Chapter 1 Command Processing; 1.1 Command Format; Figure 1.1 6-Byte Cdb Basic Format - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

Command Processing
CHAPTER 1

1.1 Command Format

1.2 Status
1.3 Outline of Command Processing
1.4 Command Queuing Function
1.5 UNIT ATTENTION Condition
1.6 Sense Data Hold State
1.7 Command Processing Exceptions
1.8 Data Block Addressing
This chapter describes the basic logical specifications of the IDD command processing functions.
Note: The IDD operates as the target (TARG) on the SCSI bus. In the explanations in this chapter, the IDD
is mentioned as "TARG", except in cases where a particularly clear distinction is necessary.
1.1 Command Format
Input/output operation commands from INIT (initiator) to the IDD are accomplished by the CDB
(Command Descriptor Block).
COMMAND phase. In a number of commands, the parameters which are necessary for command
execution in the DATA OUT phase may be specified in addition to the CDB specification. Details
concerning these are described in the specifications for each individual command in Chapter 3.
The CDB used by the IDD has 3 formats, these formats have length of 6, 10 and 12 bytes.
The basic format of each respective CDB is shown in Figures 1.1, 1.2 and 1.3.
Bit
7
Byte
0
1
2
3
4
5
C141-C010
The CDB is information transferred from INIT to TARG in the
6 5 4
Operation Code
LUN
Logical Block Address
Logical Block Address (LSB)
Transfer Data Length
Control Byte
Figure 1.1 6-Byte CDB Basic Format
3 2
Logical Block Address (MSB)
1 0
1-1