All the loose bios files in the \system folder match the bios files listed here:

https://raw.githubusercontent.com/libretro/libretro-database/master/dat/BIOS.dat	version 2019-05-15


The various .rar files contain the folder structures\files for a few other cores. 
Each has it's own readme to tell you what it's for.


Atari ST_STE_TT_Falcon (Hatari) BIOS Collection.rar contains different versions of the same bios.


The folders \Machines and \Databases provide the needed assets for ColecoVision/Spectravideo/SG-1000 support
on the blueMSX core.


The \PPSSPP folder provides PlayStation Portable assets. 
It contains a different version of the ppge_atlas.zim bios, but it works fine.


SuperGameBoy.rar contains the folders \SGB1.sfc & \SGB2.sfc and bios files.


2 additional files have been added:

nes.pal (custom NES palette) in the NES folder. optional custom palette for FCEUmm emulator. 
File was found here: http://www.firebrandx.com/graphics/nespalettes/nespalette-nes-classic-fbx.zip
and renamed accordingly.

sgb.boot.rom (super gameboy boot image, renamed) in the SNES folder. Emulator bsnes-mercury Balanced says it's optional.


