Hitachi 7K250 - Deskstar - Hard Drive Specifications page 226

Cylinder High/Low
H
The drive internally uses 52 bytes of ECC on all data read or writes. The 4-byte mode of operation is provided by
means of an emulation technique. As a consequence of this emulation it is recommended that 52-byte ECC mode
be used for all tests to confirm the operation of the ECC hardware of the drive. Unexpected results may occur if
such testing is performed using 4-byte mode.
This indicates the cylinder number of the sector to be transferred. (L = 0)
In LBA mode this register contains current the LBA bits 8–15 (Low) and bits 16–23
(High). (L = 1)
This indicates the head number of the sector to be transferred. (L = 0)
In LBA mode this register contains current the LBA bits 24–27. (L = 1)
Deskstar 7K250 Hard Disk Drive Specification
212