<PAGE>
 
    
 AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON FEBRUARY 4, 1994     
                                                     
                                                  REGISTRATION NO. 33-51747     
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                                --------------
                                 
                              AMENDMENT NO. 1     
                                       
                                    TO     
                                    FORM S-3
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                                --------------
 
                               UNISYS CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
             DELAWARE                              38-0387840
     (STATE OF INCORPORATION)         (I.R.S. EMPLOYER IDENTIFICATION NO.)
 
                     TOWNSHIP LINE AND UNION MEETING ROADS
                         BLUE BELL, PENNSYLVANIA 19424
                                 (215) 986-4011
  (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
                          PRINCIPAL EXECUTIVE OFFICES)
 
                                HAROLD S. BARRON
                           SENIOR VICE PRESIDENT AND
                                GENERAL COUNSEL
                               UNISYS CORPORATION
                     TOWNSHIP LINE AND UNION MEETING ROADS
                         BLUE BELL, PENNSYLVANIA 19424
                                 (215) 986-5299
 (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
                             OF AGENT FOR SERVICE)
 
                                --------------
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
 
From time to time after the effective date of this registration statement.
 
                                --------------
 
If the only securities being registered on this form are being offered pursuant
to a dividend or interest reinvestment plan, please check the following
box. [_]
 
If any of the securities being registered on this form are to be offered on a
delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, as amended, other than securities offered only in connection with
dividend or interest reinvestment plans, check the following box. [X]
 
                                --------------
          

  THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT
SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID
SECTION 8(A), MAY DETERMINE.
 
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- --------------------------------------------------------------------------------

<PAGE>
 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A         +
+REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE   +
+SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY  +
+OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT        +
+BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR   +
+THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE      +
+SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE    +
+UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF  +
+ANY SUCH STATE.                                                               +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                     
                  SUBJECT TO COMPLETION, FEBRUARY 4, 1994     
 
PROSPECTUS
 
                               UNISYS CORPORATION
 
                        7,000,000 SHARES OF COMMON STOCK
 
                                  -----------
 
  This Prospectus relates to the offering, from time to time, by Harris Trust
and Savings Bank (or any successor trustee), as trustee for the Unisys Pension
Plan (the "Plan" or the "Selling Stockholder"), of up to 7,000,000 shares (the
"Shares") of the Common Stock, par value $.01 per share (the "Common Stock"),
of Unisys Corporation (the "Company") which have been contributed by the
Company to the Plan.
   
  The Shares have been placed into portfolios managed by independent investment
managers appointed by the Plan. Each investment manager is responsible, in its
discretion, for determining the timing of any sales of the Shares under its
management. See "Plan of Distribution". Any sales of the Shares will be at
market prices (plus customary or negotiated brokerage commissions) prevailing
at the time of sale in the case of transactions on the New York Stock Exchange
or the other exchanges on which the Common Stock is traded and at negotiated
prices related to prevailing market prices in the case of transactions off the
floor of such exchanges. The Company will not receive any proceeds from the
sale of the Shares by or for the account of the Plan.     
   
  The Common Stock is listed on the New York Stock Exchange. The closing sale
price of the Common Stock on the New York Stock Exchange was $14.375 per share
on February 2, 1994.     
 
                                  -----------
 
SEE "CERTAIN INVESTMENT CONSIDERATIONS" FOR A DISCUSSION OF CERTAIN FACTORS
WHICH SHOULD BE CONSIDERED BY PROSPECTIVE PURCHASERS OF THE SHARES.
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS.  ANY REPRESENTATION TO THE CONTRARY IS
A CRIMINAL OFFENSE.
 
                                  -----------
 
THE DATE OF THIS PROSPECTUS IS      .

<PAGE>
 
                             AVAILABLE INFORMATION
 
  The Company has filed with the Securities and Exchange Commission (the
"Commission") a Registration Statement on Form S-3 under the Securities Act of
1933, as amended (the "Securities Act"), with respect to the Securities being
offered hereby (the "Registration Statement"). As permitted by the rules and
regulations of the Commission, this Prospectus, which constitutes a part of the
Registration Statement, does not contain certain information, exhibits and
undertakings contained in the Registration Statement. Such additional
information can be inspected at and obtained from the Commission in the manner
set forth below. For further information, reference is made to the Registration
Statement and to the exhibits thereto. Statements contained herein concerning
any documents are not necessarily complete and, in each instance, reference is
made to the copy of such document filed as an exhibit to the Registration
Statement. Each such statement is qualified in its entirety by such reference.
 
  The Company is subject to the informational requirements of the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), and in accordance
therewith is required to file periodic reports, proxy statements and other
information with the Commission relating to its business, financial statements
and other matters. Such reports, proxy statements and other information, as
well as the Registration Statement, may be inspected and copied at the public
reference facilities maintained by the Commission at Room 1024, Judiciary
Plaza, 450 Fifth Street, N.W., Washington, D.C. 20549, and at the Regional
Offices of the Commission located in the Northwestern Atrium Center, 500 West
Madison Street, Suite 1400, Chicago, Illinois 60661-2511, and 7 World Trade
Center, New York, New York 10007. Copies of such material can also be obtained
from the Commission at prescribed rates by addressing written requests for such
copies to the Public Reference Section of the Commission at 450 Fifth Street,
N.W., Washington, D.C. 20549. Such reports, proxy statements and other
information are also available for inspection at the offices of the New York
Stock Exchange, Inc., 20 Broad Street, New York, New York, 10005.
 
                     INFORMATION INCORPORATED BY REFERENCE
 
  The following documents have been filed with the Commission pursuant to the
Exchange Act and are incorporated by reference into this Prospectus:
 
    1. The Company's Annual Report on Form 10-K for the year ended December
  31, 1992 (as amended on Form 8 dated March 31, 1993).
 
    2. The Company's Current Report on Form 8-K dated April 16, 1993.
 
    3. The Company's Quarterly Reports on Form 10-Q for the quarterly periods
  ended March 31, 1993, June 30, 1993 and September 30, 1993.
 
    4. The description of the Company's Common Stock contained in the
  registration statement of Burroughs Corporation ("Burroughs"), the
  predecessor to the Company, on Form 8-B dated May 22, 1984 (as amended on
  Form 8 dated May 7, 1991), filed pursuant to Section 12 of the Exchange
  Act, including any amendment or report filed for the purpose of updating
  such description.
 
    5. The description of the Company's Preferred Share Purchase Rights
  contained in the Registration Statement of Burroughs on Form 8-A dated
  March 11, 1986 (as amended on Forms 8 dated, respectively, April 16, 1986,
  July 8, 1987 and May 7, 1991) and in the Registration Statement of
  Burroughs on Form 8-A dated October 3, 1986 (as amended on Forms 8 dated,
  respectively, July 8, 1987 and May 7, 1991), filed pursuant to Section 12
  of the Exchange Act, including any amendment or report filed for the
  purpose of updating such description.
 
