What we need is a set of consistent and clear algorithms for particular Macs so anyone can get their SCSI chains right.
SCSI is easy.
Both the beginning and the end of the chain must always be terminated. SCSI-1 requires passive termination (that cheap plug you just stick on, or a jumper). SCSI-2 requires active termination (an expensive plug, or a jumper).
Only add a mid-chain terminator if there are long cable runs, or cheap badly shielded cables, to prevent extraneous reflections. You can tell if you need this because you have a long chain (greater than 2 or 3 meters), both ends are already properly terminated, and you're still getting periodic system freezes.
Now, there is one caveat: If your SCSI chain is extremely short, you can *sometimes* get away with NOT terminating it. But this is NOT part of the SCSI spec: it works because of luck. You're better off terminating.
For both the internal and external (off the built in SCSI) chain in the 7600/7300, I know one for sure: The Mac 7600/7300 is terminated and has ID 7
The 7300 has two *separate* SCSI buses (chains).
The internal is Fast SCSI-2 (10 MB/sec).
The external is regular SCSI-1 (5 MB/sec).
Each chain is terminated on the motherboard. That means *you* only need to terminate the *last* device in *each* chain.
Remember: SCSI ID numbers have NOTHING to do with the termination. You have to look at the actual cabling...
HTH, - Dan.
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