PURPOSE: To improve the efficiency of the whole system and to simplify the modification of the system at the increase or transfer of terminals by transferring the processing of queue control and data conversion to respective terminal controllers.

CONSTITUTION: When an output request from an output request processing program group 5 to a terminal 3aa e.g. is generated, a transmission processing handler 8 is started and the output data are transmitted to a terminal controller 2a through a data way transmission loop 20 as the original format without data conversion. A transmission processing handler 10 in the terminal controller 2a starts a data receiving program 21 enqueues the output data in an output request main memory queue 22 and starts a terminal output request program 11. The program 11 fetches the output data from the main memory queue 22 in the order of input executes necessary data conversion and outputs the converted result to the terminals 3aa.