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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
5 .2. 3 . MODE SENSE CollUlland
==============================================================================
Bit I
Byte :
7
6
5
4
3
2
1
o
=============================================================================-
o
i
Operation Code (lAh)
-----i-----------------------------------------------------------------------
1
: Logical Unit Number
i
Reserved
-----1-----------------------------------------------------------------------
2
i
PC
i
Page Code
-----i-----------------------------------------------------------------------
3
:
Reserved
I
-----1-----------------------------------------------------------------------i
4
1
Allocation Length
1
-----1-----------------------------------------------------------------------\
5
1
Control Byte
:
==============================================================================
The MODE SENSE command provides a means for a controller to report
parameters to the initiator.
It is a complementary command to the MODE SELECT
command.
The page control (PC) field defines the type of parameter values to be
returned as shown below.
Table 5-5: Page Control Bit Definition
======================================
DB(7)
DB(6)
Type of Parameter Values
------------------------
0
0
Current Values
0
1
Changeable Values
1
0
Default Values
1
1
Default Values
======================================
5.2.3.1. Current Values
A PC field value of Oh requests the controller return the current values for
the page code specified.
The current values returned are either the
parameters set in the last successful MODE SELECT command or the default
values if a MODE SELECT command has not been executed.
5.2.3.2. Changeable Values
A PC field value of lh requests the controller return the changeable values
for the page code specified.
The page requested will be returned with the
bits that are allowed to be changed set to one.
Parameters that are not
changeable will be set to zero.
If any part of a field is changeable all bits
in that field are set to one.
The page descriptor as defined in this document will always be returned even
if none of parameters are changeable within the page.
5-11
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