Fujitsu MBA3073RC, MBC2036RC, MBC2073RC Bit Byte Operation Code, Control Byte, Operation code

								2.1	Command Format
			Table 2.3 12-Byte CDB basic format
	Bit	7	6	5		4	3	2	1	0
Byte
0						Operation Code
1			Reserved			0	0	0	0	0
2					Logical Block Address (MSB)
3					Logical Block Address
4					Logical Block Address
5					Logical Block Address (LSB)
6					Transfer Data Length (MSB)
7					Transfer Data Length (LSB)
8					Transfer Data Length (MSB)
9					Transfer Data Length (LSB)
10		0	0	0		0	0	0	0	0
11					Control Byte

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

Table 2.4 Operation code

Bit 7		6	5	4	3		2	1	0
	Group Code					Command 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 HDD uses the commands of the groups shown below.

Group 0 ("000"): 6-byte CDB (Shown in Table 2.1)

Group 1 ("001"): 10-byte CDB (Shown in Table 2.2)

Group 2 ("010"): 10-byte CDB (Shown in Table 2.2)

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