a television display system having a remote control unit which sends different command codes , upon activation of the same button , dependent upon which mode the remote control unit is in ; has a simplified operation by translating a noneffective command code from the transmitter into an effective command at the display unit when the display unit is not in a signal source which can act upon the noneffective command code . further simplifying the keypad operation of the remote control transmitter by allowing function and adjustment keys to perform double duty depending on the operating mode of the display is also discussed .