.3  Terms and Conditions.  All options granted under the Plan shall be
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subject to the following terms and conditions to the extent applicable and to
such other terms and conditions not inconsistent therewith as the Committee or
the Board of Directors shall determine:

         7.3.1  Exercise Price.  The exercise price per share of Common Stock
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    with respect to each option shall be as determined by the Committee but in
    the case of an Incentive Stock Option not less than 100% (110% in the case
    of an Incentive Stock Option granted to a Ten Percent Stockholder) of the
    Fair Market Value per share at the time the option is granted. In the case
    of an option which does not qualify as an Incentive Stock Option, the
    exercise price per share of Common Stock shall be not less than par value.

         7.3.2  Value of Shares of Common Stock Subject to Incentive Stock
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    Options.  Each eligible employee may be granted Incentive Stock Options
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    only to the extent that, in the aggregate under this Plan and all incentive
    stock option plans of the Company and any related corporation, such
    Incentive Stock Options do not become exercisable for the first time by such
    employee during any calendar year in a manner which would entitle the
    employee to purchase more than $100,000 in fair market value (determined at
    the time the Incentive Stock Options were granted) of Common Stock in that
    year. Any options granted to an employee in excess of such amount will be
    granted as Non-Qualified Options.

         7.3.3  Period of Options.  An option shall be exercisable during such
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    period of time as the Committee or Board of Directors may specify (subject
    to subsection 7.4 below), but in the case of an Incentive Stock Option not
    after the expiration of ten years (five years in the case of an Incentive
    Stock Option granted to a Ten Percent Stockholder) from the date the option
    is granted.

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         7.3.4  Exercise of Options.
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                7.3.4.1   Each option shall be made exercisable at such time or
         times as the Committee or the Board of Directors shall determine. In
         the case of an option made exercisable in installments, the Committee
         or the Board of Directors may later determine to accelerate the time at
         which one or more of such installments may be exercised.

                7.3.4.2   Any exercise of an option shall be in writing signed
         by the proper person and delivered or mailed to the General Counsel of
         the Company, accompanied by an option exercise notice and payment in
         full for the number of shares in respect to which the option is
         exercised.

                7.3.4.3   In the event an option is exercised by the executor or
         administrator of a deceased Participant, or by the person or persons to
         whom the option has been transferred by the Participant's will or the
         applicable laws of descent and distribution, the Company shall be under
         no obligation to deliver stock thereunder until the Company is
         satisfied that the person or persons exercising the option is or are
         the duly appointed executor or administrator of the deceased
         Participant or the person or persons to whom the option has been
         transferred by the Participant's will or by the applicable laws of
         descent and distribution.

                7.3.4.4   The Committee or the Board of Directors may at the
         time of grant condition the exercise of an option upon agreement by the
         Participant to subject the Common Stock to any restrictions on transfer
         or repurchase rights in effect on the date of exercise, upon
         representations of continued employment and upon other terms not
         inconsistent with this Plan. Any such conditions shall be set forth in
         the option certificate or other document evidencing the option.

                7.3.4.5   In the case of an option that is not an Incentive
         Stock Option, the Committee shall have the right to require that the
         individual exercising the option to remit to the Company an amount
         sufficient to satisfy any federal, state, or local withholding tax
         requirements (or makes other arrangements satisfactory to the Company
         with regard to such taxes) prior to the delivery of any Common Stock
         pursuant to the exercise of the option. In the case of an Incentive
         Stock Option, if at the time the Incentive Stock Option is exercised
         the Committee determines that under applicable law and regulations the
         Company could be liable for the withholding of any federal or state tax
         with respect to a disposition of the Common Stock received upon
         exercise, the Committee may require as a condition of exercise that the
         individual exercising the Incentive Stock Option agree (i) to inform
         the Company promptly of any disposition 

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         (within the meaning of Section
         422 (a) (1) of the Code and the regulations thereunder) of Common Stock
         received upon exercise, and (ii) to give such security as the Committee
         deems adequate to meet the potential liability of the Company for the
         withholding of tax, and to augment such security from time to time in
         any amount reasonably deemed necessary by the Committee to preserve the
         adequacy of such security.

