User's Manual

DLT4000 SCSI Interface
8-46 DLT4000/DLT4500/DLT4700 Cartridge Tape Subsystem
8.4.9 MODE SELECT (15h)
Bit
7 6 5 4 3 2 1 0
0 Operation Code (15h)
1 Logical Unit Number PF Reserved SP(0)
Byte 2 Reserved
3 Reserved
4 Parameter List Length
5 Unused (00) Reserved Flag Link
Figure 8-29 MODE SELECT CDB
MODE SELECT enables the host to configure the device. Implementing MODE
SELECT and MODE SENSE requires a certain amount of handshaking between the
host and the drive. Before configuring the drive, the host should issue a MODE
SENSE to get the current configuration and determine what parameters are
configurable. The host interprets this information and may then issue MODE
SELECT to set the drive to the host's preferred configuration.
The drive always powers up with its default configurations set. This is also true if the
drive receives a BUS DEVICE RESET message or a hard reset through the RST line
on the SCSI bus.
PF
The Page Format bit indicates that the data sent by the host after the MODE SELECT
header and block descriptors complies with the definition of pages in the SCSI-2
specification. The SCSI-1 format will not be implemented, so this bit is required to be
set. It is an ILLEGAL REQUEST to have page parameters while the PF bit is off.
SP
This bit must be zero. The save Parameters bit instructs the drive to save all savable
pages. This is not supported.
PARAMETER LIST LENGTH
This specifies the length in bytes of the MODE SELECT parameter list that is
transferred during the DATA OUT phase. A zero Parameter List Length indicates that
no data is transferred.