LSI Ultra160 - Manual (Page 25)

Terminating the SCSI Bus 2-9
The Ultra160 SCSI host adapters automatically control SCSI bus
termination for various bus configurations.
In one case, you may disable termination by using BIOS software control
to change the BIOS termination from Automatic to Off.
In another case where jumpers are provided on the board, you would
locate the shunts on the board for autotermination override. Termination
can be disabled by placing a manual shunt over the post. When the
shunt is off, the terminator is active. When the shunt is on the post, the
terminator is disabled.
Figure 2.7 illustrates how the shunt controls
autotermination.
Figure 2.7 Autotermination Shunt
2.3.1 Internal and External SCSI Terminations
If you are making internal SCSI device connections to your host adapter,
you must terminate the last internal device on the SCSI bus. If you are
making external SCSI device connections to your host adapter, you must
terminate the last external device on the SCSI bus. You must disable the
termination on all other devices. Termination on your host adapter is
automatically enabled in this case.
2.3.2 Setting SCSI IDs
You must set each SCSI device and the host adapter to a separate SCSI
ID. The IDs are 0 through 7 for an 8-bit bus and 0 through 15 for a 16-bit
bus. SCSI ID 7 is the preset host adapter setting, giving it the highest
priority on the SCSI bus.
If you plan to boot your computer from a hard disk drive on the SCSI
bus, that drive should have SCSI ID 0, or the lowest SCSI ID on the bus.
Normally, you do not change the host adapter SCSI ID setting. If you
wish to do so, refer to the PCI Storage Device Management System
SDMS 4.0 User’s Guide, which explains how to set your host adapter ID
using the SCSI BIOS Configuration Utility.
Autotermination enabled (no jumper installed)
Termination disabled (jumper installed)