
<PAGE>   1
 
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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                                SCHEDULE 14D-1/A
          TENDER OFFER STATEMENT (AMENDMENT NO. 5 AND FINAL AMENDMENT)
                          PURSUANT TO SECTION 14(d)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
 
                                 SCHEDULE 13D/A
                               (AMENDMENT NO. 7)
                           (PURSUANT TO SECTION 13(d)
                    OF THE SECURITIES EXCHANGE ACT OF 1934)

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                               AMDAHL CORPORATION
                                    (ISSUER)
 
                                FUJITSU LIMITED
                                    (BIDDER)

                            ------------------------
 
                     COMMON STOCK, PAR VALUE $.05 PER SHARE
                         (TITLE OF CLASS OF SECURITIES)

                            ------------------------
 
                                  023905 10 2
                     (CUSIP NUMBER OF CLASS OF SECURITIES)

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                                 TAKASHI TAKAYA
                          DIRECTOR AND GROUP PRESIDENT
                  CORPORATE PLANNING AND BUSINESS DEVELOPMENT
                                FUJITSU LIMITED
                           MARUNOUCHI CENTER BUILDING
                            6-1, MARUNOUCHI 1-CHOME
                          CHIYODA-KU, TOKYO 100, JAPAN
                           TELEPHONE: 81-3-3216-0570
          (NAME, ADDRESS AND TELEPHONE NUMBER OF PERSONS AUTHORIZED TO
            RECEIVE NOTICES AND COMMUNICATIONS ON BEHALF OF BIDDER)

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                                    COPY TO:
                            ROBERT S. TOWNSEND, ESQ.
                            MORRISON & FOERSTER LLP
                               425 MARKET STREET
                      SAN FRANCISCO, CALIFORNIA 94105-2482
                           TELEPHONE: (415) 268-7000

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          This Amendment No. 5, the final amendment, to the Tender Offer
Statement on Schedule 14D-1 (the "Schedule 14D-1") of Fujitsu Limited, a
Japanese corporation (the "Parent"), and Fujitsu International, Inc., a Delaware
corporation and a wholly owned subsidiary of the Parent (the "Purchaser"), dated
August 5, 1997, and Amendment No. 7 to Schedule 13D (the "Schedule 13D") of the
Parent, dated March 24, 1993, amend and supplement the Schedule 14D-1 and the
Schedule 13D, in each case as amended. The Schedule 14D-1 and the Schedule 13D
relate to the tender offer by the Purchaser to purchase any and all outstanding
shares of common stock, par value $.05 per share (the "Shares"), of Amdahl
Corporation, a Delaware corporation (the "Company"), at a price of $12.40 per
Share, net to the seller in cash, upon the terms and subject to the conditions
set forth in the Offer to Purchase, dated August 5, 1997, as supplemented by the
supplement thereto, dated August 22, 1997, and in the related Letter of
Transmittal. Capitalized terms used and not otherwise defined herein have the
respective meanings given such terms in the Schedule 14D-1.  

ITEM 6.   INTEREST IN SECURITIES OF THE SUBJECT COMPANY.

          Item 6 is hereby amended and supplemented by addition of the 
following information thereto.

          On Friday, September 12, 1997 at 5:00 p.m. Eastern Daylight
Time, the Offer expired. On Tuesday, September 16, 1997, the Purchaser accepted
all Shares validly tendered. A total of 67,208,526 Shares (or approximately 94%
of the issued and outstanding Shares not already owned by the Parent or the
Purchaser) were purchased pursuant to the Offer. The Purchaser has paid for all
such Shares at the Offer Price of $12.40 per Share, in cash, net to the
tendering stockholder.

ITEM 10.  ADDITIONAL INFORMATION.

          Item 10(f) is hereby amended and supplemented by addition of the
following information thereto:

          On Thursday, September 18, 1997, the merger of the Purchaser with and
into the Company, pursuant to the short-form merger provisions of the Delaware
General Corporation Law, was completed and the Company thereby became a wholly
owned subsidiary of the Parent. As a result of the merger, the Purchaser ceased
to exist. In the merger, Shares not previously purchased by the Purchaser were
converted into the right to receive $12.40 per Share in cash.
  
          A copy of the Parent's press releases with respect to the closing of
the tender offer and the consummation of the merger are filed as Exhibits
(a)(20) and (a)(21) to this Statement and is incorporated herein by reference.

ITEM 11.  MATERIAL TO BE FILED AS EXHIBITS.

