From owner-freebsd-hackers Tue Jan 5 12:32:15 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id MAA03306 for freebsd-hackers-outgoing; Tue, 5 Jan 1999 12:32:15 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from whizzo.transsys.com (whizzo.TransSys.COM [144.202.42.10]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id MAA03301 for ; Tue, 5 Jan 1999 12:32:13 -0800 (PST) (envelope-from louie@whizzo.transsys.com) Received: from whizzo.transsys.com (localhost.transsys.com [127.0.0.1]) by whizzo.transsys.com (8.9.1/8.9.1) with ESMTP id PAA39633; Tue, 5 Jan 1999 15:31:22 -0500 (EST) (envelope-from louie@whizzo.transsys.com) Message-Id: <199901052031.PAA39633@whizzo.transsys.com> X-Mailer: exmh version 2.0.2 2/24/98 To: Drew Baxter cc: Terry Lambert , sthaug@nethelp.no, jamie@itribe.net, freebsd-hackers@FreeBSD.ORG From: "Louis A. Mamakos" Subject: Re: PnP PCI modem References: <14757.915110288@verdi.nethelp.no> <4.1.19990105145650.00bf39d0@genesis.ispace.com> In-reply-to: Your message of "Tue, 05 Jan 1999 14:58:17 EST." <4.1.19990105145650.00bf39d0@genesis.ispace.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 05 Jan 1999 15:31:21 -0500 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > At 07:54 PM 1/5/99 +0000, Terry Lambert wrote: > >> > So, does this mean motherboards with a decent number of PCI slots will > >> > start appearing? > >> > >> I wouldn't count on it - I think it's more likely that you'll see more > >> USB equipment. > >> > >> AFAIK it's rather difficult electrically to have more than five slots in > >> one PCI bus. Thus if you need more, you'll need a system with more than > >> one system bus to PCI bridge. Thus higher cost, lower volume. > > > >This is a current issue, and is related to the chipset. > > > >Apple has a good PCI chipset, as does DEC; I believe both support > >6 slots without a bridge because they have seperate lines for 6 > >slots. The Intel chips tend to have only 4 lines; some motherboard > >manufacturers double up one of the lines to get 5 slots. I suspect > >you could double up some of the lines on the DEC chip; don't know > >about the Apple. > > There are boards out there with 7 PCI slots that run Pentium II's. If I > remember right ASUS makes one, but don't quote me on that. It's very > likely it isn't using an Intel 440 chipset at all though, probably some > other company (BTC)? I find this board more practical now than I would say > 2 years ago.. Because 2 years ago I still had a lot of ISA hardware. The > only thing ISA now is my Sound Blaster AWE32. > The slot limitiation is mostly an electrical issue, having to do with bus loading issues. The PCI spec (which I don't have handy at the moment) presumes a certain number of loads; you have to count the devices on the card as well as the rather crummy connectors used. This is one reason why CompactPCI systems with their eurocard-style bus connectors can have more slots per PCI bus - the high quality connections present less of a capacitance load on the bus. I think that most AT-style boards with more than 3 or 4 PCI slots have some of the slots behind a PCI bridge, so it's really two busses. louie To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message