Date: Mon, 4 Nov 1996 00:00:15 -0800 (PST) From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com> To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: jkh@time.cdrom.com, hardware@freebsd.org Subject: Re: OK, what's the deal with 2940W controllers and internal connectors? Message-ID: <199611040800.AAA03336@GndRsh.aac.dev.com> In-Reply-To: <199611040432.PAA12438@genesis.atrad.adelaide.edu.au> from Michael Smith at "Nov 4, 96 03:02:13 pm"
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> 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
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