>         How to use the 82C55A to controll the floppy disk drive
>         5 1/4" and 3 1/2" directly ?

It has been a long time since i've played with the WD controllers, but I
don't think it would be feasible to use the 8255. You would be able to
step to the desired track, and select a head, but it gets complex at
that point. not sure about the 3 1/2, but for the old (180k) 5 1/4 the
controller picked up a signal from a photocell looking through a hole in
the media for the sector location, and then read or wrote a MFM or FM
analog signal to the disk. The controller was responsible for generating
this signal much like a modem would.


you might look for information on the very old Apple computers. Wozniak
implemented the disk drive without using a FD controller, essentially
using it like a tape recorder and firing a bit stream at it. this,
however, resulted in a disk format unique to apple.