Re: [SI-LIST] : New VME Backplane -- Star Layout

Bob Meyer (rwmc@eci-esyst.com)
16 Sep 1998 12:47:13 -0400

Mike,
You can probably get your questions answered with a visit to the VME =
organizations's website: www.vita.com.
Bob Meyer
Raytheon Systems Co.
St. Petersburg, FL
------------------------------
Date: 9/16/98 12:36 PM
To: Bob Meyer
From: Mike Mayer

=3DI believe you are correct, it is still a transmission line. The =
comments in
=3Dthe EETimes article sound like they're coming from a marketing type.
=3DBut that said, I do believe that the settling times on this new VME
=3Dbackplane could be improved, and the loads could be more consistent. =
Every
=3Dboard would now see the same load. Currently, the board in slot 1 =
really
=3Dsees a different load than the board in the middle of the backplane. =
Also,
=3Dif the board in slot 1 was the driver, the board in slot 2 sees a very =
ugly
=3Dsignal compared to the board in slot 21....
=3DA major drawback on this approach is the huge routing resources needed =
to do
=3Da star topology, instead of a daisy-chain, on a 21 slot VME BUS!

Do you think the trace lengths are balanced? i.e., Is the length from
slot 9 tromboned to the same length as the trace from slot 1 to the
star? That would truly make every board see the same load and the
same transmission line. That would eliminate the large slot-to-slot
difference that exists now.

-- 
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Mike Mayer                               Artesyn Communication Products, =
Inc
                                         Madison, WI
                                         http://www.artesyn.com/cp
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

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------------------ RFC822 Header Follows ------------------ Received: by qmgate.eci-esyst.com with ADMIN;16 Sep 1998 12:32:42 -0400 Received: from mercury.Sun.COM (sentry) by mailserver (4.1/SMI-4.1) id AA24648; Wed, 16 Sep 98 12:23:48 EDT Errors-To: si-list-approval@silab.Eng.Sun.COM X-Proxy: callisto.eci-esyst.com protected by CyberGuard Received: from Eng.Sun.COM (engmail4 [129.144.134.6]) by mercury.Sun.COM = (SMI-8.6/mail.byaddr) with SMTP id IAA27584; Wed, 16 Sep 1998 08:57:44 = -0700 Received: from silab.eng.sun.com (silab.Eng.Sun.COM [129.146.121.121]) by Eng.Sun.COM (SMI-8.6/SMI-5.3) with SMTP id IAA16972; Wed, 16 Sep 1998 08:57:40 -0700 Received: by silab.eng.sun.com (SMI-8.6/SMI-SVR4) id IAA21759; Wed, 16 Sep 1998 08:48:20 -0700 Errors-To: si-list-approval@silab.Eng.Sun.COM Received: from Eng.Sun.COM by silab.eng.sun.com (SMI-8.6/SMI-SVR4) id IAA21755; Wed, 16 Sep 1998 08:48:15 -0700 Received: from earth.sun.com (earth.EBay.Sun.COM [129.150.69.3]) by Eng.Sun.COM (SMI-8.6/SMI-5.3) with SMTP id IAA00051 for <si-list@silab.Eng.Sun.COM>; Wed, 16 Sep 1998 08:46:29 -0700 Received: from goat.heurikon.com (goat.heurikon.com [204.95.85.80]) by earth.sun.com (8.9.1/8.9.1) with ESMTP id IAA25123 for <si-list@silab.Eng.Sun.COM>; Wed, 16 Sep 1998 08:46:24 -0700 (PDT) Received: from cheetah.heurikon.com (cheetah.heurikon.com = [192.48.244.203]) by goat.heurikon.com (8.9.1a/8.9.0) with ESMTP id KAA28264; Wed, 16 Sep 1998 10:46:19 -0500 (CDT) Received: from NT5 (nt5.heurikon.com [192.48.244.185]) by = cheetah.heurikon.com (8.7/8.7) with SMTP id KAA16695; Wed, 16 Sep 1998 = 10:46:18 -0500 (CDT) Date: Wed, 16 Sep 1998 10:46:18 -0500 (CDT) Message-Id: <199809161546.KAA16695@cheetah.heurikon.com> From: Mike Mayer <Mike.Mayer@cp.artesyn.com> To: jfpeterson@space.honeywell.com Cc: si-list@silab.Eng.Sun.COM In-Reply-To: <F40D462D6FF2D11182E800805F95330DFA0E71@fl51m01.space.honeywell.com> (jfpeterson@space.honeywell.com) Subject: Re: [SI-LIST] : New VME Backplane -- Star Layout Sender: owner-si-list@silab.Eng.Sun.COM Precedence: bulk

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