While the Sega CD BIOS is the most common association, the filename mcd-us.bin can occasionally appear in other software contexts:
: Many emulators, particularly those in RetroArch , are extremely picky about case sensitivity. Users often find that renaming it to lowercase bios_CD_U.bin or mcd-us.bin is necessary for the system to recognize it. mcd-us.bin
is the essential BIOS file required to emulate or play Sega CD (Mega CD) games from the North American region on modern hardware. While the Sega CD BIOS is the most