However, the BIOS presents a legal and ethical grey area. While the emulators themselves are open-source software, the BIOS files are copyrighted intellectual property owned by SNK Playmore (now SNK Corporation). Therefore, "true" preservation requires users to dump the BIOS from their own physical hardware.
The Neo Geo is famous for its regional censorship—not via ROM hacking, but via the BIOS itself. Three official regional BIOS versions exist for both MVS and AES: neo geo bios
For emulators like MAME, FinalBurn Neo, and NeoRAGE, the BIOS is mandatory. Unlike cartridge ROMs, the BIOS is not included with emulators because it remains copyrighted by SNK (now owned by SNK Corporation). Users must dump their own BIOS from original hardware. However, the BIOS presents a legal and ethical grey area