User's Guide

Commands Page 35
Conventions
The commands in this chapter are listed in alphabetical order. Each command is
described; its Command Descriptor Block (CDB) illustrated; and the Completion
Status is given. Bits and fields defined in the ANSI SCSI-2 document that are not
used by the drive are not described in this document. Rather, those bits and fields
are shown as 0, 1, or X (ignores), as appropriate. Bits and fields that are supported
by the drive are described.
Command Descriptor Blocks (CDBs)
A host makes request of the DAT drives by sending a command descriptor block
(CDB); some commands also require a parameter list. If the CDB or the parameter
list contains an invalid parameter, the drive terminates the command without altering
the medium.
Command Descriptor Block Formats
The SCSI-2 six-byte CDBs are arranged in the format shown in the following table.
Byte
Bits
7 6 5 4 3 2 1 0
0 Group Code | Command Code
1 LUN | Command Dependent
2 Command Dependent
3 Command Dependent
4 Command Dependent
5 vendor unique 0 0 0 0 Flag Link
The SCSI-2 ten-byte CDBs are arranged in the format shown in the following table.
Byte
Bits
7 6 5 4 3 2 1 0
0 Group Code | Command Code
1 LUN | Command Dependent
2 Command Dependent
3 Command Dependent
4 Command Dependent
5 Command Dependent
6 Command Dependent
7 Command Dependent
8 Command Dependent
9 Vendor Unique 0 0 0 0 Flag Link