Mode Select, Mode
Sense'>
DBD (Dbable Block
Ueseriptors).This
field 'indicates whether
or
not
the
target will
return
any block descriptors. A DBD bit of:zero (0) indicates
that
zero
or
more block descriptors will
be
returned. A
DBDbit
of
one
(l)jndicates
that
no block descriptors will be returned.
PC
(Page Control). This field defines the Parameter Page type
to
be returned.
The
supported
values for this field are:
00
=
Report
Current Values: Returns
the
parameters set in
the
last successful MODE
SELECT
command; or
the
saved values if a MODE SELECT command has not been
executed since the last
Power On, Hard Reset, or Bus Device Reset; or the default values if
saved values are not available.
01
= Report Changeable Values: The changeable values are listed in
the
Parameter Values
table
that
follows each of the page format tables.
10
= Report Default Values: The default values are listed
in
the Parameter Values table
that
follows each of the page format tables.
11
= Report Saved Values: Returns
the
saved values of
the
requested Parameter Pages.
(Savable Pages
are indicated in the following table and in the title block for each page
format ta.ble.) The
Save Block size
is
reported in the Block Length field of
the
Block
Descriptor.
Page Code. This field specifies which page(s) are
to
be returned
to
the initiator. The
target
supports
the
following Mode Sense page codes:
Page
Code
OOH
OIH
02H
03H
04H
OSH
09H
OAH
3FH
Description
Savable
Retwn
No
Pages
nfa
Error
Recovery
Parameters
Yes
Device Disconnect/Reconnect
Parameters
Yes
Direct
Access Device
Format
Parameters
Yes
Rigid Disk Drive Geometry
Parameters
No
Cache
Control
Parameters
Yes
Peripheral
Device
Parameters
Control Mode
Parameters
Retwn
All
Pages
Yes
Yes
n/a
Allocation Length. This field specifies the number of bytes
that
the
initiator has allocated for
returned
MODE SENSE data. An Allocation Length of zero indicates
that
no MODE SENSE
data
will be transferred. This condition is not considered an error. Any other value indicates
the maximum number of bytes
that
will be transferred. The target will terminate the
Data
In
phase when the specified number of bytes have been transferred or when all available
MODE
SENSE
data
have been transferred
to
the initiator, whichever is less.
A·18
SCSI
Command Descriptions
DRAFT
1/18/93 09:58
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