The Atari7800 is emulated in XMESS on the GP2X but is very slow. Here is a link to the PSP version with source. Anyone that is interested could have a look.
http://zx81.zx81.free.fr/serendipity/index....3-bug-fix.html
http://zx81.zx81.free.fr/serendipity/index....3-bug-fix.html