US Patent 7350038 Disk system and medium with contents play-back restriction mechanism

A disk system has contents play-back restriction mechanism. A contents storage section, which contents received from a regular server are stored in. A capacitor charged with power supplied from the server. A volatile memory backed up by the capacitor and stores data necessary for the play-back of the contents received from the server. A controller for controlling the contents storage section and the volatile memory for reading and writing data when supplied with power from a regular player or the server.