10 CLV:CLS
15 COPY #900,#D00,768
20 LC X,Y:?CHR$(!SCR(X,Y));
30 WAIT 3
40 K=INKEY()
50 LC X,Y:?CHR$(!SCR(X,Y)^(K=32));
60 X=X-(K=28)+(K=29)
70 Y=Y-(K=30)+(K=31)
80 IF K=8 CLS
100 IF K!=10 GOTO 20
110 COPY #D00,#900,768:SAVE