From owner-freebsd-hardware Mon Nov 4 00:01:11 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id AAA05009 for hardware-outgoing; Mon, 4 Nov 1996 00:01:11 -0800 (PST) Received: from GndRsh.aac.dev.com (GndRsh.aac.dev.com [198.145.92.241]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id AAA04994 for ; Mon, 4 Nov 1996 00:01:05 -0800 (PST) Received: (from rgrimes@localhost) by GndRsh.aac.dev.com (8.7.5/8.7.3) id AAA03336; Mon, 4 Nov 1996 00:00:15 -0800 (PST) From: "Rodney W. Grimes" Message-Id: <199611040800.AAA03336@GndRsh.aac.dev.com> Subject: Re: OK, what's the deal with 2940W controllers and internal connectors? In-Reply-To: <199611040432.PAA12438@genesis.atrad.adelaide.edu.au> from Michael Smith at "Nov 4, 96 03:02:13 pm" To: msmith@atrad.adelaide.edu.au (Michael Smith) Date: Mon, 4 Nov 1996 00:00:15 -0800 (PST) Cc: jkh@time.cdrom.com, hardware@freebsd.org X-Mailer: ELM [version 2.4ME+ PL25 (25)] 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 > Jordan K. Hubbard stands accused of saying: > > > > Then I was talking to Poul-Henning last night who pooh-pooh'd my > > foolish conservatism and stated that I could have used both internal > > connectors on my 2940UW no problem. Since I could use that 1542 as my > > spare again (which is why I have it), I'd sort of like to know which > > one of us is correct? :-) > > Stub length limit on the SCSI bus is spec'ed at 7" IIRC. Pick one arm > of the Y, say "hello stub", and make it as short as possible. SCSI-II and SCSI-III revised that, if I recall correctly it is now down to 3.5" on SCSI-II and 1.75" on SCSI-III (Ultra). > I've run longer stubs (over about 50cm things get nasty), but only on > old/slow stuff (old workstations, 1542 clones, slow disks). 50cm at 20MHZ gets pretty darn ugly on any transmission line stub I have looked at. Forced Perfect termination might make it work at these speeds, but then again it might not... :-). -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation, Inc. Reliable computers for FreeBSD