ATA PASS-THROUGH (12) command

ATA PASS-THROUGH (12) command (A1h)

Bit Byte	7	6	5		4	3	2	1	0
0	OPERATION CODE (A1h)
1	MULTIPLE_COUNT				PROTOCOL			Reaseved
2	OFF_LINE			CK_COND	Reserved	T_DIR	BYT_BLOK	T_LENGTH
3	FEATURES (0:7)
4	SECTOR_COUNT (0:7)
5	LBA_LOW (0:7)
6	LBA_MID (0:7)
7	LBA_HIGH (0:7)
8	DEVICE
9	COMMAND
10	Reserved
11	CONTROL

ATA Protocols

Protocol	Description
0	Hard Reset
1	SRST
2	Reserved
3	Non-data
4	PIO Data-In
5	PIO Data-Out
6	DMA
7	DMA Queued
8	Device Diagnostic
9	DEVICE RESET
10	UDMA Data In
11	UDMA Data Out
12	FPDMA
13, 14	Reserved
15	Return Response Information

ATA PASS-THROUGH (12/16) DEVICE field

Bit	7	6	5	4	3	2	1	0
	Obsolete	Command Specific	Obsolete	DEV	Command Specific

T_LENGTH Values

Protocol	Description
00h	No data is transferred
01h	The transfer length is specified in the FEATURE field.
02h	The transfer length is specified in the SECTOR_COUNT field.
03h	The transfer length is specified in the STPSIU field.

Extended ATA Status Return Descriptor

Bit Byte	7	6	5	4	3	2	1	0
0	DESCRIPTOR CODE (09h)
1	ADDITIONAL DESCRIPTOR LENGTH (0ch)
2	Reserved							EXTEND
3	ERROR
4	SECTOR_COUNT (8:15)
5	SECTOR_COUNT (0:7)
6	LBA_LOW (8:15)
7	LBA_LOW (0:7)
8	LBA_MID (8:15)
9	LBA_MID (0:7)
10	LBA_HIGH (8:15)
11	LBA_HIGH (0:7)
12	DEVICE
13	STATUS
14
15