PicoDrive is a Megadrive/Genesis and Sega CD emulator ported to PSP by Notaz.

Changes:

mp3 code should no longer fail on 1.5 firmware.
added gamma adjustment option.
added .cso ISO format support. Useful for non-FMV games.
it is now possile to force a region after the ROM is loaded.
fixed a sram bug in memhandlers (fixes Shining in the Darkness saves).
fixed another bug in memhanlers, which crashed the emu for some games (like NBA Jam and NHL 9x).
added suspend/resume handling for Sega CD games.
some other small tweaks I forgot about.

http://www.dcemu.co.uk/vbulletin/showthread.php?t=80319