Processing device and method for displaying a state of tone generation apparatus

An electronic musical instrument is capable of generating tones in correspondence with individual ones of a plurality of sound generation parts and allocating desired sound colors and pitch ranges to the individual sound generation parts. A display area for displaying information related to the plurality of sound generation parts is presented on a display device. The individual sound generation parts are set either in a sound generating state or in a non-sound-generating state. The display area is divided in order to set sub display areas corresponding to one or more of the sound generation parts having been set in the sound generating state. The information related to the sound generation parts, having been set in the sound generating state, is displayed in the corresponding sub display areas.