[Coco] Chinon floppy drive and coco3

[Gene Heskett]

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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