When Computers Go Wrong 250
Barence writes "PC Pro's Stewart Mitchell has charted the world's ten most calamitous computer cock-ups. They include the Russians' stealing software that resulted in their gas pipeline exploding, the Mars Orbiter that went missing because the programmers got their imperial and metric measurements mixed up, the Soviet early-warning system that confused the sun for a missile and almost triggered World War III, plus the Windows anti-piracy measure that resulted in millions of legitimate customers being branded software thieves."
therac 25 (Score:5, Informative)
List fails without the therac 25
Ariane 5 missing on the list (Score:5, Informative)
It isn't smart to assign a 64 bit floating point to a 16 bit integer - unless you want to crash you first flight of the heavy Ariane 5 rocket... (http://en.wikipedia.org/wiki/Ariane_5#Notable_launches)
Re:therac 25 (Score:5, Informative)
1 Page Read (Score:5, Informative)
http://www.pcpro.co.uk/features/363580/when-computers-go-wrong/print [pcpro.co.uk]
Re:Computers do what they are told to (Score:5, Informative)
I'm surprised they didn't mention incidents where people actually died, such as the Therac-25 [wikipedia.org] incident.
Comment removed (Score:5, Informative)
Re:Computers do what they are told to (Score:5, Informative)
And of course there is the Patriot missile software clock issue - that led to a failure to engage a SCUD on February 25, 1991 at Dhahran, Saudi Arabia, killing 28 soldiers.
This failure is rather similar to the Soviet defense and NORAD errors mentioned in the article in that it was a weakness designed into the system that did not account for the range of operational condition and issues. In the Petrov Incident case - a natural condition, in the NORAD case an easy to make operator error, in the Dhahran barracks Patriot incident it was a failure to consider that a unit might be operated for weeks without a restart.
MS London stock exchange crash (Score:5, Informative)
Re:Computers do what they are told to (Score:5, Informative)
No, he clearly meant "The Fucking TFA Article."
Kids today.
1982 explosion did not happen (Score:5, Informative)
Te Soviet pipeline explosion seems to be an urban legend, traced to a single source: At the Abyss: An Insider's History of the Cold War, by Thomas C. Reed.
There is no mention of this explosion anywhere else, either in Russian or Western sources. If you can read Russian, some debunking is here:
link [wikipedia.org]
One of the facts mentioned there is that there was no SCADA on Soviet pipelines until late 80-s. All control was still pneumatic in 1982, with no software involved.
Re:Computers do what they are told to (Score:5, Informative)
It's not confirmed that the gas pipeline blowup was due to computers going wrong.
http://en.wikipedia.org/wiki/Siberian_pipeline_sabotage#Hoax_Theory [wikipedia.org]
Here are a few more "logic cock ups":
http://en.wikipedia.org/wiki/Ariane_5_Flight_501 [wikipedia.org]
http://it.slashdot.org/article.pl?sid=07/02/25/2038217 [slashdot.org]
And Wired's list: http://www.wired.com/software/coolapps/news/2005/11/69355 [wired.com]
Re:therac 25 (Score:2, Informative)
Somebody did their research using Wikipedia? From the first line of the floating point article [wikipedia.org] as it currently stands:
In computing, floating point describes a system for representing numbers that would be too large or too small to be represented as integers.
Re:Computers do what they are told to (Score:5, Informative)
A system using proper fractions can actually get exactly the right answer every time OR it will overflow and we will know for a fact the answer isn't exact.
What theory of numeration are you using, that has all numbers rational? I'm sorry, but even the humble square root is something I don't want to give up, to say nothing of transcendental functions. The theory of exact arithmetic on the reals is not all that well developed. Bill Gosper [plover.com] makes a start, and a handful of researchers take it somewhat further, but actually using exact arithmetic for everything you'd want to do remains a mirage.
Re:Computers do what they are told to (Score:5, Informative)
None at all. I just presumed it was understood that my statement applied to rational numbers.
You could take it to the next step and handle irrational numbers symbolically, but that's probably best left to software rather than hardware. You could keep a hardware function called squareish root though if you like that returns a fraction matching the current approximation. You won't actually lose anything that way.
I'm pretty sure we will at least be improving matters by not losing on simple division.
Re:Imperial - Metric (Score:4, Informative)
Yes, getting a decent kitchen scales in the US is a pain. In Europe, every reasonably equipped kitchen has a set of kitchen scales on the counter.
On the other hand, measuring certain ingredients by volume is better. For example, the specific weight of flour changes quite a bit with humidity, while volume stays pretty much the same.