MAME is great free emulator that lets you play thousands of games for PC! MAME’s purpose is to preserve decades of software history. As electronic technology continues to rush forward, MAME prevents this important “vintage” software from being lost and forgotten. This is achieved by documenting the hardware and how it functions. The source code to MAME serves as this documentation. The fact that the software is usable serves primarily to validate the accuracy of the documentation (how else can you prove that you have recreated the hardware faithfully?). Over time, MAME absorbed the sister-project MESS (Multi Emulator Super System), so MAME now documents a wide variety of (mostly vintage) computers, video game consoles and calculators, in addition to the arcade video games that were its initial focus.
MAME, formerly was an acronym which stood for Multi Arcade Machine Emulator, documents and reproduces through emulation the inner components of arcade machines, computers, consoles, chess computers, calculators, and many other types of electronic amusement machines. As a nice side-effect, MAME allows to use on a modern PC those programs and games which were originally developed for the emulated machines.
At one point there were actually two separate projects, MAME and MESS. MAME covered arcade machines, while MESS covered everything else. They are now merged into the one MAME. MAME is mostly programmed in C with some core components in C++. MAME can currently emulate over 32000 individual systems from the last 5 decades.