HP SureStore 220mx User Manual page 89

Operating This Jukebox on a SCSI Bus
The SCSI Bus and This Jukebox
can't "see" the upper 8 data bits, that translates to it not being able to
"see" wide devices with a SCSI ID of 8 or above. Remember the host
adapter is a device, so if you're mixing wide and narrow devices on the
bus, your host adapter must be at an ID that all devices can address.
If mixing narrow and wide devices is unavoidable, use the configuration
shown in the following diagram. When looking at the diagram note that,
while this is a "legal" SCSI configuration, it is not a configuration that is
recommended by Hewlett-Packard. As a general rule, HP recommends
that the jukebox be the only device on a bus. If there are multiple devices
on the bus, performance of one or all of the devices on the bus can be
affected
[1]Bus Adapter - connecting point for all SCSI devices
[2] Wide SCSI Device - accepts IDs from 0 to 15
[3] Wide SCSI Cable - 68-pin SCSI Cable
[4] 68-50-Pin SCSI Cable - adapts from wide to narrow connectors - high 18 lines
must be terminated
[5] Narrow SCSI Device - accepts IDs from 0 to 7
[5] Terminator - device on the ends of a SCSI bus to prevent reflected signals on
the bus (50-pin)
It is very important that the 68-pin to 50-pin cable is properly configured
to assure that the eighteen truncated lines are properly terminated.
Appendix B B-9