Disk unit, magnetic disk unit and information storage unit

A disk unit comprising:

• a disk-shaped recording medium;
• a head assembly that reads and writes information from and to the recording medium;
• a control device that controls operation modes for reading and writing on the recording medium performed by the head assembly;
• and
• an authentication storage section for storing authentication information in which each operation mode is given unique authentication information;
• wherein the control device comprises:
• a verification section that reads out the authentication information from the authentication storage section, compares each authentication information with input information entered via an interface by using a predefined method, and checks whether each authentication information coincides with the input information;
• an operation mode control section that outputs an operation mode signal corresponding to an authentication signal that is supplied from the verification section when the corresponding authentication information coincides with the input information;
• and
• a controller that controls execution of the operation mode according to an operation mode signal that is supplied from the operation mode control section.