IBM DBCA-204860 Hard Drive Specifications - Page 90
Protected Area Function
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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 ('F8'h) ('F9'h) 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 : 536,870,912 byte (536MB) : 1,048,575 (0FFFFFh) : 8,388,608 byte : 16,384 (004000h) : 528,482,304 byte (528MB) : 1,032,192 (0FC000h) : 0FC000h to 0FFFFFh 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 0FFFFFh 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. 82 OEM Specifications of DBCA-2xxxxx 2.5 inch H D D