Fujitsu MHV2120AT Device/Head register X’1F6’, DEV HS3 HS2 HS1 HS0, Status register X’1F7’, Bsy

5.2 Logical Interface

(8) Device/Head register (X’1F6’)

The contents of this register indicate the device and the head number.

When executing INITIALIZE DEVICE PARAMETERS command, the contents of this register defines “the number of heads minus 1” (a maximum head No.).

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
X	L	X	DEV	HS3	HS2	HS1	HS0

-Bit 7: Unused

-Bit 6: L. 0 for CHS mode and 1 for LBA mode.

-Bit 5: Unused

-Bit 4: DEV bit. 0 for the master device and 1 for the slave device.

-Bit 3: HS3 CHS mode head address 3 (23). bit 27 for LBA mode. Unused under the LBA mode of the EXT command.

-Bit 2: HS2 CHS mode head address 2 (22). bit 26 for LBA mode. Unused under the LBA mode of the EXT command.

-Bit 1: HS1 CHS mode head address 1 (21). bit 25 for LBA mode. Unused under the LBA mode of the EXT command.

-Bit 0: HS0 CHS mode head address 0 (20). bit 24 for LBA mode. Unused under the LBA mode of the EXT command.

(9)Status register (X’1F7’)

The contents of this register indicate the status of the device. The contents of this register are updated at the completion of each command. When the BSY bit is cleared, other bits in this register should be validated within 400 ns. When the BSY bit is 1, other bits of this register are invalid. When the host system reads this register while an interrupt is pending, it is considered to be the Interrupt Acknowledge (the host system acknowledges the interrupt). Any pending interrupt is cleared (negating INTRQ signal) whenever this register is read.

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit	2	Bit	1	Bit 0
BSY	DRDY	DF	DSC	DRQ	0		0		ERR

C141-E218 5-11