MICROPROCESSOR CAPABLE OF CHANGING CLOCK AND OPERATING

摘要

PROBLEM TO BE SOLVED: To operate a microprocessor at a maximum operation speed. SOLUTION: This microprocessor 20 has a CPO(critical path operation) block 21. A decision circuit 23 decides a maximum operation state of the microprocessor based on test results of the CPO. An output signal of the decision circuit or a signal desired to be externally controlled is selected and a control signal for making a clock signal variable is outputted. A PLL(phase- locked loop) circuit 22 changes the clock signal and operates the microprocessor based on a control signal of its controlling part 25.