To realize both a reduction in power consumption and the execution of an advanced application.

If a client 34 does not make a connection in a server mode, a CPU 16 sets a CPU clock to a low speed and a CPU power source to a low voltage, turns off a cooler 20 and keeps a server on standby. If the ability of the connecting client 34 is not high, the CPU 16 sets the CPU clock to a medium speed and the CPU power source to a medium voltage, turns off the cooler 20 and operates the server at low speed. When the ability of the client 34 is high and a power supply source is a battery, the CPU 16 sets the CPU clock to a medium speed and the CPU power source to a medium voltage, turns off the cooler 20 and operates the server at low speed. When the power supply source is an AC power source 30, the CPU 16 sets the CPU clock to a high speed and the CPU power source to a high voltage, turns on the cooler 20 to prevent heat generation and operates the server at high speed.

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