DozyWannabe, #2114:
For the techies on this thread, I've managed to dig up this report from my old Software Engineering/Reliability professor, Peter Mellor. In it, he details the visit he made to Airbus Industrie in January 1993
Interesting report and just confirms what I had seen in terms of rigorous development standards. Interesting set of references at the end as well. From the description, it looks like the code was not running continuously, but was run in a strict sequence with each module running to completion. Started by a system tick clock and probably no rtos. In those days, probably no interrupt driven hardware and no stack usage either. Effectively, a hardware state machine equivalent...
Good stuff and thanks...