Gotcha! Our intent with quizzes is mainly educational - highlighting something about the Macintosh, Apple, or the Mac OS - rather than trying to come up with a question that's likely to fool most of the quiz respondents. However, last week's quiz asking how many Unix-derived operating systems Apple has released apparently did both: only about five percent of the over 950 respondents knew the correct answer (five or more), with over seventy percent of the respondents guessing at two or three.
We count at least six Unix-derived operating systems that have come in some way from Apple: A/UX, AIX, MkLinux, Mac OS X Server, Darwin, and Mac OS X Public Beta. So even if you're tempted to argue Mac OS X Server and Mac OS X are the same thing (they aren't, under the hood) the correct answer still would have been "five or more."
A/UX was a version of Unix developed by Apple in the late 1980s for 68K machines; it pioneered Unix-based sharing of Macintosh files. Apple stopped supporting A/UX in the early 1990s and never ported it to PowerPC, but it was a solid product that gained some die-hard supporters. (TidBITS first wrote about A/UX way back in TidBITS-006.)
AIX: Back in 1996, Apple shipped IBM's AIX on the short-lived Network Server line. The Network Servers were enormous systems with dual PCI buses, six PCI slots, secure hot-swappable drive bays, and (then) top-of-the-line PowerPC 604 processors.
MkLinux: In mid-1996, Apple ported Linux to PowerPC Macs and eventually issued three developer releases of MkLinux. The last release supported G3 systems (but not the iMac), and although Apple has ceased development on MkLinux, some of its engineering know-how found its way into Mac OS X. MkLinux development has subsequently been taken over by the MkLinux user community. (Tom Gewecke wrote two articles for TidBITS covering running various Linux operating systems on his Mac, one in TidBITS-407 and another in TidBITS-461.)
Mac OS X Server: More recently, Apple released Mac OS X Server, which (like the forthcoming Mac OS X) is built on BSD Unix and the Mach microkernel. Unlike Mac OS X, however, Mac OS X Server has been shipping for some time and lacks the new Aqua interface and associated technologies, but offers QuickTime streaming and unique Mac-only capabilities like the NetBoot server.
Darwin is a bare-bones open source operating system which exposes the guts of Mac OS X and Mac OS X Server without including proprietary Apple technologies like the Aqua interface. Darwin is being ported to Intel processors by the larger developer community, although there's no expectation at this time that Apple will develop Mac OS X or Mac OS X Server for Intel processors.
Mac OS X Public Beta: Of course, the public beta of Mac OS X is based on BSD Unix, although the command-line is safely tucked away behind the Aqua interface, since Apple eventually intends Mac OS X to be the default operating system for all Macintosh users. Apple plans to ship Mac OS X in early 2001.
Counting these six Unix-derived operating systems from Apple leaves aside other Apple forays into the Unix world, like MAE (Macintosh Applications Environment, which let some Mac programs run under some flavors of Unix) and Mac X (an X Windows server for Mac OS) which weren't actual operating systems. It also leaves out the various Linux for PowerPC products (check the MkLinux.org site above for a good list) and efforts like Tenon Intersystems' long-standing MachTen, which is a full-fledged Unix running as a standard Macintosh application.