5 rem Generates an alarm siren
  10 dim speaker as pin pt2 for frequency output, x, y, z
  20 let y = 440*4
  25 let z = 440
  30 while 1 do
  40   for x = z to y step 10
  50     let speaker = x
  60     sleep 1 ms
  70   next
  80   for x = y to z step -10
  90     let speaker = x
 100     sleep 1 ms
 110   next
 120 endwhile