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From: billkatt@sol.engin.umich.edu (Steve Bollinger)
Newsgroups: comp.sys.mac
Subject: Re: Apple HD80SC... Quantum ???
Message-ID: <40f20383.a590@mag.engin.umich.edu>
Date: 18 Jan 89 22:26:00 GMT
References: <19105@agate.BERKELEY.EDU> <8400055@m.cs.uiuc.edu> <40f1d90b.10342@fir.engin.umich.edu>
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In article <40f1d90b.10342@fir.engin.umich.edu> swerling@caen.engin.umich.edu (Ace Swerling) writes:
>standard SCSI is that Apple uses a 25 pin port while the standard
>calls for a 50 pin port.  Apple claims not to need the extra 25
>pins, so they're not going to use them.  Recently, a bunch of
>computer manufacturers got together to discuss the standard.
>Apple, surprisingly, was not one of the first organizations to
>attend.  They got their act together later though and seem to be
>working towards more standardization.  Maybe we'll see more
>standards coming out of Apple...   Nahh.  ;-)

In standard SCSI half the wires are tied to ground.  Apple just removed these
wires and substitutes one ground wire.  Apple saved a lot of space that way.
They are used to help supress interference.  However, most of us don't use
anywhere near the maximum length of SCSI which is well over 100 feet
(1000 ft?).  The signals are carried through the cables, they just merge to
one ground at the connector.  The Laserwriter IINTX uses a "standard connector",
as well as all Apple hard drives.  I use standard connector in quotes because
it is no more standard than the 25 pin DB.  Look at the back of a Sun some
time, their connector is no more standard than the DB-25.

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| Steve Bollinger      | Internet: billkatt@caen.engin.umich.edu            |
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