Locate the directory on your device storage: Storage/MAME4all/roms/ (or the custom folder you selected at startup). Keep them as .zip archives.

For example, Neo Geo titles (like Metal Slug or King of Fighters ) all rely on the same neogeo.zip BIOS. Similarly, CPS-1 and CPS-2 games by Capcom require a specific encryption key BIOS.

If you cannot find the complete , consider these options:

The bios folder in MAME 0.139u1 is not a single file but a directory of zipped ROMs. Each .zip file corresponds to a system board.

In the world of arcade emulation, many games share the same hardware platform. For instance, every Neo Geo game relies on the same system board software. To save space and maintain accuracy, MAME developers split these common files into separate "BIOS ROMs" rather than including them in every individual game file. Mame 0139u1 Bios Pack Hot Extra Quality

This usually indicates a video rendering or sample error rather than a BIOS issue. Check if the game requires an additional audio sample pack ( .sam files) or a Compressed Hunk Data ( .chd ) hard drive image file inside a subfolder. A Note on Legality and Safe Downloading