pSX is one of the lessor known emulators for the PlayStation 1. It claims that it manages to fully emulate the PlayStation 1, however its actual accuracy and ability to emulate games without large issues is questionable.
The original website for pSX is sadly now offline so its hard to find to much information on this emulator.
The emulator also includes an R3000 debugger for those who are interested in the inner working of the PlayStation and those who are also interested in doing translations of games.
Compatibility of the emulator however is still decent, and well worth trying, its not as developed as ePSXe or PCSX Reloaded but is well worth checking out still if you have issues with the other emulators.
Note: you will need a PS1 BIOS image (not supplied) – it should be called SCPH1001.bin and placed in the bios folder of the emulator.