When the display/operation instruction program 112 is started by the starting program 117 as the portable device 6-1 is connected to the USB port 23-1, or as the portable device 6-3 is connected to the USB port 23-3, the display/operation instruction program 112 reads out from the portable device 6-1 or 6-3 data related to the content, such as music title, playing time and the like, recorded in th