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Advanced Mac Substitute is an API-level reimplementation of 1980s-era Mac OS

In MacPaint, the word 'hello' is written in cursive.

MacPaint running in Advanced Mac Substitute (click to see video)

Advanced Mac Substitute icon: A grey desktop and arrow cursor, on a grayed-out Macintosh

Advanced Mac Substitute

Advanced Mac Substitute is an API-level reimplementation of 1980s-era Mac OS. It runs 68K Mac applications in an emulator without an Apple ROM or system software.

"But those times are now only legend." "But those times are now only legend."

System’s Twilight running in Advanced Mac Substitute.

The first level of Lode Runner that it autoplays in its Attract mode The player is burning a hole in the floor to trap an approaching guard.

Lode Runner running in Advanced Mac Substitute

The white-on-black title screen of the prologue cinematic from The Fool’s Errand The same title, but with a rain-against-the-camera-lens effect.

The opening of the prologue cinematic from The Fool’s Errand running in Advanced Mac Substitute

Amazing, a maze-tracing game by Steve Capps When you solve the maze, a picture appears of a penguin blowing a triumphant note on a bugle.

Amazing running in Advanced Mac Substitute (point to see the solved maze)

Unlike traditional emulators, Advanced Mac Substitute doesn’t emulate the hardware on which an operating system runs (except for the 680x0 processor), but actually replaces the OS — so it launches directly into an application, without a startup phase.

A parody of the Macintosh loading screen.

Welcome to Advanced Mac Substitute.

(This is an application, not a real loading screen.)

Advanced Mac Substitute is a factored application. The backend includes a 68K emulator and should build and run on any POSIX-like system. The frontend is a generic bitmapped terminal abstraction, provided by SDL2 (for various platforms) along with custom implementations for macOS, X11, and Linux framebuffer (fbdev).

Advanced Mac Substitute is capable of running several applications written for the original Macintosh computer. Examples include four games from 1984: Amazing, Solitaire, Missile, and IAGO.

Missile, a Missile Command clone for Macintosh from 1984 Another incoming ICBM is destroyed, yet many more remain — including a MIRV warhead

Missile running in Advanced Mac Substitute (point to see the next frame)

IAGO, an Othello game for Macintosh from 1984 Game over: White has beaten Black, 48-16

IAGO running in Advanced Mac Substitute (point to see who won)

Current support includes 1-bit-deep graphics, regions, circles and roundrects, lines, cursors, GrafPorts, text, windows, controls, menus, dialogs, and more.

Source

Source code for Advanced Mac Substitute is on GitHub.

If you’re feeling adventurous, you can try out Advanced Mac Substitute in macOS / OS X, the X Window System, a Linux framebuffer console, or a VNC client.

Still image of monochrome nyancat using patterns instead of colors Animation of monochrome nyancat using patterns instead of colors

Nyanochrome Cat running in Advanced Mac Substitute (point to animate)

(Older documentation has moved while revision is under way.)