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5-38 C141-E050-02EN
(14) SET FEATURES (X’EF’)
The host system issues the SET FEATURES command to set parameters in the
Features register for the purpose of changing the device features to be executed.
For the transfer mode (Feature register = 03), detail setting can be done using the
Sector Count register.
Upon receipt of this command, the device sets the BSY bit of the Status register
and saves the parameters in the Features register. Then, the device clears the BSY
bit, and generates an interrupt.
If the value in the Features register is not supported or it is invalid, the device
posts an ABORTED COMMAND error.
Table 5.5 lists the available values and operational modes that may be set in the
Features register.
Table 5.5 Features register values and settable modes
Features Register
Drive operation mode
X’02’
Enables the write cache function.
X’03’
Transfer mode depends on the contents of the Sector Count register.
(Details are given later.)
X’55’
Disables read cache function.
X’66’
Disables the reverting to power-on default settings after software reset.
X’82’
Disables the write cache function.
X’AA’
Enables the read cache function.
X’BB’
Specifies the transfer of 4-byte ECC for READ LONG and WRITE
LONG commands.
X’CC’
Enables the reverting to power-on default settings after software reset.
At power-on or after hardware reset, the default mode is the same as that is set
with a value greater than X’AA’ (except for write cache). If X’66’ is specified, it
allows the seting value greater than X’AA’ which may have been modified to a
new value since power-on, to remain the same even after software reset.