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Re: Mathematica and Lisp
Regarding the Therac-25 (not theravac); you can read about it on Wikipedia. http://en.wikipedia.org/wiki/Therac-25 and also look at the links, especially Nancy Leveson's report http://sunnyday.mit.edu/papers/therac.pdf especiall page 7, top. which I think is the most significant. As I recall, the operator editing the display screen used carriage returns etc to go between fields and thought that the actual settings were reflected by what appeared on the screen. This was not the case. There are other factors too. Lack of hardware interlocks, certainly a systems design error, also meaningless error messages (how could THAT happen?) hard to debug programming language (assembler).