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Barracuda Serial ATA V Product Manual, Rev. B 35
4.2.2 Set Features command
This command controls the implementation of various features that the drive
supports. When the drive receives this command, it sets BSY, checks the
contents of the Features register, clears BSY and generates an interrupt. If
the value in the register does not represent a feature that the drive supports,
the command is aborted. Power-on default has the read look-ahead and
write caching features enabled. The acceptable values for the Features regis-
ter are defined as follows:
Table 9: Set Features command values
02
H
Enable write cache (default).
03
H
Set transfer mode (based on value in Sector Count register). Sector
Count register values:
00
H
Set PIO mode to default (PIO mode 2).
01
H
Set PIO mode to default and disable IORDY (PIO mode 2).
08
H
PIO mode 0
09
H
PIO mode 1
0A
H
PIO mode 2
0B
H
PIO mode 3
0C
H
PIO mode 4 (default)
20
H
Multiword DMA mode 0
21
H
Multiword DMA mode 1
22
H
Multiword DMA mode 2
40
H
Ultra DMA mode 0
41
H
Ultra DMA mode 1
42
H
Ultra DMA mode 2
43
H
Ultra DMA mode 3
44
H
Ultra DMA mode 4
45
H
Ultra DMA mode 5
05
H
Enable advanced power management
42
H
Auto acoustic management
FE
H
Performance seek
80
H
Quiet acoustic seek
55
H
Disable read look-ahead (read cache) feature.
82
H
Disable write cache