Hitachi HDT725025VLA380 Specifications - Page 86

Drive Address Register, Device/Head Register

Page 86 highlights

9.8 Drive Address Register Table 52: Drive Address Register 7 6 5 4 3 HIZ -WTG -H3 -H2 -H1 2 1 0 -H0 -DS1 -DS0 This register contains the inverted drive select and head select addresses of the currently selected drive. Bit HIZ -WTG -H3, -H2,H1,-H0-DS1 -DS0 Definitions High Impedance. This bit is not a device and will always be in a high impedance state. Write Gate. This bit is 0 when writing to the disk device is in progress. -Head Select. These four bits are the one's complement of the binary coded address of the currently selected head. Bit -H0 is the least significant. Drive Select 1. The Drive Select bit for device 1 is active low. DS1 = 0 when device 1 (slave) is selected and active. Drive Select 0. The Drive Select bit for device 0 is active low. DS0 = 0 when device 0 (master) is selected and active. 9.9 Device/Head Register Table 53: Device Head/Register 7 6 5 4 3 2 1 0 1 L 1 DRV HS3 HS2 HS1 HS0 This register contains the device and head numbers. Bit Definitions L DRV HS3, HS2, HS1, HS0 Binary encoded address mode select. When L = 0, addressing is by CHS mode. When L = 1, addressing is by LBA mode. Device. When DRV = 0, device 0 (master) is selected. When DRV = 1, device 1 (Slave) is selected. Head Select. These four bits indicate the binary encoded address of the head. Bit 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. Deskstar T7K500 Hard Disk Drive Specification 72

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Deskstar T7K500 Hard Disk Drive Specification
72
9.8
Drive Address Register
Table 52: Drive Address Register
This register contains the inverted drive select and head select addresses of the currently selected drive.
9.9
Device/Head Register
Table 53: Device Head/Register
This register contains the device and head numbers.
Bit
Definitions
7
6
5
4
3
2
1
0
HIZ
-WTG
-H3
-H2
-H1
-H0
-DS1
-DS0
Bit
Definitions
HIZ
High Impedance. This bit is not a device and will always be in a high impedance state.
-WTG
Write Gate. This bit is 0 when writing to the disk device is in progress.
-H3, -H2,-
H1,-H0-
-Head Select. These four bits are the one's complement of the binary coded address of the cur-
rently selected head. Bit -H0 is the least significant.
-DS1
Drive Select 1. The Drive Select bit for device 1 is active low. DS1 = 0 when device 1 (slave) is
selected and active.
-DS0
Drive Select 0. The Drive Select bit for device 0 is active low. DS0 = 0 when device 0 (master) is
selected and active.
7
6
5
4
3
2
1
0
1
L
1
DRV
HS3
HS2
HS1
HS0
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 the binary encoded address of the head. Bit 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.