                7.3.4.6  In the case of an option that is exercised by an
         individual that is subject to taxation in a foreign jurisdiction, the
         Committee shall have the right to require the individual exercising the
         option to remit to the Company an amount sufficient to satisfy any
         federal or withholding requirement of that foreign jurisdiction (or
         make other arrangements satisfactory to the Company with regard to such
         taxes prior to the delivery of any Common Stock pursuant to the
         exercise of the option).

         7.3.5  Payment for and Delivery of Stock.   The shares of stock
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     purchased on any exercise of an option granted hereunder shall be paid for
     in full in cash or, if permitted by the terms of the option, in shares of
     unrestricted Common Stock at the time of such exercise or, if so permitted,
     a combination of such cash and Common Stock.  A Participant shall not have
     the rights of a stockholder with respect to awards under the Plan except as
     to stock actually issued to him.

         7.3.6  Listing of Stock, Withholding and Other Legal Requirements.
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     The Company shall not be obligated to deliver any stock until all federal
     and state laws and regulations which the Company may deem applicable have
     been complied with, nor, in the event the outstanding Common Stock is at
     the time listed upon any stock exchange, until the stock to be delivered
     has been listed or authorized to be added to the list upon official notice
     of issuance to such exchange.  In addition, if the shares of stock subject
     to any option have not been registered in accordance with the Securities
     Act of 1933, as amended, the Company may require the person or persons who
     wishes or wish to exercise such option to make such representation or
     agreement with respect to the sale of stock acquired on exercise of the
     option as will be sufficient, in the opinion of the Company's counsel, to
     avoid violation of said Act, and may also require that the certificates
     evidencing said stock bear an appropriate restrictive legend.

         7.3.7  Non-transferability of Options.   No option may be transferred 
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     by the Participant otherwise than by will, by the laws of descent and
     distribution or pursuant to a qualified domestic relations order, and
     during the Participant's lifetime the option may be exercised only by him
     or her; provided, however, that the Board of Directors or the Committee, as
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     applicable, in its discretion, may allow for transferability of non-
     qualified stock options by the Participant to "Immediate Family Members."
     Immediate Family Members means children, grandchildren, spouse or common
     law spouse, siblings or parents of the Participant or to bona fide trusts,
     partnerships or other entities controlled by and of which the 

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     beneficiaries are Immediate Family Members of the Participant. Any option
     grants that are transferable are further conditioned on the Participant and
     Immediate Family Members agreeing to abide by the Company's then current
     stock option transfer guidelines.

         7.3.8   Death.   If a Participant dies at a time when he is entitled
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     to exercise an Incentive Stock Option, then at any time or times within
     three years after his death such Incentive Stock Option may be exercised,
     as to all or any of the shares which the Participant was entitled to
     purchase thereunder immediately prior to his death, by his executor or
     administrator or the person or persons to whom the Incentive Stock Option
     is transferred by will or the applicable laws of descent and distribution,
     and except as so exercised such Incentive Stock Option shall expire at the
     end of such three-year period.  In no event, however, may any Incentive
     Stock Option granted under the Plan be exercised after the expiration of
     ten years (five years in the case of an Incentive Stock Option granted to a
     Ten Percent Stockholder) from the date the Incentive Stock Option was
     granted.

         7.3.9  Termination of Employment.   If the employment of a Participant
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     terminates for any reason other than his death, all options held by the
     Participant shall thereupon expire on the date of termination unless the
     option by its terms, or the Committee or the Board of Directors by
     resolution, shall allow the Participant to exercise any or all of the
     options held by him after termination.  In the case of an Incentive Stock
     Option, the Incentive Stock Option shall in any event expire at the end of
     three months after such termination of employment, or after the expiration
     of ten years (five years in the case of an Incentive Stock Option granted
     to a Ten Percent Stockholder) from the date the Incentive Stock Option was
     granted, whichever occurs first.  If the Committee or the Board of
     Directors so decides, an option may  provide that a leave of absence
     granted by the Company or Subsidiary is not a termination of employment for
     the purpose of this subsection 7.3.9, and in the absence of such a
     provision the Committee may in any particular case determine that such a
     leave of absence is not a termination of employment for such purpose. The
     Committee shall also determine all other matters relating to continuous
     employment.

