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CHAPTER 1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
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). The CDB is information transferred from INIT to TARG
in the 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 2 formats, one with a length of 6 bytes and the other with a
length of 10 bytes. The basic format of each respective CDB is shown in Fig. 1.1 and Fig. 1.2.
COMMAND PROCESSING
Command Format
Status Byte
Outline of Command Processing
Command Queuing Function
UNIT ATTENTION Conditions
Sense Data Maintenance State
Command Processing Exceptions
Data Block Addressing
C141-E039-01EN
1 - 1
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