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1.1 Command Format
C141-E167 1 - 5
Note:
It is possible that bits 7 and 6 of the control byte will be used in future product specifications
as an inherent control field. It is recommended that zeros be specified in this field.
(6) Handling an illegal CDB
If there is an error in the contents of a description (specification) in the CDB, or if there is an error in
the specifications in parameters transferred from the INIT by CDB specifying, that command ends
with a CHECK CONDITION status. In the case of a command to change the data on the disk media,
when there is an error in the CDB’s specifications, the disk media is not changed by that command.
But when there is an error in the parameters transferred in the DATA OUT phase, the contents of the
disk media in the range specified by the command may be changed. Also, even in cases where there
is an error in the CDB’s specifications in a command accompanying the DATA OUT phase, the
DATA OUT phase is executed after the COMMAND phase is terminated, but those data are not
used. For example, if there is an error in the CDB specification of a WRITE command, the IDD
executes the transfers several bytes of data (the data length to be transferred is not specified), but
those data are not written to the disk media. Details are described in the individual command
specifications in Chapter 3.
If there is an error in the CDB specification in a command which executes disconnect processing
(shown in Section 1.3.3), the disconnect processing may be executed after the COMMAND phase is
terminated. In this case, reconnect processing is executed afterward and the status (CHECK
CONDITION) is reported.
Note:
If a CDB with an undefined group code (group 3, 4) is specified, the IDD requests transfer of 10
bytes in the COMMAND phase. After that has been received, the status (CHECK CONDITION)
is reported.