Just copy this one line of basic code by Demoniak and paste it in WinApe in the File Menu (or Ctrl + F11, or with any other Amstrad CPC emulator. Just for fun, like the Nyan Cat.
10 MODE 0:e=-1.3:FOR y%=0 TO 199:d=-2.4:FOR x%=0 TO 159:z=0:i=0:a%=0:WHILE a%<15 AND (z*z+i*i)<4:s=(z*z)-(i*i)+d:r=(2*i*z)+e:z=s:i=r:a%=a%+1:WEND:PLOT x%*4,y%*2,a%:d=d+0.0215:NEXT:e=e+0.013:NEXT
P.S. : in the general settings of WinApe, click on display every 1 frame and Turbo Mode, or you may have to wait a bit...
P.P.S : the second image is another basic source (more than 1 line) by Tronic-GPA.