MM11-L core memory

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The MM11-L was a popular, and common, 16 Kbyte core memory for the early PDP-11 UNIBUS machines. An MM11-L was composed of a three board set:

  • G110 - hex-format memory control logic and data channels
  • G231 - hex-format memory driver logic
  • H214 - quad-format core stack

There was also a parity variant, the MM11-LP, which added an M7259 dual-format parity controller, and substituted an H215 (with two more bits per word) for the H214, and a G109 for the G110.

The MM11-L required a custom backplane, although some CPU's (e.g. the PDP-11/05) had processor backplanes wired to hold an MM11-L set as well as the CPU.

The MM11-S was a four-slot backplane plus a single MM11-L board set. The MF11-L was a nine-slot backplane plus a single MM11-L board set; the backplane has room for two more MM11-L board sets. The ME11-L was an MF11-L in a 5-1/4" rack-mount box, with power supply (the -LA was wired for 115V supply, the -LB for 230V).

Parity versions (with a 'P' suffix) were available for all of the above.