User Guide

ASUS PCI-SC875 User’s Manual 9
III. INSTALLATION
(SCSI IDs)
III. INSTALLATION
SCSI IDs
Each device on the SCSI bus, including the host adapter, must have a unique SCSI
ID. The SCSI ID serves two purposes:
• It uniquely defines each SCSI device on the bus.
• It determines which device controls the bus when two or more devices try to use
it at the same time.
SCSI IDs on one channel do not interfere with the IDs on another channel. This
applies to two SCSI host adapters that implement different buses as well as dual
channels on a single host adapter.
SCSI ID Priority
On an 8bit SCSI bus, SCSI ID 7 has the highest priority, and SCSI ID 0 has the
lowest priority. From highest to lowest, the complete order is: 7, 6, 5, 4, 3, 2, 1, 0.
On a 16bit SCSI bus, the priority scheme goes from SCSI ID 7 (the highest priority)
to SCSI ID 0, and then from SCSI ID 15 to SCSI ID 8, so that SCSI ID 8 is the very
lowest priority. From highest to lowest, the complete order is: 7, 6, 5, 4, 3, 2, 1, 0, 15,
14, 13, 12, 11, 10, 9, 8.
Setting SCSI IDs
Setting SCSI IDs is a two-step process:
1. Determine the SCSI ID of each device on the SCSI bus.
The default SCSI ID for the host adapter is 7, the highest priority on the bus.
You can change the SCSI ID of the host adapter using the Symbios SCSI Firmare
Setup (see section IV), if necessary, but it is recommended that you leave the ID
on 7. To determine the SCSI IDs of SCSI devices, read the devices’ documenta-
tion and examine their switch settings or jumper settings.
2. Set the SCSI IDs so that no IDs are duplicated on the same SCSI channel.