User's Guide

Commands: Request Block Address (02h) Page 131
REQUEST BLOCK ADDRESS (02h)
The REQUEST BLOCK ADDRESS command requests the drive to transfer the
current block address to the Initiator. This command returns the block address
number on tape.
REQUEST BLOCK ADDRESS Command Descriptor Block
The following table shows the layout of the CDB.
Byte
Bits
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 1 0
1 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0
4 Allocation Length
5 vendor unique* 0 0 0 0 Flag Link
* This vendor-unique field is reserved and must be set to zero.
Command Descriptor Block Field Description
The following table defines the fields in the CDB.
Field
Name Bytes Bits Description
Allocation
Length
4 Set to 0, the default Transfer Length (3) is used. When nonzero, the
number of bytes specified in the Allocation Length (to a maximum of 3
bytes) is transferred.
REQUEST BLOCK ADDRESS Address Data Format
The following table provides the address data format.
Byte
Bits
7 6 5 4 3 2 1 0
0 MSB—Block Address
1 Block Address
2 Block Address—LSB