Apple's Cancelled Copland OS Runs in the Browser via WebAssembly

Copland, the microkernel-based operating system Apple built in the 1990s to succeed System 7, was scrapped before shipping and has been almost impossible to run since — even on period hardware. A developer has now gotten the final D11E4 build booting inside a modified version of the DingusPPC PowerPC emulator, compiled to WebAssembly so it runs directly in a browser. Boot takes about 30 seconds, roughly matching real hardware, and users can click into the window to hand it keyboard and mouse control and poke at bundled apps like GXSlidemaster and Eric’s Solitaire.

Getting Copland to run required 11 patches, published on a branch of the developer’s DingusPPC fork, with a separate branch carrying the WebAssembly build. Notably, the author flags that these patches were written with AI assistance — and since the upstream DingusPPC project refuses AI-generated contributions, the fixes can’t be merged as-is. The commit messages explain each change in enough detail that someone could reimplement them by hand for upstream acceptance.

The project is a piece of computing archaeology as much as an emulation feat: Copland’s failure is what pushed Apple to acquire NeXT, whose OpenStep foundation became Mac OS X. Making the abandoned system publicly runnable offers a rare hands-on look at the road Apple didn’t take. The AI-patch caveat also surfaces a live tension in open-source governance, where projects are increasingly setting explicit policies on machine-generated code.