screenres 80*8,50*8
do
  screenlock
  for Y as long = 0 to 49
    randomize ((Y\2)+33)*timer
    dim as long iR
    for X as long = 0 to 79
      if (X and 1)=0 then iR = cint(rnd)
      print chr(iif((X+Y+iR) and 1,32,47+iR*45));
    next X
  next Y
  screenunlock : sleep 500,1
loop