4 Feb
2015
4 Feb
'15
7:44 p.m.
On Wed, Feb 4, 2015 at 7:09 PM, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
Longer explanation: The PMI memory used in the PDP-11/84 is sufficiently
different
from the PMI memory used in the PDP-11/83 that the magic smoke might be
released
if the incorrect PMI memory is used. The MSV11-JB (1 MB) and MSV11-JC (2
MB)
are used in the PDP-11/84. The MSV11-JD (1 MB) and the MSV11-JE (2 MB) are
used in the PDP-11/83.
The MSV11-JD and MSV11-JE are documented as being compatible with both
the PDP-11/84 and Q-bus systems. The documented restriction is that
the MSV11-JB and MSV11-JC are only compatible with PDP-11/84 systems
and incompatible with Q-bus systems.
http://www.bitsavers.org/pdf/dec/qbus/oemMicronotes.pdf
uNote # 028
MSV11-Q/M/J MEMORY COMPARISONS
MSV11-J
-------
The MSV11-J has four versions, the MSV11-JB and the MSV11-JC which are
used in the PDP-11/84 UNIBUS systems and the MSV11-JD and the MSV11-JE
are used in either the MicroPDP-11/83 Q-bus systems, or the PDP-11/84
UNIBUS systems. All four modules use ECC memory for error correction,
as well as using 256K bit MOS RAM parts on either a half for fully
populated quad size module.
NOTE:
-----
NONE OF THE FOUR MSV11-J MODULES CAN BE PLACED IN A Q/Q BACKPLANE
SLOT. IF THIS IS ATTEMPTED PERMANENT DAMAGE WILL BE DONE TO THE BOARDS
AND TO THE SYSTEM.
The MSV11-JB (M8637-BA) is a half populated quad size PMI memory
module containing 1MB of memory. The second version of the MSV11-J is
the MSV11-JC (M8637-CA), this is a fully populated MSV11-JB quad size
PMI memory module containing 2MB of memory. These two module can not
be used in a Q-bus system due to gate array incompatibilities, and can
only be used in the PDP-11/84 systems which use the UNIBUS/PMI bus
interface (KTJ11-A). The third version of the MSV11-J is the MSV11-JD
(M8637-DA) which is a half populated quad size PMI memory module
containing 1MB of memory. The last version of the MSV11-J is the
MSV11-JE, (M8637-EA) which is a fully populated MSV11-JD quad size PMI
memory module containing 2MB of memory. These last two modules can be
used with either the MicroPDP-11/83 system which uses the Q-bus/PMI
bus interface or the PDP-11/84 system which was mentioned above.
Although the MSV11-JD and MSV11-JE are PMI memories they can be used
in two other Q-bus configurations.
(more details follow...)