The MS11-M is a semiconductor memory for the extended Unibus on the
PDP-11/44. It goes into a MUD slot and must have a +/-12V
instead of +/-15V.
||128K Byte ECC MOS Memory
||256K Byte ECC MOS Memory
|| +12V is used and taken from the +15BB pins. For
for the MS11-M, the pins are +12V supplied from a battery backed
|| +5V is taken from the standard pins.
||-12V is used and taken from the -15BB pins. For
backplanes configured for the MS11-M, the pins are -12V supplied from a
Internally, the board drops this down to -5V for the DRAMs. This is a
low current source.
Wiring Harness Adapter
The early PDP-11/40 chassis wiring harness requires adaptation before
it can be used with a DD11-DK backplane. Most signals on the harness
are straightforward, but three are of special note.
- +12BB - This voltage is derived from the +15V supply using
TO-3 package regulator.
- +5BB - This voltage is taken directly from the standard +5V
- -12BB - This voltage is derived from the -15V supply using
diodes in series. The resulting voltage is -12.5V.
On initial powerup the processor hangs with the BUS and PROC lights on
and the rest off. This indicates that a processor bus cycle has
stalled. I believe this is because the memory is initializing itself
right after power is applied. Pressing the boot button on the
terminator card starts the boot console as normal. What is supposed to
happen is that the MS11 holds AC LO L asserted during initialization so
that the processor does not boot. Perhaps this is not occuring or the
processor is ignoring AC LO.
The MS11-M is supported by the following diagnostic programs:
- ZMSDD0 - MS11-L/M Memory Test
- This diagnostic ran for 61 passes without an error.
- ZMSPB0 - MS11-L/M/P Memory Test
- Does NOT run on a PDP-11/40 processor!