  All documents filed by the Company with the Commission pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange Act after the date hereof and prior
to the termination of the offering of the Shares shall be deemed to be
incorporated by reference herein and to be a part hereof from the date of
filing of such documents. Any statements contained in a document incorporated
by reference herein shall be deemed to be
 
                                       2

<PAGE>
 
modified or superseded for purposes hereof to the extent that a statement
contained herein or in any other subsequently filed document which also is
incorporated by reference herein modifies or supersedes such statement. Any
statement so modified or superseded shall not be deemed to constitute a part
hereof except as so modified or superseded.
 
  The Company will provide without charge to each person to whom a copy of this
Prospectus is delivered, on written or oral request, copies of any or all
documents incorporated by reference herein (other than the exhibits thereto
unless such exhibits are incorporated specifically by reference therein).
Requests should be directed to Unisys Corporation, Township Line and Union
Meeting Roads, Blue Bell, Pennsylvania 19424, Attention: Corporate Secretary;
Telephone (215) 986-3206.
 
                                  THE COMPANY
 
  The Company makes and markets computer-based information systems and software
and offers professional services on a worldwide basis. The Company designs,
manufactures and supports a complete line of enterprise servers and
peripherals, departmental servers and workstations, and applications and
systems software, and provides services and systems integration, equipment
maintenance and defense custom products and services.
 
  The address and telephone number of the principal executive offices of the
Company are Township Line and Union Meeting Roads, Blue Bell, Pennsylvania
19424, telephone number (215) 986-4011.
 
                       CERTAIN INVESTMENT CONSIDERATIONS
 
  Prospective investors should consider carefully, in addition to the other
information contained in this Prospectus, the following factors before
purchasing the Shares offered hereby.
 
THE COMPUTER INDUSTRY; COMPANY REPOSITIONING ACTIONS
 
  The Company operates in an industry that has undergone dramatic changes in
recent years, highlighted by technological advances, which have significantly
lowered the cost of computing and have led to increased competition, lower
prices and lower profit margins; a shift towards standards and open computing
systems, which has resulted in increasing "commoditization" of hardware
products and lower profit margins; and a growing focus by customers on service
and software solutions rather than on hardware. These factors have combined to
render previous cost structures obsolete.
   
  The Company has moved aggressively to realign its financial structure to
reflect the rapidly changing market for information processing products and
services. It has lowered its cost structure significantly by reducing its
workforce, consolidating plants and facilities and streamlining product lines.
In connection with these repositioning actions, the Company recorded special
charges of $1.2 billion in 1991, $181.0 million in 1990 and $231.0 million in
1989. Losses in each of those years amounted to $1.4 billion, $436.7 million
and $639.3 million, respectively. Principally as a result of the lower costs
associated with the repositioning actions, the Company has reported profits for
nine consecutive quarters, beginning with the fourth quarter of 1991. Net
income for the year ended December 31, 1993 was $565.4 million. No assurance
can be given, however, that the Company will not experience losses in the
future, particularly if worldwide adverse economic conditions and weakness in
the computer industry persist.     
 
HIGH LEVERAGE
   
  As of December 31, 1993, the Company had total long-term debt (including
current maturities) of $2,050.0 million. Total long-term debt maturities for
1994, 1995, 1996, 1997 and 1998 were $25.0, $72.2, $354.0, $436.0 and $211.0
million, respectively. The percentage of total debt to total capitalization for
the Company was 43% at December 31, 1993. Total interest expense in 1993 was
$241.7 million.     
 
                                       3

<PAGE>
 
DIVIDEND SUSPENSIONS; DIVIDEND LIMITATIONS
   
  In September 1990 and February 1991, the Company suspended the quarterly cash
dividends on its outstanding Common Stock and Preferred Stock, respectively. In
October 1992, the Company resumed paying dividends on outstanding Preferred
Stock, with payments being applied to reduce the accumulated dividend
arrearage. Under the terms of the Preferred Stock, the Company may not pay cash
dividends on its Common Stock until all dividend arrearages on the Preferred
Stock are satisfied. As of December 31, 1993, dividends on Preferred Stock were
$107.8 million in arrears. In addition, certain of the Company's credit
facilities and debt instruments contain financial covenants which could limit
dividends on the Company's capital stock.     
 
IMPORTANCE OF INTERNATIONAL OPERATIONS
   
  Revenue from international operations accounted for approximately half of the
Company's total revenue in each of 1991, 1992 and 1993. As a result, the
Company's business is sensitive to worldwide economic conditions. In 1993, the
Company's business was affected by deterioration in the European marketplace
and continuing weakness in Japan. In addition, because the Company operates in
approximately 100 countries, its international business is also affected by
other factors beyond its control, such as fluctuations in foreign currency
exchange rates, U.S. and foreign government laws and policies affecting trade
and investment and governmental changes.     
 
DECLINE IN DEFENSE INDUSTRY EXPENDITURES
   
  During 1991, 1992 and 1993, the Company received approximately 20% of its
revenue from custom defense systems. A substantial portion of this revenue was
derived from contracts with agencies of the U.S. Department of Defense and the
Canadian Department of National Defence. Any future declines in U.S. and
Canadian defense industry spending could affect the Company's ability to obtain
new defense contracts, and no assurance can be given that current, in-process,
multiple-year contracts will not be downsized or discontinued.     
                               
                            RECENT DEVELOPMENTS     
   
  On January 24, 1994 the Company reported, for the year ended December 31,
1993, net income of $565.4 million, or $2.31 per fully diluted common share,
including $203.8 million or 83 cents per share from special one-time items. In
1992, the Company reported net income of $361.2 million, or $1.40 per common
share, which included a special item of $65.0 million or 36 cents per share.
Excluding the special items, earnings per share for 1993 were $1.48 compared to
$1.04 in 1992. Revenue in 1993 was $7.74 billion compared with $8.42 billion in
1992. For the fourth quarter ended December 31, 1993, the Company reported net
income of $117.7 million or 46 cents per fully diluted common share. In the
fourth quarter of 1992, the Company reported net income of $101.2 million or 43
cents per common share, before special items of $38.0 million or 15 cents per
share. Revenue for the fourth quarter of 1993 was $2.10 billion compared to
$2.26 billion in the comparable quarter a year ago.     
 
                                USE OF PROCEEDS
 
  The Shares are being offered hereby for the account of the Plan. Accordingly,
the Company will not receive any proceeds from the sale of the Shares.
 
                              SELLING STOCKHOLDER
 
  The Plan is a qualified defined benefit pension plan under Section 401(a) of
the Internal Revenue Code and is funded by Company contributions to a tax
qualified trust maintained for the sole benefit of Plan participants. The
Company contributed the Shares to the Plan on December 29, 1993.
 
