Interface
5-6 C141-E042-01EN
5.2 Logical Interface
The device can operate for command execution in either address-specified mode;
cylinder-head-sector (CHS) or Logical block address (LBA) mode. The
IDENTIFY DEVICE information indicates whether the device supports the LBA
mode. When the host system specifies the LBA mode by setting bit 6 in the
Device/Head register to 1, HS3 to HS0 bits of the Device/Head register indicates
the head No. under the LBA mode, and all bits of the Cylinder High, Cylinder
Low, and Sector Number registers are LBA bits.
The sector No. under the LBA mode proceeds in the ascending order with the
start point of LBA0 (defined as follows).
LBA0 = [Cylinder 0, Head 0, Sector 1]
Even if the host system changes the assignment of the CHS mode by the
INITIALIZE DEVICE PARAMETER command, the sector LBA address is not
changed.
LBA = [((Cylinder No.) × (Number of head) + (Head No.)) × (Number of
sector/track)] + (Sector No.) − 1

5.2.1 I/O registers

Communication between the host system and the device is done through input-
output (I/O) registers of the device.
These I/O registers can be selected by the coded signals, CS0-, CS1-, and DA0 to
DA2 from the host system. Table 5.2. shows the coding address and the function
of I/O registers.