Set Features Command (Ef H ) - Seagate ST3780A Product Manual

Medalist Family AT Product Manual, Rev. A
Word Description
Minimum PIO
68
transfer with IORDY
Reserved
69–127
Seagate-reserved
128–159
160– 255 Reserved
3.1.2 Set Features command (EF
The host uses the Set Features command (command code EF
establish parameters that affect the execution of certain drive features.
The command is used to enable or disable the Read Look-ahead, write
immediate and write merging features and to set the transfer mode.
These features are enabled during startup.
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.
At power-on or after a hard reset, the feature selections are restored to
the factory-default values.
The following table shows alterable features supported by the ST31220
family drives. Where a factory-default value exists, that value is listed.
Feature Value Feature
02 Enable write immediate and write merging
H
55 Disable cache
H
82 Disable write immediate and write merging
H
AA Enable cache
H
03 Set transfer mode
H
Value
120 nsec
xxxx
H
xxxx
H
xxxx
H
)
H
27
) to
H