OS X and the iPhone
This is quite possibly 2lmc bait, but I’m trying to work out exactly what it is that Apple’s done to get OS X running on the iPhone, other than the usual re-compile/Marklar-esque port to ARM. My understanding is that for at least the phone-y/radio-y bits of a mobile you’d need some sort of RTOS and while my reading has pointed to the fact that OS X is possibly a soft RTOS (drop video frames, etc.), I’m not exactly sure what else Apple might have had to tweak to get a phone running on the thing in the first place.
Other questions: For example, is Palm OS an RTOS? OS X has clearly got some low-latency parts (all that mucking about with AudioUnits, etc.) , and perhaps the phone bits have been stuck in at the XNU level (do the radio drivers etc need to be any more integrated than just I/O Kit?)
The parts that I have seen include a rather dubious conversation in the #iphone / iphone dev-wiki IRC channel with some person wittering on about the iPhone’s OS being radically different from OS X, and in turn being told in rather certain terms that that didn’t appear to the case at all.