Term: MacOS, Description: Operating system for Apple computers, Question: Has MacOS been the only operating system for Apple computers?, Answer:No
Fact1: The "classic" Mac OS is the original Macintosh operating system that was introduced in 1984 Fact2: The Apple Real-time Operating System Environment (A/ROSE) was a small embedded operating system which ran on the Macintosh Coprocessor Platform, an expansion card for the Macintosh Fact3:  MkLinux is an open source operating system that was started by the OSF Research Institute and Apple in February 1996 to port Linux to the PowerPC platform, and thus Macintosh computers. Fact4: Taligent (a portmanteau of "talent" and "intelligent") was the name of an object-oriented operating system and the company dedicated to producing it. Started as a project within Apple to provide a replacement for the classic Mac OS, it was later spun off into a joint venture with IBM as part of the AIM alliance, with the purpose of building a competing platform to Microsoft Cairo and NeXTSTEP. The development process never worked, and Taligent is often cited as an example of a project death march. Apple pulled out of the project in 1995 before the code had been delivered.[22] 