| 摘要 |
PURPOSE:To suppress the deterioration of the performance by providing a rewriting means for setting a difference value to a counting means when a new difference output from a difference output means is smaller than the output of the counting means, if a new instruction rewriting is detected before the detected instruction rewriting is outputted. CONSTITUTION:Every time when the instruction is executed, the contents of a count register 9 is subtracted by '1' by a '-1' subtracter 10, and when it is detected that the contents of the count register 9 '0' by a comparator 12, it is judged to be an execution of the rewritten instruction and the instruction rewriting is outputted. When the instruction rewriting is detected by an instruction rewriting control circuit 8 again, the difference between the contents of an address store address register 2 and the contents of an address register 4 and the contents of the count register 9 are compared in a comparator 11 and if the value of the difference is smaller than the value of the count register 9, the contents of the count register are replaced by a new difference. During the comparison of the store address, when the contents of the store address register 2 are equal to the contents of the address register 4, the instruction rewriting is outputted immediately through an OR gate 14.
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