Terminating The Scsi Bus - Adaptec 1821900 Reference

SCSI ID 7 has the highest priority on the SCSI bus. The priority
of the remaining IDs, in descending order, is 6 to 0, then 15 to 8.
The Adaptec SCSI Card 29160 is preset to SCSI ID 7 and should
not be changed. This gives it the highest priority on the SCSI
bus.
Most internal SCSI hard disk drives come from the factory pre-
set to SCSI ID 0.
If you have 8-bit (or Narrow) SCSI devices, they must use SCSI
IDs 0, 1, 2, 3, 4, 5, or 6. SCSI ID 0 is recommended for the first
SCSI hard disk drive.
If you are booting your computer from a SCSI hard disk drive
connected to the Adaptec SCSI Card 29160, the Boot SCSI ID
setting in the SCSISelect utility must correspond to the SCSI ID
of the device from which you are booting. By default, the Boot
SCSI ID is set to 0. We recommend that you do not change this
setting.
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In Windows 95/98, you can use the Device Manager to deter-
mine which SCSI ID is assigned to each installed SCSI device.

Terminating the SCSI Bus

To ensure reliable communication on the SCSI bus, the ends of the
SCSI bus must be properly terminated. This is accomplished when
the device at the end of each cable, or the end of the cable itself, has a
terminator installed (or enabled). Terminators must be removed, or
termination must be disabled, on devices between the ends of each
cable.
Since the method for terminating a SCSI device can vary widely,
refer to the device's documentation for instructions on how to
enable or disable termination. Here are some general guidelines for
termination:
Internal Ultra160 and Ultra2 SCSI devices come from the fac-
tory with termination disabled and cannot be changed. Proper
termination for internal Ultra160 and Ultra2 SCSI devices is
provided by a 68-pin Internal LVD (low voltage differential)
SCSI cable, which has a built-in terminator at its end.
Overview
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