operating system from the higher-level object libraries to create a cross-platform object-oriented API standard derived from NeXTSTEP. OpenStep is hosted on multiple underlying operating systems, including NeXT's own OPENSTEP. It was released for Sun's Solaris, Windows NT, and NeXT's version of the Mach kernel. NeXT's implementation is called "OPENSTEP for Mach" and its first release (4.0) superseded NeXTSTEP 3.3 on NeXT, Sun, and Intel IA-32 systems. Following an announcement on December 20, 1996, Apple Computer acquired NeXT on February 4, 1997, for $429 million. Based upon the "OPENSTEP for Mach" operating system, and developing the OPENSTEP API to become Cocoa, Apple created the basis of Mac OS X, and eventually of iOS, iPadOS, watchOS, and tvOS. GNUstep is a free software implementation of the OpenStep standard. Release history Versions up to 4.1 are general releases. OPENSTEP 4.2 pre-release 2 is a bug-fix release published by Apple and supported for five years after its September 1997 release. See also OpenStep, the object-oriented application programming interface derived from NeXTSTEP GNUstep, an open-source implementation of Cocoa API respectively OpenStep API Window Maker, a window manager designed to emulate the NeXT GUI for the X Window System Bundle (macOS) Miller Columns, the method of directory browsing that NeXTSTEP's File Viewer used Multi-architecture binary NeXT character set Previous, an emulator for NeXT hardware capable of running some versions of NeXTSTEP References External links NeXTComputers.org The Next Step BYTE Magazine 14-03, Object Oriented Programming with NextStep 1989 software Berkeley Software Distribution Discontinued operating systems Mach (kernel) NeXT Object-oriented operating systems Unix variants Window-based operating systems