JPCSP is an open-source PlayStation Portable emulator. It requires Java Runtime environment to be installed.
It requires the Java Runtime Environment to be installed, which has a history of security issues. Because it uses Java, it is also much slower than PPSSPP.
The developers of JPCSP never intended for it to become a standard emulator. It was created to better understand the PSP's inner workings. Thanks to the JPCSP team, PPSSPP is developing quickly. Both teams communicate and contribute with each other.