Daniel Eran Dilger
Windows Mobile, Palm OS, Linux, and Symbian currently power the world’s smartphones. How does each stack up against Apple’s OS X in the iPhone? This article presents an overview and lineage of Symbian. 
 
Like the Palm OS and Microsoft's WinCE, Symbian also originated out of a software platform designed for PDAs.
 
However, Symbian has been in development specifically for use in mobile phone devices since 1998; work to adapt the Palm OS and WinCE for use in mobile phones didn't get really going until around 2002, and was largely bolted on the side of platforms that were already of dubious value.
 
• The Egregious Incompetence of Palm
• The Spectacular Failure of WinCE and Windows Mobile
 
Symbian was formed in a partnership between British PDA maker Psion and some the world's largest mobile manufacturers, including Nokia and Ericsson. Symbian's software origins at Psion help to explain why the system is regarded as stable and sophisticated. Psion, EPOC, Acorn, ARM, Newton.

In AAC, 15 minutes.

Based on the Article:
Origins: Why the iPhone is ARM, and isn't Symbian