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12.5.3 Download with offsets and save microcode
A Features register value of 03h indicates that the microcode will be transferred in one or more Download Microcode
DMA commands using the offset transfer method. The buffer offset value is defined by the value in Cylinder registers.
The buffer offset value is the starting location in the microcode file, which varies in 512 byte increments. All microcode
segments will be sent to the device in sequence.
12.5.4 Download with offsets and save microcode for future use
A Features register value of 0Eh indicates that the microcode will be transferred in one or more Download Microcode
DMA commands using the offset transfer method and stored for deferred update. The buffer offset value is defined
by the value in Cylinder registers. The buffer offset value is the starting location in the microcode file, which varies in
512 byte increments. All microcode segments will be sent to the device in sequence.
12.5.5
Activate downloaded 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.
After the transfer of the last data segment has completed, the device performs any device required verification and
stores the complete set of downloaded microcode which has not been activated. The new firmware will be activated
after the device receives following Download Microcode DMA command with a Features register value of 0Fh.
Power on reset prior to the receipt of the last segment or activate downloaded microcode will discard all of the
microcode segments which are received or stored.
12.5.6 Error Outputs
ABT will be set to 1 in the Error Register if the value in the Feature register is neither 03h, 07h, 0Eh nor 0Fh, or the
device is in Security Locked mode. When the reload of new microcode is requested in the data sent by the host for
this Download command, UNC error will be set to 1 in the Error Register if the device fails to reload new microcode.
This error is reported only when the reload of microcode is requested.
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Hard Disk Drive Specification