PDACheck out the Smartphone section for the latest developments in mobile.
PDA is an abbrivation for Personal Digital Assistent (more info on Wikipedia)
Problems with PDA's is that it has to be compact, because of that the clear display of Chinese characters is very difficult. Because of the lack of a keyboard it requires on input methodes. Most have a touchscreen, in which a virtual keyboard is used.
There are several operating systems for PDA, there is Windows CE, PalmOS and several versions of (embedded) linux. The integration of PDA functions in cellphones has let to the creation of Symbian, a operating system for cellphones.
Windows CE / Mobile
Windows CE was Microsoft's first attempt to create a mobile operating system and was already Unicode based, it was superseded by Windows Mobile. Both operating systems are now no longer developed. They have been replaced by the Windows Phone operating system.
A German site on how to use Chinese on CE 3.0 using CE-Star-suite
CJKOS : CJKOS(Chinese, Japanese, Korean Operation System) is used to enhance the English version of PalmOS to become multi-language system, supporting Chinese, Japanese and Korean. It is developed by DYTS.
PalmOS is officially available in simplified Chinese.
A PDA based on linux, see 'related stories' for more info on linux on handheld devices.
d-EAR IME SDK for Win, PalmOs and Symbian
Chinese handwriting for palm