MM11-E and MM1-F core memories

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The MM11-E and MM11-F core memories were UNIBUS main memory units; the first UNIBUS memory produced by DEC. They came out with the first PDP-11, the PDP-11/20. They were both 4K word (8K bytes), and had an access time of 500 nsec and a cycle time of 1.2 μsec.

They consisted of a quad H207 core plane board, along with a number of dual and single cards, plugged into a quad system unit. The MM11-F was almost identical to the MM11-E, differing only in one card.

Board locations

These are the board locations for the MM11-E and F (as seen from the board side) of the backplane:

Connector Slot 4 Slot 3 Slot 2 Slot 1
Power   UNIBUS
B   M109@
C H207 G226 G226 G729
D G102 G102
E G102 G102 G225
F G226 G226 G103