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3.2.3 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 and 4 bytes of ECC.
The acceptable values for the Features register are defined as follows:
01
H
Obsolete
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), enable IORDY
01
H
Set PIO mode to default (PIO mode 2), disable IORDY
08
H
PIO Mode 0
09
H
PIO Mode 1
0A
H
PIO Mode 2
(default)
0B
H
PIO Mode 3
0C
H
PIO Mode 4
10
H
Obsolete
11
H
Obsolete
12
H
Obsolete
20
H
Multiword DMA Mode 0
21
H
Multiword DMA Mode 1
22
H
Multiword DMA Mode 2
04
H
Enable auto-read reassignment
(default)
33
H
Not implemented
44
H
Sixteen bytes of ECC apply on read long and write long
commands
54
H
Not implemented
55
H
Disable read look-ahead (read cache) feature
66
H
Disable reverting to power-on defaults
77
H
Not implemented
81
H
Obsolete
82
H
Disable write cache
84
H
Not implemented
88
H
Not implemented
32 Marathon 2250 and Marathon 1680 Product Manual