The MA31751 Memory Management Unit/Block Protect Unit (MMU/BPU) is an optional chip which may be used to expand the capabilities of the MA31750. User configurable, the MA31751 can perform as an MMU, a BPU or both MMU and BPU, conforming to MIL-STD-1750A and 1750B. MMU mapping and BPU protection for 1M words of memory is provided by the internal memory. Up to 16 MA31751 devices can be used to give 16M words of logical mapped onto 8M words of physical address space with protection in 1750B mode.