From: Ethan Dicks
One of these?
Wow; that's pretty impressive! Not only will it talk to an RK05, it also
works with drives from Ampex, Control Data, Diable, Pertec, etc, etc. I
didn't realize they were all similar enough (in terms to the controller
interface) to be interchanged like that.
For the RK05, it must have used a flat cable from the Berg header on the card
to a custom dual card that plugged into the mini-backplane in the RK05
(similar to the RKV11-D).
From: Chris Zach
I have wondered if the Plessy can do 22 bit DMA
Depends on whether or not it's program compatible with the RK11. That's
because on almost alll UNIBUS controllers, DEC was in the habit of putting
the A16/A17 bits of the buffer address in the CSR (usually in the 060 bits).
So they could only handle 18-bit DMA addresses.
Early QBUS contollers just copied that, so that they were then 100% software
compatible. That's why the RLV11 and RLV12 differ a bit: the RLV11 is 18-bit
address only; to add 22-bit capability to the RLV12, they had to add an extra
register (the RLBAE).
(Interestingly, the Dilog card above claims to the RKV11 compatible; but also
says it has "memory addressing capability" to 256KB. They can't both be
though; although the RKV11-D has the A16/A18 bits in the CSR, they aren't
connected to anything! See EK-RKV11-OP-001, pg. 3-5.)