Originally Posted by
Piper_Driver
Back in ancient times I designed memory systems to be resistant to bit flipping involving cosmic rays. It was in conjunction with a computer that used a 286 processor, the same one in use in the suspect flight systems. Our solution was to use error detecting and correcting memory. This architecture used extra memory bits that would allow any single bit error in a memory word to be corrected on the fly. The technology was mature at the time the flight control computers were developed. Does anyone know if memory correction technology was used on the Boeing flight control computers? If so it would rule out random bit flips as an error condition.
Please read the link quoted above, it gives a lot of useful details:
Originally Posted by
BDAttitude
Specifically:
There are error correction schemes that can detect and correct single bit flips (and schemes for multiple bit errors).
DRAM errors come in many types, some correctable, others not, and no scheme is foolproof.
In some cases there may be permanently stuck bits (on or off).
There is a substantial correlation between errors, such that they are neither random nor independent.
Cosmic rays are only one potential cause, simple ageing of hardware is also a factor.
Given these facts, it seems unreasonable to rely on statistical improbability, to excuse a single point of failure, with catastrophic consequences.
All of the news reports indicate that Boeing have accepted the FAA ruling on this. IMO further argument is futile, though more details might be enlightening.