PURPOSE: To modify or emphasize the background color of a character display so as to display a clear character by providing an exclusive circuit to modify the background color of a character display and a terminal which sends the modified signals to the external to change video signals.

CONSTITUTION: A character modifying circuit 20 for modifying the background color in a control microcomputer 1 for display and a mixer 21 externally located are provided. Assume that the output of the circuit 20 is specified, for example, to a green color and the display color of the corresponding part of a CRT 14 screen is blue in the lower half. On the other hand, assume the character display is '1'. At that time, OUT data without the background, which is the output of an OR circuit 9, outputs a prescribed signal and provides a background color display screen after deleting OUT. Moreover, the microcomputer 1 provides red color display character data, thus, the last display screen of the CRT 14 becomes a prescribed color display. Thus, the character display becomes conspicuous.