Bad information that is becoming a forum urban legend, probably because many don't understand the TTL operations. The arduino can send tx to a large number of rx, and the arduino can receive rx from a large numbet of tx if each tx has a properly aligned diode in the tx line.
Zoomkat. My bad then. This is the first that I have heard of this and would like to know more about the technique. Would one also need a protocol to identify the sender and/ or receiver?