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
