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From: mj@myrias.UUCP (Michal Jaegermann)
Newsgroups: net.micro.atari16
Subject: TOS bites again...
Message-ID: <254@myrias.UUCP>
Date: Mon, 23-Jun-86 21:05:14 EDT
Article-I.D.: myrias.254
Posted: Mon Jun 23 21:05:14 1986
Date-Received: Wed, 25-Jun-86 06:43:37 EDT
Organization: Myrias Research, Edmonton
Lines: 33

[ munch, munch ... ]

I was hit by a rather obscure bug in TOS, Below is an exact description
of what happened.  Does anybody else happen to stumble upon the same
problem?
--------
SYSTEM
    Atari 1040 ST. TOS in ROM (of course). One DS drive.
    Only operating system and basic accesories loaded.  No RAM-drive
    at the moment.
ACCESORIES  (which you need to reproduce events)
    A disk which sometimes in a past was initialized as two-sided.
    Currently re-initialized as a single sided and completely filled
    with files.
SITUATION
    At the Desktop, by a mistake I tried to copy one more file to
    the disk.  Without RAM-drive I used "copy a: to b: and swap, swap,
    swap..." method.
RESULTS
    Operating system happily went throgh motions.  No error reported
    during the whole operation.  First indication that something went
    amiss was that a directory listing looked exactly as before the
    operation.  As it turned out some parts of a file which I tried 
    to copy - a program file - were deposited on the disk overwriting
    an end of one file and a begin of the next one.  Apparently some
    pointers in FAT for the second file were changed making the last
    sector of the second file its begin - at least in some circumstances.
HOW TO AVOID
    I don't know.  Be careful and tip-toe around.
-----
Michal Jaegeramnn
Myrias Research Corporation
Edmonton, Alberta, CANADA