[Coco] Chinon floppy drive and coco3

[Arthur Flexser]

Gene, I believe the index hole is used by the CoCo only for formatting.  So
if that's the problem, it should be readily identifiable by the drive's
working okay for reading and writing to existing CoCo disks, but giving an
error when it gets to the verify stage of formatting.

Art


On Sat, Feb 22, 2014 at 10:16 PM, Gene Heskett <gheskett at wdtv.com> wrote:

> On Saturday 22 February 2014 22:06:50 Mike Howard did opine:
>
> > Has anyone been able to get a chinon floppy drive to work with coco3. I
> > can get it to read tracks but get io error when it trys to
> > verify...How bout a nec drive. the nec is fd1177c ad chinon is 506l ?
>
> ISTR I have used them ok.  But be aware that some Chinon drives could be
> fugitives from an amiga, and have 2 problems, the first is the head drive
> wire and its spring leaf to help it stay in the motor shafts spiral groove
> is going to need cleaning back down to bare metal & re-oiled, the second
> being that the amiga versions have no "index" pulse which confuses the
> coco's WD1773 (or 93) FDC chip.  I don't think its fixable.  The amiga did
> not read "sectors" but the whole track was read into a buffer, and then the
> buffer was searched for the correct "sector".  Ditto on writes, it read the
> whole track, located the data to be updated in the buffer, and then wrote
> the whole track back to the disk, leaving a small gap between the end of
> the track and the same track coming back around as the disk was spinning.
> So it didn't care where the disk was in its rotation when it decided to
> write.
>
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>
> Cheers, Gene
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