The general consensus in the emulation community is: Match the BIOS region to the game region . Therefore, if you are building a library of European PS1 games (like Colin McRae Rally , Micro Machines V3 , or Harry Potter and the Philosopher's Stone ), you need the scph5502.bin as your primary BIOS.
For modern frontend emulators like RetroArch or OpenEmu, you typically need to place the scph5502.bin file in the system directory. Ensure the file is named exactly scph5502.bin . Case Sensitivity: It is usually case-sensitive.