Bios-cd-u.bin Bios-cd-e.bin | Bios-cd-j.bin

Those files represent the BIOS ROM images for the Sega CD (Mega-CD) console, with u, e , and j corresponding to the , , and regions, respectively.

(all lowercase except for the region letter) to avoid the "Failed to load content" error often reported by users on forums like The "System" Folder : Most modern handhelds (like the bios-cd-u.bin bios-cd-e.bin bios-cd-j.bin

Here’s a clear, informative piece: