40 HGR : POKE 49234,0: HCOLOR= 3
50 FOR DI = 0 TO 3
60 GOSUB 100
70 NEXT DI
90 REM INITIALIZATION AND MAIN
91 :SP = 0:H = INT ((H0 / 4) + .5):X = 2 * H:Y = 3 * H:I = 0
100 H0 = 191:SP = 0:H = INT ((H0 / 4) + .5):X = 2 * H:Y = 3 * H:I = 0
110 I = I + 1:X = X - H:H = INT (H / 2):Y = Y + H
120 IF I < DI THEN 110
130 PS = I: GOSUB 600
140 GOSUB 200:A = H:B = - H: GOSUB 800
150 GOSUB 300:A = - H:B = - H: GOSUB 800
160 GOSUB 400:A = - H:B = H: GOSUB 800
170 GOSUB 500:A = H:B = H: GOSUB 800
180 GOSUB 700
190 RETURN
200 REM SUBROUTINE A
210 IF TP < = 0 THEN RETURN
220 PS = TP - 1: GOSUB 600
230 GOSUB 200:A = H:B = - H: GOSUB 800
240 GOSUB 300:A = 2 * H:B = 0: GOSUB 800
250 GOSUB 500:A = H:B = H: GOSUB 800
260 GOSUB 200
270 GOSUB 700
280 RETURN
300 REM SUBROUTINE B
310 IF TP < = 0 THEN RETURN
320 PS = TP - 1: GOSUB 600
330 GOSUB 300:A = - H:B = - H: GOSUB 800
340 GOSUB 400:A = 0:B = - 2 * H: GOSUB 800
350 GOSUB 200:A = H:B = - H: GOSUB 800
360 GOSUB 300
370 GOSUB 700
380 RETURN
400 REM SUBROUTINE C
410 IF TP < = 0 THEN RETURN
420 PS = TP - 1: GOSUB 600
430 GOSUB 400:A = - H:B = H: GOSUB 800
440 GOSUB 500:A = - 2 * H:B = 0: GOSUB 800
450 GOSUB 300:A = - H:B = - H: GOSUB 800
460 GOSUB 400
470 GOSUB 700
480 RETURN
500 REM SUBROUTINE D
510 IF TP < = 0 THEN RETURN
520 PS = TP - 1: GOSUB 600
530 GOSUB 500:A = H:B = H: GOSUB 800
540 GOSUB 200:A = 0:B = 2 * H: GOSUB 800
550 GOSUB 400:A = - H:B = H: GOSUB 800
560 GOSUB 500
570 GOSUB 700
580 RETURN
600 REM PUSH SUBROUTINE
610 SP = SP + 1:ST(SP) = PS
620 TP = PS: RETURN
700 REM POP SUBROUTINE
710 SP = SP - 1:TP = ST(SP): RETURN
800 REM PLOTTING SUBROUTINE
810 HPLOT X,Y TO X + A,Y + B
820 X = X + A:Y = Y + B: RETURN