Hitachi HDT725025VLA380 Specifications - Page 84

Alternate Status Register, Command Register, Cylinder High Register, Cylinder Low Register

Page 84 highlights

9.2 Alternate Status Register Table 50: Alternate Status Register 7 6 5 4 3 2 1 0 BSY RDY DF DSC/ SERV DRQ COR IDX ERR This register contains the same information as the Status Register. The only difference between this register and the Status Register is that reading the Alternate Status Register does not imply an interrupt acknowledge or a clear of a pending interrupt. See section 9.14 'Status Register" on page 70 for the definition of the bits in this register. 9.3 Command Register This register contains the command code being sent to the device. Command execution begins immediately after this register is written. The command set is shown in Table 67: 'Command Set" on page 129 and Table 74: 'Command Set (2 of 2)" on page 106. All other registers required for the command must be set up before writing to the Command Register. 9.4 Cylinder High Register This register contains the high order bits of the starting cylinder address for any disk access. At the end of the command, this register is updated to reflect the current cylinder number. In LBA Mode this register contains Bits 16-23. At the end of the command, this register is updated to reflect the current LBA Bits 16-23. The cylinder number may be from zero to the number of cylinders minus one. When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 16-23 and the "previous content" contains Bits 40-47. The 48-bit Address feature set is described in Section 9.16, "48-Bit Address Feature Set" on page 93. 9.5 Cylinder Low Register This register contains the low order 8 bits of the starting cylinder address for any disk access. At the end of the command, this register is updated to reflect the current cylinder number. In LBA Mode this register contains Bits 8-15. At the end of the command, this register is updated to reflect the current LBA Bits 8-15. The cylinder number may be from zero to the number of cylinders minus one (1). When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 8-15 and the "previous content" contains Bits 32-39. Deskstar T7K500 Hard Disk Drive Specification 70

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Deskstar T7K500 Hard Disk Drive Specification
70
9.2
Alternate Status Register
Table 50: Alternate Status Register
This register contains the same information as the Status Register. The only difference between this register and the
Status Register is that reading the Alternate Status Register does not imply an interrupt acknowledge or a clear of a
pending interrupt. See section 9.14 ‘Status Register” on page 70 for the definition of the bits in this register.
9.3
Command Register
This register contains the command code being sent to the device. Command execution begins immediately after
this register is written. The command set is shown in Table 67:
‘Command Set” on page 129 and Table
74:
‘Command Set (2 of 2)” on page 106. All other registers required for the command must be set up before writ-
ing to the Command Register.
9.4
Cylinder High Register
This register contains the high order bits of the starting cylinder address for any disk access. At the end of the com-
mand, this register is updated to reflect the current cylinder number.
In LBA Mode this register contains Bits 16–23. At the end of the command, this register is updated to reflect the
current LBA Bits 16–23.
The cylinder number may be from zero to the number of cylinders minus one.
When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 16-23 and the
"previous content" contains Bits 40-47. The 48-bit Address feature set is described in Section 9.16, "48-Bit
Address Feature Set" on page 93.
9.5
Cylinder Low Register
This register contains the low order 8 bits of the starting cylinder address for any disk access. At the end of the
command, this register is updated to reflect the current cylinder number.
In LBA Mode this register contains Bits 8–15. At the end of the command, this register is updated to reflect the
current LBA Bits 8–15.
The cylinder number may be from zero to the number of cylinders minus one (1).
When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 8-15 and the
"previous content" contains Bits 32-39.
7
6
5
4
3
2
1
0
BSY
RDY
DF
DSC/
SERV
DRQ
COR
IDX
ERR