Recursive circles explained

Here is the GCODE. Please copy and print it out and follow it as the video proceeds.

N010 (Recursive circles)
N020 G90 G90.1 G80
N030 G49 G64
N040 m5 (make sure the spindle is off)
N050 (Set some parameters)
N060 #1=0 (val1 init Xctr - LH side of paper)
N070 #2=0 (val2 init Yctr - Middle of paper)
N080 #3=64 (val3 init circle dia)
N090 #4=0 (val4 Init angle around circle)
N100 #5=5.25 (scale factor)
N110 #7=120 (angle increment)
N120 #8=0.5 (iteration reduction factor)
N130 #50=1000 (Init stack base)
N140 g0 z5 (safe height)

N150 m98 p111 L1 (RUN THE MAIN SUBROUTINE)

N160 g0 z5 (safe height)
N170 M30 (End program)

;########## THE SUBROUTINES ##########
; The Main subr
o111
N180 ##50=#1 (push #1 value)
N190 #50=[#50+1] (inc stack ptr)
N200 ##50=#2 (push #2 value)
N210 #50=[#50+1] (inc stack ptr)
N220 ##50=#3 (push #3 value)
N230 #50=[#50+1] (inc stack ptr)
N240 ##50=#4 (push #3 value)
N250 #50=[#50+1] (inc stack ptr)

N260 #3=[#3*#8] (calculate new circle dia)
N270 m98 p112 L[fix[#3] or 0] (if circle dia greater than 1 recall subr o112)

N280 #50=[#50-1] (dec stack ptr)
N290 #4=##50 (pop #4 value)
N300 #50=[#50-1] (dec stack ptr)
N310 #3=##50 (pop #3 value)
N320 #50=[#50-1] (dec stack ptr)
N330 #2=##50 (pop #2 value)
N340 #50=[#50-1] (dec stack ptr)
N350 #1=##50 (pop #1 value)
m99

;The iterative subr
o112
g0 x#1 y#2
N360 #1=[#1+#3*cos[#4]*#5] (new Xctr)
N370 #2=[#2+#3*sin[#4]*#5] (new Yctr)
N380 #4=[#4+#7] (change angle)
N390 g0 x[#1-#3*#5/2] y#2 (go to start point of circle)
N400 g1 z-1.5 f500 (pen down)
N410 g2 x[#1+#3*#5/2] y#2 i#1 j#2 f2000 (draw half of circle)
N420 g2 x[#1-#3*#5/2] y#2 i#1 j#2 (draw rest of circle)
N430 g0 z2 (pen up)
N440 m98 p111 L[fix[#3] or 0] (if circle dia greater than 1 recall subr o111)
N450 #4=[#4+#7] (change angle)
N460 m98 p111 L[fix[#3] or 0]
N470 #4=[#4+#7] (change angle)
N480 m98 p111 L[fix[#3] or 0]
m99