PURPOSE: To improve processing efficiency in plural input/output devices by means of a command from a host device without increasing a DMA control channel and an IRQ line on an input/output controller to which one DMA control channel and an interruption request signal are allocated with the host device and to which the plural input/output devices are connected.
CONSTITUTION: A command holding means 2 and a status holding means 3, which respectively hold plural commands and status are provided for the input/ output controller 1. When the commands which require data transfer by the DMA control channel are continuously generated from the host device to the plural input/output devices 5, the command holding means 2 hold the plural commands and a control part 4 executes control so that the held commands are executed for the corresponding input/output devices 5 one by one. When the status showing requests to the host device are generated from the respective input/output devices 5 executing the commands, the input/output controller 1 controls the status holding means 3 to hold the status.
NAGABORI KAZUO
FUJIZONO KENJI
YUKI KEIKO
