Date: Wed, 31 Jan 96 23:21:48 -0800 From: Bakul Shah <bakul@netcom.com> To: hackers@freebsd.org Subject: Re: Watchdog timers (was: Re: Multi-Port Async Cards) Message-ID: <199602010721.XAA06480@netcom22.netcom.com>
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May be one of those single board computers (aka SBC) built around a 286 will do the trick? 2ser+1par+memory+cpu etc. are all on an ISA card and you can plug one or more of these in an ISA `passive backplane'. If you are in the SF Bay area you can look into the Microtimes for ads from people who make `industrial computers'. `Multi-micro systems' comes to mind. Another alternative is to use a robotics board like a `miniboard' or a `handyboard'. Both are designed by Fred Martin of MIT Media Labs. Handyboard has 32K battery backed SRAM. Other than that they are fairly similar. They are based on mc68hc11 which is an 8 bitter with on chip EEROM (or PROM) + some RAM, timers, serial I/O, 8 analog inputs, many digital input/outputs etc. With suitable sensors you can measure/monitor all sorts of things. I'd hook up one of these boards to the reset switch + a spare parallel port + and add a temp. switch or a thermistor to monitor temperature, add power line monitoring circuit (and stuff to switch to a backup power supply under program control), may be even a sensor to verify that the power supply fan is spinning (stopped fan due to dirt is how some machines heat up and die). The parallel port can be used as a console + can be programmed to provide a heart beat. The serial port can be hooked to a modem or terminal server for remote debugging and diagnostics. Since this board will be running from a separate power supply and is *very* tolerant of power supply voltage range, a hosed computer won't crash it (unlike an ISA based board). Heck, you can even get FORTH for the hc11 from Motorola :-) FTP to cher.media.mit.edu and poke around there to learn more about these two boards. Hang around comp.robotics.misc for a few days/weeks and someone will surely offer a kit or or complain about some such kit :-) Quite a few companies sell hc11 based boards. Probably any such board will do. All that is required is for someone to package it all up for the care and feeding of a computer.
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