Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!marque!uunet!portal!cup.portal.com!Thomas_E_Zerucha
From: Thomas_E_Zerucha@cup.portal.com
Newsgroups: comp.sys.atari.st
Subject: Re: PC compatible(?) format on the ST
Message-ID: <8662@cup.portal.com>
Date: 2 Sep 88 01:05:23 GMT
References: <3461@druhi.ATT.COM>
Organization: The Portal System (TM)
Lines: 18
XPortal-User-Id: 1.1001.3273

"... But the PC only checks the media descriptor byte and if it is F9 then
it assumes that it is a standard PC disk with 3 sectored FATs..."

I wrote a utility and put F8 for the media descriptor byte (normally only
for Hard Disks), and mine work fine.  There are all kinds of bytes in the
boot sector which will theoretically tell the PC *exactly* how many bytes
and sectors and tracks are on the disk and used for each part (number and
size of FAT's, etc.).  I think the BIOS on my PC may be a little smarter
as well.  I even had 800K (10 sector) disks work fine on my PC.  If your
disk driver isn't reading these bytes to determine how many sectors per
FAT, don't blame Atari, blame the writer of your BIOS for not following
their own rules and reading the number of sectors per FAT directly from the
boot sector.

But while I am at it, does the BIOS now support any sector size other than
512 bytes?  Any other cluster size besides 2 sectors/cluster?  All the other
stuff in the Bios Parameter Block and Boot sector that are supposed to set
up all these values?