Microprocessor executing instruction having operand field including portion used as part of operation code

摘要

A microprocessor is so constructed that executes each of LOAD or STORE instructions to transfer data between a register and a memory in one-byte units, two-byte units, four-byte units or so forth in response to the instruction to be executed. Of these instructions, there are provided such instructions that have the same content of an operation field as each other. In order for an execution unit to discriminate an instruction to be executed, not only the operation field but also a part of an operand field are used.