Window-based operating systems

thumb|ReactOS 0.4.14 running the Firefox [[web browser]] ReactOS is a free and open-source operating system for i586/amd64 personal computers that is intended to be binary-compatible with computer programs and device drivers developed for Windows Server 2003 and later versions of Microsoft Windows. ReactOS has been noted as a potential open-source drop-in replacement for Windows and has been of interest for its information on undocumented Windows APIs.

NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT, founded by Steve Jobs, in the late 1980s and early 1990s and was initially used for its range of proprietary workstation computers such as the NeXT Computer. It was later ported to several other computer architectures and was later bought by Apple Inc. to replace the older Classic Mac OS with macOS.

operating system

computer operating system

A/UX is a Unix-based operating system from Apple Computer for Macintosh computers, integrated with System 7's graphical interface and application compatibility. It is Apple's first official Unix-based operating system, launched in 1988 and discontinued in 1995 with version 3.1.1. A/UX requires select 68k-based Macintosh models with an FPU and a paged memory management unit (PMMU).

operating system of the Atari ST range of computers

graphical operating system (8-bit)

Apple IIGS operating system

graphical operating system (16-bit)

orthogonally persistent managed-code general purpose operating system