Quarry turtle

while true do
  event = os.pullEvent()
  if(event == "redstone") then
    on = redstone.getInput("back")
    if(on==true) then
      e = 64
      while (e~=0) do
        turtle.select(16)
        turtle.dropDown()
        e = turtle.getItemCount(16)
      end
      turtle.dig()
    else
      turtle.select(16)
      turtle.place()
    end
  end
end