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2012年8月28日 星期二

WRITE FPDMA QUEUED (61h) - NCQ(Native Command Queuing)


WRITE FPDMA QUEUED (61h)
Inputs:
Register
7
6
5
4
3
2
1
0
Features
Current
Sector count (7:0)
Previous
Sector count (15:8)
Sector Count
Current
TAG
Reserved
Previous
PRIO(1:0)
Reserved
LBA Low
Current
LBA (7:0)
Previous
LBA (31:24)
LBA Mid
Current
LBA (15:8)
Previous
LBA (39:32)
LBA High
Current
LBA (23:16)
Previous
LBA (47:40)
Device
FUA
1
0
0
Reserved
Command
61h
TAG: The TAG value shall be assigned by host software to be different from all other TAG values corresponding to outstanding commands. The assigned TAG value shall not exceed the value specified in IDENTIFY DEVICE word 75.
PRIO: The Priority (PRIO) value is assigned by the host based on the priority of the command issued. The device should complete high priority requests in a more timely fashion than normal and isochronous requests. The device  hould complete isochronous requests prior to its associated deadline.
00b Normal Priority
01b Isochronous – deadline dependent priority
10b High priority
11b Reserved
FUA: When set to one forces the data to be retrieved from the storage media regardless of whether the storage device holds the requested information in its buffers or cache. If the device holds a modified copy of the requested data as a result of having cached writes, the modified data is first written to the media before being retrieved from the storage media as part of this operation. When cleared to zero the data may be retrieved either from the device’s storage media or from buffers/cache that the device may include.
Others: All other registers as specified for the WRITE DMA QUEUED EXT command defined in the ATA8-ACS standard, including the Sector Count 15:0 convention where a value of zero specifies that 65,536 sectors are to be transferred.

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