Abstract: An operation controller, an operation unit and a memory are provided. The operation controller always receives a non-gated clock signal from a clock controller. When an operation initiating signal and a parameter signal indicating resources to be used in the operation unit are generated by a microcontroller, the operation controller asserts a request signal. In response to the request signal, respective gated clock signals are supplied from the clock controller to the operation unit and to the memory. The operation controller determines whether or not a status signal supplied from the operation unit satisfies a predetermined end condition. If the signal satisfies the end condition, the operation controller negates the request signal. As a result, the supply of the clock signals to the operation unit and to the memory is stopped.