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The Therac-25 Incident (2021)

(thedailywtf.com)
449 points lemper | 2 comments | 27 Aug 25 06:57 UTC | HN request time: 0.001s | source
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benrutter ◴[27 Aug 25 08:18 UTC] No.45036836[source]▶
> software quality doesn't appear because you have good developers. It's the end result of a process, and that process informs both your software development practices, but also your testing. Your management. Even your sales and servicing.

If you only take one thing away from this article, it should be this one! The Therac-25 incident is a horrifying and important part of software history, it's really easy to think type-systems, unit-testing and defensive-coding can solve all software problems. They definitely can help a lot, but the real failure in the story of the Therac-25 from my understanding, is that it took far too long for incidents to be reported, investigated and fixed.

There was a great Cautionary Tales podcast about the device recently[0], one thing mentioned was that, even aside from the catasrophic accidents, Therac-25 machines were routinely seen by users to show unexplained errors, but these issues never made it to the desk of someone who might fix it.

[0] https://timharford.com/2025/07/cautionary-tales-captain-kirk...

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1. sonicggg ◴[27 Aug 25 10:50 UTC] No.45037874[source]▶
Not sure why the article is focusing so much on software development. That was just a piece of the problem. The entire product had design flaws. When the FDA for involved, the company wasn't just told to make software updates.
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2. speed_spread ◴[27 Aug 25 11:40 UTC] No.45038272[source]▶
Yet It doesn't take much to swamp a team of good developers. A poorly defined project, mismatched requirements, sent to production too early and then put in support mode with no time planned to plug the holes... There's only so much smart technicians can do when the organization is broken.