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11.26 Security Unlock (F2h)
Command Block Output
Registers
Register
Data
Feature
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Command
Error Register
7
6
5
CRC
UNC
0
0
V
0
Figure 127. Security Unlock Command (F2h)
This command unlocks the password and causes the device to enter device unlock mode. If a 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 infor-
mation specified in the figure below.
If the Identifier bit is set to master and the drive is in high security mode, the password supplied will be
compared with the stored master password. If the drive is in maximum security mode, the security unlock
will be rejected.
If the Identifier bit is set to user, the drive 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 this counter reaches zero, all password protected commands are rejected until a hard reset or a
power off.
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
1 - 1 D - - - -
1 1 1 1 0 0 1 0
4
3
2
1
0
IDN
0
ABT
T0N
AMN
0
0
V
0
0
Deskstar 120GXP hard disk drive specifications
Command Block Input
Registers
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
Status Register
7
6
5
4
BSY
RDY
DF
DSC
0
V
0
–
149
7 6 5 4 3 2 1 0
- - - - - - - -
see below
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
see below
3
2
1
0
DRQ
COR
IDX
ERR
–
0
–
V
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