ME10 core memory

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The ME10 was a core main memory system for the mid-period PDP-10s, principally the KI10. It connected to the so-called external memory bus of either the 18-bit or 22-bit address form; address bits 14-17 can be set to 'ignore' when an ME10 is connected to a KA10, which uses the 18-bit bus version. Parity is provided to protect the memory contents. An ME10 contained 16KW; it had an access time of .55 µseconds (maximum .61 µseconds) and a cycle time of 1.0 µseconds.

It was a multi-port memory, with 4 ports per memory system: each port can be independently disabled. The CPU uses one port (in a multi-processor system, one per CPU); the others are used by channels (such as a DF10) for mass storage such as disks.

Each port could be independently set for its address, and for either 2- or 4-way interleaving (using address bits 21 and 35, and bits 20 and 34, respectively; recall that the PDP-10 uses big-endian numbering, so bit 35 is the low-order bit).