The bandwagon for the UNIX operating system appears to be gaining a great deal of steam. UNIX is already the de facto standard in the engineering and technical marketplaces, and is gaining ground in most other applications. UNIX makes it possible for application developers to target only one operating system environment which can be supported by several different machines, thus decreasing dependence on a single hardware manufacturer and increasing the size of the potential market. The operating system is closely identified with C, a high-level programming language.
In practice, this promise or portability from one hardware to another doesn't exist quite yet because there are many versions of UNIX. AT&T, the original developer of UNIX, offers System V, Release 3.11, the latest descendant in a long tradition of UNIX software which dates back to 1969. This version has an enhancement which facilitates the implementation of the OSI Reference Model standards. However, the AT&T version is currently being outsold by the University, of California at Berkeley Software Distribution Version 4.2 (BSD 4.2). Nearly 50 percent of the facilities of the operating systems differ between the two versions. Other versions of UNIX include Microsoft's XENIX and VenturCom's XENIX-both micro-oriented products.
Thus, while UNIX is an excellent tool for the developer, users cannot assume that they can move a UNIX-based product from one hardware environment to another without adjusting for possible differences among UNIX versions.