The Parts of a Typical X11 System

The SPU contains the logic circuitry that performs all the processing that takes place. The SPU runs the server, takes care of foreground and background processing, and controls local and remote accessing of your system's resources.

The hard disk stores programs and data files. Some configurations are called diskless clusters because groups of users share the same hard disk.

The keyboard is an input device used to type information into the computer. Although the keyboard is frequently used in conjunction with a mouse, it does not need to be. You can configure X11 so that you can use the keyboard for both text entry (its usual purpose) and for pointing and selecting (the mouse's usual purpose). Mouseless operation may be beneficial in situations where desk space is at a premium.

	NOTE: There are now two keyboards available for Hewlett-Packard workstations, the 46021 keyboard, and the C1429 keyboard. See appendix B, Using the Keyboards, for more information on using these keyboards and the differences between them.

A pointing device lets you point to a specific area on the screen and select it. A mouse is the most common pointing device. Mouse movements and button presses can be associated with keyboard key presses for mouseless operation.

The server also supports other pointing devices—for example a digitizer tablet or track ball. References to mouse actions apply also to corresponding actions with other devices.

The display is the principal output device. A typical display consists of one physical screen per mouse and keyboard. However, a display can include as many as four physical screens, all using the same mouse and keyboard.

The screen becomes the root window when you boot X11. The root window contains all the windows, menus, and icons that comprise the visual elements of your X11 environment.

Technically, the screen is known as a bitmapped device because the graphical elements (windows and icons) that it displays are stored by the computer as a bitmap, a pattern of bits (dots) that can be readily displayed as graphical images.

The LAN is composed of hardware and software. The hardware connects the computer system physically to a network that includes other computer systems at your site and could connect to other networks at different locations. The LAN enables you to take advantage of remote processing capabilities of X11.

The operating system is the software that controls the operation of the computer system. The X Window System runs on the Hewlett-Packard HP-UX operating system. This is a multi-user, multi-tasking environment. A multi-user environment means more than one user can be on the system at the same time. A multi-tasking environment means that each of those users can run more than one program at a time.

The central part of the X Window System is the server, also called the X server or display server. The server is the program that controls the screen, keyboard, and mouse, and processes communication requests. The server updates the windows on the screen as a client generates new information or as you enter information through an input device. All client programs communicate through the server.

The font server allows a font administrator to distribute fonts to all X servers in a networked environment from a central point. The font server is covered in chapter 6.

The window manager is your main means of dynamically controlling the size, shape, state (icon or normal), and location of the windows on your screen. It also supplies the frames and menus for the windows.

The window manager is the first client started during a session after the X server has started. All other clients with their own windows must be able to interact with the window manager.

This manual covers the OSF/Motif Window Manager (mwm). Using the window manager is covered in chapter 4. Configuring the window manager is covered in chapter 7.

Figure 2-2 Windows, Clients, Menus, and Icons

Clients are programs designed to run under the X Window System.

There are a number of clients that are included with the X Window System. For example, the xrdb client provides the ability to view and modify current resources.

Some clients (for example, xwininfo and xmodmap) do not create windows. They use an existing terminal emulation window to display their output.

Clients are discussed in chapter 8.

Non-client programs are designed to run alone on display screens or "terminals" and are therefore referred to as terminal-based programs. Terminal-based programs must have terminal emulator windows created for them so that they can run in a window environment.