FYI:
The KS11 MMU for the 11/20 was built by CSS and was not on the product
list as it were. To my knowledge, no hardware or prints of it survive.
I've been told it was much more similar to the MMU in the KA10 than the
scheme eventually done for the 11/45/55/70 and the 11/40 class systems -
but I think Noel has done more investigation than I have. So if others
have more info, please chime in.
There
is a KT11B paging option that makes the PDP11/20 a 18 bit machine. It
looks a bit like the TC11 DECtape controller. I've got the schematics
from the internet. But I have no idea how it compares to the later MMU
units from the software perspective.
As
Warner points out the oldest code base we have is Fifth Edition. I'm
not sure if the KS11 code is still there. I did not think so. I
thought it ran on 11/40 and 11/45.
Yes, that is what I found too. V5 expects an 11/40 with at least 18 bits memory address space.
The
V1 work was for a PDP-7 and is before the first 11/20 was secured. The
point is that I think there is a hole in the the SW we have.
Too bad, but you never know what is still hidden in some attics...
As for RK03 vs. RK05 -- I think I can help a little.
RK02/RK03 used an RK-11C. I'm fairly sure that the RK05, used the
RK11-D controller. The '72 peripherals' handbook describes the former
and the '76 the later. But if you believe the handbook, both supported
203 cylinders and 2.45M bytes/disk with 512 byte sectors. The
difference seems to have been in drive performance.
Yes
the RK03 was the Diablo 31 with a DEC label on it. 100% compatible with
RK11D and RK05. You can swap the packs between these drives as well...
So I'm hoping for a disk image for such a drive... 😊