OpenStep is both an operating system and a class framework originally developed by NeXT, but now owned by Apple. As an OS under that title, it is based on Mach; the last released version was 4.2. Since then, it has been converted into Rhapsody by Apple, merging in a Mac OS look and feel, and is undergoing further merging into Mac OS X. The class framework part of OpenStep is currently code-named Yellow Box by Apple.

OpenStep is the descendent of NeXTSTEP originally developed by a company founded by Steve Jobs called NeXT. OpenStep provides a cross-platform API. Based upon BSD mach it runs on NeXT and Intel platforms as well upon the native operating systems of Hewlett Packard's Apollo Workstations, and Sun's Sparcs.

Please note that a GPL'd implementation of the OPENSTEP API has been under development for quite some time. It is called GNUstep and is doing quite nicely; although, there is still much work to be done. Cruise on over to and have a look around.

OPENSTEP 4.2 for Mach is the last incarnation of NeXT's OS to be actually sold by NeXT, or to run on their hardware. It was succeeded by Rhapsody and later Mac OS X, and descended directly from NeXTSTEP. Its interface is virtually identical to that of NeXTSTEP 3.3, featuring the global menus, Workspace Manager and Dock that made it so iconic. Unfortunately, the revamped user interface seen in the NeXTSTEP 4.0 developer betas, featuring a shade button, gradient-filled titlebars, flat window decorations and a tabbed shelf did not make it into OPENSTEP, and appears to be lost in the mists of time. The major difference between NeXTSTEP 3.3 and OPENSTEP is in the API, which has been standardized to the OpenStep (note the capitalization difference) specification. It will therefore run most NeXTSTEP applications, but also supports a new, superior API that its predecessor did not have. Also, significantly, OPENSTEP dropped support for the various HP PA-RISC workstations, though support for the Sun SPARCstations remained. NeXT intended to port the OS to the Motorola 88000 and PowerPC, and possibly also to the DEC Alpha and Sun UltraSPARC, but NeXT folded before this could happen.

Supported configurations

NeXT hardware

Any Motorola 68040-based NeXT. The original MC68030 Cubes are officially not supported, though many sources state that it does indeed work, albeit slowly. This is the original platform, and obviously, all hardware is fully supported.

Sun SPARC hardware

The only machines officially supported are the sun4m series, though there are sporadic reports of people convincing OPENSTEP to run on sun4c systems. In either case, the only supported processors are the SuperSPARC and MicroSPARC series. The Ross HyperSPARC and Texas Instruments TurboSPARC processors aren't supported at all, and the kernel will choke and refuse to boot. It's also rather picky about graphics devices - the only framebuffers that work are the BW2 (monochrome), CG6/GX (8-bit color, accelerated), CG14/SX (24-bit color, accelerated, SPARCstation 20 and rare SPARCstation 10s only), and the TCX (8-bit or 24-bit color, accelerated, AFX bus). This last one is hard to find, and works only on the SPARCstation 4 and SPARCstation 5.

Other hardware, such as ethernet, sound and SCSI, along with the standard Sun serial and parallel ports work. The SPARCstation 10's onboard ISDN does not, however. (It works only with Solaris).

x86 hardware

Hardware support on x86 is a can of worms. There are fairly few hardware drivers available, but a surprising amount of modern hardware can be convinced to work. In any case, you'll need an 80486 or later CPU, the 386 won't cut it. You'll also need some sort of supported mass storage controller - IDE works, as do a fair few SCSI cards, but Fibre Channel is right out. Graphics is a challenge, too, but a good general rule is that cards which work under OS/2 work under OPENSTEP. Later patches also add a VESA graphics driver which allows nearly any card to work, at least somewhat. Sound and ethernet are challenges too.

All that said, OPENSTEP will run on some surprisingly modern systems, and is quite performant relative to NeXT or Sun hardware.

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