Beetle PC Engine Fast is a port/fork of Mednafen's PC Engine Fast module to the libretro API. This libretro core contains CD-ROM2 support but unlike Mednafen's PCE Fast module, lacks SuperGrafx support. A separate libretro PC Engine core with SuperGrafx support can be found here: https://github.com/libretro/beetle-supergrafx-libretro
This repository also contains a port/fork of Mednafen's PC Engine module on the pce branch. This PC Engine module is more accurate than the Fast module, which trades away typically unneeded accuracy in favor of speed. Unlike the Fast module however, this module fork retains built-in SuperGrafx support.
The PCE Fast core can be built with make in the master branch while the PCE "non-Fast" core can be built with make in the pce branch.