5 rem Generates a siren sound
  10 dim speaker as pin pt2 for frequency output, x, y, z
  20 configure timer 0 for 10 ms
  30 let x = 110
  40 on timer 0 do gosub tones
  50 while 1 do
  60   rem on timer 0 do gosub tones
  70   if x>500 then
  80     let x = 110
  90   endif
 100 endwhile
 110 sub tones
 120   let speaker = x
 130   let x = x+5
 140 endsub