Soywiz PSP Emu
Soywiz PSP Emu is a PSP emulator written in C# for Windows and Linux. It could run several commercial PSP games at a decent speed, and development moved quickly until the developer moved on to a new project, jspspemu.
It had a strong dynamic recompiler core and several extra features, including the option to increase the render resolution so games look better on larger screens.
Like many emulators, it made great progress on emulating the PSP before development was abandoned.

