4 operating systems independent of Windows, Linux, Unix

Haiku, AmigaOS, KolibriOS, and TempleOS trace no lineage to Windows, Linux, or Unix. Haiku's kernel derives from NewOS, AmigaOS uses Exec and TRIPOS, KolibriOS fits on a 1.44MB floppy, and TempleOS is a single-author system written in HolyC.