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:
01HObsolete
02HEnable write cache
(default)
03HSet transfer mode (based on value in Sector Count register)
Sector Count register values:
00H Set PIO mode to default (PIO mode 2), enable IORDY
01H Set PIO mode to default (PIO mode 2), disable IORDY
08H PIO Mode 0
09H PIO Mode 1
0AH PIO Mode 2
(default)
0BH PIO Mode 3
0CH PIO Mode 4
10H
Obsolete
11H
Obsolete
12H
Obsolete
20H
Multiword DMA Mode 0
21H
Multiword DMA Mode 1
22H
Multiword DMA Mode 2
04HEnable auto-read reassignment
(default)
33HNot implemented
44HSixteen bytes of ECC apply on read long and write long
commands
54HNot implemented
55HDisable read look-ahead (read cache) feature
66HDisable reverting to power-on defaults
77HNot implemented
81HObsolete
82HDisable write cache
84HNot implemented
88HNot implemented
32 Marathon 2250 and Marathon 1680 Product Manual