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The Therac-25 was much more of a management and engineering failure than a technical problem, though. While the immediate cause of the deaths was a race conditi
by gamble 17y ago
The Therac-25 was much more of a management and engineering failure than a technical problem, though. While the immediate cause of the deaths was a race condition in the software, it was only capable of causing harm because the hardware safety mechanism had been removed as a cost-saving measure, without proper verification that the software was capable of doing the same job. Worse, it was widely known among the Therac's users that the hardware safety would regularly trip during normal operation without apparent cause, yet the problem was never investigated until after the deaths.
Ultimately, the Therac was a failure of software engineering more than a software failure. I don't blame the technology any more than I would blame a girder for buckling because a careless structural engineer didn't realize it was overloaded.
- deleted 17y ago[deleted]
- jrockway 17y agoIf the software had worked, it would have mattered if the hardware safety was removed. I'm not saying to design without hardware safety mechanisms, of course, but it's nice to know that you'll never need them.
- gamble 17y agoThe problem is that no one bothered to check whether the software worked when they removed the hardware. It's not a good thing that there was a bug in the first place, but proper procedures could easily have caught it before people were killed. That's why you have multiple systems to prevent catastrophic failures. What makes the Therac-25 notable is the novelty of a software problem killing people. If it had been a second hardware safety mechanism that had been removed, it wouldn't be as notorious - but the engineering failure would be equivalent.