PURPOSE: To eliminate the useless time for the input/output control as well as to prevent the lowering of the processing efficiency by realizing the setting for the minimum response monitor time and the like based on the types of the input/output unit connected to the terminal unit.
CONSTITUTION: Transmission control circuit 7, time control circuit 8 and transmission/reception control circuit 9 are provided at input/output control part 5 of terminal control unit 2 which is connected to data transmission MODEM1 for control of input/output unit 6. The input/output control is carried out via circuit 7 and by the indication given from unit control part 4, and circuit 9 performs the serial-parallel conversion of the data, the parity bit control, the level conversion, the error detection and others. At the same time, the command transmission time is controlled by the circuit provided at circuit 8 and consisting of command transmission time control register 26, selector 10, comparator 11, counter 32 and others. And the monitor is given to the response via the circuit comprising response monitor register 27, selector 17, comparator 18, counter 16 and others, and the minimum response monitor time and the like are set based on the types of the input/output unit. Thus the useless time can be eliminated for the input/output control.