I have a more general question - what is the minimum that is needed to qualify as an operating system? Is there something agreed on generally? Searching operating system minimum requirements leads to the wrong kind of info for me....
I thought about what would be the minimum I have to build in order to run some userland software that does "something". That to me looked like: spawn guest applications, make them persist something.
With slightly more leeway, I would probably do memory management as the next thing (besides what I mentioned in another thread here)