My understanding is that the Therac-25 UI was essentially a CAD program that allowed the operator to design treatment programs.<p>The software failed to prevent the operator from entering invalid treatment programs which then killed patients.<p>I seem to remember that this was made worse by operators using a shortcut from a previous version which was safe because of some additional hardware, but the hardware lock was removed in the 25, and it killed people.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Therac-25" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Therac-25</a>