A short but eye-catching program.
// Adapted to Yabasic by Galileo, 04/2018
// I no remember the origin of this code
open window 512,512
backcolor 0,0,0
clear window
w=512 : h=512
sx=-2.2 : sy=-1.7 : sw=3.4 : sh=3.4
do
x = int(ran(h/10)) * 11
y = int(ran(w/10)) * 11
gx=x/w*sw+sx
gy=y/h*sh+sy
zx=gx
zy=gy
for c=0 to 255
cl = c
nzx = zx*zx - zy*zy + gx
zy = 2*zx*zy+gy
zx = nzx
if zx*zx + zy*zy > 4 then
cl = c
break
end if
next c
r = cl
g = cl*32
b = cl*64
if g > 255 g = mod(g,255)
if b > 255 b = mod(b,255)
color 0, 0, 0
fill rectangle x, y+2, x+5, y+13
color r,g,b
bit$ = chr$(ran()+48.5)
text x, y, bit$, "lt"
loop