Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!umd5!hans
From: hans@umd5.umd.edu (Hans Breitenlohner)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Help!
Message-ID: <4778@umd5.umd.edu>
Date: 28 Apr 89 19:47:38 GMT
References: <38777@bbn.COM>
Reply-To: hans@umd5.umd.edu (Hans Breitenlohner)
Organization: University of Maryland, College Park
Lines: 21

In article <38777@bbn.COM> slackey@BBN.COM (Stan Lackey) writes:
<1. I am trying to use SIO directly.  I am doing this so I can do physical
<   sector accessing of the disk.  (I really want to do this, so don't try
<   to talk me out of it.)  I was successful in reading 1050 and 810 density
<   disks, on both the 1050 and XF551.  I haven't tried writing yet.
< 
<   My problem is: I get error# 138,139,144 which are device errors, NAK's
<   and timeouts accessing DSDD disks on the XF551.  I assumed that you
<   just set the byte count from 128 to 256.  Some of the data I read
<   might have been right, but with all the trash it was hard to tell.  I
<   tried setting the byte count back to 128, but the symptoms were the
<   same.  I turned the drive off and back on again, and got the same.
<   Apparently, there is something different you must do when accessing DD
<   disks.
<
From all i've heard about it I assume that the XF551 switches to the 
appropriate density when you insert single, double, or enhanced density
disks.  It does not, however, switch to double sided mode on its own,
you need to send it a configuration command to do so.  
Are you familiar with the commands to change drive configuration?  If not
I could send you some info.