8.5 Data Register
This register is used to transfer data blocks between the device data buffer and the host. It is also the
register through which sector information is transferred on a Format Track command and configuration
information is transferred on an Identify Device command.
All data transfers are 16 bits wide, except for ECC byte transfers which are 8 bits wide. Data transfers are
PIO only.
The register contains valid data only when DRQ=1 in the Status Register.
8.6 Device Control Register
Figure 70. Device Control Register
Bit Definitions
HOB (high order byte) is defined by the 48-bit Address feature set. A write to any
HOB
Command Register shall clear the HOB bit to zero.
SRST (RST) Software Reset. The device is held reset when RST=1. Setting RST=0 re-enables the
device.
The host must set RST=1 and wait for at least 5 µs before setting RST=0 to ensure that
the device recognizes the reset.
Interrupt Enable. When -IEN=0 and the device is selected, device interrupts to the host
-IEN
will be enabled. When -IEN=1 or the device is not selected, device interrupts to the host
will be disabled.
8.7 Drive Address Register
Figure 71. Drive Address Register
This register contains the inverted drive select and head select addresses of the currently selected drive.
Bit Definitions
High Impedance. This bit is not driven and will always be in a high impedance state.
HIZ
-Write Gate. This bit is zero when writing to the disk device is in progress.
-WTG
Device Control Register
7
6
5
HOB
–
–
Drive Address Register
7
6
5
HIZ
–WTG
–H3
Deskstar 180GXP hard disk drive specifications
4
3
2
–
1
SRST
–IEN
4
3
2
–H2
–H1
–H0
–DS1
67
1
0
0
1
0
–DS0