Hitachi HDS723020BLA642 Specifications page 110

The following symbols are used in the command descriptions:
Output Registers
0 Indicates that the bit must be set to 0.
1 Indicates that the bit must be set to 1.
D The device number bit. Indicates that the device number bit of the Device/Head Register should be
specified. This bit is reserved since all Serial ATA devices behave like Device 0.
H Head number. Indicates that the head number part of the Device/Head Register is an output parameter
and should be specified.
L LBA mode. Indicates the addressing mode. Zero specifies CHS mode and one does LBA addressing
mode.
R Retry. Original meaning is already obsoleted, there is no difference between 0 and 1. (Using 0 is
recommended for future compatibility.)
B Option Bit. Indicates that the Option Bit of the Sector Count Register should be specified. (This bit is used
by Set Max ADDRESS command)
V Valid. Indicates that the bit is part of an output parameter and should be specified.
x Indicates that the hex character is not used.
- Indicates that the bit is not used.
Input Registers
0 Indicates that the bit is always set to 0.
1 Indicates that the bit is always set to 1.
H Head number. Indicates that the head number part of the Device/Head Register is an input parameter and
will be set by the device.
V Valid. Indicates that the bit is part of an input parameter and will be set to 0 or 1 by the device.
- Indicates that the bit is not part of an input parameter.
The command descriptions show the contents of the Status and Error Registers after the device has completed
processing the command and has interrupted the host.
Please refer to ATA interface specifications about other commands‟ descriptions which are not described in this
SATA interface specification. However, be careful that Serial ATA Device/Head register bit-4 (d) is different
from that of Parallel ATA. In Serial ATA, Device/Head register bit-4 is reserved for all commands.
Hitachi hard disk drive specifications
110