PURPOSE: To improve processing performance of a system and also to shorten turn around time at a terminal by grouping several terminals and then by providing several processors which provide simultaneous polling control of each group.

CONSTITUTION: Terminals 1-1∼1-N are divided into several groups and terminal controller 2 is equipped with several processors 4-1∼4-n which provides simultaneous polling control of each group and several message buffers 5-1∼5-n stored temporarily with response information from a central processor and informaton from a terminal. Information stored in each message buffer is sent out 6 and 8 to unit 10 at a time and response information is received 7 and 9 from unit 10 at a time. As a result, the overhead time of the monitoring of CPU10 is shortened to improve processing performance of this system, so that the turn around time from the request transmission of a terminal and its response reception can be shortened.