9 Jul
2009
9 Jul
'09
1:05 p.m.
Date: Thu, 9 Jul 2009 12:00:48 -0400
From: Ethan Dicks <ethan.dicks at gmail.com>
I tried to look that up and found it easy to see that
the IIfx needed
something odd (I couldn't find specifics), so well done there. It
would be interesting to get the details to see where Apple went off
the rails from the SCSI spec.
IIRC, it's a matter of adding a capacitor and maybe a resistor to a
regular terminator. There's an Apple Technical Note or similar available
somewhere. I probably have a copy squirreled away on my hard drive at
home. And I think I remember that they use a somewhat higher value
capacitor (so add a smaller one in parallel on an existing terminator) and
a lower resistance (so again, add a resistor in parallel). But I could
be misremembering.
Again, IIRC, the IIfx's SCSI was too noise sensitive. But I've also
heard/read that that was only true for the early production run and that
the later built machines did not need the funny terminator.
Then I would
only need to find an AUI to RJ-45 doodad
which is skinny enough to fit into the recessed ports on the IIfx. I
have an AUI thingy now, but it's too fat to reach the db-15 connector
on the network card.
http://lowendmac.com/ii/macintosh-iifx.html
Are you sure that's an AUI connection? I would expect a Mac of that
vintage to have a DA-15 for video but not Ethernet. 
9 Jul
9 Jul
11:14 p.m.
----- Original Message -----
From: <trag at io.com>
To: <undisclosed-recipients:>
Sent: Thursday, July 09, 2009 4:05 PM
Subject: Re: Classic mac fun (and some questions)
(continued...again...)
From: "Jeff Walther" <trag at io.com
To: cctech at classiccmp.org
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> Date: Thu, 9 Jul 2009 12:00:48 -0400
> From: Ethan Dicks <ethan.dicks at gmail.com
Neither of my IIfx systems need that terminator to work.
I tried to look that up and found it easy to see
that the IIfx needed
something odd (I couldn't find specifics), so well done there. It
would be interesting to get the details to see where Apple went off
the rails from the SCSI spec.
IIRC, it's a matter of adding a capacitor and maybe a resistor to a
regular terminator. There's an Apple Technical Note or similar available
somewhere. I probably have a copy squirreled away on my hard drive at
home. And I think I remember that they use a somewhat higher value
capacitor (so add a smaller one in parallel on an existing terminator) and
a lower resistance (so again, add a resistor in parallel). But I could
be misremembering.
Again, IIRC, the IIfx's SCSI was too noise sensitive. But I've also
heard/read that that was only true for the early production run and that
the later built machines did not need the funny terminator. 
10 Jul
10 Jul
4:27 a.m.
Teo Zenios wrote:
----- Original Message ----- From: <trag at io.com>
To: <undisclosed-recipients:>
Sent: Thursday, July 09, 2009 4:05 PM
Subject: Re: Classic mac fun (and some questions)
(continued...again...)
From: "Jeff Walther" <trag at io.com
To: cctech at classiccmp.org
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> Date: Thu, 9 Jul 2009 12:00:48 -0400
> From: Ethan Dicks <ethan.dicks at gmail.com
Neither of my IIfx systems need that terminator to work.
I wonder if using an active terminator would work as a substitute for the
special Apple terminator ?
Anyone know a way to check a terminator to see if it is the special one ? I
have one black one that was given to me as a believed IIfx terminator,
but it is
not an Apple one.... so I don't want to trust what it is merely because
it is black.
Anyone know how to ID which IIfx systems need the black one, and which
ones are
of later rev that don't need it ?
-- Curt
I tried to look that up and found it easy to see
that the IIfx needed
something odd (I couldn't find specifics), so well done there. It
would be interesting to get the details to see where Apple went off
the rails from the SCSI spec.
IIRC, it's a matter of adding a capacitor and maybe a resistor to a
regular terminator. There's an Apple Technical Note or similar
available
somewhere. I probably have a copy squirreled away on my hard drive at
home. And I think I remember that they use a somewhat higher value
capacitor (so add a smaller one in parallel on an existing
terminator) and
a lower resistance (so again, add a resistor in parallel). But I could
be misremembering.
Again, IIRC, the IIfx's SCSI was too noise sensitive. But I've also
heard/read that that was only true for the early production run and that
the later built machines did not need the funny terminator. 
4:44 a.m.
On Fri, Jul 10, 2009 at 6:27 AM, Curtis H. Wilbar
Jr.<rescue at hawkmountain.net> wrote:
I wonder if using an active terminator would work as a
substitute for the
special Apple terminator ?
I'm not sure, but I doubt it.
Anyone know a way to check a terminator to see if it
is the special one ? ?I
have one black one that was given to me as a believed IIfx terminator, but
it is
not an Apple one.... so I don't want to trust what it is merely because it
is black.
The only identifying information I could find was that it was black.
The one I ordered has the normal embossed apple logo on it, but
otherwise looks identical to the apple terminators with the centronics
connectors at either end.
Anyone know how to ID which IIfx systems need the
black one, and which ones
are
of later rev that don't need it ?
Everything I read said that it wasn't particular revisions of machines
that allowed you to get away without the terminator, rather, it was
that certain devices that you plugged into the bus seemed to let you
get away with a normal terminator. The black terminator just ensured
that you could use anything.
brian
11 Jul
11 Jul
6:56 a.m.
2009/7/9 <trag at io.com>:
Seconded. ?There were NuBus AUI ethernet cards, but
much more common would
be a card with AUI and either or both of a BNC and RJ45. ? If the card
only has a DA-15 there's a very good chance that it is a video card. ? If
it has a big 'BT' labeled chip near the connector, it is almost certainly
a video card.
Jeff Walther
I don't recall ever seeing a Mac with a standard AUI connector,
because it was too similar to an Apple monitor connector. Apple
generally used AAUI - Apple AUI.
http://en.wikipedia.org/wiki/AAUI
--
Liam Proven ? Profile: http://www.linkedin.com/in/liamproven
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