On 4/7/21 1:23 PM, Noel Chiappa via cctalk wrote:
.....
(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
true,
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.)
Noel
Perhaps the marketing assumption is that if you are compatible with 16
bit addressing, you don't even bother to check for 18 bit
functionality.? I always wondered why the RKV11-D was only 16 bit
addressable.? In those early days of the QBUS, perhaps the evolution of
the architecture wasn't as clear.? Or was it an intention limitation?
The DEC RK05 disk subsystem cost $10K list circa 1978? (drive, RKV-11D?
controller and cabinet), so this wasn't a trivial purchase.
I used the the Dilog card (IIRC) with both the Diablo 31 and Dec RK05
drives on LSI 11/23+ and 11/73's.? We had a cable that connected to the
Diablo and then we daisy chained to the RK05.? We had to be careful
since we were mixing 1 of N and decode N drive selection, but if you
only had a few drives it was not too bad.
???? Jerry