tl;dr: PCjs is a JavaScript-based emulator project that runs vintage hardware and software in the browser, including IBM PC compatibles, minicomputers (PDP-11), programmable calculators (TI-57), terminals, and arcade games. The collection spans decades of computing history, from Space Invaders (1978) and VisiCalc (1981) to Windows 95, Wolfenstein 3D, and classic DOS utilities. The project is open-source on GitHub and aimed at preserving early computing artifacts.