Address Offset Feature (Vendor Specific); Enable/Disable Address Offset Mode; Table 54: Set Max Security Mode Transition - Hitachi 5K100 - Travelstar - Hard Drive Specifications

The password, the Set Max security mode, and the unlock counter do not persist over a power cycle but persist over
a hardware or software reset.
NOTE: If this command is immediately preceded by a Read Native MAX ADDRESS command, it shall be
interpreted as a Set Max ADDRESS command regardless of Feature register value.

Table 54: Set Max security mode transition

11.12 Address Offset Feature (vendor specific)

Computer systems perform initial code loading (booting) by reading from a predefined address on a disk drive. To
allow an alternate bootable operating system to exist in a reserved area on a disk drive this feature provides a Set
Features function to temporarily offset the drive address space. The offset address space wraps around so that the
entire disk drive address space remains addressable in offset mode. The Set Max pointer is set to the end of the
reserved area to protect the data in the user area when operating in offset mode. This protection can be removed by
a Set Max Address command to move the Set Max pointer to the end of the drive. But any commands which access
sectors across the original native maximum LBA are rejected with error, even if this protection is removed by a Set
Max Address command.

11.12.1 Enable/Disable Address Offset Mode

Subcommand code 09h Enable Address Offset Mode offsets address Cylinder 0, Head 0, Sector 1, LBA 0, to the
start of the nonvolatile protected area established using the Set Max Address command. The offset condition is
cleared by Subcommand 89h Disable Address Offset Mode, Hardware reset or Power on Reset. If Reverting to
Power on Defaults has been enabled by Set Features command, it is cleared by Soft reset as well. Upon entering
offset mode the capacity of the drive returned in the Identify Device data is the size of the former protected area. A
subsequent Set Max Address command with the address returned by the Read Max Address command allows access
to the entire drive. Addresses wrap so the entire drive remains addressable.
If a nonvolatile protected area has not been established before the device receives a Set Features Enable Address
Offset Mode command, the command fails with Abort error status.
Travelstar 5K100 Hard Disk Drive Specification
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