4 ms·
> Always include hardware safe guards when it comes to safety. What does that actually mean? Maybe in the Therac-25 case the maximum dosage could somehow have
by IfOnlyYouKnew 7y ago
> Always include hardware safe guards when it comes to safety.
What does that actually mean? Maybe in the Therac-25 case the maximum dosage could somehow have been limited by a hardware dial in addition to software. But what form would hardware safeguards take for the millions of decisions software makes every second on a starting rocket? And considering hardware has far higher failure rates than no-moving-parts software, wouldn't any system that lets hardware dominate software decrease safety?
- ClassyJacket 7y agoI don't know exactly but the previous generation model had the hardware interlock that would have prevented this problem so it is possible. From Wikipedia: "One, when the operator incorrectly selected X-ray mode before quickly changing to electron mode, which allowed the electron beam to be set for X-ray mode without the X-ray target being in place. A second fault allowed the electron beam to activate during field-light mode, during which no beam scanner was active or target was in place. Previous models had hardware interlocks to prevent such faults, but the Therac-25 had removed them, depending instead on software checks for safety."
- ridgeguy 7y agoPerhaps just a dose integrator with an alarm limit? There's probably a total dose above which you could likely say "this is a mistake". A dose integrator would be a detector + an integrator independent of the therapeutic delivery software. If it goes over limit, it shuts the system down.