In the mid-1990s, Apple developed an operating system called Copland, which was announced but never commercially released due to project management issues and feature creep. Parts of Copland were later included in Mac OS 7.6 and Mac OS 8, but the project was ultimately canceled. Michael Steil, who reverse engineers vintage hardware and software, recently got Copland running in emulation by modifying the open-source Power Mac emulator DingusPPC. He applied 11 patches to achieve this and has made a browser version available on his website, along with the patches needed to boot Copland.

During its development, Apple released three beta versions of Copland, with the last being D11E4, which Steil successfully got to work. He noted that Copland is "notoriously hard to run on real hardware" and had not previously been available in emulation. After Apple canceled Copland in August 1996, the company sought a new operating system externally, leading to the purchase of NeXT in 1997 and the return of Steve Jobs. NeXTSTEP, NeXT's operating system, became the precursor to Mac OS X.