>UNIX-like kernels are easy, in that you don't have to have >that much running before you can run "Hello World".

Well, it depends on what you mean by "Hello World". Simply printing it out from the kernel? Easy. Getting a workable userspace up and running so a user program prints out "Hello World"? Hard. Also, you can have a microkernel that gives you a UNIX-like personality too (as is it is often the case when implemented), so I am not sure how one precludes the other.

>Also, the emphasis on virtual memory and page faults is >becoming dated. Paging out to disk is obsolete technology. >RAM is too cheap, and mobile devices don't page.

Uh, of course mobile devices use paging and virtual memory. You might be conflating virtual memory with swapping here.