Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!tut.cis.ohio-state.edu!ucbvax!decwrl!sun-barr!newstop!sun!imagen!atari!apratt
From: apratt@atari.UUCP (Allan Pratt)
Newsgroups: comp.sys.atari.st
Subject: Re: DOES TOS 1.4 DO THIS?
Message-ID: <1629@atari.UUCP>
Date: 31 Jul 89 17:35:44 GMT
References: <8907260006.AA28980@ucbvax.Berkeley.EDU> <1625@atari.UUCP> <660@electro.UUCP>
Organization: Atari Corp., Sunnyvale CA
Lines: 24

ignac@electro.UUCP (Ignac Kolenko) writes:
>if it has always marked bad sectors, why does the desktop stop and say that
>the disk is unusable sometimes, and other times it finished a format ...

If there are too many bad sectors, or if Track 0 of the disk is bad,
you get the "unusable" message.  I forget how many is "too many." As
for writing to these bad sectors, it shouldn't happen.  If it does,
perhaps the sectors in question are marginal: they formatted ok but
subsequent accesses were bad.

It's also possible that I'm totally wrong and old TOS didn't mark bad
sectors correctly.  What version are you using?  (Original) TOS 1.0 or
(Mega) TOS 1.2?

After a format of a disk with "known bad sectors" try looking at the
FAT. Are there any entries (after the first two) which are not $000? 
$FF7 is the bad-sector mark, I think.  The alert after the format
should show the size of the disk after accounting for bad sectors and
the two unused clusters at the end of the disk.  (Don't open that can
of worms, please!)

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt