Newsgroups: comp.sys.mac.misc
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!sdd.hp.com!wuarchive!uunet!stanford.edu!neon.Stanford.EDU!kaufman
From: kaufman@neon.Stanford.EDU (Marc T. Kaufman)
Subject: Re: Question: startup beeps diagnostic?
Message-ID: <1991May29.065735.24092@neon.Stanford.EDU>
Organization: Computer Science Department, Stanford University, Ca , USA
References: <0E010021.q0z3vc@gla-aux.uucp>
Date: Wed, 29 May 1991 06:57:35 GMT
Lines: 24

In article <0E010021.q0z3vc@gla-aux.uucp> glenn%gla-aux.uucp@skinner.cs.uoregon.edu writes:

(regarding a disk drive...)

>If it's internally terminated, then it won't work with the IIfx.  That is
>the reason for the black terminator shipped with the IIfx.  It should be
>the ONLY one used to terminate the SCSI bus.

I have quit responding to Mr. Austin's claims that all simms in a bank must
be the same speed.  However, before everyone rips up their internally
terminated disks, I would like to state that internal termination works
just fine on all of the disks I have used on an fx.  The purpose of the new,
black, terminator is to provide a stiffer decoupled power supply for
terminators at the end of a cable -- in order to prevent crosstalk between
the SCSI signals.  In the case of internal termination, especially when
it is powered from the drive itself, the power is local and supplied by a
low impedence source -- so there is essentially no crosstalk introduced by
coupling between the termination resistors.

The black terminator should absolutely be used if the termination (either
internal or external) is powered through the SCSI cable -- but this is rare
in the case of internal termination.

Marc Kaufman (kaufman@Neon.stanford.edu)