Set Features Command - Seagate ST32122A - Medalist 2.1 GB Hard Drive Product Manual

Medalist 4342, 3232, 2122, 1722 and 1012 Product Manual

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:
02 Enable write cache (default)
H
03 Set transfer mode (based on value in Sector Count register)
H
Sector Count register values:
00 Set PIO mode to default (PIO mode 2)
H
01 Set PIO mode to default and disable IORDY (PIO mode 2)
H
08 PIO mode 0
H
09 PIO mode 1
H
0A PIO mode 2 (default)
H
0B PIO mode 3
H
0C PIO mode 4
H
20 Multiword DMA mode 0
H
21 Multiword DMA mode 1
H
22 Multiword DMA mode 2
H
40 Ultra DMA mode 0
H
41 Ultra DMA mode 1
H
42 Ultra DMA mode 2
H
55 Disable read look-ahead (read cache) feature
H
82 Disable write cache
H
Enable read look-ahead (read cache) feature (default)
AA
H
F1 Report full capacity available
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.
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