Such large-capacity disk medium can be, for example, an optical disk such as CD-ROM or DVD disk, a magnetic disk or a magnetooptical disk. [0037] The electronic devices 101 to 106 are mutually connected through a digital interface 110 based on the IEEE 1394 standard and its expansions, for example IEEEP1394.a constituting a revision of the IEEE 1394 standard (hereinafter called 1394 interface).