Fujitsu MPD3XXXAT manual Logical Interface, 1 I/O registers

5.2Logical 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

5.2.1I/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 5.3. shows the coding address and the function of I/O registers.

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