Toots from 2023-09-14

“A naive assumption is often made that reusing software or using commercial off-the-shelf softw…

“A naive assumption is often made that reusing software or using commercial off-the-shelf software will increase safety since the software will have been exercised extensively. Reusing software modules does not guarantee safety in the new system to which it is transferred and

sometimes leads to awkward and dangerous designs. Safety is a quality of the system in

which the software is used; it is not a quality of the software itself.”

https://web.stanford.edu/class/cs240/old/sp2014/readings/therac-25.pdf

Mastodon Source 🐘

Evergreen checklist from Leveson & Turner (1993) from their review of the tragic Therac-25 fatal patient dosages:

“Some basic software engineering principles that apparently were violated

in the case of the Therac-25 include:

• Documentation should not be an afterthought.

• Software quality assurance practices and standards should be established.

• Designs should be kept simple.

…”

Mastodon Source 🐘

“• Ways to get information about errors, i.e, software audit trails, should be designed

into the software from the beginning.

• The software should be subjected to extensive testing and formal analysis at the

module and software level; system testing alone is not adequate. “

This is a great paper that highlights core safety principles stemming from a truly horrible series of events.