All addressing of data sectors recorded on the device's media is by a logical sector address. The mapping of logical sector addresses to the actual physical location of the data sector on the media is vendor specific.

A device shall support at least one logical CHS translation known as the default translation if the device capacity is less than 8 GB 16 515 072 sectors. The device shall enter this translation following a power-on reset. A device shall support LBA translation regardless of capacity. If the device capacity is greater than 8 GB 16 515 072 sectors, the LBA translation shall be the default translation and the device shall enter this translation following a power-on reset. If the device capacity is greater than 8 GB 16 515 072 sectors, the device may support a CHS translation providing up to 8 GB 16 515 072 sectors of capacity. A device may support other logical translations if the device capacity is less than 8 GB 16 515 072 sectors and the host may use the INITIALIZE DEVICE PARAMETERS command to select the translation. The default translation is described in the Identify Device information. The current translation may also be described in the Identify Device information.

A CHS address is made up of three fields: the sector address, the head number and the cylinder number. Sectors are numbered from 1 to the maximum value allowed by the current CHS translation but can not exceed 255. Heads are numbered from 0 to the maximum value allowed by the current CHS translation but can not exceed 15. Cylinders are numbered from 0 to the maximum value allowed by the current CHS translation but cannot exceed 65 535.

When the host selects a CHS translation using the INITIALIZE DEVICE PARAMETERS command, the host requests the number of sectors per logical track and the number of heads per logical cylinder. The device then computes the number of logical cylinders available in requested translation.

Sequential access to logical sectors shall be accomplished by treating the sector number as the least significant portion of the logical sector address, the head number as the middle portion of the logical sector address and the cylinder number as the most significant portion of the logical sector address.

A device shall not change the addressing method and shall return status information utilizing the addressing method specified for the command.

The following LBA support shall be supported by the device:

1. The host may select either the currently selected CHS translation addressing or LBA addressing on a command-by-command basis by using the LBA bit in the Device/Head register;
2. The device shall support LBA addressing for all media access commands, except for the FORMAT TRACK command. Implementation of LBA addressing for the FORMAT TRACK command is vendor specific. The LBA bit of the Device/Head register shall be ignored for commands that do not access the media;
3. Logical sectors on the device shall be linearly mapped with the first LBA addressed sector (sector 0) being the same sector as the first logical CHS addressed sector (cylinder 0, head 0, sector 1). Irrespective of the logical CHS translation currently in effect, the LBA address of a given logical sector does not change. The following is always true:

LBA = ( (cylinder * heads_per_cylinder + heads ) * sectors_per_track ) + sector - 1

The optional Power Management Feature Set permits a host to modify the behavior of a device in a manner which reduces the power required to operate. The Power Management Feature Set provides a set of commands and a timer that enable a device to implement low power consumption modes. A device that implements the Power Management feature shall implement the following minimum set of functions:

1. A Standby timer;
2. IDLE command;
3. IDLE IMMEDIATE command;
4. SLEEP command;
5. STANDBY command;
6. STANDBY IMMEDIATE command.

Additional vendor specific commands and functions are allowed.

1. Power modes

In Active mode the device is capable of responding to commands. During the execution of a media access command a device shall be in Active mode. Power consumption is greatest in this mode.

In Idle mode the device is capable of responding to commands but the device may take longer to complete commands than when in the Active mode. Power consumption may be reduced from that of Active mode.

In Standby mode the device is capable of responding to commands but the device may take longer to complete commands than in the Idle mode. The time to respond could be as long as 30 s. Power consumption may be reduced from that of Idle mode.

In Sleep mode the device requires a reset to be activated. The time to respond could be as long as 30 s. Sleep provides the lowest power consumption of any mode.

2. Power management commands

The CHECK POWER MODE command allows a host to determine if a device is currently in, going to or leaving Standby or Idle mode.