  After giving effect to the contribution of the Shares, the Plan owned
approximately 7,016,000 shares of Common Stock, representing approximately 4.1%
of the outstanding shares of Common Stock.
 
                                       4

<PAGE>
 
                              PLAN OF DISTRIBUTION
   
  The Shares have been placed into portfolios managed by independent investment
managers (the "Investment Managers"). Each Investment Manager will be
responsible, in its sole judgment and discretion, for making any decision to
hold or sell any or all of the Shares under its management. The Investment
Managers have been advised that any sales must be effected in ordinary trading
transactions without special selling efforts or methods. Such sales will be at
market prices prevailing at the time of sale in the case of transactions on the
New York Stock Exchange or any other exchange on which the Common Stock is
traded and at negotiated prices related to prevailing market prices in the case
of transactions off the floor of such exchanges.     
 
  The Plan, and any brokers or dealers effecting sales on its behalf, may be
deemed to be "underwriters" within the meaning of the Securities Act. No
payment of any underwriting commissions or discounts in connection with any
sales of the Shares by the Plan is expected other than customary or negotiated
brokerage commissions. The Company will pay the expenses of the registration of
the Shares under the Securities Act.
 
                          DESCRIPTION OF CAPITAL STOCK
 
  The following descriptions do not purport to be complete and are subject to,
and qualified in their entirety by reference to, the more complete descriptions
thereof set forth in (1) the Company's Certificate of Incorporation; (2) the
Company's By-Laws and (3) the Rights Agreement (as defined below), all of which
are exhibits to the Registration Statement.
 
  The Company's authorized capital stock consists of 360,000,000 shares of
Common Stock and 40,000,000 shares of Preferred Stock, par value $1 per share
(the "Preferred Stock"). Pursuant to the Company's Certificate of
Incorporation, the Board of Directors may, by resolution, establish series of
Preferred Stock having such voting powers and such designations, preferences
and relative, participating, optional or other special rights, and
qualifications, limitations or restrictions thereof, as the Board of Directors
may determine.
   
  As of December 31, 1993, there were 170,364,844 shares of Common Stock
outstanding, and the Company had reserved approximately 147,320,000 additional
shares of Common Stock for issuance pursuant to various employee benefit plans
and upon the conversion of outstanding shares of Preferred Stock and other
outstanding securities.     
   
  The Board of Directors has authorized the issuance of 30,000,000 shares of
Series A Cumulative Convertible Preferred Stock (the "Series A Preferred
Stock"), 10 shares of Series B Cumulative Convertible Preferred Stock (the
"Series B Preferred Stock"), 20 shares of Series C Cumulative Preferred Stock
(the "Series C Preferred Stock") and 1,500,000 shares of Junior Participating
Preferred Stock (the "Junior Preferred Stock"). As of December 31, 1993, there
were 28,404,439 shares of Series A Preferred Stock, 10 shares of Series B
Preferred Stock, 20 shares of Series C Preferred Stock and no shares of Junior
Preferred Stock outstanding.     
 
COMMON STOCK
 
 General
 
  Subject to the rights of the holders of shares of Preferred Stock, holders of
shares of Common Stock (1) are entitled to receive dividends when and as
declared by the Board of Directors of the Company from funds legally available
for that purpose; (2) have the exclusive right, except as otherwise may be
required by law, to vote for the election of directors and for all other
purposes and (3) are entitled, upon any liquidation, dissolution or winding up
of the Company, to a pro rata distribution of the assets and funds of the
Company available for distribution to stockholders. Each share of Common Stock
is entitled to one vote on all matters on which stockholders generally are
entitled to vote. Holders of shares of Common Stock do not have preemptive
rights to subscribe for additional shares of Common Stock or securities
convertible into shares of Common Stock. The Common Stock is traded on the New
York Stock Exchange and prices are reported by the New York Stock Exchange
Composite Tape under the symbol UIS. Harris Trust Company of New York is the
transfer agent for the Common Stock.
 
                                       5

<PAGE>
 
 Dividend Limitations
 
  The Company suspended the quarterly dividend on the Common Stock in
September 1990. The Company's outstanding Preferred Stock currently prohibits
the Company from paying dividends on the Common Stock while dividends on the
Preferred Stock are in arrears. See "Cumulative Convertible Preferred Stock--
Dividend Limitations". In addition, the Company's most restrictive credit
facility limits dividends on the Company's capital stock generally to an
amount no greater than the accumulated arrearages on the Series A, Series B
and Series C Preferred Stock plus 50% of cumulative consolidated net income
since October 1, 1992.
 
 Preferred Share Purchase Rights and Junior Participating Preferred Stock
 
  The Company has distributed to its stockholders one Preferred Share Purchase
Right (the "Rights") with respect to each outstanding share of Common Stock
pursuant to a Rights Agreement (the "Rights Agreement") dated as of March 7,
1986 between the Company and Harris Trust Company of New York, as Rights
Agent. Each Right entitles the holder thereof, until the earlier of March 17,
1996 or the redemption of the Rights, to buy one three-hundredth of a share of
the Junior Preferred Stock at an exercise price of $75. The Rights are
represented by the certificates for shares of Common Stock and will not be
exercisable, or transferable apart from the shares of Common Stock, until the
earlier of the tenth day after the announcement that a person or group has
acquired beneficial ownership of 20% or more of the shares of Common Stock (a
"20% holder") or the tenth day after a person commences, or announces an
intention to commence, an offer, the consummation of which would result in a
person beneficially owning 30% or more of the shares of Common Stock as of
such date (the earlier of such dates being called the "Distribution Date").
The Rights could then begin trading separately from the shares of Common
Stock.
 
  In the event that the Company is acquired in a merger or other business
combination transaction, each Right will entitle its holder to purchase, at
the exercise price of the Right, that number of shares of common stock of the
surviving company which, at the time of such transaction, would have a market
value of two times the exercise price of the Right. Alternatively, if a 20%
holder were to acquire the Company by means of a reverse merger in which the
Company and its stock survive, or were to engage in certain "self-dealing"
transactions, each Right not owned by the 20% holder would become exercisable
for the number of shares of Common Stock which, at that time, would have a
market value of two times the exercise price of the Right.
 
  The Rights are redeemable at $.01 2/3 per Right at any time prior to the
time that a person or group has acquired beneficial ownership of 20% of the
shares of Common Stock. The Rights will expire on March 17, 1996 (the "Final
Expiration Date"), unless the Final Expiration Date is extended or unless the
Rights are earlier redeemed by the Company in accordance with their terms. At
no time will the Rights have any voting rights.
 
