PURPOSE: To attain a system which performs automatic operation with low cost and a small area for installation by providing the 1stW3rd power supply devices and a switch which turns off the 2nd and 3rd power supply devices under the 1st power supply device is kept on state.

CONSTITUTION: In a normal operation mode, a data processor can be turned on and off with the operation of a switch SW1. In an automatic operation mode, the software is set in an automatic operation mode and then a switch SW2 is operated to stop the supply of power to a disk 18, floppy disk 19, display device 20, etc. In this case, the power supply of a power supply device 15 is turned on. When a telegram is sent from the center side, a communication circuit 14 confirms a start instruction for a total system by the communication with a CPU2 and a memory 1. When said start instruction is confirmed, a signal is sent to a power supply device 16 from the CPU2 to make the disk 18 operational. When the automatic operation mode is reset to a normal operation mode, a switch SW2 is operated to turn on devices 16 and 17.