Section 5
SCSI Programming Guidelines
PARAMETER
LIST
LENGTH
(Byte 4) - Specifies the length
in
bytes
of
the MODE
SELECT 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 should not be considered an error.
5.11.10.2 MODE SELECT Parameter List
The MODE SELECT parameter list (Table 5-24) contains a four-byte header, followed
by
zero or one block
descriptor, then zero
or
more "pages".
TABLE 5-24 MODE
SELECT
Parameter List
Bit 7
6 5
4
3
2 1 o
Byte
Mode Select Header:
0 RESERVED
=0
1 MEDIUM TYPE = 0
2 RESERVED
=0
3
BLOCK DESCRIPTOR LENGTH (BYTES)
Block Descriptors
0 DENSITY CODE = 0
1-3
(MSB)
NUMBER
OF
BLOCKS = 0
(LSB)
4
RESERVED
=0
5-7
(MSB)
BLOCK
LENGTH
(LSB)
p
age
D
( )
escrlptor
s :
0 RESERVED
=0
I
PAGE CODE
t PAGE LENGTH
2
ton
REFER TO PAGE DESCRIPTION
MEDIUM
TYPE
(Byte 1) - Set to zero for default (currently mounted medium type) since the
ProDrive has non-removable media.
BLOCK
DESCRIPTOR
LENGTH
(Byte 3) - Specifies the length in bytes
of
all the block
descriptors. It is equal to the number
of
block descriptors times eight; it does not include the pages,
if
any. A block descriptor length
of
zero indicates that no block descriptors wil be included
in
the
parameter list. A single block descriptor is used for the
ProDrive.
BLOCK
DESCRIPTORS:
The block descriptors specify the logical block length for the drive
including a density code, number
of
blocks, and block length.
DENSITY
CODE
(Byte 0) - Set to zero, indicating the default density
of
the medium, since the
ProDrive uses only one density.
5·42
SCSI
Programming
Guidelines
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