Run Mednafen from the command line with -bi or check the log output. Mednafen will complain if a BIOS is missing or has a bad checksum.
If you have stumbled upon the term "Mednafen Bios Pack" while trying to configure your setup, you are likely looking for the missing piece of the puzzle. This article serves as an extensive guide to understanding what BIOS files are, why Mednafen requires them, the legal landscape surrounding them, and how to manage your BIOS pack effectively for a seamless retro gaming experience. Mednafen Bios Pack