The final developer build offers a glimpse of the future Cupertino abandoned for NeXT.
Thirty years after Apple abandoned Copland, its doomed attempt to create a modern Mac operating system, a new emulator lets you try the final developer build in your browser.
Copland was intended to replace Apple's System 7 with a PowerPC-native operating system built around a microkernel, protected memory, and preemptive multitasking for system services.
Relatively few people outside Apple's developer community in the mid-1990s ever had the opportunity to use them.
Now you can boot Apple Copland D11E4 in your browser and explore the unstable prerelease OS without installing anything. Developer Michael Steil, also known as Mist, made it possible with an experimental fork of the DingusPPC Power Mac emulator.
Steil says the 11 patches that enable DingusPPC to boot Copland were written with AI help.
The emulator runs D11E4, the final build Apple distributed to developers, dating from June 1996.
Apple CEO Gil Amelio had showed Copland at the company's 1995 Worldwide Developers Conference, but the project never approached the stability needed for release.
In 2009, Steil assembled an extensive archive of that material in Apple Copland Reference Documentation.
Copland overran so badly that Amelio recruited the late Ellen Hancock from IBM as Apple's chief technology officer and tasked her with getting the project back on track.
Mac OS 8, released in 1997, gained Copland's Platinum interface and a PowerPC-native, multithreaded Finder.
Further pieces of Copland's work appeared across Mac OS 8 and 9, allowing Apple to improve the old platform while Mac OS X was being prepared.