
<PAGE>   1
 
                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                        TENDER OF SHARES OF COMMON STOCK
                                       OF
 
                               AMDAHL CORPORATION
                                       TO
 
                          FUJITSU INTERNATIONAL, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
 
                                FUJITSU LIMITED
                   (NOT TO BE USED FOR SIGNATURE GUARANTEES)
 
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           THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 5:00 P.M.,
               NEW YORK CITY TIME, ON FRIDAY, SEPTEMBER 12, 1997,
                         UNLESS THE OFFER IS EXTENDED.
--------------------------------------------------------------------------------
 
     This Notice of Guaranteed Delivery, or one substantially in the form
hereof, must be used to accept the Offer (as defined below) if (i) certificates
("Share Certificates") evidencing shares of common stock, par value $.05 per
share (the "Shares"), of Amdahl Corporation, a Delaware corporation (the
"Company"), are not immediately available, (ii) Share Certificates and all other
required documents cannot be delivered to The Bank of New York, as Depositary
(the "Depositary"), prior to the Expiration Date (as defined in the Offer to
Purchase (defined below), as amended and supplemented by the supplement thereto
dated August 22, 1997 (the "Supplement")) or (iii) the procedure for delivery by
book-entry transfer cannot be completed on a timely basis. This Notice of
Guaranteed Delivery may be delivered by hand or mail or transmitted by facsimile
to the Depositary. See the Offer to Purchase, dated August 5, 1997 (the "Offer
to Purchase").
 
                        THE DEPOSITARY FOR THE OFFER IS:
 
                              THE BANK OF NEW YORK
               By Mail:                       By Hand or Overnight Courier:
 
         The Bank of New York                      The Bank of New York
     Tender & Exchange Department              Tender & Exchange Department
            P.O. Box 11248                          101 Barclay Street
        Church Street Station                   Receive and Deliver Window
    New York, New York 10286-1248                New York, New York 10286
                                             
                     By Facsimile for Eligible Institutions:
                                 (212) 815-6213
 
                           Confirmation by Telephone:
                                 (800) 507-9357
 
     DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TRANSMISSION OTHER
THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
 
     This form is not to be used to guarantee signatures. If a signature on a
Letter of Transmittal is required to be guaranteed by an Eligible Institution
(as defined in the Offer to Purchase) under the instructions thereto, such
signature guarantee must appear in the applicable space provided in the
signature box on the Letter of Transmittal.
                                             
                                             
                                             
                                             
                                             
                                             
<PAGE>   2
 
Ladies and Gentlemen:
 
     The undersigned hereby tenders to Fujitsu International, Inc., a Delaware
corporation and a wholly owned subsidiary of Fujitsu Limited, a corporation
organized and existing under the laws of Japan, upon the terms and subject to
the conditions set forth in the Offer to Purchase, the Supplement and the
related Letter of Transmittal (which together, as amended or supplemented from
time to time, constitute the "Offer"), receipt of which are hereby acknowledged,
the number of Shares specified below pursuant to the guaranteed delivery
procedures described in the Offer to Purchase.
 
                               Number of Shares:
                         -----------------------------
Certificate Nos. (If Available):
===================================================
Check ONE box if Shares will be
delivered by book-entry transfer:
 
[ ] The Depository Trust Company
 
[ ] Philadelphia Depository Trust Company
Account Number:
-------------------------------
 
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         Signature(s) of Record Holder(s)
 
Dated:
------------------ , 1997
Name(s) of Holder(s):
===================================================
               Please Type or Print
 
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                      Address
 
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                     Zip Code
 
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            Area Code and Telephone No.
 
                                   GUARANTEE
 
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
     The undersigned, a bank, broker, dealer, credit union, savings association
or other entity which is a member in good standing of the Securities Transfer
Agents Medallion Program, the New York Stock Exchange Medallion Signature
Guarantee Program or the Stock Exchange Medallion Program, or a bank, broker,
dealer, credit union, savings association or other entity which is an "eligible
guarantor institution," as such term is defined in Rule 17Ad-15 under the
Securities Exchange Act of 1934, as amended, hereby guarantees the delivery to
the Depositary of the Shares tendered hereby, together with a properly completed
and duly executed Letter of Transmittal (or manually signed facsimile(s)
thereof) and any other required documents, or an Agent's Message (as defined in
the Offer to Purchase) in the case of a book-entry delivery of Shares, all
within three New York Stock Exchange trading days after the date hereof.
 
     The Eligible Institution that completes this form must communicate the
guarantee to the Depositary and must deliver the Letter of Transmittal and Share
Certificates to the Depositary within the time period shown herein. Failure to
do so could result in a financial loss for such Eligible Institution.
 
<TABLE>
<S>                                              <C>
--------------------------------------------     --------------------------------------------
                NAME OF FIRM                                 AUTHORIZED SIGNATURE
 
--------------------------------------------     Name:
                                                 --------------------------------------------
                  ADDRESS                                    PLEASE TYPE OR PRINT
 
--------------------------------------------     --------------------------------------------
                  ZIP CODE                                          TITLE
 
--------------------------------------------     Dated:
                                                 ----------------------------------------, 1997
        AREA CODE AND TELEPHONE NO.
</TABLE>
 
      DO NOT SEND SHARE CERTIFICATES WITH THIS NOTICE. SHARE CERTIFICATES
                SHOULD BE SENT WITH YOUR LETTER OF TRANSMITTAL.
