10 rem Generates a fire siren sound
  20 dim y
  30 dim x, z
  40 dim led as pin pt2 for frequency output
  50 let z = 440
  60 let y = z*3
  70 while 1 do
  80   for x = z to y
  90     let led = x
 100     sleep x*2 us
 110   next
 120   for x = y to z step -1
 130     let led = x
 140     sleep x*3 us
 150   next
 160 endwhile