On Wed, Apr 10, 2024 at 8:07 PM W2HX via cctalk <cctalk(a)classiccmp.org> wrote:
1. I have read that the card and the drives were
compatible with the dec rx02 drives. Why would the CRDS even bother to redesign a card
where DEC had perfectly good working ones? Anyone know if there is any value in keeping
the FC-202 or just keep with the DEC cards?
The easy first answer is DEC's drives were expensive so there was room
for competition to bring in a less expensive product and then _they_
would get the profits. The second answer is that DEC's implementation
was basic - read and write single-sided floppies and that's it - no
media (re)formatting. Third parties could add features to extend what
DEC had.
The DEC implementation relied on a custom processor board inside the
disk drive and a unique/proprietary way to have the controller tell
the drives what to do. By the late 80s. Shugart interface drives were
plentiful and processors like the Z-80 were totally capable so there
were several RX01 and RX02 imitators. I have at least one Qbus card
that just has a Shugart interface and was connected to a standard
floppy drive mechanism (and it can low-level format disks). In order
to work with existing drivers, though, the third party cards did have
to emulate them at the I/O register level but as long as it's
registers on one end and 8" media on the other, they were free to
reimplement the middle part.
-ethan