27 Oct
2013
27 Oct
'13
5:03 p.m.
On 27/10/2013 02:59, Jerome H. Fine wrote:
That's not right.
The 11/93 and 11/94 were not supported with memory other than on the CPU
board, but some revisions did allow that.
The 11/84 uses exactly the same processor boards as the 11/83 and also
uses exactly the same PMI memory boards. The difference is that the
11/84 has also a Qbus to Unibus converter for the rest of the system and
does not support QBus peripherals.
Actually the very earliest MSV11-J modules would work in an 11/84 but
were not supported in an 11/73 or /83 because of a bug in an ASIC, but
later revisions were fixed and worked in all 11/73, 11/83, and 11/84.
Christian
Gauger-Cosgrove wrote:
The CD interconnect is also used on the PMI capable QBUS cards, so the
11/83 and 11/93 processors (and third party replacements for those),
Just a suggestion, but you might mean 11/84 instead of 11/93.
Both the 11/93 and 11/94 support ONLY memory on the CPU
board. The 11/83 is all Qbus and uses Qbus PMI memory. The
11/84 is very special and uses special PMI memory that is ONLY
for an 11/84 system. However, with the uVAX II, there is also a cable over
the top
connecting the CPU to the memory, so perhaps the CD portion
of the ABCD slot is not used in the same manner as with a
PDP-11/83.
Indeed, it's not, because it doesn't (can't) use PMI nor normal QBus
memory. The over-the-top cabling carries the signals for wider larger
memory, along with some of C/D for memory access. But the C/D signals
are used differently to PMI.
As far as I remember, all quad CPU boards which use
the J11
chip (11/53, 11/73, 11/83 and 11/93) may be inserted into
an ABAB slot and the memory below it will then be used as
normal memory. I do not know about the use of PMI memory
in an ABAB slot, but I definitely have placed a KDJ11-BF in a
VT103 which is definitely an ABAB slot with a 4 MB quad memory
board below it. RT-11 reported the CPU as PDP-11/73 in that
case.
Are you sure you're remembering that correctly? All the manuals say
not, and Micronote 039 explicitly states "KDJ11-B cannot be used in a
backplane (or that part of the backplane) where there is Q-bus in both
AB and CD slots" and that's because it will get some signals on pins
that expect either nothing or PMI.
PMI memory will definitely not work in Q/Q backplanes because it needs
the C/D Interconnect. Moreover, PMI memory manuals take great trouble
to point out "Do not install MSV11-J in a Q-Q backplane since this
backplane shorts Q-bus signals to PMI bus signals and the system will
not operate. This can also result in damage to the MSV11-J and other
modules in a Q-Q backplane."
For example, some of the PMI signals will be shorted to ground, one to
+5V, one will be shorted to the QBus HALT line, and several others
shorted to incompatible QBus signals.
Also, with all of this discussion of ABCD slots and
PMI memory,
most, maybe all, M8190 boards also support the use of PMI
memory if placed in ABCD slots with the CPU below the memory.
True, all M8190 can use QBus memory if it's below the processor. But
then it's not operating as PMI memory; a PMI board below the processor
operates as ordinary QBus memory, and that's why it's slower.
--
Pete Peter Turnbull
Network Manager
University of York