PPSSPP is an open source project, licensed under the GPL 2.0. Anyone is welcome to contribute their improvements to the code, and the hope is that over time this will resolve the compatibility problem.

Fast and portable
PPSSPP is written in C++, and translates PSP CPU instructions directly into optimized x86, x64 and (soon) ARM machine code, using an efficient JIT compiler.

PPSSPP can thus run on quite low-spec hardware, including stronger Android phones and tablets, as long as there's support for OpenGL ES 2.0.