Device/Head Register; Error Register; Figure 72. Device/Head Register; Figure 73. Error Register - IBM IC35L040AVVN07-0 - 40GB IDE Deskstar 120GXP 7200RPM UATA-100 07N9682 Specifications

-DS1 -Drive Select 1. Drive select bit for device 1, active low. DS1=0 when device 1 (slave) is
selected and active.
-DS0 -Drive Select 0. Drive select bit for device 0, active low. DS0=0 when device 0 (master) is
selected and active.

8.8 Device/Head Register

Figure 72. Device/Head Register

This register contains the device and head numbers.
Bit Definitions
L Binary encoded address mode select. When L=0, addressing is by CHS mode. When
L=1, addressing is by LBA mode.
DRV Device. When DRV=0, device 0 (master) is selected. When DRV=1, device 1 (slave) is
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 con-
tains a diagnostic code. See Figure 77 on page 74 for the definition.
Device/Head Register
7 6 5
1 L 1
Error Register
7 6 5
CRC UNC 0 IDNF
Deskstar 120GXP hard disk drive specifications
4 3 2
DRV HS3 HS2 HS1
4 3 2
0 ABRT TK0NF
70
1 0
HS0
1 0
AMNF