Fujitsu MHU2100AT Product Manual page 86

Interface
(5) Sector Number register (X'1F3')
The contents of this register indicates the starting sector number for the
subsequent command. The sector number should be between X'01' and [the
number of sectors per track defined by INITIALIZE DEVICE PARAMETERS
command.
Under the LBA mode, this register indicates LBA bits 7 to 0.
Under the LBA mode of the EXT system command, LBA bits 31 to 24 are set in
the first setting, and LBA bits 7 to 0 are set in the second setting.
(6) Cylinder Low register (X'1F4')
The contents of this register indicates low-order 8 bits of the starting cylinder
address for any disk-access.
At the end of a command, the contents of this register are updated to the current
cylinder number.
Under the LBA mode, this register indicates LBA bits 15 to 8.
Under the LBA mode of the EXT system command, LBA bits 39 to 32 are set in
the first setting, and LBA bits 15 to 8 are set in the second setting.
(7) Cylinder High register (X'1F5')
The contents of this register indicates high-order 8 bits of the disk-access start
cylinder address.
At the end of a command, the contents of this register are updated to the current
cylinder number. The high-order 8 bits of the cylinder address are set to the
Cylinder High register.
Under the LBA mode, this register indicates LBA bits 23 to 16.
Under the LBA mode of the EXT system command, LBA bits 47 to 40 are set in
the first setting, and LBA bits 23 to 16 are set in the second setting.
5-10 C141-E202-01EN