PURPOSE: To ensure compression of the screen data by giving numbers to the data featuring a high transfer frequency at the side of the display unit to hold the data and then reloading the data according to the numbers sent from the central unit.

CONSTITUTION: The data regions featuring a high transfer frequency are numbered respectively and then hild in table memory unit 5. If control character A indicating continuation of the data regions is contained in the information sent from central processor 9 through buffer 8, the information storage of screen memory unit 3 is discontinued. Then the next character is delivered from buffer 8 to be stored in number memory unit 7, and at the same time the information transmission through buffer 8 is discontinued. The character next to character A is compared with the value of memory 7 through comparator 6 at the moment when character A is delivered into the data table which is read out from unit 5. This comparison is re- peated until a coincidence is obtained. And when a coincidence is obtained, the data is sent and stored into unit 3 until control signal B indicating the end of the data region emerges