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From: WALDI@DHDIHEP1.BITNET
Newsgroups: comp.sys.atari.st
Subject: IBM-PC floppy disk format
Message-ID: <8711060947.AA19132@ucbvax.Berkeley.EDU>
Date: Fri, 6-Nov-87 04:48:02 EST
Article-I.D.: ucbvax.8711060947.AA19132
Posted: Fri Nov  6 04:48:02 1987
Date-Received: Sun, 8-Nov-87 14:13:45 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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Date: 6 November 1987, 10:38:51 SET
From: Roland Waldi              phone (6221) 564334  WALDI    at DHDIHEP1
      Inst. fuer Hochenergiephysik
      D-6900 Heidelberg
To:   INFO-ATA at SCORE.ST

I tried the "200% MS-DOS compatible" disk formatter recently posted
to this group: It fails to create disks readable by my IBM PC
(the same as DCFORMAT 2.2)! However, disks formatted on the PC
still can be read/written on the Atari without any problems, even
new folders can be created on the ST and read on the PC!
Also, if I copy those disks with a special copy program (designed
for backup of copy-protected disks), the copies made (formatted)
on the Atari work fine. So I decided to investigate further, and
actually found the difference, which makes normal Atari-formatted
disks fail on the PC: The IBM-PC's 3 1/2" drive needs a larger Gap
before the first sector of the disk (usual error message: "sector
not found"). The Atari formatting programs have about 70 bytes before
the first sector header, my IBM disks have more than twice that much!
Obviously, the Atari gap is too small for the IBM controller, which can
only read sectors 2...9 of a track. Since this may vary between
different drives due to hardware tolerances, many people may be
quite happy with DCFORMAT or IBMFMT -- others (like me) cannot
use it.

Roland Waldi