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From: dml@loral.UUCP (Dave Lewis)
Newsgroups: net.micro.6809
Subject: Re: R.S. floppy controller query
Message-ID: <1179@loral.UUCP>
Date: Wed, 25-Jun-86 11:06:56 EDT
Article-I.D.: loral.1179
Posted: Wed Jun 25 11:06:56 1986
Date-Received: Sat, 28-Jun-86 08:38:30 EDT
References: <1970@osu-eddie.UUCP>
Reply-To: dml@loral.UUCP (Dave Lewis)
Distribution: net.micro.6809
Organization: Loral Instrumentation, San Diego
Lines: 36
Keywords: Funny cables

In article <1970@osu-eddie.UUCP> pritch@osu-eddie.UUCP (Norman Pritchett)
writes:
>I have been under the impression that the floppy controller for the Color
>Computer (the one sold with the slim-line drives if it makes a difference)
>supported 4 single-sided drives.  After adding my fourth drive I found that
>it wouldn't select the 4th drive but it would select the second side of my
>double-sided drives.
>                  Norm Pritchett, The Ohio State University

  Radio Shack did a funny thing when they made that controller. They used the
first 3 drive select lines on the bus, then connected the /D3 select line to
the side select. If you buy your disk cables from Radio Shack you find that
they've connected each of these four lines, in turn, to the /D0 select line
on one connector. All the drives are jumpered as drive 0, and the drive on
the first connector actually responds to the /D0 select. They want you to buy
THEIR cables you see (at $30 a shot too). Actually, you're better off with
three double-sided drives anyway (3 * 2 == 6, 4 * 1 == 4) IF both your drives
and your software will support it. None of Radio Shack's standard software,
including OS-9, will support double sided disks.

  While I will readily agree that they picked a strange way to handle the
thing it does make it simpler to rewrite their software for double sided
drives.

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		Dave Lewis    Loral Instrumentation   San Diego

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