woodelf> chris wrote: woodelf> I guess nobody in DC watches Classic Star Trek and installed woodelf> "manual over rides". Funny in WWI & WWII warships worked woodelf> well with out puters but then they had 'sound powered woodelf> phones" for commication on ship -- no electricty needed -- woodelf> just wire between phones. In fairness, a lot of modern machinery can't be controlled by hand. Don't know about ships, but, for example, most fighter planes can't be flown without the help of their computers. Then again, that's why those computers are 3-way (or more) redundant, and their software development practices are supposed to be far more rigorous than PC desktop software. In extreme cases (Space Shuttle) you may see multiple control computers with separately-developed software in them. In the case of the space shuttle, that didn't prevent a startup sync problem that tripped up the countdown to the first launch, but in general it's a good concept. Hard to do and expensive, of course... paul

Ah yes, halon, we have two big tanks of those also hangin in our systems room. There's also a big red light on the outside of that room for obvious reasons....

"Absorb any oxygen" is a bit harsh. Halon is pretty good at stopping things from burning but it doesn't make it impossible to breathe. It's not the most healthy thing to breathe but in the 80's and earlier a very common demo of halon extinguishers had the salesman in a halon filled booth, demonstrating how all fires go out, while happily breathing the stuff. Now, CO2 oxygen-displacement extinguishers, that's a different story. Tim.

Oh yeah, getting back to the "manual override" OT thread: Our halon dump system has at least three manual overrides: 1. A switch on the wall by the door to initiate a dump. (I don't know if the delay and alarms get sounded before this kind of dump or not.) 2. A momentary toggle switch on the wall to inhibit a dump. I think the idea behind it being momentary is that it's a dead-man switch - when you abandon the room the dump will go ahead without you :-). 3. One intentional non-electronic way to initiate a dump. It's this big brass handle on the valve mechanism. My cow orkers have examined this and we think that after the valve opens a little bit, the flow will blow the valve the rest of the way open. And then there's the fourth way, which is to have a contractor messing around with the electric valve solenoid and trip it when nobody expects! The plumbing is quite impressive. The halon cylinders stand about 6 feet tall by about two feet in diameter, and the pipe is like 4 inches in diameter. The computer rooms (about 60 feet by 40 feet each) have 3 cylinders, and the operating theater (about half the size of a football field) has several clusters of 6 cylinders. Tim.

FWIW, The Radio story was the five-minute introduction to the book "When Computers Were Human" by David Alan Grier. The author tracked down survivors stories from math workers before 1945. Sounds like he found out a lot about how people lived their careers before the Univac, etc took over. A book to check out at the store. John A. No affiliation with anybody mentioned, NPR, etc. re: http://www.amazon.com/exec/obidos/ASIN/0691091579 or Amazon.com, or "In Living Color",