mister-devel/apple-iigs_mister

This project recreates the classic Apple IIgs home computer from the 1980s so it can run on a MiSTer, which is a piece of hardware that uses a reprogrammable chip called an FPGA to behave like old computers and game consoles at the hardware level, rather than software pretending to be them. The goal is timing accuracy close enough that old software, including copy-protected games, runs the way it did on the real machine. The recreation covers the original processor running at its correct speed, plus an optional speed boost mode that mimics a popular accelerator upgrade some real Apple IIgs owners installed back in the day. It reproduces the computer's memory system, all of its original graphics modes including its highest-color mode, sound generation through the original sound chip, and support for keyboard, mouse, and joystick input the way the real hardware handled them. It also supports the different kinds of disks the Apple IIgs used: large-capacity hard disk style storage, older style hard disk images, and both sizes of floppy disk the machine originally read, including detailed floppy formats that preserve intentional copy-protection tricks some old games relied on. To use this, you need a physical MiSTer device. You also need to legally obtain the original Apple IIgs system ROM yourself, since Apple's ROM code cannot be included in this repository, then run an included build step to generate the ROM files the core needs before it will even compile. Once built, the resulting files get copied onto the MiSTer's storage card alongside those generated ROM files. This is aimed at people who already own MiSTer hardware and want to play or preserve original Apple IIgs software and games with a high degree of hardware accuracy, rather than a general emulator you install on a regular computer.