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The Therac-25 Incident (2021)

(thedailywtf.com)
449 points lemper | 1 comments | 27 Aug 25 06:57 UTC | HN request time: 0s | 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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ChrisMarshallNY ◴[27 Aug 25 12:39 UTC] No.45038827[source]▶
I worked for a company that manufactured some of the highest-Quality photographic and scientific equipment that you can buy. It was expensive as hell, but our customers seemed to think it was worth it.

> It's the end result of a process

In my experience, it's even more than that. It's a culture.

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franktankbank ◴[27 Aug 25 12:49 UTC] No.45038936[source]▶
A culture of high-quality engineering, no doubt. Made up of: high quality engineers!
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herval ◴[27 Aug 25 15:14 UTC] No.45040858[source]▶
you don't need "high quality engineers" to have high-quality outputs. And vice-versa - lots of places with very high quality engineers produce terribly low-quality software
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1. Cthulhu_ ◴[28 Aug 25 08:58 UTC] No.45049974[source]▶
The article and GP mentions this as well in a roundabout fashion; a high-quality engineer is a waste if the organization around it fails. It's better to have mediocre developers in a mature organization than a hero developer working in the shadows. I've seen a few.