PSP2600 is a port on PSP of the version v2.2 of Stella. It’s based on the work of Aenea who was the first to port Stella to PSP.

Changes:

– Auto-fire mode, press RTrigger+X to switch it on/off
useful for games such as space invaders !
On given games, the auto fire can’t be stopped, so an
option to stop it, is available in the settings menu.
– It uses now only PSP GU for rendering
– Speed improvements while using GU render modes
– IR keyboard support !
– Add .a26 as valid rom extention
– Add several new hotkeys :
. settings such as fps, render mode, auto fire speed
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)
– New speed limiter options in settings menu
– RTrigger/LTrigger keys can be used in the keyboard
settings menu to navigate between Normal, LTrigger
and RTrigger compose mapping.
– Analog pad can be used in the rom file requester
– Default Hotkeys can now be set in the keyboard mapping menu
(useful to add hotkeys on existing/previous keyboard files)
– Bug fix in the low battery watchdog
– Increase memory heap size in 3.x

http://zx81.zx81.free.fr/serendipity/index.php?/archives/279-guid.html