Sony SDX-700C, Product Specifications Manual

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READ POSITION 6.Command Specification
SONY AIT-3 drive SDX-700 series Ver.2.1 6-79
6.15. READ POSITION 34h
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (34h)
1 Logical Unit Number Reserved TCLP LONG BT
2 Reserved
3 Reserved
4 Reserved
5 Reserved
6 Reserved
7 Reserved
8 Reserved
9 Unused (00b) Reserved Flag Link
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 6-61: READ POSITION Data Format, short form
Bit
Byte
7 6 5 4 3 2 1 0
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.