  The foregoing summary of the Rights does not purport to be complete and is
qualified in its entirety by reference to the Rights Agreement, which is an
exhibit to the Registration Statement.
 
  The shares of Junior Preferred Stock purchasable upon exercise of the Rights
will be nonredeemable. Each share of Junior Preferred Stock will have a
minimum preferential quarterly dividend of $15 per share, but will be entitled
to a dividend of 300 times the aggregate dividend declared per share of Common
Stock. In the event of liquidation, the holders of the shares of Junior
Preferred Stock will receive a preferred liquidation payment of $100 per
share, but will be entitled to receive an aggregate liquidation payment per
share equal to 300 times the payment made per share of Common Stock. Each
share of the Junior Preferred Stock will have 300 votes, voting together with
the shares of Common Stock. In the event of any merger, consolidation or other
transaction in which shares of Common Stock are exchanged, each share of the
Junior Preferred Stock will be entitled to receive 300 times the amount
received per share of Common Stock. The Junior Preferred Stock has customary
antidilution provisions to protect the dividend, liquidation and voting rights
described above.
 
                                       6

<PAGE>
 
  The purchase price payable, and the number of shares of Junior Preferred
Stock or other securities or property issuable, upon exercise of the Rights are
subject to adjustment from time to time to prevent dilution (1) in the event of
a stock dividend on, or a subdivision, combination or reclassification of the
shares of Junior Preferred Stock; (2) as a result of the grant to holders of
the shares of Junior Preferred Stock of certain rights or warrants to subscribe
for shares of Junior Preferred Stock or of securities convertible into shares
of Junior Preferred Stock (at a price, or with a conversion price,
respectively, less than the then current market price for the shares of Junior
Preferred Stock) or (3) as a result of the distribution to holders of the
shares of Junior Preferred Stock of evidences of indebtedness or assets
(excluding regular periodic cash dividends at a rate not in excess of 125% of
the rate of the last cash dividend theretofore paid or dividends payable in
shares of Junior Preferred Stock) or of subscription rights or warrants (other
than those referred to above). With certain exceptions, no adjustment in the
purchase price will be required until cumulative adjustments require an
adjustment of at least 1% in such purchase price. The percentage of a share of
Junior Preferred Stock for which a Right is exercisable and the number of
Rights outstanding are also subject to adjustment in the event of dividends on
the shares of Common Stock payable in shares of Common Stock or subdivisions,
combinations or consolidations of the shares of Common Stock, occurring, in any
case, before the Rights become exercisable or transferable apart from the
shares of Common Stock.
 
  One Right is presently associated with each issued and outstanding share of
Common Stock. The Company will issue one Right with each share of Common Stock
issued prior to the Final Expiration Date unless, prior to such issuance, the
Rights are redeemed or become exercisable and transferable apart from the
shares of Common Stock.
 
  The Rights have certain anti-takeover effects. The Rights may cause
substantial dilution to a person or group that attempts to acquire the Company
on terms that the Board of Directors determines are not in the best interests
of the Company's stockholders, except pursuant to an offer conditioned on a
substantial number of Rights being acquired. The Rights should not interfere
with any merger or other business combination approved by the Board of
Directors since the Rights may be redeemed by the Company at $.01 2/3 per Right
prior to the time that a person or group has acquired beneficial ownership of
20% or more of the shares of Common Stock.
 
 Anti-Takeover Provisions
 
  The Company is a Delaware corporation and subject to Section 203 of the
Delaware General Corporation Law. Generally, Section 203 prohibits a publicly
held Delaware corporation from engaging in a "business combination" with an
"interested stockholder" for a period of three years after the date of the
transaction in which the person became an interested stockholder, unless (1)
prior to such date, either the business combination or such transaction is
approved by the board of directors of the corporation, (2) upon consummation of
the transaction which resulted in the stockholder becoming an interested
stockholder, the interested stockholder owns at least 85% of the outstanding
voting stock, or (3) on or after such date the business combination is approved
by the board and by the affirmative vote of at least 66 2/3% of the outstanding
voting stock that is not owned by the interested stockholder. A "business
combination" includes mergers, asset sales and other transactions resulting in
a financial benefit to the interested stockholder. An "interested stockholder"
is a person who, together with affiliates and associates, owns (or within three
years, did own) 15% or more of the corporation's outstanding voting stock.
 
  The Company's Certificate of Incorporation and By-Laws contain certain anti-
takeover provisions that are intended to enhance the likelihood of continuity
and stability in the composition of the Board of Directors and that may have
the effect of delaying, deferring or preventing a future takeover or change in
control of the Company unless such takeover or change in control is approved by
the Board of Directors. Such provisions may also render the removal of the
current Board of Directors more difficult.
 
  The Company's Certificate of Incorporation and By-Laws provide that the Board
of Directors shall consist of not less than 10 nor more than 20 directors
(subject to any rights of the holders of shares of
 
                                       7

<PAGE>
 
Preferred Stock to elect additional directors), with the exact number to be
fixed by the Board of Directors pursuant to a resolution adopted by a majority
of the entire Board. The Board of Directors is divided into three classes of
directors, which classes are as nearly equal in number as possible. One class
of directors is elected each year for a term of three years. Directors may be
removed from office only for cause and only by the affirmative vote of the
holders of at least 80% of the voting power of all capital stock of the Company
entitled to vote generally in the election of directors (the "Voting Stock"),
voting as a single class. Subject to any rights of the holders of shares of
Preferred Stock, vacancies in the Board of Directors and newly created
directorships are filled for the unexpired term only by the vote of a majority
of the remaining directors in office. Pursuant to the Certificate of
Incorporation, advance notice of stockholder nominations for the election of
directors must be given in the manner provided in the Company's By-Laws. The
By-Laws provide that written notice of the intent of a stockholder to make a
nomination at a meeting of stockholders must be delivered to the Secretary of
the Company not less than 90 days prior to the date of the meeting, in the case
of an annual meeting, and not more than seven days following the date of notice
of the meeting, in the case of a special meeting. The notice must contain
certain background information about the nominee and the number of shares of
the Company's capital stock beneficially owned by the nominee. The affirmative
vote of the holders of 80% or more of the voting power of the then outstanding
shares of Voting Stock, voting as a single class, is required to amend, alter
or repeal the provisions of the Certificate of Incorporation and the By-Laws
discussed above.
 
  The Company's Certificate of Incorporation also provides that certain
mergers, consolidations, sales or other transfers of assets of, issuances or
reclassifications of securities of, or adoptions of plans of liquidation of the
Company (individually, a "Business Combination") must be approved by an
affirmative vote of the holders of 80% or more of the voting power of the then
outstanding shares of Voting Stock, voting as a single class, when such action
involves a person (an "Interested Stockholder") who beneficially owns more than
20% of the voting power of the then outstanding shares of Voting Stock, unless
certain minimum price, form of consideration and procedural requirements (the
"Fair Price Provisions") are satisfied or unless a majority of the directors
not affiliated with the Interested Stockholder approve the Business
Combination. The affirmative vote of the holders of 80% or more of the voting
power of the then outstanding shares of Voting Stock, voting as a single class,
is required to amend, alter or repeal such provisions of the Certificate of
Incorporation.
 
