From owner-freebsd-hardware Mon Sep 16 17:53:24 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id RAA24850 for hardware-outgoing; Mon, 16 Sep 1996 17:53:24 -0700 (PDT) Received: from genesis.atrad.adelaide.edu.au (genesis.atrad.adelaide.edu.au [129.127.96.120]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id RAA24844; Mon, 16 Sep 1996 17:53:19 -0700 (PDT) Received: from msmith@localhost by genesis.atrad.adelaide.edu.au (8.6.12/8.6.9) id KAA27601; Tue, 17 Sep 1996 10:23:10 +0930 From: Michael Smith Message-Id: <199609170053.KAA27601@genesis.atrad.adelaide.edu.au> Subject: Re: passive backplane (was Re: Any Pentium boards with more than 4 PC) slots? To: hsu@freefall.freebsd.org (Jeffrey Hsu) Date: Tue, 17 Sep 1996 10:23:10 +0930 (CST) Cc: hardware@freefall.freebsd.org In-Reply-To: <199609161636.JAA15362@freefall.freebsd.org> from "Jeffrey Hsu" at Sep 16, 96 09:36:55 am MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hardware@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk Jeffrey Hsu stands accused of saying: > > Speaking of passive backplanes, I have a question. What are they > used for? The hardware engineer I asked a while ago didn't give > a satisfying answer. In fact, I've forgotten what it was. But it > must be good for something, because I keep seeing passive backplanes > advertised in embedded systems magazines. Some good things about PB's : - Easy motherboard replacement (dike the card and drop in a new one). - Space efficiency (no footprint area that's not covered by plugins). - Small footprints (3xISA16 is not uncommon). - Huge footprints (20xISA16 is not uncommon). - Robustness (board flex on card insertion/removal is a non-problem). Take a 20xISA16 PB, a small 486, ethernet and 18 dual-8255 cards and you have 864 digital I/O lines. You can do a hell of a lot of machine control with that 8) -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] Collector of old Unix hardware. "Where are your PEZ?" The Tick [[