Notes: MS11-M MOS Memory (M8722)

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 supply instead of +/-15V.

MS11-MA M8722-A 128K Byte ECC MOS Memory
MS11-MB M8722-B 256K Byte ECC MOS Memory

Power Requirements

Voltage Current Descr. Pins Notes
+15 0 +15V Not used.
+12 1A +15BB +12V is used and taken from the +15BB pins. For backplanes configured for the MS11-M, the pins are +12V supplied from a battery backed source.
+5 3A +5V +5V is taken from the standard pins. 
-12 0.1A -15BB -12V is used and taken from the -15BB pins. For backplanes configured for the MS11-M, the pins are -12V supplied from a battery backed source. Internally, the board drops this down to -5V for the DRAMs. This is a low current source.
+15 0 +15V Not used.

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.

Notes

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.

Diagnostics

The MS11-M is supported by the following diagnostic programs: