On Wed, Apr 10, 2024 at 8:07 PM W2HX via cctalk <cctalk@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
