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CDU-54! CD-ROM DRIVE SCSI INTERFACE MANUAL
5.2.32. SEND DIAGNOSTIC Command
==============================================================================
Bit:
7
6
5
4
3
2
!
o
Byte
1
==============================================================================
o
:
Opera tion Code (!Dh)
:
-----1-----------------------------------------------------------------------1
1
I
Logical Unit Number
:
Reserved
: SelfTest
I
Reserved
:
-----------------------------------------------------------------------:
2
Reserved
I
I
------------------------------------------------~----------------------1
3
(MSB)
I
I
Parameter List Length
4
---I
(LSB) :
-----------------------------------------------------------------------1
5
1
Control Byte
1
==============================================================================
The SEND DIAGNOSTIC command requests the controller to perform diagnostic
tests on itself, on the attached peripheral devices, or on both.
Except when
the self-test bit is one, this command is usually followed by a RECEIVE
DIAGNOSTIC RESULTS command.
A self-test bit of one directs the controller to complete its default self-
test.
If the self-test is
requ~sted,
the parameter list length shall be set
to zero.
If the self-test bit is set to one and the parameter list length is
not zero, the
comm~~d
will be terminated with CHECK CONDITION status.
The
sense key is set to ILLEGAL REQUEST and the additional sense code set to
INVALID VALUE IN COB.
The controller will not disconnect during self-test.
If the self-test does not fail, the command will be terminated with a GOOD
status; otherwise, the command will be terminated with CHECK CONDITION status
and the sense key will be set to HARDWARE ERROR.
The parameter list length specifies the length in bytes of the parameter
list that will be transferred during the DATA OUT phase.
A parameter list
length of zero indicates that no data will be transferred.
This condition
will not be considered as an error.
If the self-test is not requested the controller will return GOOD status
upon receiving a valid command descriptor block and parameter list.
The
parameter list length is set to eight if user specified diagnostics are
requested.
The results of the diagnostic test are returned to the initiator
by a RECEIVE DIAGNOSTICS RESULTS command.
5-58
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