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ACL 4/52 Software Interface Guide
Document 6211225-03
Version 3.0
3-26
SCSI Interface
DBD
The disable block descriptors (DBD) field can be one or zero. A bit
of zero indicates that the target may return zero or more block
descriptors in the returned Mode Sense data at the target’s
discretion. A DBD bit of one specifies that the target does not
return any block descriptors in the returned Mode Sense data.
PC
The Page Control (PC) field defines the type of parameter values to
be returned:
0
requests the current parameter values for the specified
page code for the library. The current values returned are
the default values.
1
requests the target to return the changeable parameter
mask for the page code specified. The page requested is
returned containing information that indicates which
parameters are changeable.
2
requests the target return the default values for the page
code specified.
3
requests the target return saved values for the page code
specified. Only the Vendor Unique Page has
changeable/savable parameters. Otherwise, the current
setting for each parameter is always the same as the setting
that parameter had when the library was turned on.
Page Codes
The valid page codes are:
00h
Vendor Unique Page 00h
1Dh
Element Address Assignment Page
1Eh
Transport Geometry Parameters Page
1Fh
Device Capabilities Page
20h
Vendor Unique Page 20h
3Fh
Return All Pages
Allocation Length
This should be set according to the number of bytes in the page
that has been requested:
44h
Vendor Unique Page 00h
18h
Element Address Assignment Page
08h
Transport Geometry Parameters Page
18h
Device Capabilities Page
08h
Vendor Unique Page 20h
84h
Return All Pages
The parameter data returned for each Mode Sense command is
preceded by a Mode Parameter Header Block. The header block is then
followed by either the requested parameter page or all pages if the
Return All Pages page code was used.