MEDIA CHANGE R COMMANDS M2488 PRODUCT GUIDE
6-6 CG00000-011503 REV. A March 1997
6-2.2 MODE SELECT MC command 15h
The MODE SELECT medium-changer command provides a means for the initiator to specify
medium changer device parameters to the target by sending data relevant to such parameters in a data
phase following the command. Initiators should issue MODE SENSE prior to MODE SELECT to
determine supported pages, page lengths, and other parameters. A single set of Mode Select parame-
ters kept by the controller are common to all initiators for a specific LUN. Buffered write data is syn-
chronized to tape prior to activating the new mode parameters.
Mode Select parameters remain in effect until modifie d by another MODE SELECT comm and or
until reset to their saved values following a power on sequence, SCSI bus reset, or SCSI device reset.
Refer to the description of the Mode Sense command for an explanation of the different types of
parameters (PC field).
6-2.2.1 MODE SELECT CDB D escription
MODE SELECT is a six-byte command. The bytes are shown below and described in the follow-
ing paragraphs. Common fields are described in paragraph 4-3.1 on page 4-4.
BITS
BYTES 7 6 5 4 3 2 1 0
000010101
1LUN PF Reserved SP
2Reserved
3Reserved
4Parameter List Length
5Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 6-4. MODE SELECT Field D escription
BYTE BIT VALUE DESCRIPTION
0 0-7 15h Operation code.
1 0 0
1
A Save Pages (SP) bit of zero indicates the target shall perform the specified MODE
SELECT operation, and shall not save any pages in non-volatile memory.
An SP bit of one indicates that the target shall perform the specified MODE
SELECT operation, and shall save to a non-volatile location all the savable pages
sent during the DATA OUT phase.
1 4 0, 1 A PF bit of 0 or 1 both indicate that the Mode Select parameters are structured as
pages of related parameters as defined by the ANSI standard.
4 0-7 >0 The parameter list length field specifies the length in bytes of the MODE SELECT
parameter list to be transferred from the initiator to the target.
A parameter list length of zero indicates that no data is transferred. This condition is
not an error.