24 January 2006

Milestones: Unix (2)

Flavors & "the Unix Wars"

(Part 1)

The huge range of choices IT managers could make with respect to Unix installations and interface meant that a lot of firms saw in Unix an opportunity to add value by making choices about interface and capabilities professionally. Unix can be made to run on so many different machines, while allowing the same programs to run on any of them with almost no modification (meaning, the Unix "flavors" all have consistent API's), that they have become the most popular software for running servers. Finally, there was the critical aspect of applications. Unix provides a comparatively easy programming environment, and has attracted a lot of hobbyists. As a result, a very large number of utilities were developed for Unix first, for free.

The first professional version of Unix was developed by the University of California at Berkeley (UCB) for the Pentagon; it was known as BSD Unix, and contained significant amounts of AT&T code (1980). AT&T, meanwhile, was suddenly able to sell Unix as a product as a result of the 1982 consent decree that broke it up. In '83 it therefore released System V, with the decided advantage that it fully supported the now-essential TCP/IP (internet) protocol. Further BSD releases were compelled to replace a lot of AT&T code with new freeware. AT&T and many of its rivals embraced the proprietary software model, which nearly ruined Unix.

In one sense, the competition and legal struggles of software vendors which became known as "the Unix Wars" was a battle over how to make money from specialized, high-performance software. The large corporate actors gradually realized that they could not sell the software as they had in the past, by licensing copies to paying customers. Instead, they would have to give much of their R&D away to the public domain, so that they could sell specialized hardware or applications (that did not compete with Intel or Microsoft).

In another sense, however, the "Unix Wars" were also about the form that Unix would take. There was a long series of agreements and new standards that eventually restored the unified API's. The resolution of the disputes was made possible by continued refinement and adoption of new approaches not available to original "combatants," who had been limited by smaller memories and slower processors. The landscape of the computer market changed considerably, with minicomputers becoming largely servers in large networks rather than lower-end mainframes. Unix began to dominate servers and workstations, such as Sun Microsystems (founded 1984) and Hewlett-Packard (HP-UX). In 1985, the advent of the Intel 386 chip made it possible to address 4 megabytes of memory with a flat address space. A major impact of this was the massive surge in workstations, which would require the specialized performance available mainly from Unix. Needless to say, the wholly closed development environment of Apple Macintosh and the consumer-oriented market for DOS/Windows were wildly unsuited to specialized graphical systems.

Hardware was an issue for the Unix market. The first Unix machines were the minicomputers, especially the Hewlett Packard 3000 & 9000 series. The first workstations used the same Motorola 68000's used in Macintoshes. Sun introduced 386-based workstations, then its own specialized SPARC architecture. HP developed the Precision Architecture (PA-RISC). A firm called MIPS Computer Systems (later bought by SGI and renamed MIPS Technologies) developed the first RISC architecture microprocessors, which were adopted by Unix workstations such as SGI's IRIS. SGI's products were particularly interesting since they blurred any boundary that had existed between high-end workstations and supercomputers; and they were used largely for the entertainment industry. In the 1990's, the Power PC chip developed by IBM, Motorola, and Apple became prominent for high-end servers.

By the late '90's, however, the industry was once more dominated by Intel-based workstations and servers, often physically indistinguishable from Windows machines. However, many of the innovations, such as RISC architecture and multiple threads, were developed for Unix and revolutionized the computer industry generally. Intel's rivals drifted back into producing application-specific semiconductors (ASICs) such as those used in appliances or videogames.

Linus Torvalds developed a variant of GNU with some Unix components that became known as Linux; this was a huge success. Later, in 2001, Apple released Mac OS X, which was based on a BSD kernal; this would make Macintosh the first mainstream computer to use a Unix kernal.

(Part 3)
ADDITIONAL READING & SOURCES: Wikipedia Unix; Unix System V; Berkeley Software Distribution (BSD); Tru64 UNIX (also known as OSF/1); Unix Wars;

USENIX Association website (fmrly Unix Users' Group); The Open Group: History and Timeline;

Living Internet: Unix; Eric Steven Raymond, The Art of Unix Programming

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