Copyright control system
 A copyright control system for performing access control to copyright digital information. The copyright control system is equipped with an encryption/decryption hardware 11 which accepts encrypted copyright digital information from an option hardware 6 or an FDD unit 3 through a sub-data bus 23. The encryption/decryption hardware 11 decrypts the encrypted digital information using a decryption key obtained from a copyright control center for primary utilization of the encrypted digital information and inputted from an CPU 1. 
Mitsubishi Denki Kabushiki Kaisha
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Atsuhiro Hidetoshi Makoto
Yamagishi Kambe Saito