Wikipedia:AtheOS

AtheOS is a discontinued free and open source operating system for x86-based computers. It was initially intended as an AmigaOS clone, but that objective was later abandoned. It is no longer in development, and has been superseded by the Syllable operating system.

History
It was created entirely by a Norwegian programmer, Kurt Skauen, from 1994 to the early 2000s; AtheOS was announced to the world in March 2000 on Usenet. Although it was licensed as free software, Skauen was more hesitant to accept contributions from the public than other free and open source operating system projects. The availability of the code under the GNU GPL allowed other developers to launch Syllable, a fork from the AtheOS code base, which continued until 2012.

Skauen ported KHTML to AtheOS in order to create the ABrowse web browser.

Features

 * Its own native 64-bit journaling file system, the AtheOS File System (usually called AFS)
 * Support for symmetric multiprocessing
 * An original, legacy-free, object-oriented GUI architecture
 * Support for most of the POSIX standard
 * Pre-emptive multitasking with multithreading
 * C++ oriented API