10 rem Archimedean spiral
20 graphics 0
30 graphics cls
40 a = 3 : b = 1.4
50 x0 = 320 : y0 = 200
60 graphics moveto x0,y0
70 for t = 0 to 40*pi step 0.2
80 r = a+b*t
90 x = r*cos(t)+320 : y = r*sin(t)+200
100 graphics lineto x,y
110 next t
120 end