| 摘要 |
PURPOSE:To execute even the instruction different in instruction form with one microprocessor by selecting an instruction decoding part in accordance with the instruction form to be executed. CONSTITUTION:When the instruction form selecting signal of an instruction form B is inputted to a selector 7, the selector 7 selects an instruction decoding part 2B, a microprogram storing part 3B, a memory control part 4B and a bus control part 5B applicable to the instruction form B. When the instruction is inputted from an external bus through a control part 5B, a decoder 2B decodes the instruction and outputs a common instruction format. An instruction executing part 1 accesses to the storing part 3B in accordance with the instruction and executes a microprogram in accordance with the instruction. Thus, even the instruction different in instruction form can be executed by one microprocessor.
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