Radiolab does Bit Flip.. and you don't know how Often (til you listen)

Post #430,139 by Ashton 8/3/19 6:07:42 PM 8/3/19 6:07:42 PM Reply	Radiolab does Bit Flip.. and you don't know how Often (til you listen) Radiolab Bit Flip Today on Radiolab: a cosmic chain of events that causes computer chaos. We travel from a voting booth in Brussels to the driver's seat of a runaway car in the Carolinas, exploring the massive effects tiny bits of stardust can have on us unwitting humans. Sure ..we'unses all know some thingabout Cosmic Rays (A-3xx plane nose-dives 1000' ... when taken out of Auto-pilot ..not magically, but [da capo]) tl'dr ... stirring tales of (likely candidate-events) Ionizing Radiation: ~~Don't!~~ Can't leave home/or stay, without E = h ν
Post #430,160 by a6l6e6x 8/4/19 10:37:54 PM 8/4/19 10:37:54 PM Reply	Heard that podcast earlier in the week. Made me think the need to use parity bits in memory chips. You use 9 bits for a byte with the parity bit taking the value that makes the number of 1's in a byte odd. That way, if a single memory bit flips, you can at least detect it. I once wrote code to restore that flipped bit, assuming it was the only bit flip in a chunk of memory containing code. We had a kind of a checksum for each chunk of code. It was fun trying to test my code. You couldn't wait for a cosmic ray, so I used an "electrostatic discharge" to shock the device. To know the code actually ran, I had the device show "OUCH" on the 4 character ststus display for a second. Interesting days! This would have been in the early 1980's when the RAM chips went from either 1 Kb to 4 Kb or 4 Kb to 16 Kb in density and there was concern the smaller physical bit size made it susceptible to cosmic rays. Given the density of memory chips these days, that was a foolish concern. Alex "There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge." -- Isaac Asimov
Post #430,162 by Ashton 8/5/19 6:36:19 AM 8/5/19 6:36:19 AM Reply	Recall NASA's means for "whatever-goes-Rong". Fun times! 'course having double redundancy via a mirror CPU+ memory: would handle the {un-tracked-down) random bit-flip, I might imagine, but I like your approach ..where space/cost matters too, eh? Visited Houston once, enroute to N'Orleans w/friend; got the mini-VIP attendant; sent friend off for the newbie-Tour (as her physics was ~normal USian.) Deja-vu on some hardware du jour: they used same exact square illum. swithches all over, as did Bevatron C.R. (begun in early '53!) Reliable those--it it ain't broke, keep Using it! Bet few realize: recall that famous monster room with all the Stations, (full-of-men + One1111ONE O N E female mathematician). ... There was a full-DUPLICATE ROOM below that one! (!!) Idea was, should a none-such local zap or whatever we can imagine: tHey'd race downstairs, where the SPARE (presumably with its own separate main-power feed as well? forgot to ask that) ... already hotted-up! Gather they never had-to use it--or we'd have heard all about it. But Imagine That! [in 2019 crap-dollars..] (There was triple-redundancy w/'voting' for the absolutely critical matters, but believe we all knew that). Clever Lads, those. It's a mad.. Mad.. MAD... mutifarious World ... with lots-too-many of 'US' than in 1969. (Most troubling? ..since then: a %disturbing of the inmates: became The Eloi ... (and we all thought that was fiction. in ~1896.) Nothing can Surprise anymore.
Post #430,163 by Ashton 8/5/19 6:38:20 AM 8/5/19 6:40:37 AM Reply	Ignore, PEBKAC. Edited by Ashton Aug. 5, 2019, 06:40:37 AM EDT Expand All History
Post #430,165 by crazy 8/5/19 9:07:37 AM 8/5/19 9:07:37 AM Reply	My standard excuse on system failure I'd start with "software rot" and then dive into bit flipping via cosmic radiation. When I was done they'd never trust a computer again.
Post #430,167 by boxley 8/5/19 10:14:46 AM 8/5/19 10:14:46 AM Reply	software rot starts with a :wq! "Science is the belief in the ignorance of the experts" – Richard Feynman

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