170 DIM X(3),Y(3),XD(3),YD(3)
180 SCREEN2:R=150:XL=100:YU=50:N=60
220 X(0)=XL:X(1)=XL+R:X(2)=XL+R:X(3)=XL
230 Y(0)=YU+R:Y(1)=YU+R:Y(2)=YU:Y(3)=YU
240 SMU=.08:RMU=1-SMU
250 FOR I=1 TO N:FOR J=0 TO 3
260 XD(J)=RMU*X(J)+SMU*X((J+1)MOD4)
270 YD(J)=RMU*Y(J)+SMU*Y((J+1)MOD4)
280 NEXT
290 FOR J=0 TO 3:LINE (X(J),Y(J))-(X((J+1)MOD4),Y((J+1)MOD4))
310 NEXT
320 FOR J=0 TO 3:X(J)=XD(J):Y(J)=YD(J):NEXT:NEXT
360 GOTO 360