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 |
| data to the host. |
| * For information about the format of the insurance failure threshold value data, |
| see Table 5.10. |
X’D2’ | SMART |
| 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.
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