   I want use a hand hold device or smallest machine as my development system
  I want use a hand hold device as my development system.So, is there any ANSI C compiler can run on it(the hand hold device) and can compile C source file into local executable, and the device support OpenGL/OpenGL ES?Or, which is the smallest machine for my purpose available?Thanks!   
  Why would you want to do that? A good Dev machine needs a chunk of memory, to avoid disc acess during compilation, decent processing speed to compile the code, which can be quite large, a decent screen res to show everything, A good storage system to hold all the resources, and a decent input system, ie keyboard and mouse.Why take all that away?Anyway, don't know of any PDA based compilers, but I imagine its not impossible to find something.Most practicle "handheld" dev system would probably be a tablet PC of some kind.   ;  Yes, there are a few C and C++ compilers out there that work on the Dragonball and ARM4 chipsets under PalmOS and WindowsCE.  No, I wouldn't recommend it.Handhelds have slow processors, don't have much memory, have a tiny screen, and have horrible data entry abilities.  Even with the fold-up keyboards, typing into a text editor is a pain, even on the high-end VGA resolution devices (480x640) it is hard to see enough text to make it worth the effort.I have heard of a few people trying it out, and all of them giving it up for serious work.  The only person who stuck with it was a friend teaching the basics of programming, who would load up his source from the computer and show it from his handheld on a projector.  He only did it because he didn't have a laptop and didn't want to lug around an entire desktop computer for the task.If your heart is set really on developing on your mobile non-laptop computer, get a TabletPC running Windows XP and install your compiler on there.   ;  Or, you can freely download and use OnBoardC, an opensource compiler for PalmOS.  I used to use it alot, although i've sort of lost interest.  Anyway, it exists... and it works.   