🚀 go-pugleaf

I am seeing some unexplained behavior on the SCSI bus of my Mac IIci.
It's as if there was a hidden terminator on the bus, or perhaps
terminator power is shorted to ground.

Some time ago I added an external drive and played around with
terminators.  The only combination that seemed to work was to completely
remove termination from the external end of the SCSI chain.  This seems
bizarre; you need a terminator at both ends of the chain, or so I've
been led to believe.  Even removing the terminators from the internal
hard drive didn't help.

So I suspect the external terminator power is shorted to ground
somewhere in the SCSI chain.  That's the only rational explanation for
the behavior I saw.  Is this true of all Mac 25-pin <-> Centronics
50-pin cables?

Now I've replaced the internal hard drive with a larger one, and I need
to know two more things:
 - Does the IIci supply terminator power to the internal SCSI bus?
 - Is there a terminator somewhere on the logic board of the IIci,
separate from the internal terminator on the drive?

If I seem confused, I am.  I would appreciate authoritative answers on
these questions.  Thanks in advance.
 -- Chuck
-- 
Chuck Fry  chucko@best.com  chucko@rahul.net  chucko@ptolemy.arc.nasa.gov
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