PROSPECTUS SUPPLEMENT                         FILED PURSUANT TO RULE 424(b)(3)
(To Prospectus dated July 10, 1997)           Registration No. 333-30199


                            DATA GENERAL CORPORATION

                 $212,750,000 Principal Amount of 6% Convertible
                           Subordinated Notes due 2004
                    (Interest payable May 15 and November 15)

                        8,122,089 Shares of Common Stock



        This document supplements the Prospectus dated July 10, 1997 relating to
(i) $212,750,000 aggregate principal amount of 6% Convertible Subordinated Notes
due 2004 (the "Notes") of Data General Corporation,  a Delaware corporation (the
"Company"), and (ii) 8,122,089 shares of common stock, par value $.01 per share,
(the "Common Stock") of the Company which are initially issuable upon conversion
of the Notes plus such additional indeterminate number of shares of Common Stock
as may become  issuable upon  conversion of the Notes as a result of adjustments
to the  conversion  price  (the  "Shares").  The Notes and the  Shares are being
offered  for the  account  of the  holders  thereof.  The Notes  were  initially
acquired from the Company by Morgan Stanley & Co.  Incorporated and Dillon, Read
& Co., Inc in May 1997 in connection  with a private  offering.  This Prospectus
Supplement is incorporated by reference into the Prospectus,  and all terms used
herein shall have the meaning  assigned to them in the Prospectus.  On September
11, 1997 the last sale price of the Common  Stock of the Company on the New York
Stock  Exchange was $32 7/8ths.  The Common Stock of the Company is traded under
the symbol "DGN."

         Selling Securityholder:      NatWest Markets
                                      175 Water Street
                                      New York, NY  10038

         Securities Being Sold:       $5,000,000.00  aggregate principal amount
                                                     of 6% Convertible
                                                     Subordinated Notes due 2004



         As of September 11, 1997, and prior to giving effect to the sale of the
Notes  being  offered  by  the  Selling   Securityholder   hereby,  the  Selling
Securityholder  beneficially owned  $5,000,000.00  aggregate principal amount of
Notes, [representing 2.4% of the Notes outstanding as of such date]. [As of such
date, the Selling  Securityholder  did not beneficially own any shares of Common
Stock of the Company, other than the shares of Common Stock into which the Notes
beneficially owned by the Selling Securityholder are convertible].



SEE "RISK  FACTORS"  BEGINNING ON PAGE 4 OF THE  ACCOMPANYING  PROSPECTUS  FOR A
DESCRIPTION  OF  CERTAIN  FACTORS  THAT  SHOULD  BE  CONSIDERED  BY  PROSPECTIVE
INVESTORS.




            THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY
               THE SECURITIES AND EXCHANGE COMMISSION OF 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 Supplement is
                               September 12, 1997.