PURPOSE: To handle a two-byte half-size character as a mere half-size character on a display and to use the two-byte half-size character even when the two-byte half-size character cannot be displayed through hardware by replacing the two-byte half-size character with a corresponding half-size character and displaying it.

CONSTITUTION: A video display control mechanism 21 writes display contents in a display buffer 22 and a video controller 23 makes a display on a display 24. On the display buffer, a cell 331 of one byte 31 of a character code and one byte 32 of a character attribute corresponds to one half-size character. A full-size character uses two adjacent cells; and the high-order bytes are put in one cell and the lower-order bytes are put in the other cell. Then the video display control mechanism when writing the two-byte half-size character in the display buffer decides whether or not a character is a two-byte character (full-size character plus two-byte half-size character) and then decides whether the character is a two-byte half-size character or not, and converts this character into a half-size character when the character is the two-byte half-size character and then writes it in the display buffer.