          (a)(20)  Press release, dated September 19, 1997, issued by 
                   the Parent.

          (a)(21)  Press release, dated September 19, 1997, issued by 
                   the Parent.
 
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                                   SIGNATURE
 
     After due inquiry and to the best of the undersigned's knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, complete and correct.
 
Dated: September 19, 1997

                                   FUJITSU LIMITED
 
                                   By: /s/ Kazuto Kojima
                                   ----------------------------------------
                                   Name:   Kazuto Kojima
                                   Title:  Director and Group President
                                           Marketing Group and International
                                           Computer Business Group
 
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                                  EXHIBIT LIST
 
<TABLE>
<CAPTION>
 EXHIBIT                                                                                 PAGE
 NUMBER                                     DESCRIPTION                                 NUMBER
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<S>          <C>                                                                        <C>
(a)(1)*      Form of Offer to Purchase, dated August 5, 1997.
(a)(2)*      Form of Letter of Transmittal.
(a)(3)*      Form of Letter from Lehman Brothers Inc. to Brokers, Dealers, Commercial
             Banks Trust Companies and Other Nominees.
(a)(4)*      Form of Letter from Brokers, Dealers, Commercial Banks, Trust Companies
             and Other Nominees to Clients.
(a)(5)*      Form of Notice of Guaranteed Delivery.
(a)(6)*      Form of Guidelines for Certification of Taxpayer Identification Number on
             Substitute Form W-9.
(a)(7)*      Summary Advertisement as published in The Wall Street Journal on August
             5, 1997.
(a)(8)       Text of Joint Press Release, dated July 30, 1997, issued by Fujitsu
             Limited and Amdehl Corporation(1).
(a)(9)*      Text of Joint Press Release, dated August 5, 1997, issued by Fujitsu
             Limited and Amdahl Corporation.
(a)(10)*     Text of Press Release, dated August 14, 1997, issued by Fujitsu 
             Limited. 
(a)(11)*     Supplement, dated August 22, 1997,  to Offer to Purchase, dated 
             August 5, 1997.

(a)(12)*     Revised form of Letter of Transmittal.

(a)(13)*     Revised form of Letter from Lehman Brothers, Inc. to Brokers, Dealers,
             Commercial Banks, Trust Companies and Other Nominees.

(a)(14)*     Revised form of Letter from Brokers, Dealers,
             Commercial Banks, Trust Companies and Other Nominees to Clients. 

(a)(15)*     Revised form of Notice of Guaranteed Delivery.

(a)(16)*     Text of Joint Press Release, dated August 20, 1997, issued by
             Fujitsu Limited and Amdahl Corporation.

(a)(17)*     Text of Joint Press Release, dated August 22, 1997, issued by Fujitsu
             Limited and Amdahl Corporation.

(a)(18)*     Text of Press Release, dated September 10, 1997, issued by Fujitsu
             Limited.  
(a)(19)*     Text of Press Release, dated September 15, 1997, issued by Fujitsu
             Limited.  
(a)(20)      Text of Press Release, dated September 19, 1997, issued by Fujitsu
             Limited.  
(a)(21)      Text of Press Release, dated September 19, 1997, issued by Fujitsu
             Limited.
(b)          Not applicable.
(c)(1)*      Agreement and Plan of Merger, dated as of July 30, 1997, by and among
             Fujitsu Limited, Fujitsu International, Inc. and Amdahl Corporation
             (incorporated herein by reference to Exhibit III to the Offer to Purchase
             filed as Exhibit (a)(1) hereto).
(c)(2)       Confidentiality Agreement, dated June 30, 1997, between Fujitsu Limited
             and Amdahl Corporation(1).
(c)(3)       Letter Agreement, dated July 9, 1997, between Fujitsu Limited and Amdahl
             Corporation(1).
(c)(4)*      Amdahl/Fujitsu 1982 Agreement, dated March 4, 1982, between Fujitsu
             Limited and Amdahl Corporation.
(c)(5)*      Letter Agreement, dated April 3, 1984, between Fujitsu Limited and Amdahl
             Corporation.

(c)(6)*      Memorandum of Understanding, dated August 20, 1997. 

(d)          Not applicable.
(e)          Not applicable.
(f)          Not applicable.
</TABLE>
 
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  * Previously filed.

(1) Filed as an Exhibit to Amendment No. 1 to the Schedule 13D filed by Fujitsu
    Limited with the Securities and Exchange Commission on July 31, 1997 and
    incorporated herein by reference.
