Commands 115
Commands
READ POSITION 34h
The READ POSITION command returns data representing the current logical
position to the host. The position is the count of all marks and blocks between
BOM and the current logical position. The first block is block 0.
Two forms of the command are supported, the ’traditional’ short form with
BT=0 and a new (SCSI-2) long form where a distinction between partitions,
marks and blocks is drawn.
The Read Position command is complimented by the
LOCATE command.
Pre-Execution Checks:
Command Descriptor Block:
CDB Fields:
Illegal Field Reservation Deferred Error
Unit Attention Media Access Diagnostic Status
7 6 5 4 3 2 1 0
0
Operation Code (34h)
1
Reserved(0) TCLP Long BT (0)
2
Reserved (0)
8
9
Control
TCLP Total Current Logical Position
0 The drive will return data specifying the first and last block location with the
number of bytes and blocks in the buffer.
1 The drive will return data specifying the partition, file, and set number with the
current logical position.
Long 0 The drive will return 20 bytes of data.
1 The drive will return 32 bytes of data.
