Sony SDX-800V/R manual Read Position 34h, Tclp Long, Bop Eop, Bpu

READ POSITION 6.Command Specification

6.16.READ POSITION 34h

Bit	7	6	5	4		3	2	1	0
Byte
0				Operation		Code (34h)
1		Obsolete			Reserved		TCLP	LONG	BT
2					Reserved
3					Reserved
4					Reserved
5					Reserved
6					Reserved
7					Reserved
8					Reserved
9					Control

The READ POSITION command reports the current position of the logical unit. No medium movement shall occur as a result of the command. The position is given in two parts:

TCLP: The Total Current Logical Position (TCLP) bit of ONE indicates the drive shall return data specifying the partition, file, and set number with the current logical position. The TCLP bit of ZERO indicates the drive shall return data specifying the first and last block location with the number of bytes and blocks in buffer.

LONG: The Long Format (LONG) bit of ONE indicates the drive shall return 32 bytes of data. The LONG bit of ZERO indicates the drive shall return 20 bytes of data.

The LONG bit and the TCLP bit shall be equal. If the LONG and TCLP bits are not equal, or if both the LONG and the Block Address Type (BT) bits are ONE, the command is rejected with a CHECK CONDITION status and an ILLEGAL REQUEST sense key set.

BT: The Block Address type (BT) bit controls the content of the short format data. The BT bit if one requests the drive to return its current First Block Location shall include data block only. The BT bit of ZERO requests the drive to return the First Block Location are a SCSI Logical Block Address (data blocks, File-marks and Save Set Marks are counted.)

Table 6-75: READ POSITION Data Format, short form

Bit	7	6	5		4	3	2	1		0
Byte
0	BOP	EOP			Reserved		BPU		Reserved
1					Partition Number
2					Reserved
3					Reserved
4	(MSB)				First Block Location
7										(LSB)
8	(MSB)				Last Block Location
11										(LSB)
12					Reserved
13	(MSB)			Number of Blocks in Buffer
15										(LSB)
16	(MSB)		Number of Bytes in Buffer			(00 00 00 00h)
19										(LSB)

BOP: A Beginning Of Partition (BOP) bit of one indicates that the logical unit is at the beginning-of-partition in the current partition. A BOP bit of ZERO indicates that the current logical position is not at the beginning-of-partition.

EOP: An End Of Partition (EOP) bit of one indicates that the logical unit is positioned between early-warning and end-of-partition in the current partition. An EOP bit of ZERO indicates that the current logical position is not between early-warning and end-of-partition. Note that this bit is mutually exclusive with the BOP bit.

SONY AIT-3Ex drive SDX-800V series Ver.1.1 6-75