MESS (Multi Emulator Super System), the sister project of MAME1). MESS is a source-available project which documents the hardware for a wide variety of (mostly vintage) computers, video game consoles, and calculators through software emulation, as MAME does for arcade games. As a nice side effect to this documentation, MESS allows software and games for these hardware platforms to be run on modern PCs.
As of version 0.140, MESS supports 514 unique systems with 1,381 total system variations and is growing all the time. However, not all of the systems in MESS are functional.