The IDLE and IDLE IMMEDIATE commands move a device to Idle mode immediately from the Active or Standby modes. The Idle command also sets the Standby Timer count and enables or disables the Standby Timer.

The SLEEP command moves a device to Sleep mode. The device's interface becomes inactive at the completion of the SLEEP command. A reset is required to move a device out of Sleep mode. When a device exits Sleep mode it may enter Active, Idle or Standby mode. The mode selected by the device is based on the type of reset received and on vendor specific implementation.

The STANDBY and STANDBY IMMEDIATE commands move a device to Standby mode immediately from the Active or Idle modes. The STANDBY command also sets the Standby Timer count and enables or disables the Standby Timer.

3. Standby timer

The Standby timer provides a method for the device to automatically enter Standby mode from either Active or Idle mode following a host programmed period of inactivity. If the Standby timer is enabled and if the device is in the Active or Idle mode, the device waits for the specified time period and if no command is received, the device automatically enters the Standby mode.

If the Standby Timer is disabled, the device may not automatically enter Standby mode.

4. Idle mode transition

The transition to Idle mode is vendor specific, and may occur as a result of an IDLE or IDLE IMMEDIATE command, or in vendor specific way.

5. Status

In Sleep mode, the device's interface is not active. The content of the Status register is invalid in this mode.

6. Power mode transitions

Figure 3 shows the minimum set of mode transitions that shall be implemented.

The Security mode features allow a host to implement a security password system to prevent unauthorized access to the internal disk drive.

The Commands supported by this feature set are:

• SECURITY SET PASSWORD
• SECURITY UNLOCK
• SECURITY ERASE PREPARE
• SECURITY ERASE UNIT
• SECURITY FREEZE LOCK
• SECURITY DISABLE PASSWORD

Support of the Security mode feature set is indicated in IDENTIFY DEVICE response Word 128.

1. Security mode default setting

The Master Password shall be set to a vendor specific value during manufactuing and the lock function disabled.

The system manufacturer/dealer may set a new Master Password using the SECURITY SET PASSWORD command, without enabling the lock function.

2. Intial setting of the user password

When a user password is set, the device shall automatically enter lock mode the next time the device is powered-on.

3. Security mode operation from power-on

When lock is enabled, the device rejects media access commands until an SECURITY UNLOCK command is successfully completed.

4. User password lost

If the user password is lost and High level security is set, the device shall not allow the user to access data. The device shall be unlocked using the master pasword.

If the user password is lost and Maximum security level is set, data access shall be impossible. However, the device shall be unlocked using the ERASE UNIT command with the master password to unlock the device and shall erase all user data.

Figure 5 - Password set Ssecurity mode power-on flow

Figure 6 - User password lost

The SMART commands provide access to attribute values, attribute thresholds and other logging and reporting information. These commands use a single command code and are differentiated by the value placed in the Features register. See Clause 8.

If the SMART feature set is implemented, SMART ENABLE OPERATIONS, SMART DISABLE OPERATIONS, and SMART RETURN STATUS commands the folloing commands shall be implemented. The implementation of other SMART commands is optional.

• SMART ENABLE OPERATIONS
• SMART DISABLE OPERATIONS
• SMART RETURN STATUS

If the SMART feature set is implemented, the following commands may be implemented. These commands are not recommended and may be removed in a future ATA standard.

• SMART ENABLE/DISABLE ATTRIBUTE AUTOSAVE
• SMART READ ATTRIBUTE THRESHOLDS
• SMART READ ATTRIBUTE VALUES
• SMART SAVE ATTRIBUTE VALUES

1. SMART operation with power management modes

It is recomended that, when used in a system that is utilizing the Power Management Feature set, a SMART enabled device automatically saves its attribute values upon receipt of an IDLE IMMEDIATE, STANDBY IMMEDIATE or SLEEP command. If the device has been set to utilize the Standby timer, it is recommended that the device automatically perform a SMART SAVE ATTRIBUTE VALUES function prior to going from an Idle state to the Standby state.