sz81 is a Sinclair ZX80/ZX81 emulator very much based upon the work of Ian Collier’s xz80 and Russell Marks’s z81 but employing the highly portable SDL and including additional functionality and features for desktop computers and portable devices.

http://dl.openhandhelds.org/cgi-bin/gp2x.cgi?0,0,0,0,72,2830