Hitachi T7K250 - Deskstar - Hard Drive Specifications page 156

Cylinder High/Low
H
In LBA mode this register contains the current LBA bits 0–7. (L = 1)
This indicates the cylinder number of the last transferred sector. (L = 0).
In LBA mode this register contains the current LBA bits 8–15 (Low) and bits16–23
(High). (L=1)
This indicates the head number of the sector to be transferred. (L = 0)
In LBA mode this register contains the current LBA bits 24–27. (L = 1)
Deskstar T7K250 Hard Disk Drive Specification
142