Minecraft wiki entry for Telegraph, associated text: The redstone torch is a primitive, but compact receiver, displaying each pulse as it arrives from the sender. It does not record, loop or display the entire message, and it cannot be interpreted easily without a solid understanding of the language being transmitted. It is most common in the one-way and classic telegraph systems, where simplicity and instantaneous viewing are most valuable. In addition, they are the only type of receiver that can be wall-mounted.