Hitachi 7K400 - Deskstar Hard Drive Specifications page 254

Cylinder High/Low 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 16–23 (High).
(L = 1)
H This indicates the head number of the last transferred sector. (L = 0)
In LBA mode this register contains the current LBA bits 24–27. (L = 1)
Deskstar 7K400 Hard Disk Drive Specification
240