Path: utzoo!mnetor!uunet!husc6!bbn!uwmcsd1!ig!agate!ucbvax!decvax!decwrl!aim.dec.com!goldstein
From: goldstein@aim.dec.com (fred, k1io@FN42jk, +1 617 486 7388)
Newsgroups: comp.sys.atari.st
Subject: How compatible are MS-DOS and TOS disks, REALLY?
Message-ID: <8802051651.AA00683@decwrl.dec.com>
Date: 5 Feb 88 18:13:00 GMT
Organization: Digital Equipment Corporation
Lines: 31

Weird stuff.

Okay, I've read it a thousand times.  MS-DOS disks are formatted like 
TOS disks, the only difference being the MS-DOS boot sector.  So I
can exchange files freely, right?  Well, usually, but sometimes it
gets very, very strange.

Take this nice, shiny SONY MF2DD sitting next to me.  I formatted it
on a NEC Multispeed (MS-DOS 3.2), labeled it, and used it for some
MS-DOS work.  Fine.  Then I used MS-DOS Kermit to move a couple of
ARC files, one an MS-DOS ARC and one a TOS ARC, to said diskette.
I took it home to the 1040STf and copied the TOS ARC to another
disk for de-arcing.  Fine.  Then I did some work and copied a text
file back to same disk so I could read it on the NEC as well.
Lo and behold, doing a DIR on the Atari (both GEM desktop and using
PCOMMAND shell) showed only ONE file on the disk, that being the one
which I just put there!  So far as the 1040STf is concerned, all
the other files on the disk are gonzo.  Todt.

So I take the disk back to the NEC and do a DIR, and lo and behold,
the old files are still in the directory!  But not intact; looking
at an old TXT file I see the new one (Atari-generated) and the old
one (NEC generated) intermingled.  Yep, the Atari overwrote sectors
used by the NEC.  It really didn't see the directory.

It sounds like I have to restrict my floppies to being written only
by one or the other OS.  I can format on MS-DOS and read/write
on Atari, but if I want to write under MS-DOS I can't write to the
same disk with the Atari.  Boo hiss.  Anybody understand what's
really going on?  thanx.
    fred