From running multitasking on a single CPU, MultiFinder and cooperative multitasking, massively parallel systems using Transputers, to building concurrency into the Swift language.
Occam
It’s time to replace Occam’s Razor with a more appropriate principle: if you’ve found one bug, don’t stop until you have dug deeper and found the others.
Designing algorithms which can benefit from multiple cores and GPUs is not only non-trivial, it remains desperately difficult for humans.
The Eclectic Light Company 