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READ POSITION
BPU: A Block Position Unknown (BPU) bit of one indicates that the First and Last Block Locations are not known or
cannot be obtained. A BPU bit of ZERO indicates that the First contains valid position information. Support for this
option of the READ POSITION command is indicated by a BIS bit set to one in the MODE SELECT Device
Configuration page.
Partition Number: reports the current partition number for the current logical position.
First block location: indicates the Block Address associated with the current logical position. The value shall
indicate the Block Address of the next data block to be transferred between the initiator and the target if a READ or
WRITE command is issued. See BT field for description of Logical Block Address. Note that the Logical Block
Address at BOT/P is 0.
Last block location: indicates the Block Address associated with the next block to be transferred from the buffer to
the medium. The value shall indicate the Block Address of the next data block to be transferred between the buffer
and the medium. If the buffer does not contain a whole block of data or is empty, the value reported for the last block
location shall be equal to the value reported for the first block location.
Number of Blocks in Buffer: indicates the number of data blocks in the buffer of the logical unit that have not been
written to the medium.
Number of Bytes in Buffer: This field is not supported and is always set to ZERO.
Bit
7
Byte
0
BOP
1
2
3
4
(MSB)
7
8
(MSB)
15
16
(MSB)
23
24
(MSB)
31
The BOP, EOP, and Partition Number are as defined in the READ POSITION data returned when the TCLP bit is set
to 0.
BPU: The Block Position Unknown (BPU) bit of ONE indicates the partition number or block number are not know or
accurate reporting is not currently available. The BPU bit of ZERO indicates the partition number and block number
fields contain valid position information.
MPU: The Mark Position Unknown (MPU)bit of ONE indicates the file number and set number are not known or
accurate reporting is not currently available. The MPU bit of ADRO indicates the File number and Set number fields
contain valid position information.
Block Number: Block Number reports the number of logical blocks between beginning-of-partition and current
logical position. Set-marks and File-marks count as one logical block each.
File Number: File Number reports the number of file-marks between beginning-of-partition and the current logical
position.
Set Number: Set Number reports the number of set-marks between beginning–of-partition and the current logical
position.
SONY AIT-2 Turbo drive SDX-550V series Ver.1.0
Table 6-62: READ POSITION Data Format, long form
6
5
EOP
Reserved
4
3
MPU
BPU
Reserved
Reserved
Reserved
Partition Number
Block Number
File Number
Set Number
6.Command Specification
2
1
0
Reserved
(LSB)
(LSB)
(LSB)
(LSB)
6-73
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