PDP-10 memories

There were three generations of main memory systems for the PDP-10; the first two with the so-called external memory bus, in 18- and 22-bit address forms (for the KA10. and KI10 and early KL10, respectively), and the internal 'S-bus' (for the later KL10). (Memory for the KS10, which was sui generis, is not covered here.)

18-bit external:

• MA10
• MB10
• MC10
• MD10

22-bit external:

• ME10
• MF10
• MG10
• MH10

Internal:

• MA20
• MB20
• MF20

The first two groups are all multi-port memory (generally 4 ports per memory system); the CPU uses one port, the others are used by channels for mass storage such as disks.