Apple Duo 270C manual Checking that the Scsi chain is properly terminated, Scsi terminator

Checking that the SCSI chain is properly terminated

To ensure accurate transmission of information, a chain of SCSI devices must have a terminator at each end. Terminators are built into some SCSI devices and can also be added externally.

SCSI terminator

nThe Duo Dock and the Duo MiniDock both have built-in terminators.

nExternal SCSI devices from Apple do not have built-in terminators.

nExternal SCSI devices from other vendors may have built-in terminators; see the documentation that came with the device.

What these facts mean to you: You do not need to add a terminator at the beginning of the chain. You need to make sure that the last (and only the last) device in the chain has an internal or an external terminator.

If you are attaching one SCSI device

Make sure that there is

nan internal terminator in that device, or

nan external terminator attached to that device.

If you are attaching more than one SCSI device

Make sure that there is

nan internal terminator in, or an external terminator attached to, the last device; and

nno other terminator (internal or external) in the chain.

If you have too many devices with internal terminators, your Apple-authorized service provider can remove extra terminators.

Correct chain configurations are shown in the illustration on the following page.

258 Chapter 13: Building a PowerBook Duo System