PURPOSE: To execute multiplexing at an arbitrary time point by confirming it when the operating preparation of a system is completed that the operating preparation of an external storage device is completed and multiplexed, and announcing the result to a host device in the main body of the system.
CONSTITUTION: In the main body 10 of the system, a multiplexing control device 13 is provided to write the same data to all the multiplexed external storage devices 15a and 15b when writing the data to the devices 15a and 15b and to read the data from one of the devices 15a and 15b when reading the data. In this case, since the operating preparation of all the multiplexed devices 15a and 15b is not completed when starting the system, it is confirmed that the operating preparation of these devices 15a and 15b is completed and multiplexed when the operating preparation is completed later. The confirmed result is controlled to be announced to a host device 12 in the main body 10 of the system. Thus, the plural devices 15a and 15b, which can be multiplexed, can be multiplexed at the arbitrary time point.
KOMATSU TADAHIDE
ARIGA KENICHI
