Processor system for varying clock frequency and voltage in response to a comparison of instruction execution rate to a reference value

Abstract

A processor system includes a processor which has an internal memory, an external memory, and a bus controller which controls a bus to which the processor and the external memory are connected. The processor system also includes a measurement unit for measuring an instruction-execution rate of the processor, a clock controller for supplying the processor, the external memory, and the bus controller with clock signals having clock frequencies corresponding to the instruction-execution rate measured by the measurement unit, respectively, and a voltage controller for controlling a source voltage or a threshold voltage which are supplied to the processor, the external memory, and the bus controller, in accordance with the respective clock frequencies of the clock signals supplied to the processor, the external memory, and the bus controller.