Standardizing Unconformity 11 at NeXTWORLD asked me what the difference was between AIX and A/UX. “AIX is Unix from IBM. A/UX is Unix from Apple.” “What’s the difference?” he asked. “I’m not sure. They’re both AT&T System V with gratuitous changes. Then there’s HP-UX which is HP’s version of System V with gratuitous changes. DEC calls its system ULTRIX. DGUX is Data General’s. And don’t forget Xenix—that’s from SCO.” NeXT, meanwhile, calls their version of Unix (which is really Mach with brain-dead Unix wrapped around it) NEXTSTEP. But it’s impossible to get a definition of NEXTSTEP: is it the window sys- tem? Objective-C? The environment? Mach? What? Originally, many vendors wanted to use the word “Unix” to describe their products, but they were prevented from doing so by AT&T’s lawyers, who thought that the word “Unix” was some kind of valuable registered trade- mark. Vendors picked names like VENIX and ULTRIX to avoid the possi- bility of a lawsuit. These days, however, most vendors wouldn’t use the U-word if they had a choice. It isn’t that they’re trying to avoid a lawsuit: what they are really trying to do is draw a distinction between their new and improved Unix and all of the other versions of Unix that merely satisfy the industry standards. It’s hard to resist being tough on the vendors. After all, in one breath they say that they want to offer users and developers a common Unix environ- ment. In the next breath, they say that they want to make their own trade- marked version of Unix just a little bit better than their competitors: add a few more features, improve functionality, and provide better administrative tools, and you can jack up the price. Anybody who thinks that the truth lies somewhere in between is having the wool pulled over their eyes. Date: Sun, 13 May 90 16:06 EDT From: John R. Dunning jrd@stony-brook.scrc.symbolics.com To: jnc@allspice.lcs.mit.edu, UNIX-HATERS Subject: Unix: the last word in incompatibility. Date: Tue, 8 May 90 14:57:43 EDT From: Noel Chiappa jnc@allspice.lcs.mit.edu [...]

12 Unix I think Unix and snowflakes are the only two classes of objects in the universe in which no two instances ever match exactly. I think that’s right, and it reminded me of another story. Some years ago, when I was being a consultant for a living, I had a job at a software outfit that was building a large graphical user-inter- face sort of application. They were using some kind of Unix on a PDP-11 for development and planning to sell it with a board to OEMs. I had the job of evaluating various Unix variants, running on various multibus-like hardware, to see what would best meet their needs. The evaluation process consisted largely of trying to get their test program, which was an early prototype of the product, to compile and run on the various *nixes. Piece of cake, sez I. But oops, one vendor changed all the argument order around on this class of system functions. And gee, look at that: A bug in the Xenix compiler pre- vents you from using byte-sized frobs here you have to fake it out with structs and unions and things. Well, what do you know, Venix’s pseudo real-time facilities don’t work at all you have to roll your own. Ad nauseam. I don’t remember the details of which variants had which problems, but the result was that no two of the five that I tried were compatible for anything more than trivial programs! I was shocked. I was appalled. I was impressed that a family of operating systems that claimed to be compatible would exhibit this class of lossage. But the thing that really got me was that none of this was surprising to the other *nix hackers there! Their attitude was something to the effect of “Well, life’s like that, a few #ifdefs here, a few fake library inter- face functions there, what’s the big deal?” I don’t know if there’s a moral to this story, other than one should never trust anything related to Unix to be compatible with any other thing related to Unix. And oh yeah, I heard some time later that the software outfit in question ran two years over their original schedule, finally threw Unix out completely, and deployed on MS-DOS machines. The claim was that doing so was the only thing that let them get the stuff out the door at all! In a 1989 posting to the Peter Neumann’s RISKS mailing list, Pete Schill- ing, an engineer in Alcoa Laboratories’ Applied Mathematics and Com- puter Technology Division, criticized the entire notion of the word