PURPOSE: To increase the processing speed of a channel program by setting a direct data designation bit within a flag part of a channel command entry CCE and obtaining data out of the CCE in response to designation of said designation bit.

CONSTITUTION: The input/output control is carried out by a channel 23 according to a channel program containing a CCE provided in the area of a main memory 22 designated by a channel start instruction given from a CPU 21. The CCE includes an action code part where the action of an input/output device, e.g., a magnetic disk device 24 is designated, a main memory information part where an area in a main memory of the data corresponding to the action of the device 24 is usually designated and a flag part consisting of plural bits. Then a direct data designation bit is set within the flag part to show that the contents of the main memory information part are equal to data themselves. The channel 23 obtain data out of the CCE in response to the designation of said designation bit of the CCE.