Product manual

If the drive detects invalid parameter data during the Mode Select
command, the drive sends a sense key of
illegal request with an
additional sense code of
invalid field in parameter list and no parameters
are changed.
Bit
Byte
7 6 5 4 3 2 1 0
0 0 0 0 1 0 1 0 1
1 LUN PF = 1 0 0 0 SP
2 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0
4 Parameter list length
5 0 0 0 0 0 0 Flag Link
Byte 1 The
page format (PF) bit is always one. This means that the data
sent by the initiator after the mode select header and block
descriptors complies with the page format.
When the
SP (save mode parameters) bit is 1, the drive saves
the savable pages in RAM and on the disc. When the
SP (save
mode parameters)
bit is 0, the drive saves the savable pages in
RAM only, which means that the parameters are lost when the
drive is powered down. When the drive executes the Mode
Select command, it does not save the Format Device page (03
H
)
and the Rigid Disc Geometry page (04
H
); it saves these pages
during the Format Unit command.
Byte 4 The
parameter list length specifies the length, in bytes, of the
header and mode page transferred to the drive. A parameter list
length of 0 means that no data is transferred. To calculate the
parameter list length for any given mode page, add the parame-
ter list header (4 bytes), the block descriptor (if any, 8 bytes), the
2-byte mode page header and the length of the mode page. For
the lengths of the mode pages, refer to Appendix C.
ST3655 Family SCSI Drives Product Manual, Rev. A 49