What is Symbian OS?, FROM: http://www.wisegeek.com/ Symbian OS is an open source operating system for mobile phones primarily used on Nokia advanced or data enabled smart phones. Symbian OS runs exclusively on ARM processors and has evolved from Psion's EPOC which was developed as a rudimentary operating system for early electronic organizers. The Psion EPOC OS was refered to EPOC16 beginning in the late 1990's to help distinguish it from the newer 32bit Operating system EPOC32, which eventually became Symbian OS. Psion software created a joint venture with several mobile hardware manufacturers, Ericsson, Motorola, and Nokia called Symbian and eventually took on the name Symbian Software, renaming EPOC32 Symbian OS.