Milo emulators

NES, SNES, and Genesis emulators written in Milo — a memory-safe systems language with no GC and no lifetime annotations. Cycle-driven CPU cores, scanline PPU/VDP rendering, and audio, with SDL2 for video, sound, and input.

No unsafe. No garbage collector. Commercial games run at full speed.

Documentation · Download a release — SDL2 is statically linked, so nothing needs installing.

Install

P=$(uname -s | tr A-Z a-z)-$(uname -m | sed 's/x86_64/x64/;s/aarch64/arm64/')
curl -fsSL https://github.com/milo-language/emulators/releases/download/latest/milo-emulators-$P.tar.gz | tar xz
cd milo-emulators-$P
./nes path/to/rom.nes

Download through a browser instead and macOS quarantines the archive: the unsigned binary is killed on first run and moved to the Trash. Either install with curl as above, or clear the flag with xattr -dr com.apple.quarantine <dir> before running.

--version prints the commit the binary was built from. Releases roll on the latest tag, so re-running the install command is the update path.

Core	Directory	State
NES	nes/	Games play with audio. APU incl. DMC, multiple mappers. See PROGRESS.md
Genesis	genesis/	68000 + Z80 + VDP. Sonic, Golden Axe, Aladdin play. See PROGRESS.md
SNES	snes/	Super Mario World and Donkey Kong Country play; Star Fox boots (Super FX/GSU). See PROGRESS.md

Also here:

• retro/ — a console front-end that builds all three cores and launches them from one menu
• shared/ — SDL bindings, bitmap font, and menu core shared by the front-end
• menu.milo — fullscreen SDL ROM browser, scans roms/{nes,genesis,snes}
• arcade.sh — dispatches a ROM to the right core by file extension

Build

Requires the milo compiler and SDL2.

milo build nes/nes.milo -o nes --release
./nes path/to/rom.nes

SDL2 is linked via Milo's @link attribute — no manual -lSDL2 needed.

To build every core plus the front-end:

./retro/build.sh release

Correctness

The cores are checked against reference implementations rather than eyeballed:

• NES traces are diffed against jsnes
• Genesis and SNES CPU cores run the SingleStepTests Harte suites (harte.sh, harteSpc.sh)
• Genesis is additionally diffed against Musashi

ROMs are not distributed here.