Always verify your BIOS in the emulator’s log. DuckStation, for example, prints: "BIOS: SCPH5500 (Japan) v3.0" if it’s genuine.

PSX homebrew developers often target the V30 BIOS as their baseline because:

The SCPH-5500 BIOS is classified as a kernel.

Check your file with:

PlayStation SCPH-5500 (v3.0 Japan) BIOS , typically found as the file scph5500.bin