I don't disagree that "hardware interlocks" are a good idea for such equipment. But now that I think about it, I'm annoyed that we can't know if software was co

I don't disagree that "hardware interlocks" are a good idea for such equipment. But now that I think about it, I'm annoyed that we can't know if software was competently written and tested - is it really that different from hardware in that respect? How about, we require that the source be open, and if it's too convoluted for the hospital's respected experts to check, then it fails inspection? Hardware uses many standard parts and materials, and similarly, the software could use a few plain-simple-standard libraries, like libc (but not the floating point functions), zlib, libpng. The Therac 25 case was just incompetence. The vendor was told about the problem, but was in denial, then later supplied a hardware fix which didn't fix the problem. The problem had to be thoroughly investigated and proven by a doctor and operator over many months. Why couldn't the vendor have investigated more thoroughly themselves, in a week or so? Why weren't they more careful about race conditions? (The problem was triggered by a human able to type into the interface too fast. An actual human.)