Comment by cyberax
12 hours ago
QNX is hard realtime. At one point, its kernel had O(1) guarantees for message passing and process switching. It could have been rewritten without any loops. I'm not sure if that's still true.
It's also really compact. This used to be a great selling point for underpowered car infotainment systems. Some cars had around 1Mb of RAM for their infotainment, yet they were able to run fairly complex media systems.
QNX is also used for non-UI components, just as a good realtime OS.
I think it is mostly used for non-UI stuff. I could be wrong but outside of car infotainment I've never seen it used for UI stuff. Mostly it just sits headless quietly running some branch of industry that we all depend on. The joke used to be that if QnX had a y2k bug that had been missed civilization would end and never mind windows because you won't have any water, food, energy or transportation anymore.