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12.44 Security Unlock (F2h)
This command unlocks the password and causes the device to enter device unlock mode. If power on reset or hard
reset is done without executing the Security Disable Password command after this command is completed, the device
will be in device lock mode. The password has not been changed yet.
The Security Unlock command requests to transfer a single sector of data from the host including information specified
in the following tables.
Table 200 Security Unlock Command (F2h)
Command Input
Field
Description
FEATURE
N/A
COUNT
N/A
LBA
N/A
Bit Description
DEVICE
7 Obsolete
6 N/A
5 Obsolete
4 Transport Dependent
3:0 Reserved
Command
7:0 F2h
Table 201 Security Unlock Information
Word
Description
Control word
00
Bit Description
15:1 Reserved
0 Identifier (1-Master, 0-User)
01-16
Password (32 bytes)
17-255
Reserved
If the Identifier bit is set to master and the file is in high security mode then the password supplied will be compared
with the stored master password. If the file is in maximum security mode the security unlock will be rejected.
If the Identifier bit is set to user, then the file compares the supplied password with the stored user password.
If the password compare fails, then the device returns an abort error to the host and decrements the unlock attempt
counter. This counter is initially set to 5 and is decremented for each password mismatch.
When security is disabled and the Identifier bit is set to User, then the device shall return command aborted.
When this counter reaches zero then all password protected commands are rejected until a hard reset or a power off.
Identifier
Zero indicates that device regards Password as User Password. One indicates that device regards
Password as Master Password.
The user can detect if the attempt to unlock the device has failed due to a mismatched password as this is the only
reason that an abort error will be returned by the file AFTER the password information has been sent to the device.
If an abort error is returned by the device BEFORE the password data has been sent to the file then another problem
exists.
Normal Outputs
See Normal Outputs in Section 12.7 Flush Cache (E7h)
Error Outputs
See Error Outputs in Section 12.4 Download Microcode (92h)
274
Hard Disk Drive Specification