Path: utzoo!mnetor!uunet!mcvax!ukc!dcl-cs!bath63!pes
From: pes@ux63.bath.ac.uk (Smee)
Newsgroups: comp.sys.atari.st
Subject: Re: Changing  to / in TOS
Message-ID: <2204@bath63.ux63.bath.ac.uk>
Date: 22 Feb 88 10:56:21 GMT
References: <4805@ihlpg.ATT.COM> <981@atari.UUCP> <909@xn.LL.MIT.EDU>
Reply-To: pes@ux63.bath.ac.uk (Smee)
Organization: AUCC c/o University of Bath
Lines: 49

In article <909@xn.LL.MIT.EDU> singer@XN.LL.MIT.EDU (Matthew R. Singer) writes:
>Why does tos sometimes say a file is not there when it is, if the
>   file has been added to a disk after some subdirectories have been
>   added?

Don't know about most of the things Matthew is on about -- though I would
agree that Atari do appear not to be the speediest folk in the world; and
that they need to improve both 'fix output' and 'documentation' if they
want to be taken seriously as professional machines.  However...

Apropos of the particular question quoted (and the converse, why does TOS
sometimes say a file is there when it isn't), a warning...  (I'm not saying
it can't happen at other times, but) the only time I've seen either of these
effects, it's because the system has been fed 2 disks back-to-back which
have the same 'unique serial number' in the header block.  This is a 24-bit
number generated randomly by the standard disk format routine, so the odds
are very much against your ending up with a matched pair if you use the
standard desktop formatter.

HOWEVER, some of the PD formatters (only the first version of TWISTER, to
my knowledge, but might be others) had a bug which meant that they would
format all your disks with the same number.

OR, if you use a 'bit-copier' ('backup-utility', 'protected disk copier',
...  ProCopy which i use comes to mind) then, BY DEFINITION, the copy of a
disk which it makes you will have the same unique serial number as the
original.  If you then actively use both disks you'll have this problem.
(At one point, the ProCopy folks decided to make 'twisted' format generally
available, by distributing ProCopy on a 'twisted' disk, and telling you
you could get other 'twisted' disks by bit=copying their disk and deleting
all the files.  They very rapidly backed off from this.  The problem is
obvious.)

OR, I would also bet that if you have multiple ORIGINAL copies of the same
commercial product, the disks will be IDENTICAL including the unique serial
number -- whether for protection, or for ease of production, doesn't matter.

I trawled through my disks the other day and found 3 disks with identical
serials (all began as bit-copies of a single disk).  Re-arranging to fix
that has eliminated some annoying little glitches.  (I'm fortunate in that
all 3 were disks I use write-protected, so I didn't actually manage to garbage
any of them.)

If you are experiencing this sort of problem, THINK about whether any of the
above cases might hold.  (If you've got a disk doctor, look at the 24-bit
number at offset 8 from the beginning of the boot block (sector 0) on the
disks -- the disk showing the problem, and the disk you had in that drive
immediately previous.)  If you do have pairs or sets with matched unique
IDs, you will eventually regret it.