     7.4  Authority of the Committee.   The Committee shall have the authority,
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either generally or in particular instances, to waive compliance by a
Participant with any obligation to be performed by him under an option and to
waive any condition or provision of an option, except that the Committee may not
(i) increase the total number of shares covered by any Incentive Stock Option
(except in accordance with Section 8), (ii) reduce the option price per share of
any Incentive Stock Option (except in accordance with Section 8) or (iii) extend
the term of any Incentive Stock Option to more than ten years, subject, however,
to the provisions of Section 10.

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8.   CHANGES IN STOCK.
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     In the event of a stock dividend, stock split or other change in corporate
structure or capitalization affecting the Common Stock that becomes effective
after the adoption of the Plan by the Board of Directors, the Committee shall
make appropriate adjustments in (i) the number and kind of shares of stock on
which options may thereafter be granted hereunder, (ii) the number and kind of
shares of stock remaining subject to each option outstanding at the time of such
change and (iii) the option price.  The Committee's determination shall be
binding on all persons concerned.  Subject to any required action by the
stockholders, if the Company shall be the surviving corporation in any merger or
consolidation (other than a merger or consolidation in which the Company
survives but in which a majority of its outstanding shares are converted into
securities of another corporation or are exchanged for other consideration), any
option granted hereunder shall pertain and apply to the securities which a
holder of the number of shares of stock of the Company then subject to the
option would have been entitled to receive, but a dissolution or liquidation of
the Company or a merger or consolidation in which the Company is not the
surviving corporation or in which a majority of its outstanding shares are so
converted or exchanged shall cause every option hereunder to terminate; provided
that if any such dissolution, liquidation, merger or consolidation is
contemplated, the Company shall either arrange for any corporation succeeding to
the business and assets of the Company to issue to the Participants replacement
options (which, in the case of Incentive Stock Options, satisfy, in the
determination of the Committee, the requirements of Section 424 of the Code) on
such corporation's stock which will to the extent possible preserve the value of
the outstanding options or shall make the outstanding options fully exercisable
at least 20 days before the effective date of any such dissolution, liquidation,
merger or consolidation.  The existence of the Plan shall not prevent any such
change or other transaction and no Participant thereunder shall have any right
except as herein expressly set forth.

9.   EMPLOYMENT RIGHTS.
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     Neither the adoption of the Plan nor any grant of options confers upon any
employee of the Company or a Subsidiary any right to continued employment with
the Company or a Subsidiary, as the case may be, nor does it interfere in any
way with the right of the Company or a Subsidiary to terminate the employment of
any of its employees at any time.

10.  DISCONTINUANCE, CANCELLATION, AMENDMENT AND TERMINATION.
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     The Committee or the Board of Directors may at any time discontinue
granting options under the Plan and, with the consent of the Participant, may at
any time cancel an existing option in whole or in part and grant another option
to the Participant for such number of shares as the Committee or the Board of
Directors specifies.  The Board of Directors may at any time or times amend the
Plan for the purpose of satisfying the 

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requirements of any changes in applicable laws or regulations or for any other
purpose which may at the time be permitted by law or may at any time terminate
the Plan as to any further grants of options, provided that no such amendment
shall without the approval of the stockholders of the Company (a) increase the
maximum number of shares available under the Plan, (b) change the group of
employees eligible to receive options under the Plan, (c) reduce the exercise
price of outstanding incentive options or reduce the price at which incentive
options may be granted, (d) extend the time within which options may be granted,
(e) alter the Plan in such a way that incentive options granted or to be granted
hereunder would not be considered incentive stock options under Section 422 of
the Code, or (f) amend the provisions of this Section 10, and no such amendment
shall adversely affect the rights of any employee (without his consent) under
any option previously granted.

11.  EFFECTIVE DATE.
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     The Plan became effective immediately upon its approval by the stockholders
of the Company at the Annual Meeting on May 12, 1993.

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