PURPOSE: To realize the continuous operation of a computer system with no regeneration nor restarting by registering the identification of the corresponding console device when a user grant request is received from a requester device and recognizing automatically the changed console device when an input/output request is received from the requester device.

CONSTITUTION: When the use grant requests are received from a requester device 1 to the console devices 3 and 4, a register means 21 starts a recognizing means 22 to send and register the decided driver identification numbers of the devices 3 and 4 to a register part 231. When the input/output requests are received from the device 1 to both devices 3 and 4, a retrieving means 24 retrieves a driver and a start means 25 starts the driver of the retrieved identifi cation number. As a result, the changed device 3 or 4 is automatically recog nized by producing a use grant request when the device 4 is changed. Thus it is possible to continuously operate a computer system with its no regeneration nor restarting.