The Therac-25 relied more heavily on software for safety functions and did not duplicate all of the hardware safety mechanisms and interlocks used in earlier machines.

Format Online paper / PDF

Location PART 1 - TONS OF PUNKS, ONE BIG JERK CHAPTER 2: NO MOAT IN BLOAT From Cosmic Rays to Bungee Jumps

"The Therac-25 relied more heavily on software for safety functions and did not duplicate all of the hardware safety mechanisms and interlocks used in earlier machines."

The investigation explains that AECL shifted more safety responsibility into software and chose not to duplicate all existing hardware interlocks and backup mechanisms.

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Source title An Investigation of the Therac-25 Accidents

Source authors Nancy G. Leveson; Clark S. Turner

Source year 1993

Confidence high

Importance high