| 摘要 |
A program counter circuit is composed of two kinds of registers, a down counter, an up counter, a selector, and a logic circuit. The two kinds of registers hold a pre-jump PC value and a post-jump PC value of a jump that is prescribed by a program. The down counter holds the number of repetitions of a repeat sequence that is prescribed by the program. The up counter holds a PC value that is counted up for each clock pulse. The selector selects, as a PC value to be output next, the post-jump PC value or the value that is held by the up counter. The logic circuit refers to the output value of the program counter and the output values of the registers and the down counter, and generates a signal that instructs the selector what PC value should be selected as the next output value.
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