Excellent reason to roll back any PSP, a Commodore 64 emulator! – “64psp began life as an experiment to learn how to program the PSP. No PSP C64 emulators existed at the time and the Frodo source code appeared to have a gentler learning curve. A PSP port of VICE is also in progress. Both emulators have their plus and minus points, so why not try both?” [via] Link.
Commodore 64 emulator for the PSP