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From: sdyer@bbncca.ARPA (Steve Dyer)
Newsgroups: net.micro.6809
Subject: OS-9 and double sided disks
Message-ID: <321@bbncca.ARPA>
Date: Fri, 18-Nov-83 02:23:44 EST
Article-I.D.: bbncca.321
Posted: Fri Nov 18 02:23:44 1983
Date-Received: Sat, 19-Nov-83 02:13:47 EST
Organization: Bolt, Beranek and Newman, Cambridge, Ma.
Lines: 37

I'm trying to get OS-9 to use all 40 tracks and both sides of my Remex
floppy, and have it seek at the higher 6ms rate.  (Standard R/S disk
is single sided, 35 track, 30ms seek time.)  It seems I've been partially
successful--those with 40tk, fast step-rate drives will find this useful.
I'm also looking for any help with the problem I describe below...

First, I do the following (refer to page 39 of the OS-9 Technical Information
booklet):

OS9: debug      (all numbers in hexadecimal)
L d1            (my Remex is drive 1--use dN where N is your drive #)
. .+14          (select step rate)
= 3             (change from 0 [30ms] to 3 [6ms])
-               (move back to verify change)
. .+4           (select no of tracks)
= 28            (change from 35 tracks [23] to 40 [28])
= 2             (change from 1 side to two sides)
q               (quit the debugger)

A "format /d1" procedes fine until it gets past track 0x27 (which looks like
the last track on the first side.)  At that point, it gets read errors.
Looks like there's some problem accessing the other side.  For the record,
I should state that I'm using a special drive cable from Frank Hogg Labs
which allows me to use their FLEX with a double sided drive.  The only
difference (I think) with this cable and the standard R/S one is that
the controller's "side select" signal is passed to the selected drive, rather
than being used to select drive 3 (as in R/S DOS).

Perhaps the current disk driver ignores side selection, since the R/S
cable doesn't supply it?  Anyone out there have any ideas or suggestions?
Have fun with everything except double-sided drives, though...

/Steve Dyer
decvax!bbncca!sdyer

P.S.: I haven't yet figured out how to save this change.  Will keep you
      posted.