  Under the Certificate of Incorporation and By-Laws, except as otherwise
required by law and subject to the rights of the holders of shares of Preferred
Stock, stockholders may not call a special meeting of stockholders. Only the
Board of Directors, pursuant to a resolution adopted by a majority of the
entire Board, may call a special meeting of stockholders. The General
Corporation Law of the State of Delaware provides that, unless specifically
prohibited by the certificate of incorporation, any action required or
permitted to be taken by stockholders of a corporation may be taken without a
meeting, without prior notice, and without a stockholder vote if a written
consent or consents setting forth the action to be taken is signed by the
holders of outstanding shares of capital stock having the requisite number of
votes that would be necessary to authorize or take such action at a meeting of
stockholders. The Company's Certificate of Incorporation requires that
stockholder action be taken at a meeting of stockholders and prohibits
stockholder action by written consent. The affirmative vote of the holders of
80% or more of the voting power of the then outstanding shares of Voting Stock,
voting as a single class, is required to amend, alter or repeal the provisions
of the Certificate of Incorporation and By-Laws discussed above.
 
  The purpose of certain provisions of the Certificate of Incorporation and By-
Laws discussed above relating to (1) a classified Board of Directors; (2) the
removal of directors and the filling of vacancies; (3) the prohibition of
stockholder action by written consent and (4) supermajority voting requirements
for the repeal of provisions (1) through (3) is to help assure the continuity
and stability of the business strategies and policies of the Company and to
discourage certain types of transactions that involve an actual or threatened
change of control of the Company. They are designed to make it more difficult
and time-consuming to change majority control of the Board of Directors and
thus to reduce the vulnerability of the Company to an
 
                                       8

<PAGE>
 
unsolicited takeover proposal that does not contemplate the acquisition of at
least 80% of the voting power of all of the Voting Stock or to an unsolicited
proposal for the restructuring or sale of all or part of the Company.
 
  Such charter and by-law provisions may make more difficult or discourage a
proxy contest, or the assumption of control, by a holder of a substantial block
of shares of Common Stock, or the removal of the incumbent Board of Directors,
and could thus increase the likelihood that incumbent directors will retain
their positions. In addition, since the Fair Price Provisions discussed above
provide that certain business combinations involving the Company and a certain
type of stockholder which do not meet specified criteria or are not approved by
supermajority vote cannot be consummated without the approval of a majority of
those directors who are not affiliated with such stockholder, such provisions
could give incumbent management the power to prevent certain takeovers. The
Fair Price Provisions may also discourage attempts to effect a "two-step"
acquisition in which a third party purchases a controlling interest in cash and
acquires the balance of the Voting Stock of the Company for less desirable
consideration. Under the classified board and related provisions, the third
party would not immediately obtain the ability to control the Board of
Directors through its first-step acquisition and, under the Fair Price
Provisions, having made the first-step acquisition, the third party could not
acquire the balance of the Voting Stock for a lower price without a
supermajority vote or the approval of a majority of such unaffiliated
directors.
 
  These provisions of the Certificate of Incorporation and By-Laws help ensure
that the Board of Directors, if confronted with an unsolicited proposal from a
third party which has acquired a block of shares of Common Stock, will have
sufficient time to review the proposal and appropriate alternatives for the
Company's stockholders.
 
  Such charter and by-law provisions are intended to encourage persons seeking
to acquire control of the Company to initiate such an acquisition through
arm's-length negotiations with the Board of Directors, who would then be in a
position to negotiate a transaction which would treat all stockholders in
substantially the same manner. Such provisions may have the effect of
discouraging a third party from making an unsolicited tender offer or otherwise
attempting to obtain control of the Company, even though such an attempt might
be beneficial to the Company and its stockholders. In addition, since the
provisions are designed to discourage accumulations of large blocks of shares
of Common Stock by purchasers whose objective is to have such shares
repurchased by the Company at a premium, such provisions could tend to reduce
the temporary fluctuations in the market price of Common Stock caused by such
accumulations. Accordingly, stockholders of the Company could be deprived of
certain opportunities to sell their shares at a temporarily higher market
price.
 
  The Rights could also have the effect of delaying, deferring or preventing a
takeover or change in control of the Company. See "Common Stock--Preferred
Share Purchase Rights and Junior Participating Preferred Stock".
 
CUMULATIVE CONVERTIBLE PREFERRED STOCK
 
  The Series A Preferred Stock, the Series B Preferred Stock and the Series C
Preferred Stock rank on a parity with each other, and prior to the Common Stock
and the Junior Preferred Stock, as to payment of dividends and as to
distribution of assets upon liquidation, dissolution or winding up of the
Company.
 
 Series A Preferred Stock
 
  The Series A Preferred Stock accrues quarterly cumulative dividends at the
annual rate of $3.75 per share and is entitled to receive $50 per share, plus
accrued and unpaid dividends, upon liquidation. The shares of Series A
Preferred Stock are convertible, at the option of the holders thereof, into
shares of Common Stock at a conversion price of $29.93 per share, subject to
adjustment to prevent dilution under certain circumstances. For purposes of
calculating the number of shares of Common Stock into which shares of Series
 
                                       9

<PAGE>
 
A Preferred Stock are convertible at the conversion price, the price per share
of the Series A Preferred Stock is $50. Each share of Series A Preferred Stock
is currently convertible into 1.67 shares of Common Stock. The Series A
Preferred Stock is redeemable at the option of the Company under certain
circumstances and at varying prices. If dividends on the shares of Series A
Preferred Stock and any class or series of stock ranking on a parity with the
Series A Preferred Stock as to dividends (the "Parity Dividend Stock") are in
arrears in an amount equal to at least six quarterly dividends, the number of
directors of the Company will be increased by two as of the date of the next
meeting of stockholders at which directors are to be elected, and the holders
of shares of Series A Preferred Stock and of Parity Dividend Stock (voting
together as a separate class) will be entitled to vote for and to elect such
additional directors. The holders of shares of Series A Preferred Stock have
certain voting rights if the Company determines to authorize, create or issue,
or increase the authorized amount of, any class or series of stock ranking
prior to or on a parity with the Series A Preferred Stock. The consent of the
holders of a majority of the outstanding shares of Series A Preferred Stock
(voting separately as a class with all other series of capital stock ranking on
a parity as to dividends or upon liquidation with the Series A Preferred Stock
and also being affected) is also required to amend the Company's Certificate of
Incorporation if the amendment would have a materially adverse effect on the
powers, preferences or special rights of the Series A Preferred Stock.
 
