Sector Addressing Mode; Logical Chs Addressing Mode; Lba Addressing Mode - IBM DARA-206000 - Travelstar 12 GB Hard Drive Specifications

10.4 Sector Addressing Mode

All addressing of data sectors recorded on the device's media is by a logical sector address. The logical CHS
address for DARA-2xxxxx is different from the actual physical CHS location of the data sector on the disk
media.
DARA-2xxxxx support both Logical CHS Addressing Mode and LBA Addressing Mode as the sector
addressing mode.
The host system may select either the currently selected CHS translation addressing or LBA addressing on a
command-by-command basis by using the L bit in the DEVICE/HEAD register. So a host system must set
the L bit to 1 if the host uses LBA Addressing mode.

10.4.1 Logical CHS Addressing Mode

The logical CHS addressing is made up of three fields: the cylinder number, the head number and the sector
number. Sectors are numbered from 1 to the maximum value allowed by the current CHS translation mode
but can not exceed 255(0FFh). Heads are numbered from 0 to the maximum value allowed by the current
CHS translation mode but can not exceed 15(0Fh). Cylinders are numbered from 0 to the maximum value
allowed by the current CHS translation mode but cannot exceed 65535(0FFFFh).
When the host selects a CHS translation mode using the INITIALIZE DEVICE PARAMETERS
command, the host requests the number of sectors per logical track and the number of heads per logical
cylinder. The device then computes the number of logical cylinders available in requested mode.
The default CHS translation mode is described in the Identify Device Information. The current CHS trans-
lation mode also is described in the Identify Device Information.

10.4.2 LBA Addressing Mode

Logical sectors on the device shall be linearly mapped with the first LBA addressed sector (sector 0) being
the same sector as the first logical CHS addressed sector ( cylinder 0, head 0, sector 1). Irrespective of the
logical CHS translation mode currently in effect, the LBA address of a given logical sector does not change.
The following is always true:
LBA = ( (cylinder * heads_per_cylinder + heads)
* sectors_per_track ) + sector - 1
where heads_per_cylinder and sectors_per_track
are the current translation mode values.
On LBA addressing mode, the LBA value is set to the following register.
Device/Head <---
Cylinder High <---
Cylinder Low <---
Sector Number <---
LBA bits 27-24
LBA bits 23-16
LBA bits 15- 8
LBA bits 7- 0
General Operation Descriptions
77