Bit
7
Byte
0
1
Reserved
2
3
4
5
6
7
8
9
10
0
11
The meanings of each of the fields in the CDB are explained below. Depending on
the type of command, the basic format of the CDB and the definition and meaning
of a field may differ. Details are described in the specifications for individual
commands in Chapter 4.
(1) Operation code
Bit 7
6
Group Code
The top byte of all CDBs shows the format and type of command that is being
executed.
a.
Group code
The group code decides the number of bytes in the CDB and its format. The
IDD uses the commands of the groups shown below.
Group 0 ("000"): 6-byte CDB (Shown in Figure 2.1)
Group 1 ("001"): 10-byte CDB (Shown in Figure 2.2)
Group 2 ("010"): 10-byte CDB (Shown in Figure 2.2)
C141-C009
Table 2.3 12-Byte CDB basic format
6
5
4
Operation Code
0
Logical Block Address (MSB)
Logical Block Address
Logical Block Address
Logical Block Address (LSB)
Transfer Data Length (MSB)
Transfer Data Length (LSB)
Transfer Data Length (MSB)
Transfer Data Length (LSB)
0
0
0
Control Byte
Table 2.4 Operation code
5
4
3
2.1 Command Format
3
2
0
0
0
0
2
1
Command Code
1
0
0
0
0
0
0
2-3