The Therac-25 and Software Design

BAD SOFTWARE!  We've all encountered the dreaded 'Blue Screen of Death' on our PCs.  Unfortunately, there are a large number of software developers who feel that rebooting the system or reinstalling software is a normal 'fix' for problems in their code.

Imagine a safety-critical system controlled by a computer which has 'bugs' in the code.  It is not hard to imagine this, since it happened a few years ago in the THERAC-25 radiation therapy machine produced by AECL (Atomic Energy Cananda, Ltd).  Several people died from accidental overdoses of radiation. The problems were all traced back to POOR SOFTWARE.

*Andrew Tei's Therac-25 Explanation Making (dark) humour of a tragic situation, this author uses South Park characters to explain what went wrong.  The facts are indeed true here (although Kenny didn't really die :-)

* An Investigation of the Therac-25 Accidents An online paper that was published in the IEEE Computer journal.

There are numerous papers on the Therac-25 problem.  Use a search engine to find out more.


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Source:  TECH238G Lecture notes by Mark Csele