Set Features Command (Ef H ) - Seagate Decathlon 850 Product Manual

Decathlon 850 ATA Product Manual, July 1995
Word Description
Minimum PIO
68
transfer with IORDY
Reserved
69–127
Seagate-reserved
128–159
160– 255 Reserved
3.2.2 Set Features command (EF
The Set Features command (command code EF
enable and disable the multisegmented cache features and to identify
the transfer modes the drive uses. The multisegmented buffer consists
of Read Look-ahead and write-immediate and write-merging features.
The table below lists the features supported by the ST5850A. The
features that are set to default by the factory are indicated in the Feature
column.
Feature Value Feature
Enable write immediate and write merging
02
H
(default)
03 Set transfer mode
H
55 Disable read look ahead cache
H
82 Disable write immediate and write merging
H
AA Enable read look-ahead (default)
H
To use the command:
1. Write the feature value to the Features register.
2. Write the Set Features command to the command register.
Note. If the value in the Features register is not supported or is invalid,
the drive posts an Aborted Command error (04).
The factory-default values are restored at power-on or after a hard reset.
Value
120 nsec
xxxx
H
xxxx
H
xxxx
H
)
H
) allows the user to
H
31