Set Features Command - Seagate ST9655 Series Product Manual

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3.3.2 Set Features command

This command controls the implementation of various drive features.
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 supported by the drive,
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:
Enable write cache (default)
02
H
03 Set transfer mode (based on value in Sector Count register)
H
Sector Count register values:
00 Set PIO mode to default
H
08 PIO Mode 0 (default for ST9550AG and ST9385AG)
H
09 PIO Mode 1
H
0A PIO Mode 2 (default for ST9655AG)
H
0B PIO Mode 3
H
10 Single-word DMA Mode 0
H
11 Single-word DMA Mode 1
H
12 Single-word DMA Mode 2
H
20 Multiword DMA Mode 0
H
21 Multiword DMA Mode 1
H
44 Sixteen bytes of ECC apply on read long and write long
H
commands.
55 Disable read look-ahead (read cache) feature.
H
66 Disable reverting to power-on defaults.
H
82 Disable write cache.
H
AA Enable read look-ahead (read cache) feature (default).
H
BB 4 bytes of ECC apply on read long and write long commands
H
(default).
CC Enable reverting to power-on defaults (default).
H
At power-on, or after a hardware reset, the default values of the features
are as indicated above. A software reset also changes the features to
default values unless a 66
ST9655 Family Product Manual, Rev. A
command has been received.
H