| 摘要 |
PURPOSE:To efficiently form a microprogram by providing a multiplexer for selectively outputting the contents of a microprogram counter or the contents of a stack designated by a pointer according to the output of a zero detecting part. CONSTITUTION:The microprogram counter 46, the stack 47 for preserving the contents thereof and counter register groups 41 corresponding to the respective levels of the stack for subtracting one by one from the value ever execution when the prescribed number of repetitions of a loop or a subroutine in the microprogram is set and designated by the pointer are provided. Further there are provided a stack counter pointer 48 for holding the pointer for designating a specific stack and a specific counter register, the zero detecting part 42 examining whether the contents of the counter register designated by the pointer are zero or not and the multiplexer 44 for selectively outputting the contents of the microprogram counter or the contents of the stack designated by the pointer according to the output thereof.
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