GP2X-7800 is an Atari 7800 emulator for GP2x. It’s based upon ProSystem coded by Greg Stanton.

Changes:

– Many optimizations to speed up the emulation, frame rate is now 50 fps at
220Mhz in many games.
– Auto-fire mode, press RTrigger+X to switch it on/off
(useful for games such as xevious !)
– Add new hotkeys :
. settings such as fps or render mode
can now be directly modified inside the emulator
(no need to enter in the settings menu)
. quick save / quick load current state
(no need to enter in the main menu)
. setup auto fire speed
– Default Hotkeys can now be set in the keyboard mapping menu (useful to add
hotkeys on existing/previous keyboard files)

http://zx81.zx81.free.fr/serendipity/index.php?/archives/283-GP2X-7800-Atari-7800-emulator-for-GP2X-v1.0.3.html