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Encyclopedia of Computers and Computer History SAMPLE ENTRIES SAMPLE TWO LinuxLinux is an open-source operating system, functionally equivalent to Unix. Originally written for Intel X86 chips, Linux ports were later released for platforms such as the Compaq Alpha, PowerPC, Intel 64-bit Itanium, and IBM's S/390 mainframe. Linux is named after Linus Torvalds (1970- ), who created the first version of its kernel (core) while a student at the University of Helsinki in 1991. Other parts of the operating system have come from the GNU project of the Free Software Foundation. Torvalds made Linux available on the Internet at no cost. Since then, tens of thousands of programmers have offered improvements and bug fixes to the code, which is published under an open-source copyright arrangement called the GNU public license (GPL). Also known as copyleft, the GPL gives everyone the right to use and modify the software as long as any improvements made to it are contributed back to the public. Torvalds continues to lead the small group that manages the contributions that are submitted by programmers around the world for the Linux kernel. Contributing source code that is accepted into the Linux kernel is recognized as a mark of high prestige in the community of programmers. Linux's open-source nature has meant that different groups of programmers often compete to find better ways of handling existing functions, and lively debates on the various approaches are conducted openly on Internet forums. In Linux's earliest days, for example, some programmers criticized the Linux architecture for including too much code in the kernel. The Linux kernel, they proposed, should be a microkernel, which incorporates only basic functions such as memory management and message handling. Later, two competing C language libraries were under development at the same time. Eventually, a consensus formed that the newer glibc libraries represented a better approach, and they replaced the existing C libraries. Although Linux is available for free, most users are willing to pay a modest amount for the convenience of a copy of Linux on CD-ROM, which typically comes packaged with other open-source software products, such as the Apache Web server. Linux is distributed in this fashion both by noncommercial teams of volunteers, such as Debian and Slackware, and by commercial companies, which include Red Hat, Caldera, and TurboLinux in the United States, and SuSe in Germany. There are at least a dozen English-language distributions of Linux, and more than that in other languages. Linux's strengths come mostly from its robust, open-source nature. It is extremely low cost compared to commercial operating systems. The availability of the source code means that users can easily modify the system to meet their own needs. Scientists, for example, can write device drivers for specialized scientific instruments. Because of the large number of open-source developers fixing bugs and improving the system, it is also extremely reliable, frequently running for months or even years at a time without needed to be rebooted. Linux's low cost and stability, and the fact that it runs well on inexpensive hardware, led to it being widely used for important but nonglamorous applications such as file, print, or e-mail servers, and domain name (DNS) and Web servers. It became popular with internet service providers, frequently being used as a base for the Apache Web server. Its low cost, and access to its source code, also made it popular on college campuses. As students familiar with Linux graduated in growing numbers through the 1990s, and went to work in the business world, it began to pop up quietly in the back rooms of corporations. It wasn't until the late 1990s, however, when Linux began to gather support from major computer vendors such as IBM, Intel, SGI, and Oracle, that it began to come "out of the closet" in the corporate world. Many corporate IT managers, when they began asking, were surprised to find that Linux was already in use at their company. IBM's support for Linux was particularly key to its acceptance in the business world. In 1999, IBM made a strategic decision to make Linux available on all of its hardware platforms, from personal computers (PCs) to midrange Unix systems to mainframes. IBM also began porting key software products, such as its DB2 database and Lotus Domino groupware server to Linux. During the same period, other major software vendors, such as Oracle, Computer Associates, Sybase, and SAP. began offering versions of their products that ran on Linux. Although Linux has seen wide acceptance as an operating system for servers, it remains to be seen whether it will ever be widely adopted as a replacement for Microsoft Windows-based PCs. Its use for desktops systems has so far been largely limited to the desks of scientists, programmers, and other technically savvy users. Several open-source efforts, such as KDE (K Desktop Environment) and Gnome (GNU Object Modeling Environment), are under way to develop windowing systems for Linux that could compete with Microsoft Windows. There are also a number of suites of desktop software available for Linux, including ApplixWare and StarOffice. Besides wide use as a server, Linux is being adopted increasingly as an operating system for supercomputers. In 1994, two NASA researchers, Thomas Sterling and Don Becker, hooked 16 Linux PCs together into a single system. They called the system Beowulf, after the heroic figure in the early English epic poem. Other research labs and universities soon followed their lead, using Linux to build Beowulf clusters which provided performance comparable to supercomputers from IBM, Cray, or other companies, but at a fraction of the cost. In 1999, the Avalon Beowulf cluster at the Los Alamos National Laboratory in Los Alamos, New Mexico, was ranked 160 in a list of the 500 fastest supercomputers in the world. Interest is also growing in using Linux at the other end of the computing spectrum, as an embedded operating system for television set-top boxes and other consumer devices. Further Reading
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