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Path: utzoo!lsuc!jimomura
From: jimomura@lsuc.UUCP
Newsgroups: comp.sys.m6809
Subject: Re: CoCo3, Disto Controller, OS-9
Message-ID: <1631@lsuc.UUCP>
Date: Wed, 11-Mar-87 20:43:45 EST
Article-I.D.: lsuc.1631
Posted: Wed Mar 11 20:43:45 1987
Date-Received: Wed, 11-Mar-87 22:36:40 EST
References: <1608@lsuc.UUCP> <15129@amdcad.UUCP>
Sender: root@lsuc.UUCP
Reply-To: jimomura@lsuc.UUCP (Jim Omura)
Distribution: na
Organization: Consultant, Toronto
Lines: 31
Summary: Single Density

In article <15129@amdcad.UUCP> bandy@amdcad.UUCP (Andy Beals) writes:
>In article <1608@lsuc.UUCP> jimomura@lsuc.UUCP (Jim Omura) writes:
>>Tandy now puts in the connectors for polarity protection.  A more important
>>problem is that the WD-1773 chip doesn't seem to read/write single density.

>The 1773 definitely does read/write single density.  Your vendor probably
>doesn't program it correctly. :-(

     Thanks Andy.  Yes, I found that out shortly after I posted the message.
In fact, it seems to be a timing problem due to some TTY 74... chip or other.
I'm still looking for a solution, but the solution doesn't seem to be
easy to come by.  There are currently 3 commonly used disk controllers
that I know of that use the same WD-1773 controller chip.  I now have 2
of them.  I *think* that the Disto may be fixable via changing a 74LS04
variant chip, but I'm not sure about this.  I checked the new Shack controller
and it doesn't have that chip anywhere, so I think I'm dealing with two
significantly different implimentations of this controller.

     As a matter of interest, the J & M controller also uses this chip, and
I believe the Hard Disk Specialist (?) controller also uses this chip.  I
don't know about the HDS controller, but I've heard that the latest J & M
controllers have the same inability to use single density.

     Has anyone heard anything about a fix for *any* of these controllers?

Cheers!! -- Jim O.
>	andy
>-- 
>Andrew Scott Beals, {lll-crg,decwrl,allegra}!amdcad!bandy +1 408 749 3683