0 REM    LINES
10 (null)1:(null)1:(null):(null)1,0:(null):(null)1:POKE53280,0
20 X=319:Y=199
30 FORI=0TOX:(null)0,0,I,Y:(null)X,Y,X-I,0:NEXT
40 (null)40,158
50 FORI=0TO5000:NEXT:(null)