Introduction We present in this chapter the result of an exercise to design an 8-bit computer. Although a rather trivial machine, it is not without interest, either as manipulator of variable-length character strings or as an interpreter of more complex computers in a role similar to a microprogrammed Pc. In the latter role a read-only memory could be used as Mp to speed up the Pc. Although 24-bit operations are defined, their implementation might be expensive. The basic information unit is the 8-bit character.
Instructions are, in general, one character in length.
The instructions to load or store register A, from or into Mp, with or without incrementing a general register, all use the general registers as a two-character address pointer. Any general register may be loaded or stored direct from or to Mp.