The Race Condition That Killed Two Patients

The Therac-twenty-five replaced physical hardware interlocks with software controls that failed to prevent lethal radiation overdoses.

A race condition occurred when experienced operators corrected input errors in less than eight seconds.

Cryptic error codes like Malfunction fifty-four failed to warn staff that patients were receiving massive radiation doses.

An arithmetic overflow in a single-byte counter allowed the machine to bypass critical safety checks.

The Food and Drug Administration grounded all machines in February nineteen eighty-seven following three patient deaths.

Modern medical software standards now require defense-in-depth to prevent single-point failures in physical environments.