If you use emulators like , ePSXe , RetroArch (Beetle PSX HW) , or Xebra , the BIOS file is not optional. The emulator does not "guess" how a PlayStation boots; it loads the real BIOS.
: Internal HDMI mods that tap directly into the digital video signals for 1080p output.
By the time the 5500 series was released, Sony had refined the console's internal architecture. While earlier models (like the SCPH-1000 or SCPH-3000) were prone to overheating or laser alignment issues, the 5502 was lauded for its reliability. It featured an improved laser unit and a more stable motherboard layout.
The European 5502 typically carries BIOS v3.0 (PAL) . It is region-locked to Europe, meaning it will natively only boot PAL-formatted discs.