MMU, spare, floatingpoint, data/control. A minimal board will have data/control double as that's the F11 cpu. It will only be a 16 bit address. The MMU is was nearly standard and gave 18/22 bit addressing. Floating point was in two forms FIS chip, Floatingpoint Instruction Set which were microcode for floating point instructions or the M8188 module that actually did floating point in hardware (2901s!). Other options are the CIS or Commercial instruction set (aka cobal instruction set) and there was writeable control store if you wanted to write custom microcode for things like bitblting or emulation. The 11/23 did not have I&D space like the later J-11 cpus. The liniage for chip-11s is LSI11/03 (kd11-f quad width), LSI-11/2 (dual width KD-11), LSI-11/23a (KDF-11A dual width), LSI11/23b(+) (KDF-11B quad width), Then J-11 series. Note while the books said the 11/23a (kdf-11a) was 18 bit I have found many will operate as 22 bit. The KDF-11b was 22 bit addressing. Allison