Sector Addressing Mode - Hitachi HTS541616J9AT00 - Travelstar 160 GB Hard Drive Specifications

12.4

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 HTS5416XXJ9AT00 is different from the actual physical CHS location of the data sector on the disk media.
HTS5416XXJ9AT00 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 register. So a host system must set the L bit to 1 if
the host uses LBA Addressing mode.
12.4.1 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 translation
mode also is described in the Identify Device Information.
12.4.2 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
LBA High <--- LBA bits 23-16
LBA Mid <--- LBA bits 15- 8
LBA Low <--- LBA bits 7- 0
Travelstar 5K160 (PATA) Hard Disk Drive Specification
<--- LBA bits 27-24
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