Minecraft wiki entry for Telegraph, associated text: A display loop is a useful addition to both receivers and message displays. It connects the end of a redstone repeater display to its beginning, showing the message again and again until the eraser is activated. Erasing devices are an absolute necessity when creating a display loop. They end the looping message, and allow a new one to be shown before the two messages overlap pulses. A full loop and eraser system requires a customized NOR gate, through which the message is transferred and looped.