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From: dlm@druwy.ATT.COM (Dan Moore)
Newsgroups: comp.sys.atari.st
Subject: Re: 2K of disk space lost?
Message-ID: <3929@druwy.ATT.COM>
Date: 23 Mar 89 16:06:50 GMT
References: <8903211617.AA27122@uk.ac.ucl.sm.uxm>
Organization: AT&T, Denver, CO
Lines: 32

in article <8903211617.AA27122@uk.ac.ucl.sm.uxm>, andrew@uxm.sm.ucl.ac.UK
(Andrew Dawson) says:
> Now, 2*80*9-1-2*5-7 = 1422, and at 512 bytes per sector this is
> 728064 bytes. However, after formatting is complete (assuming no bad
> sectors), I am told that the disk has 726016 bytes free. 2K is
> unaccounted for.
> 
> Also, if I format a 720K disk on an MS-DOS machine, DOS reports 730112
> bytes free (a FAT is only 3 sectors under DOS). If I take this same blank
> disk and put it in my ST, a "show info" reports 728064 bytes free - another
> error of 2048 bytes.

	This is a known bug in TOS.  TOS never uses the last two
clusters on any disk (including hard disks).  TOS can read files that
include those two clusters it just won't use them when writing to the
disk.  This means that TOS floppies are 4K smaller than a floppy
formated with MSDOS, 2K is lost to overly large FATs and 2K lost in the
"missing" clusters at the end of the disk.


	It seems that Atari doesn't consider the missing 2 clusters to
be important, they (Alan Pratt) have stated that the bug will not be
fixed in TOS 1.4. 




				Dan Moore
				AT&T Bell Labs
				Denver
				dlm@druwy.ATT.COM
				dlm@druhi.ATT.COM