For 1.5 PSPs (I still haven’t gone to 2.0, very glad). Following in the footsteps of the Fastloader, here is another fine homebrew app for your pleasure. This time we present you a full featured UMD emulator, reboot & exitgame tight – you have to turn off your PSP completely (or crash it :p ) to get it back to original state. This is a semi-final version, some things are known not to work properly for now… Link.
PSP UMD Emulator V0.8