5 S=ASC("*"):D=2:C=D+D:X=S/D:Y=C+C:GRAPHICS C-C:COLOR S:POKE 755,C-C
10 FOR I=-C TO C:D=X+I:Z=Y+I:S=X-I
11 PLOT D,Z-C:DRAWTO D,Z+C
12 PLOT D-C,Z:DRAWTO D+C,Z
13 PLOT S,Z-C:DRAWTO S,Z+C
14 PLOT S-C,Z:DRAWTO S+C,Z
15 NEXT I
21 GOTO X
