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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: 0.207s | 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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1. f1shy ◴[27 Aug 25 17:40 UTC] No.45042622[source]▶
It is a culture. No doubt. And certainly not only processes. I work in a company where there are literally processes for everything. For every engineer doing actual work (requirement engineering, architecture, coding, testing) there are at least 3!doing processes. The SW we make is the ultimative piece of shit, late, expensive, and to the brim full of bugs. So process is importannt, but good engineering, and culture also.