Osborne-1 SD format

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Tue Feb 22 17:14:55 2005

On Mon, 21 Feb 2005, Dave Dunfield wrote:
> >|The HD drive reads the entire disk perfectly, EXCEPT for Sector-1 of
> >|Track-0 (the SD track) - it quite reliably refuses to read the first
> >|sector of the SD track. The remaining sectors of the SD track and all
> >|of the DD tracks read OK.
> >Try covering the index hole cutout on the disk or otherwise blocking the
> >drive's index sensor. The controller does not like to start a read too
> >close to the index hole, but it will mostly work without any index pulses.
> >(It won't format or timeout of course.)
> Interesting idea - I'll give that a try, at least it might shed some more
> light on what exactly is going on.

That solved SOME of the problems that I had with Cromemco diskettes.
They definitely started the first sector too soon after the index pulse
for the 765 FDCs to handle.

If you haven't already noticed it,...
SOME drives (such as Teac?) need the index pulse to function. In those
cases, interrupt the signal in the cable (such as taping over the
connection on the card edge, or making a special cable with a switch).

But that does not solve ALL of the Cromemco issues. IIRC, I also had
intermittent difficulty with some other sectors (#3?)

BTW, I never had complete success trying to use the read-id command for
analyzing disks. Use of a 179x controller (such as running TRAKCESS on a
TRS80 III) or TE.COM with a Central Point Option board were MUCH better
for analyzing diskettes.

Grumpy Ol' Fred     		cisin_at_xenosoft.com
Received on Tue Feb 22 2005 - 17:14:55 GMT

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