Apple Copland D11E4 Booting in the Browser

Michael Steil has published a browser demo of Apple's Copland operating system. Running inside it is build D11E4, the last version Apple produced, in an improved version of DingusPPC — a PowerPC Mac emulator compiled to WebAssembly.

Copland is notoriously hard to run on real hardware and, according to Steil, had not previously been available in emulation at all.

What the demo does

The emulator boots the system directly in the page. Clicking the screen hands the keyboard and the mouse to the emulated machine; pressing Escape returns them to the host. On real hardware the boot takes about 30 seconds, and Steil notes that a modern machine can match that speed in wasm.

If executing code hits an assertion, the emulator drops into a debugger; clicking “Continue” lets the machine run again. Steil suggests opening the Copland HD volume and starting GXSlidemaster or Eric’s Solitaire from the Applications folder.

Eleven patches behind the port

Making Copland run took 11 patches, published on the copland-boot branch of Steil’s DingusPPC fork; the patches for the wasm version live on a separate branch. DingusPPC does not accept patches written with the help of AI, so Steil invites anyone to redo the fixes using the explanations in the commit messages.

By its own description, DingusPPC aims at accurate emulation of PowerPC Macs and includes a debugging environment with a disassembler. It works best with NuBus and Old World ROM machines such as the Power Mac 6100, 7200 and G3 Beige.

Why it matters

Copland was meant to replace System 7 with a modern, microkernel-based operating system, but the project was cancelled. Apple instead bought NeXTSTEP/OpenStep, which became Mac OS X. Running the last Copland build in a browser tab makes an abandoned branch of that history directly explorable.