 Series B and C Preferred Stock
 
  Each of the Series B Preferred Stock and the Series C Preferred Stock has a
stated value of $5 million per share, accrues quarterly cumulative dividends
based on such stated value at the rate of 8 7/8% per annum until June 28, 1995,
and at the rate of 9 1/2% per annum thereafter, accrues dividends on the amount
of any unpaid dividends and is entitled to receive the stated value, plus
accrued and unpaid dividends, upon liquidation. The shares of Series B
Preferred Stock and Series C Preferred Stock are convertible at the option of
the holder thereof into shares of Common Stock at conversion prices of $20 per
share and $21 per share, respectively, subject to adjustment to prevent
dilution under certain circumstances. Shares of Series B Preferred Stock and
Series C Preferred Stock are redeemable at the option of the Company at a
premium, the amount of which is determined by reference to interest rates in
effect at the time of such redemption and the amount of time then remaining to
June 28, 1997. If the Series B Preferred Stock and Series C Preferred Stock
have not been redeemed by the Company or converted by the holder prior to June
28, 1996 (or June 28, 1995 if requested by the original holder thereof (the
"original holder"), the Company will be required thereafter to convert both
series into Common Stock at any time prior to June 28, 1997, based on the
current market price for the Common Stock at the time of conversion. Both
series are also subject to mandatory conversion into Common Stock at the
current market price for the Common Stock at the time of conversion in the
event of a change of control or certain other extraordinary corporate events.
If sufficient Common Stock is not available for issuance upon conversion
because required stockholder or other approvals have not been obtained, or
because issuance of such Common Stock upon conversion would not be in
compliance with applicable law, the Company may issue other types of equity
securities instead of Common Stock. The Common Stock received by the original
holder upon conversion of the Series B Preferred Stock and Series C Preferred
Stock pursuant to the mandatory conversion described above is required to be
sold in a manner approved by the Company, and to the extent that proceeds
received by the original holder upon such sale are less than the stated value
of the shares so converted, plus accrued dividends and a premium amount, the
Company has agreed to issue additional shares of capital stock to the original
holder until the original holder receives proceeds equal to the sum of such
amounts. Each of the Series B Preferred Stock and the Series C Preferred Stock
is non-voting except with respect to certain matters relating to the rights and
preferences of such series. With respect to such matters, each of such series
votes separately as a class.
 
 Dividend Limitations
     
  Each of the Series A, Series B and Series C Preferred Stock prohibits the
payment of cash dividends or other distributions on, and the purchase,
redemption or other acquisition of, any shares of Common Stock until all
accrued and unpaid dividends on such series of Preferred Stock have been paid.
In February 1991,      
 
                                       10

<PAGE>
 
    
the Company suspended the quarterly dividend on the Series A, Series B and
Series C Preferred Stock. In October 1992, the Company resumed paying dividends
on each of those series of Preferred Stock. Quarterly payments made since that
date have been in amounts greater than the stated quarterly dividends and have
been applied to reduce the accumulated dividend arrearages. As a result,
dividend arrearages as of December 31, 1993 on the Series A, Series B and
Series C Preferred Stock had declined to $107.8 million from $185.8 million at
September 15, 1992.      
 
ADDITIONAL SERIES OF PREFERRED STOCK
 
  The Board of Directors may, from time to time, create one or more new series
of Preferred Stock in addition to the Junior Preferred Stock, the Series A
Preferred Stock, the Series B Preferred Stock and the Series C Preferred Stock.
When and if any such new series of Preferred Stock is issued, it could affect
the dividend, voting and liquidation rights of the Common Stock.
 
                                 LEGAL MATTERS
 
  The legality of the securities offered hereby will be passed upon for the
Company by Harold S. Barron, Esq., Senior Vice President and General Counsel of
the Company. As of the date of this Prospectus, Mr. Barron owns 1,600 shares of
Common Stock and holds options to purchase 119,000 shares of Common Stock.
 
                                    EXPERTS
 
  The consolidated financial statements of the Company incorporated by
reference or appearing in the Company's Annual Report (Form 10-K) for the year
ended December 31, 1992, have been audited by Ernst & Young, independent
auditors, as set forth in their report thereon incorporated therein and
incorporated herein by reference. Such consolidated financial statements are,
and audited financial statements to be included in subsequently filed documents
will be, incorporated herein in reliance upon the reports of Ernst & Young
pertaining to such financial statements (to the extent covered by consents
filed with the Commission) given upon the authority of such firm as experts in
accounting and auditing.
 
                                       11

<PAGE>

- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
 
 NO DEALER, SALESMAN OR OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMA-
TION OR TO MAKE ANY REPRESENTATIONS OTHER THAN THOSE CONTAINED OR INCORPORATED
BY REFERENCE IN THIS PROSPECTUS, AND, IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COM-
PANY OR THE PLAN. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE
HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE AN IMPLICATION THAT THERE HAS
BEEN NO CHANGE IN THE AFFAIRS OF THE COMPANY SINCE THE DATE OF THIS PROSPEC-
TUS. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER OR SOLICITATION BY ANYONE IN
ANY JURISDICTION IN WHICH SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN
WHICH THE PERSON MAKING SUCH OFFER OR SOLICITATION IS NOT QUALIFIED TO DO SO
OR TO ANYONE TO WHOM IT IS UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION.
 
                               ----------------
 
                               TABLE OF CONTENTS
 

<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
Available Information......................................................   2
Information Incorporated by Reference......................................   2
The Company................................................................   3
Certain Investment Considerations..........................................   3
Recent Developments........................................................   4
Use of Proceeds............................................................   4
Selling Stockholder........................................................   4
Plan of Distribution.......................................................   5
Description of Capital Stock...............................................   5
Legal Matters..............................................................  11
Experts....................................................................  11
</TABLE>

 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
                                    UNISYS
 
 
                              UNISYS CORPORATION
                                 COMMON STOCK
 
                               ----------------
                                  PROSPECTUS
                               ----------------
 
 
                                        , 1994
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------

<PAGE>
 

                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
  The following statement sets forth the estimated amounts of expenses, other
than underwriting discounts and commissions, to be incurred in connection with
the offerings described in this Registration Statement:
 

<TABLE>
   <S>                                                                  <C>
   Securities and Exchange Commission Registration Fee................. $30,475
   Printing Fees and Expenses..........................................  10,000
   Accounting Fees and Expenses........................................   5,000
   Blue Sky Fees and Expenses..........................................  10,000
   New York Stock Exchange listing fees................................  20,000
   Miscellaneous Expenses..............................................   1,525
                                                                        -------
      Total............................................................ $77,000
                                                                        =======
</TABLE>

- --------
All of the amounts are estimated except for the Securities and Exchange
Commission registration fee. All expenses of registration will be paid by the
Company.
 
ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
  Section 145 of the Delaware General Corporation Law (the "DGCL") provides
for, among other things:
 
  a. permissive indemnification for expenses, judgments, fines and amounts paid
     in settlement actually and reasonably incurred by designated persons,
     including directors and officers of a corporation, in the event such
     persons are parties to litigation other than stockholder derivative
     actions if certain conditions are met;
 
  b. permissive indemnification for expenses actually and reasonably incurred
     by designated persons, including directors and officers of a corporation,
     in the event such persons are parties to stockholder derivative actions if
     certain conditions are met;
 
  c. mandatory indemnification for expenses actually and reasonably incurred by
     designated persons, including directors and officers of a corporation, in
     the event such persons are successful on the merits or otherwise in
     litigation covered by a. and b. above; and
 
  d. that the indemnification provided for by Section 145 shall not be deemed
     exclusive of any other rights which may be provided under any by-law,
     agreement, stockholder or disinterested director vote, or otherwise.
 
  The Company's Certificate of Incorporation provides that a director of the
Company shall not be personally liable to the Company or its stockholders for
monetary damages for breach of fiduciary duty as a director except for
liability (i) for any breach of the director's duty of loyalty to the Company
or its stockholders, (ii) for acts or omissions not in good faith or which
involve intentional misconduct or a knowing violation of law, (iii) for paying
a dividend or approving a stock repurchase in violation of Section 174 of the
DGCL or (iv) for any transaction from which the director derived an improper
personal benefit.
 
  The Certificate of Incorporation also provides that each person who was or is
made a party to, or is involved in, any action, suit or proceeding by reason of
the fact that he or she is or was a director or officer of the Company (or was
serving at the request of the Company as a director, officer, employee or agent
for another entity) shall be indemnified and held harmless by the Company, to
the fullest extent authorized by the DGCL, as in effect (or, to the extent
indemnification is broadened, as it may be amended) against all expense,
liability or loss reasonably incurred by such person in connection therewith.
The Certificate of Incorporation further provides that such rights to
indemnification are contract rights and shall include the right to be paid by
the Company the expenses incurred in defending the proceedings specified above,
in
 
                                      II-1

<PAGE>
 
advance of their final disposition, provided that, if the DGCL so requires,
such payment shall only be made upon delivery to the Company by the indemnified
party of an undertaking to repay all amounts so advanced if it shall ultimately
be determined that the person receiving such payment is not entitled to be
indemnified. Persons so indemnified may bring suit against the Company to
recover unpaid amounts claimed thereunder, and if such suit is successful, the
expense of bringing such suit shall be reimbursed by the Company. The
Certificate of Incorporation provides that the right to indemnification and to
the advance payment of expenses shall not be exclusive of any other right which
any person may have or acquire under any statute, provision of the Company's
Certificate of Incorporation or By-Laws, or otherwise. By resolution effective
September 16, 1986, the Board of Directors extended the right to
indemnification provided directors and officers by the Certificate of
Incorporation to employees of the Company. The Certificate of Incorporation
also provides that the Company may maintain insurance, at its expense, to
protect itself and any of its directors, officers, employees or agents against
any expense, liability or loss, whether or not the Company would have the power
to indemnify such person against such expense, liability or loss under the
DGCL.
 
  On April 28, 1988, at the Company's 1988 Annual Meeting of Stockholders, the
stockholders authorized the Company to enter into indemnification agreements
("Indemnification Agreements") with its directors, and such Indemnification
Agreements have been executed with each of the directors of the Company. The
Indemnification Agreements provide that the Company shall, except in certain
situations specified below, indemnify a director against any expense, liability
or loss (including attorneys' fees, judgments, fines, ERISA excise taxes or
penalties and amounts paid in settlement) incurred by the director in
connection with any actual or threatened action, suit or proceeding (including
derivative suits) in which the director may be involved as a party or
otherwise, by reason of the fact that the director is or was serving in one or
more capacities as a director or officer of the Company or, at the request of
the Company, as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust, employee benefit plan or other entity or
enterprise.
 
  The Indemnification Agreements require indemnification except to the extent
(i) payment for any liability is made under an insurance policy provided by the
Company, (ii) indemnification is provided by the Company under the Certificate
of Incorporation or By-Laws, the DGCL or otherwise than pursuant to the
Indemnification Agreement, (iii) the liability is based upon or attributable to
the director gaining any personal pecuniary profit to which such director is
not legally entitled or is determined to result from the director's knowingly
fraudulent, dishonest or willful misconduct, (iv) the liability arises out of
the violation of certain provisions of the Securities Exchange Act of 1934 or
(v) indemnification has been determined not to be permitted by applicable law.
 
  The Indemnification Agreements further provide that, in the event of a
Potential Change in Control, (as defined therein), the Company shall cause to
be maintained any then existing policies of directors' and officers' liability
insurance for a period of six years from the date of a Change in Control (as
defined therein) with coverage at least comparable to and in the same amounts
as that provided by such policies in effect immediately prior to such Potential
Change in Control. In the event of a Potential Change in Control, the
Indemnification Agreements also provide for the establishment by the Company of
a trust (the "Trust"), for the benefit of each director, upon the written
request by the director. The Trust shall be funded by the Company in amounts
sufficient to satisfy any and all liabilities reasonably anticipated at the
time of such request, as agreed upon by the director and the Company.
 
  The Indemnification Agreements also provide that no legal actions may be
brought by or on behalf of the Company, or any affiliate of the Company,
against a director after the expiration of two years from the date of accrual
of such cause of action, and that any claim or cause of action of the Company
or its affiliate shall be extinguished and deemed released unless asserted by
the timely filing of a legal action within such two year period.
 
  The directors and officers of the Company are insured against certain civil
liabilities, including liabilities under federal securities laws, which might
be incurred by them in such capacity.
 
                                      II-2

<PAGE>
 
ITEM 16. EXHIBITS
 
  See Index to Exhibits.
 
