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4.1.8
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 inter-
rupt. 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 12:
Features register values
02
Enable write cache (default).
H
03
Set transfer mode (based on value in Sector Count register).
H
Sector Count register values:
00
H
01
H
08
H
09
H
0A
H
0B
H
0C
H
20
H
21
H
22
H
40
H
41
H
42
H
43
H
44
H
45
H
05
Enable advanced power management
H
55
Disable read look-ahead (read cache) feature.
H
82
Disable write cache.
H
AA
Enable read look-ahead (read cache) feature (default).
H
F1
Report full capacity available
H
Note.
At power-on or after a hardware or software reset the default values of the features are as indicated
above.
38
Set PIO mode to default (PIO mode 2).
Set PIO mode to default and disable IORDY (PIO mode 2).
PIO mode 0
PIO mode 1
PIO mode 2
PIO mode 3
PIO mode 4 (default)
Abort, note supported
Abort, note supported
Abort, note supported
Ultra DMA mode 0
Ultra DMA mode 1
Ultra DMA mode 2
Ultra DMA mode 3
Ultra DMA mode 4
Ultra DMA mode 5
Momentus 5400 FDE Product Manual, Rev. C
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