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Western Digital Hard Disk Drive OEM Specification
11.5 Download Microcode DMA (93h)
Command Block Output Registers
Command Block Input Registers
Table 106 Download Microcode DMA Command (93h)
Output Parameters To The Device
Subcommand code.
03h : Download and save microcode with offsets.
07h : Download and save microcode.
0Eh : Download with offsets and save microcode.
0Fh : Activate download microcode.
Other values are reserved.
Lower byte of 16-bit sector count value to transfer from the host.
Higher byte of 16-bit sector count value to transfer from the host.
Buffer offset (only used for Feature = 03h)
This command enables the host to alter the device’s microcode. The data transferred using the DOWNLOAD
MICROCODE DMA commands is vendor specific.
The Download and save microcode with offsets subcommand(03h) transfers the updated microcode data in one or
more DOWNLOAD MICROCODE commands. This subcommand downloads data containing a segment of the
updated microcode data. On normal command completion, the COUNT field may contain additional indicators.
If the final segment has been downloaded, the device validates the downloaded updated microcode. If the
validation is successful, the downloaded updated microcode is saved to non-volatile storage and is activated.
After transferring a segment where the value of the BUFFER OFFSET field is cleared to zero, if the device begins to
process a command that is not a DOWNLOAD MICROCODE command, then the device:
1) may discard any updated microcode data that has not been saved; and
2) shall continue to process the new command.
The Download and save microcode subcommand(07h) transfers the updated microcode data in one DOWNLOAD
MICROCODE command.
After the updated microcode data has been downloaded:
1) the device shall save the updated microcode data;