Michael Mace writes:
To run on a single chip, the smartphone OS must have what’s called “hard real-time” capabilities. That means the operating system manages its own activities rigorously, so it can get out of the way when the phone needs to do something time-critical, like transmitting your voice or answering a call. If the smartphone OS doesn’t support hard real-time, it might accidentally cause a call to drop, or generate sputters in voice coverage.
Symbian OS was re-architected in version 8 to have hard real-time capabilities. Currently Palm OS doesn’t, and The Register reports that Windows Mobile can’t yet run on single processor phones either. If hard real-time is so useful, you might ask, why doesn’t every mobile OS have it? One answer is battery life.