fogleman/nes

This is an NES emulator written in Go, a programming language developed by Google. An emulator is software that mimics the hardware of an old game console so that original game cartridge files (called ROMs) can be played on a modern computer. This one targets the Nintendo Entertainment System, the classic home console from the 1980s. To run the emulator you pass it a ROM file or a folder of ROMs from the command line. When given a folder, it shows a menu with thumbnails pulled from an online database so you can pick which game to launch. Keyboard controls map the original NES buttons to keys, and physical joysticks are also supported. The emulator relies on three external libraries: one for rendering graphics using OpenGL, one for creating a window and handling input via GLFW, and one for audio output via PortAudio. PortAudio must be installed separately on your system before building. On a Mac this is a single Homebrew command. The README lists which NES mappers have been implemented. Mappers are the hardware chips inside NES cartridges that controlled how the console accessed memory. Different games used different mappers. Six mappers are currently supported, which the author says covers about 85% of all NES games. Known limitations include minor timing issues in the video chip and imperfect audio emulation, though most games work acceptably. The README also links to technical documentation for anyone interested in building their own emulator, including NES hardware references and a guide to the 6502 processor that the NES used.