Protected Area Function; Example For Operation (In Lba Mode) - IBM DBCA-204860 - Travelstar 4.8 GB Hard Drive Specifications

10.8 Protected Area Function

Protected Area Function is to provide the 'protected area' which can not be accessed via conventional
method. This 'protected area' is used to contain critical system data such as BIOS or system management
information. The contents of entire system main memory may also be dumped into 'protected area' to
resume after system power off.
The LBA/CYL changed by following command affects the Identify Device Information.
Two commands are defined for this function.
Read Native Max Address
Set Max Address

10.8.1 Example for operation (In LBA mode)

Assumptions :
For better understanding, the following example uses actual values for LBA, size, etc. Since it is just an
example, these values could be different.
Device characteristics
Capacity (native)
Max LBA (native)
Required size for protected area
Required blocks for protected area
Customer usable device size
Customer usable sector count
LBA range for protected area
1. Shipping HDDs from H D D manufacturer
When the HDDs are shipped from H D D manufacturer,the device has been tested to have a capacity of
536MB,flagging the media defects not to be visible by system.
2. Preparing HDDs at system manufacturer
Special utility software is required to define the size of protected area and store the data into it. The
sequence is :
Issue Read Native Max Address command to get the real device max of LBA/CYL. Returned value
shows that native device Max LBA is 0 F F F F F h regardless to the current setting.
Make entire device be accessible including the protected area by setting device Max LBA as
0 F F F F F h via Set Max Address command. The option could be either nonvolatile or volatile.
Test the sectors for protected area (LBA > = 0FC000h) if required.
Write information data such as BIOS code within the protected area.
Change maximum LBA using Set Max Address command to 0FBFFFh with nonvolatile option.
From this point, the protected area cannot be accessed until next Set Max Address command is
issued. Any BIOSes, device drivers, or application software access the H D D as if that is the 528MB
device because the device acts exactly same as real 528MB device does.
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O E M Specifications of DBCA-2xxxxx 2.5 inch H D D
('F8'h)
('F9'h)
: 536,870,912 byte
: 1,048,575 (0FFFFFh)
: 8,388,608 byte
: 16,384 (004000h)
: 528,482,304 byte
: 1,032,192 (0FC000h)
: 0FC000h to 0FFFFFh
(536MB)
(528MB)