SCREEN 12
RANDOMIZE TIMER
DIM R AS INTEGER
DIM C AS INTEGER
FOR R = 0 TO 59
    FOR C = 0 TO 79
        IF INT(RND + .5) = 0 THEN
            LINE (C * 8, R * 8)-(C * 8 + 8, R * 8 + 8)
        ELSE
            LINE (C * 8, R * 8 + 8)-(C * 8 + 8, R * 8)
        END IF
    NEXT C
NEXT R
DIM NEXTKEY AS STRING
DO
    NEXTKEY = INKEY$
LOOP UNTIL NEXTKEY <> ""
SCREEN 0