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The X Windows System, or X, was developed at the Massachusetts
Institute of Technology in a joint effort of the Digital
Equipment Corporation and MIT's Project Athena. The principal designers
of the system were Robert Scheifler, Jim Gettys and their colleagues at
MIT, though many of the concepts have their foundations in the W Windowing
package, which was developed at Stanford University, and other graphic
systems stretching back to the early 1970s at Xerox PARC.
Version 11 of the X Windows System, called X11 for short, was released
to the public in September of 1987, and succeeded version 10.4 of the X
Windows system. Today, virtually all graphics programs written for UNIX
use the X Windows System.
X is a network-based graphics window system using the
client/server model. Strictly
speaking, the X standard refers to the protocol for communications between
an X server and
an X client. Both the server and the client are programs,
which may be running on the same or on different computers. Most commonly,
the X server is a program running in a workstation. The X server controls
a display screen, a keyboard, and a pointing device. X client programs
communicate with the X server requesting that the server will display data
to the screen or retrieve user input from the keyboard or pointing device.
When a workstation with X server software is attached to a network, the
display, keyboard and mouse of that workstation become available to X client
programs that may be running on any other computer on the same network.
Since X is a public standard for communications between programs,
it can be implemented for any operating system. Any workstation that has
X server software can have access to X client programs running on any
networked computer, no matter what the native operating system of the
host computer may be. When new workstation hardware and/or operating
systems become available, it is not necessary to recreate or even recompile
application programs that were written as X clients. It is only
necessary to create an X server to run on the new platform to gain instant
access to all existing X client software.
The actual detailed view that an individual user would have of the X
Windows System depends on the function that the individual performs within
the organization. To an end-user of X
client software, the X Windows system is a graphical user interface, with
an electronic desktop covered with selectable icons that represent
application programs containing drop-down menus and clickable pushbuttons.
To the programmer or application
developer, the X Windows System is a collection of subroutines, which can
be used in new programs to gain access to display and user-input devices.
To the system administrator, the
X Windows System is a new set of programs and administrative files for
controlling access to workstations and network resources.
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