Conventions; Command Descriptor Blocks; Command Descriptor Block Formats - Seagate Viper 200 Scsi Interface Manual

SCSI Commands

Conventions

Command Descriptor Blocks

Command Descriptor Block Formats

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 documents that are not
used by the drive are not described in this document. Bits and fields that are
supported by the drive are described.
A host makes request of the tape drive 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, returning a
Sense Key of Illegal Request, without altering the medium.
SCSI six-byte Command Descriptor Blocks are arranged in the format shown in the
following table.
Bits
Byte 7 6
0
1 Ignored LUN
2
3
4
5
SCSI ten-byte Command Descriptor Blocks are arranged in the format shown in the
following table.
Bits
Byte 7 6
0
1 Ignored LUN
2
3
4
5
6
7
8
9
Field names that are centered represent fields that are at least one byte long. Field
names that are left-aligned with a bit number are one or more bits long. The length is
indicated by the beginning of the following field name, and by the Bits column in the
Field Descriptions table, shown below.
5 4 3
Operation Code
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Control
5 4 3
Operation Code
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Command Dependent
Control
Page 17
2 1 0
2 1 0