IEEE Bushy Tree

Nextstep was the original object-oriented, multitasking operating system that NeXT Computer developed to run on its proprietary NeXT computers ("black boxes") such as the NeXTcube. Nextstep 1.0 was released on September 18, 1989 after several previews starting in 1986. The last version, 3.3, was released in early 1995, by which time it ran not only on Motorola 68000 family processors, but also IBM PC Comaptible x86, Sun SPARC, and HP PA-RISC. Apple Inc.'s Mac OS X is a direct descendant of Nextstep.


Nextstep was a combination of several parts:

  • a Unix operating system based on the Mach kernel, plus source code from BSD Unix
  • Display PostScript and a windowing engine
  • the Objective-C language and runtime
  • an object-oriented (OO) application layer, including several "kits"
  • development tools for the OO layers
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Nextstep branch
Preceded by
Mac OS
Nextstep Followed by
Mac OS X