Mode 0: rf tune select, Mode 1: baud rate select, Mode 2: unit address select – Contemporary Research 232-FMA User Manual
Page 5: Mode 3: not used, Mode 4: front panel disable level, Mode 5: power-up volume level, Mode 6: special test mode (for factory testing), Mode 7: audio decoding, Mode 8: bass setting fixed at 0db, Front panel programming
