ATA REGISTERS |
|
DRIVE/HEAD REGISTER
The Drive/Head register is used by the host and the device to select the type of addressing (CHS or LBA), the drive letter, and either bits
Table 40: Drive/Head Register
Operation | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
Read/Write | 1 | LBA | 1 | DRV | HS3 | HS2 | HS1 | HS0 |
|
|
|
|
| LBA27 LBA26 LBA25 LBA24 | |||
Default | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
Value |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The Drive/Head register is used by the host to specify one of a pair of ATA drives present in the platform.
Bit(s) | Description |
|
|
6 | LBA. Selects between CHS (0) and LBA (1) addressing mode. |
4Drive Address (DRV). Indicates the drive number selected by the host, either 0 or 1.
•CHS to LBA conversion: LBA = (C x HpC + H) x SpH + S
•LBA to CHS conversion:
C = LBA/(HpC x SpH)
H = (LBA/SpH) mod (HpC)
S = (LBA mod(SpH)) + 1
...where:
C is the cylinder number H is the head number S is the sector count
HpC is the head count per cylinder count SpH is the sector count per head count (track)
SILICONSYSTEMS PROPRIETARY
This document and the information contained within it is confidential and proprietary to SiliconSystems, Inc.
All unauthorized use and/or reproduction is prohibited.
PAGE 53 | FEBRUARY 2, 2009 |