Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!educ-isis!teexand
From: teexand@ioe.lon.ac.uk (Andrew Dawson)
Newsgroups: comp.sys.atari.st
Subject: How do I tell Rwabs() I've got a DS disk
Message-ID: <1990Nov14.151021.7946@ioe.lon.ac.uk>
Date: 14 Nov 90 15:10:21 GMT
Reply-To: teexand@ioe.lon.ac.uk (Andrew Dawson)
Organization: Institute of Education University of London
Lines: 17

I've noticed that if I use Rwabs() to write to the floppy in drive B, and no
access of drive B has been made since reset, TOS assumes the disk is single
sided. Hence, attempting to write higher numbered blocks cause the heads to
seek beyond the end of the disk (ouch!). This is presumably because the BPB
isn't correctly set up at the time of calling. Normally, I would just call
Getbpb(), except in this case I've haven't written the boot sector yet, so it
isn't valid. Since the BPB isn't in a fixed place across TOS versions, is there
any way of locating it without calling Getbpb(). Even if this can be achieved,
is it then safe to start changing the contents? There appears to be some extra
structure members at the end that aren't documented.

Any suggestions?
-- 

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Andrew Dawson, Computer Centre, University College London, Gower Street,
London WC1E 6BT, England.