ITEM 17. UNDERTAKINGS
 
  The undersigned registrant hereby undertakes:
 
    (1) To file, during any period in which offers or sales are being made,
  a post-effective amendment to this Registration Statement:
 
       (i) To include any prospectus required by Section 10(a)(3) of the
     Securities Act of 1933 (the "Securities Act"), unless the information
     required to be included in such post-effective amendment is contained
     in a periodic report filed by the registrant pursuant to Section 13 or
     Section 15(d) of the Securities Exchange Act of 1934 (the "Exchange
     Act") and incorporated herein by reference;
 
       (ii) To reflect in the prospectus any facts or events arising after
     the effective date of the Registration Statement (or the most recent
     post-effective amendment thereof) which, individually or in the
     aggregate, represent a fundamental change in the information set forth
     in the Registration Statement, unless the information required to be
     included in such post-effective amendment is contained in a periodic
     report filed by the registrant pursuant to Section 13 or Section 15(d)
     of the Exchange Act and incorporated herein by reference;
 
       (iii) To include any material information with respect to the plan
     of distribution not previously disclosed in the Registration Statement
     or any material change to such information in the Registration
     Statement;
 
    (2) That, for the purpose of determining any liability under the
  Securities Act, each such post-effective amendment shall be deemed to be a
  new Registration Statement relating to the securities offered therein, and
  the offering of such securities at that time shall be deemed to be the
  initial bona fide offering thereof;
 
    (3) To remove from registration by means of a post-effective amendment
  any of the securities being registered which remain unsold at the
  termination of the offering; and
 
    (4) That, for purposes of determining any liability under the Securities
  Act, each filing of the registrant's annual report pursuant to Section
  13(a) or Section 15(d) of the Exchange Act that is incorporated by
  reference in the Registration Statement shall be deemed to be a new
  Registration Statement relating to the securities offered therein, and the
  offering of such securities at that time shall be deemed to be the initial
  bona fide offering thereof.
 
  Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
registrant pursuant to the provisions described in Item 15
above, or otherwise, the registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event a claim for indemnification against such liabilities (other than the
payment by the registrant of expenses incurred or paid by a director, officer
or controlling person of the registrant in the successful defense of any
action, suit or proceeding) is asserted against the registrant by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the
matter has been settled by controlling precedent, submit to a court of
appropriate jurisdiction the question whether such indemnification by it is
against public policy as expressed in the Securities Act and will be governed
by the final adjudication of such issue.
 
                                      II-3

<PAGE>
 

                                   SIGNATURES
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THE REGISTRANT
CERTIFIES THAT IT HAS REASONABLE GROUNDS TO BELIEVE THAT IT MEETS ALL OF THE
REQUIREMENTS FOR FILING ON FORM S-3 AND HAS DULY CAUSED THIS AMENDMENT NO. 1 TO
REGISTRATION STATEMENT TO BE SIGNED ON ITS BEHALF BY THE UNDERSIGNED, THEREUNTO
DULY AUTHORIZED, IN THE TOWNSHIP OF WHITPAIN, COMMONWEALTH OF PENNSYLVANIA, ON
FEBRUARY 4, 1994.     
 
                                         UNISYS CORPORATION
 
                                                                      
                                         By:        /s/ James A. Unruh
                                             ----------------------------------
                                                       JAMES A. UNRUH
                                                 CHAIRMAN OF THE BOARD AND
                                                  CHIEF EXECUTIVE OFFICER
   
  Pursuant to the requirements of the Securities Act of 1933, this Amendment
No. 1 to Registration Statement has been signed by the following persons in the
capacities indicated on February 4, 1994.     


<TABLE> 
<CAPTION> 
 
             SIGNATURE                                  TITLE
             ---------                                  -----
<S>                                      <C>  
         /s/ James A. Unruh              Chairman of the Board and Chief
- ------------------------------------      Executive Officer (principal
           JAMES A. UNRUH                 executive officer) and Director

 
        /s/ George T. Robson             Senior Vice President and Chief
- ------------------------------------      Financial Officer (principal
          GEORGE T. ROBSON                financial officer)

 
       /s/ Deborah C. Hopkins            Vice President and Controller
- ------------------------------------      (principal accounting officer)
         DEBORAH C. HOPKINS

 
                                                               
           Gail D. Fosler*                             Director
- ------------------------------------
           GAIL D. FOSLER

                                                               
          Melvin R. Goodes*                            Director
- ------------------------------------
          MELVIN R. GOODES

                                                               
          Kenneth A. Macke*                            Director
- ------------------------------------
          KENNETH A. MACKE
</TABLE>
 
 
                                      II-4

<PAGE>


<TABLE> 
<CAPTION> 
              SIGNATURE                                   TITLE
              ---------                                   -----
<S>                                                     <C> 
                                                                
       Robert McClements, Jr.*                          Director
- ---------------------------------------                           
       ROBERT MCCLEMENTS, JR.                                   
                                                                
                                                                
         William G. Milliken*                           Director
- ---------------------------------------                           
         WILLIAM G. MILLIKEN                                    
                                                                
                                                                
          Alan E. Schwartz*                             Director
- ---------------------------------------                           
          ALAN E. SCHWARTZ                                      
                                                                
                                                                
          Donald V. Seibert*                            Director
- ---------------------------------------
          DONALD V. SEIBERT
            

          /s/ George T. Robson     
*By: ----------------------------------
     GEORGE T. ROBSON, ATTORNEY-IN-FACT

</TABLE>
 
                    
                                      II-5

<PAGE>
 

                                 EXHIBIT INDEX
 

<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                        DOCUMENT DESCRIPTION
 -------                       --------------------
 <C>     <S>                                                               
  4(a)   Restated Certificate of Incorporation of Unisys Corporation (in-
         corporated by reference to Exhibit 3(a) to the registrant's An-
         nual Report on Form 10-K for the year ended December 31, 1992)

  4(b)   By-Laws of Unisys Corporation (incorporated by reference to Ex-
         hibit 3(b) to the registrant's Annual Report on Form 10-K for
         the year ended December 31, 1992)

  4(c)   Form of Rights Agreement dated as of March 7, 1986 between
         Burroughs Corporation and Harris Trust Company of New York, as
         Rights Agent (incorporated by reference to Exhibit 1 to the reg-
         istrant's Registration Statement on Form 8-A, dated March 11,
         1986)

 *5      Opinion of Harold S. Barron, Senior Vice President and General
         Counsel of Unisys Corporation

  23(a)  Consent of Ernst & Young (independent auditors)

  23(b)  Consent of Harold S. Barron (included in Exhibit 5)

 *24     Power of Attorney
</TABLE>

- --------
   
*  Previously filed     








<PAGE>
 
                                                                
                                                             Exhibit 23 (a)     
                         
                      CONSENT OF INDEPENDENT AUDITORS     
   
We consent to the reference to our firm under the caption "Experts" in
Registration Statement (Amendment No. 1 to Form S-3 No. 33-51747) and related
Prospectus of Unisys Corporation for the registration of 7,000,000 shares of
its common stock and to incorporation by reference therein of our report dated
January 20, 1993, with respect to the consolidated financial statements of
Unisys Corporation incorporated by reference in its Annual Report (Form 10-K)
for the year ended December 31, 1992 and other related financial statement
schedules included therein, filed with the Securities and Exchange Commission.
    
   
/s/ ERNST & YOUNG     
   
Philadelphia, Pennsylvania     
   
February 1, 1994