A personal computer in which a returning from a power saving mode for further suppressing power consumption to a normal operating mode is possible by detecting an operation of stick-type coordinate input device is provided. Since a pressure sensor which is an input device connected to a I/O is comprised in a pointer, it is possible to output an operation signal from the pressure sensor to a CPU by pressing an operation grip, instead of distortion sensors which can not output the operation signal from a detecting circuit to the CPU due to the stop of a clock oscillator in the idle mode. Thereby, even in the idle mode in which the clock oscillator is stopped, the computer can return to the normal operating mode by the operation of the pointer which is not feasible in the prior art.