Video cards and monitors don't matter much if you use Linux in text mode only. If you want to use the XFree86 X Window System, however, you have to pay attention to the video card and monitor. You need X to run graphical desktops such as GNOME and KDE. The X Window System (X) is a popular window system that serves as the basis of GUIs and graphical output on most UNIX workstations. XFree86 is a free implementation of X for Intel 80x86 and compatible PCs. XFree86 works with a variety of video cards, but you have to configure it to use the appropriate parameters for your video card and monitor. This chapter showed you how to configure and run X on your Red Hat Linux system.

By reading this chapter, you learned the following:

  • In a PC, the video card stores the array of pixels that constitutes the image you see onscreen. The video card converts the pixel values to analog signals that drive the red (R), green (G), and blue (B) electron guns in a monitor. These RGB electron beams, in turn, paint the color image on the phosphor-coated display screen. The combination of the video card and monitor is important to the X Window System because the X server controls the video card directly and because the monitor must be capable of handling the signals the video card generates.

  • X Window System is a network-transparent windowing system based on the client/server model. The X server, running on a workstation with a bit-mapped graphics display, manages regions of the screen known as windows, where the output from X client applications appears. The X clients often run on remote systems, but their output appears on the local X display.

  • The term graphical user interface (GUI-pronounced gooey) describes a user interface that makes use of windows, menus, and other graphical objects, so that users can interact with the application by pointing with the mouse and clicking mouse buttons. From an application developer's point of view, a GUI is a combination of a window manager, a style guide, and a library of routines or a toolkit that can be used to build the user interface.

  • X provides the basic functions that can be used to build a GUI. Many GUIs are built upon X. Motif, GNOME, and KDE are examples of such GUIs. GNOME and KDE are popular GUIs for Linux systems.

  • XFree86 is the X Window System for Linux PCs; it comes on this book's companion CD-ROMs. When you install Red Hat Linux from the CD-ROMs, you also install XFree86.

  • When the X server runs, it consults a configuration file named XF86Config (in the /etc/X11 directory) to select an appropriate video mode and to configure the video card and monitor for proper operation. Computing the valid video-mode parameters is complicated. As long as you know the technical specification of your monitor (such as horizontal-synchronization frequency and refresh rate), you do not need to compute the video-mode information.

  • You configure XFree86 as you install Red Hat Linux. However, you can reconfigure XFree86 by running the redhat-config-xfree86 program. This program prompts you for some technical information about your PC's video card, monitor, and mouse.

  • You should specify the correct information about your monitor because incorrect information may damage it.

  • You can kill the X server by pressing Ctrl-Alt-Backspace. If you have a graphical login screen, this key combination restarts the X server.

  • You can switch among different modes (screen resolutions such as 1,024x768 and 800x600) by pressing special key combinations: Ctrl-Alt-Keypad+ and Ctrl-Alt-Keypad-.