| 摘要 |
PURPOSE:To share a part of a micro instruction to reduce the memory capacity by executing continuous processing instructions or a single processing instruction on the basis of the operation code converted to an internal instruction and the discrimination result indicating whether an indication code exists or not. CONSTITUTION:If continuous processing instructions are transferred to a machine language instruction register 1, a machine language instruction decoder 2 decodes the first byte and the decoded result is stored in a prefix presence/ absence indicating part 3p of an internal instruction register 3 and the internal instruction corresponding to the operation code of the machine language instruction is transferred to an operation code part 3a. The internal instruction corresponding to the operand is transferred to an operand part 3b. Execution trigger is applied to a micro memory 4 at the time of terminating transfer to the register 3, and the indicating part 3p is checked, and continuous processing are executed in accordance with the prefix. In case of a single processing instruction, the single processing is executed because of the absence of the prefix when decoding of the operand and transfer to the operand part 3b are terminated.
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