-H3,-H2,-H1,-H0 -
-Head Select. These four bits are the 1's complement of the binary coded address of the
currently selected head. -H0 is the least significant.
-Drive Select 1. Drive select bit for device 1, active low. DS1=0 when device 1 (slave) is
-DS1
selected and active.
-Drive Select 0. Drive select bit for device 0, active low. DS0=0 when device 0 (master) is
-DS0
selected and active.
8.8 Device/Head Register
Figure 72. Device/Head Register
This register contains the device and head numbers.
Bit Definitions
Binary encoded address mode select. When L=0, addressing is by CHS mode. When
L
L=1, addressing is by LBA mode.
Device. When DRV=0, device 0 (master) is selected. When DRV=1, device 1 (slave) is
DRV
selected.
HS3, HS2, HS1, HS0
Head Select. These four bits indicate binary encoded address of the head. HS0 is the
least significant bit. At command completion these bits are updated to reflect the currently
selected head.
The head number may be from zero to the number of heads minus one.
In LBA mode HS3 through HS0 contain bits 24-27 of the LBA. At command completion
these bits are updated to reflect the current LBA bits 24-27.
8.9 Error Register
Figure 73. Error Register
This register contains status from the last command executed by the device or a diagnostic code.
At the completion of any command – except Execute Device Diagnostic – the contents of this register
are always valid even if ERR=0 is in the Status Register.
Following a power on, a reset, or completion of an Execute Device Diagnostic command, this register
contains a diagnostic code. See Figure 77 on page 72 for the definition.
Device/Head Register
7
6
5
1
L
1
Error Register
7
6
5
CRC
UNC
0
IDNF
Deskstar 180GXP hard disk drive specifications
4
3
2
DRV
HS3
HS2
4
3
2
0
ABRT
TK0NF
68
1
0
HS1
HS0
1
0
AMNF