> If you reassign the disk to 4, 5 or 6, then the CD at 3 needs to be
> terminated, and the disk un-terminated

Actually, and I don't know if anyone has said this before...

A SCSI ID is actually really a LUN (Logical Unit Number) and has nothing to
do with SCSI termination. The order the Logical units appear on the SCSI
chain *also* has nothing to do with the LUN. SCSI just sees the logical
units in order, no matter their physical order, because they are Logical
unuts (rather than fixed order units.) SCSI wouldn't work properly if this
were not true.

What matters - and this is probably where people are making mistakes - is
that the _last physical_ unit on the chain needs to be terminated. I have
had drives with completely random SCSI ID's in SCSI chains and they all work
absolutely happily - so long as the drive at the end of the chain is
terminated. Besides the fact that external drives on a lot of Mac's are
still on the SCSI bus (albeit through an external connection) and the ID's
do not follow numerical order in that scenario, SCSI was about flexibility.

For example....

7*--->4--->3--->5--->0*  is fine on an internal bus with
7*--->6--->2* on the external bus

7*--->0--->6--->1--->2*  is fine on an internal bus with
7*--->5--->3* on the external bus

(where * is terminated.)

If you start terminating devices in the middle of the chain because of their
numerical order, you'll loose half the chain or your Mac will get REALLY
confused and will fail to start or become extremely unstable.

Hope that helps,

Matt


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