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C141-E090-01EN 5 - 49
Table 5.8 Features Register values (subcommands) and functions
Features Resister Function
X’D0’ SMART Read Attribute Values:
A device that received this subcommand asserts the BSY bit and saves all the
updated attribute values. The device then clears the BSY bit and transfers 512-
byte attribute value information to the host.
* For information about the format of the attribute value information, see Table 5.9.
X’D1’ SMART Read Attribute Thresholds:
This subcommand is used to transfer 512-byte insurance failure threshold value
data to the host.
* For information about the format of the insurance failure threshold value data,
see Table 5.10.
X’D2’ SMART Enable-Disable Attribute AutoSave:
This subcommand is used to enable (SC register !!XX!! 00h) or disable (SC
register = 00h) the setting of the automatic saving feature for the device attribute
data. The setting is maintained every time the device is turned off and then on.
When the automatic saving feature is enabled, the attribute values are saved after
15 minutes passed since the previous saving of the attribute values. However, if
the failure prediction feature is disabled, the attribute values are not automatically
saved.
When the device receives this subcommand, it asserts the BSY bit, enables or
disables the automatic saving feature, then clears the BSY bit.
X’D3’ SMART Save Attribute Values:
When the device receives this subcommand, it asserts the BSY bit, saves device
attribute value data, then clears the BSY bit.
X’D8’ SMART Enable Operations:
This subcommand enables the failure prediction feature. The setting is
maintained even when the device is turned off and then on.
When the device receives this subcommand, it asserts the BSY bit, enables the
failure prediction feature, then clears the BSY bit.
X’D9’ SMART Disable Operations:
This subcommand disables the failure prediction feature. The setting is
maintained even when the device is turned off and then on.
When the device receives this subcommand, it asserts the BSY bit, disables the
failure prediction feature, then clears the BSY bit.
X’DA’ SMART Return Status:
When the device receives this subcommand, it asserts the BSY bit and saves the
current device attribute values. Then the device compares the device attribute
values with insurance failure threshold values. If there is an attribute value
exceeding the threshold, F4h and 2Ch are loaded into the CL and CH registers. If
there are no attribute values exceeding the thresholds, 4Fh and C2h are loaded
into the CL and CH registers. After the settings for the CL and CH registers have
been determined, the device clears the BSY bit
The host must regularly issue the SMART Read Attribute Values subcommand (FR register =
D0h), SMART Save Attribute Values subcommand (FR register = D3h), or SMART Return
Status subcommand (FR register = DAh) to save the device attribute value data on a medium.