Legal notice: This voids your warranty (like all homebrews and emulators) and it is illegal to download video games “that you don’t own”. And you need the PS1 BIOS file which is SCPH1001.BIN but you can probably find it on the Internet (illegally).
So, what does this do? It’s an emulator for your PSP to play PS1 games. You need certain files to run it. And it’s kinda slow because games run at 10fps. According to the emulator website it says that it is for PSP versions (I am talking firmware versions) 1.0-2.60. The game runs ROMs that are in BIN or ISO format.
It is available for download here: