  50 BORDER 0: PAPER 0: CLS : LET c=1
 100 FOR a=-8 TO 8 STEP 16
 110 FOR b=41-5*a TO 41+5*a STEP a: INK c
 120 PLOT 128-b,87-b: DRAW PAPER c;b+b,0: DRAW PAPER c;0,b+b
 130 DRAW PAPER c;-b-b,0: DRAW PAPER c;0,-b-b
 140 LET c=c+1: IF c>7 THEN LET c=1
 150 NEXT b
 160 NEXT a
 170 GO TO 100
