Date: Mon, 5 Feb 1996 11:01:55 +1030 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: uhclem@nemesis.lonestar.org (Frank Durda IV) Cc: hackers@FreeBSD.org, uhclem@nemesis.lonestar.org Subject: Re: Watchdog timer Message-ID: <199602050031.LAA05403@genesis.atrad.adelaide.edu.au> In-Reply-To: <m0tjA3e-000CN8C@nemesis.lonestar.org> from "Frank Durda IV" at Feb 4, 96 01:25:00 pm
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Frank Durda IV stands accused of saying: > > By going to PCI, you will ADD for a small-volume board (<1K units) > roughly $40 per board JUST for the PCI, both for fabrication, electronics > and mechanical packaging. Those PCI chipsets aren't cheap in low > volumes, and the packges they come in eliminate do-it-yourself > manufacturing. One can only hope that this will change; certainly for the nonce it makes PCI card design impractical for small players. (It's also conceivable that this was a consideration in the development of the spec 8( ) > As an example for a simple system: in the external model, you would simply > provide a chassis spine (those metal things on the ends of cards) with > two plugs. Inside, you would connect one cable to the RESET connector on > the MLB, and the other to either the SCSI activity light or the IDE > activity light connector on the MLB or SCSI/IDE card. Dang. This is a very neat idea (hits self). > Externally, the cables (shielded) would be run to the monitoring box, where > a couple of properly tuned NE555 timers would do an excellent job of Hmm. I'd do this internally, presuming that resetting would be enough. It's not actually as simple as you make it sound though; you need a missing-pulse detector (consider the situation where the disk light stays on) and a timer that runs for longer than the 100-second maximum for the 555. Even so, you can do the pulse detection with a capacitor and a diode, and the long-delay timer can be done with an XR2206 which is still dirt cheap. > Power would come from a wall adapter. If one timer expires and generates > a RESET and things go dead again, a second and much longer timer (five > to ten minutes) could cycle a relay and kill power to the computer chassis > for ten seconds or so, and then let things reboot. This (the power cycling) would add significantly to the cost of the unit; consider a 15A relay and the extra wiring involved in terms of assembly cost. > My point is that you should really decide exactly what is needed and > what is nice and try to control the leaping elegance demonstrated > in this thread. Feeping creaturism. Yes 8) The clock would still be a nice toy, but I'll stick on PHK's NVconsole 8) > Frank Durda IV <uhclem@nemesis.lonestar.org>|"The Knights who say "LETNi" -- ]] 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 [[ ]] "wherever you go, there you are" - Buckaroo Banzai [[
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