[Coco] 3.5" Drive Variable in the NitrOS-9 Module Header

[David Ladd]

On Sun, Jan 27, 2013 at 6:53 AM, Wayne Campbell <asa.rand at gmail.com> wrote:

> I recall that, although I never saw one, 720K floppies did exist, both in
> 5.25 and 3.5 varieties. I'm not sure it will be worth it for those, except
> for completeness as they were rare back then (89-94). I think the greatest
> issue will be the high-density drives. The 5.25 variety is 1.2 meg instead
> of 1.44 meg. Will that make a difference to the driver?
>
> When I had my Coco3 I had 3 80-track floppies, 2 5.25 and 1 3.5. I found a
> 1.44 meg 3.5, but it was only usable as a 80-track 360K because the
> descriptors and driver wouldn't work with anything larger under OS-9 Level
> 2.
>
The only thing you really needed to do for 80 track drives was to make sure
you had typ=21 and cyl=50
On the high density 5.25" drives you needed to change some jumpers is all I
can remember at this point.  As far as 1.44MB 3.5" floppy drives if you
used a real 720K floppy disk in it the detector switch automatically would
set the correct data rate of the floppy drive to double density.

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