PURPOSE: To switch system setting information during the action of a system and to attain the operation without a malfunction by a system even when a hardware environment is changed by providing a latch circuit between a switching means and a decoder circuit.

CONSTITUTION: A latch circuit 2 to latch switch information is provided between a switch means 1 and a decoder circuit 3. When a latch circuit 2 once latches the switch information from the switching means 1 and receives a resetting signal 4 of a system, the switch information is given to a decoder circuit 3. The decoder circuit 3 outputs a decoding signal 6 to decode the switch information and select the component of hardware. Thus, even when the system setting information is switched during the action of the system, the system can execute the normal operation without a malfunction, and consequently, the influence is not given to the data processing, and the hardware environment is accordance with an operating system can be easily set.