A cancer therapy machine designed to save lives instead delivered radiation doses up to 100 times too high, burning holes through patients from the inside. The killer wasn't a broken part — it was a software bug that only triggered when an experienced operator typed too fast. This is the story that still haunts every safety-critical programmer.
The definitive popular retelling: how a state-of-the-art radiotherapy device started massively overdosing patients in the mid-1980s, and why the manufacturer kept insisting it was impossible.
A calm, well-sourced short documentary that walks through each incident and victim in order, grounding the horror in the actual timeline of failures and cover-up.
An engineer's-eye account of exactly how the machine worked, where the previous model's hardware interlocks were removed, and how software was trusted to do a job it was never proven safe for.
The reference record: at least six accidents, three deaths, the shared code inherited from the Therac-20, and the concurrency bug hidden in a one-byte counter that overflowed.
A veteran Microsoft engineer dissects the actual race condition — how fast keystrokes let the beam fire before the machine finished setting up — from a working programmer's perspective.
The original scholarly autopsy by Nancy Leveson and Clark Turner — still taught in engineering courses worldwide. This paper is why 'Therac-25' is shorthand for how software safety must be engineered, not assumed.
A focused technical explainer on the concurrency flaw itself: two processes, no locking, and a timing window where a confident operator could out-type the machine's safety checks.