Adaptec SBC-599 - Manual (Page 75)

Chapter 6 SCSI Setup and Configurations 65
The AIC-7880 supports the SCSI Configured AutoMatically
(SCAM) protocol, which assigns SCSI IDs dynamically and
resolves SCSI ID conflicts automatically at bootup. If your
system includes SCSI disk drives or other devices that support
SCAM, you do not need to manually assign SCSI IDs to these
devices.
Most SCSI devices currently in use, however, do not support
SCAM. The SCSI IDs on these devices must be set manually. To
change the SCSI IDs on these devices, refer to the device’s
documentation.
If you install more than one SCSI host adapter in the computer,
each adapter forms a separate SCSI bus. SCSI IDs can be reused
as long as the ID is assigned to a device on a separate SCSI bus
(e.g., each SCSI bus can have a device with SCSI ID 0).
SCSI Terminators
To ensure reliable communication, the SCSI bus must be properly
terminated. Termination is controlled by a set of electrical
resistors, called terminators. Terminators must be placed (or
enabled) at the two extreme ends of the SCSI bus. All devices
that lie between the ends must have their terminators removed (or
disabled).
Termination on the Ultra Wide SCSI itself is controlled by
software commands via the SCSISelect utility. The default setting
is set to Automatic. When set to Automatic, if the AIC-7880
detacts that SCSI cables are connected to any of its two SCSI
connectors, it automatically sets the termination setting for the
low and high bytes of the 16-bit Wide SCSI bus. The low byte
controls 8-bit SCSI; the low and high bytes together control 16-bit
Wide SCSI.