Patent ID: 8424081

Claim:
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, checks whether each authentication information coincides with the input information, and outputs an authentication signal when one of the authentication information coincides with the input information, and increases a failed input information number when each authentication information does not coincide with the input information; an operation mode control section that outputs an operation mode signal corresponding to the authentication signal that is supplied from the verification section when the corresponding authentication information coincides with the input information, and outputs an operation lock signal when the failed input information number exceeds a threshold number; 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, locks the operation mode when the operation lock signal is received from the operation mode control section determines whether the authentication information is specified to be changed, determines whether a reset password coincides with the authentication information for the operation mode when the authentication information is specified to be changed or deleted, and updates the authentication information with a new password and suspends the operation mode when the reset password coincides with the authentication information for the operation mode.