Bill, You are correct in that Register 1 will effectively be overwritten when switching between cabs. However this will not prevent you from operating several loco's on the one register. The throttle code stores current status of each loco and recalls such at each switch. The most useful purpose of putting each loco on it's own register, is that Base Station also keeps track of each loco's status. Then one can use a more 'smart' throttle or indeed multiple 'smart' throttles joining a session. Such throttles would call <s> upon connection then parse the returned data, so synchronising with current status. Adding such code to Dave's design would be possible, and your suggested mod goes the first step, but bear in mind Dave was aiming for some simplicity in the design, and you would have to establish bi-directional communication to make it work. For a single throttle setup, it's not really worth the effort.