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12.5 Download Microcode DMA (93h)
Table 93 Download Microcode DMA Command (93h)
Command Input
Field
Description
FEATURE
SUBCOMMAND field
COUNT
BLOCK COUNT field(7:0)
LBA
Bit Description
27:24 Reserved
23:8 BUFFER OFFSET field
7:0 BLOCK COUNT field (15:8)
DEVICE
Bit Description
7:5 Obsolete
4 Transport Dependent
3:0 Reserved
Command
7:0 93h
Normal Outputs
Field
Description
FEATURE
Subcommand code.
03h : Download with offsets and save microcode. (See Section 12.5.3)
07h : Download and save microcode.
0Eh : Download with offsets and save microcode for future use. (See Section 12.5.4)
0Fh : Activate downloaded microcode. (See Section 12.5.5)
Other values are reserved.
COUNT
Lower byte of 16-bit sector count value to transfer from the host. (See Section 12.5.2)
NUMBER
Higher byte of 16-bit sector count value to transfer from the host. (See Section 12.5.2)
CYLINDER
Buffer offset (only used for Feature = 03h, 0Eh)
Error Register
See Error Register in 12.4 Download Microcode (92h)
12.5.1
Overview
This command enables the host to alter the device’s microcode. The data transferred using the Download Microcode
DMA commands is vendor specific.
In reloading new microcode, when the spin-up of the device is disabled, the device spins down after reloading new
microcode.
The device may abort the Download Microcode DMA command and discard all previously downloaded Microcode, if
the current buffer offset is not equal to the sum of the previous Download Microcode DMA command buffer offset and
the previous sector count. The first Download Microcode DMA command must have a buffer offset of zero.
The new firmware should become effective immediately after the transfer of the last data segment has completed.
When the device detects the last Download Microcode command for the firmware download the device performs any
device required verification and saves the complete set of downloaded microcode.
Power on reset prior to the receipt of the last segment will discard all of the microcode segments received.
This command is aborted when the device is in security locked mode
12.5.2 Sector Count / Sector Number
All transfers shall be an integer multiple of the sector size. The size of the data transfer is determined by the contents
of the Sector Number and Sector Count registers. The Sector Number register is used to extend the Sector Count
register to create a 16-bit sector count value. The Sector Number register is the most significant eight bits and the
Sector Count register is the least significant eight bits.
147
Hard Disk Drive Specification