X Terminal Definition

An X terminal is a low cost, dedicated computer with no hard disk drive (HDD) that is connected to a network and is designed to run an X server.

An X server is a program in the X Window System that runs on the local machines (i.e., the computers used directly by users) and handles all access to the graphics cards, display screens and input devices (typically a keyboard and mouse) on those computers. The X Window System, often referred to merely as X, is a complete, cross-platform and free client-server system for managing GUIs (graphical user interfaces) on single computers and on networks of computers. The client-server model is an architecture (i.e., network design) that divides the work between two separate but linked applications, referred to as clients and servers. 1.

An X terminal is a thin client that consists mainly of a processor, memory and a network connection. A thin client is a low-cost computing device in a client-server environment that mostly or entirely just processes keyboard input and screen output and which accesses most or all application programs and data from a central server via a network.

Once an X terminal is connected to a power supply and to the network, a filesystem can be mounted on it from an operating system running on a server, and application programs (i.e., X clients) running on that or other servers can then be displayed on the X terminal's display screen.

A system architecture consisting of an array of inexpensive X terminals that allowed a large numbers of users to simultaneously access a single mainframe was formerly popular. Indeed, such architecture very much resembles the original intention of X when it was developed at the Massachusetts Institute of Technology (MIT) beginning in 1984.

However, dedicated X terminals are no longer common. This is because the same (and usually better) functionality can be provided at a lower cost by personal computers due to the large drop in their prices in recent years.

1A server is a a software program, or the computer on which that program runs, that provides a specific kind of service to client software running on the same computer or other computers on a network. A client is a computer, program or process that makes requests for information from another computer, program or process in a client-server relationship. The terminology can be confusing because in the case of X it is somewhat reversed. That is, the X server runs on the local machines, which are client machines in the usual client-server sense, and the X clients are application programs that run on dedicated computers elsewhere on the network, which are servers in the usual client-server sense.

Created January 18, 2006.
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