Seagate SkyHawk Product Manual, Rev. A
29
SATA Interface
4.3.2 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 register are defined as follows:
Table 9
Set Features command
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
46
H
Ultra DMA mode 6
06
H
Enable the PUIS feature set
07
H
PUIS feature set device spin-up
10
H
Enable use of SATA features
55
H
Disable read look-ahead (read cache) feature
82
H
Disable write cache
86
H
Disable the PUIS feature set
90
H
Disable use of SATA features
AA
H
Enable read look-ahead (read cache) feature
(default)
F1
H
Report full capacity available
Note
At power-on, or after a hardware or software reset, the
default values of the features are as indicated above.
