The User Interface

So that you can enter data into a computer, and collect information from it, you must use a user interface. Some embedded computer control systems (like those in a washing machine) just have a simple choice of buttons and maybe one or two lights for input and output. Other forms of user interface are much more complex, requiring special devices (such as mice, keyboards and joysticks) for input and expensive VDUs for output.

The Graphical User Interface (GUI)

Most people are used to using a Graphical User Interface. This consists of multiple Windows, the use of Icons, Menus and a Pointer or cursor. These user interfaces are called WIMP interfaces. A common way to interact with the interface is to scroll through a number of drop-down menus (like the ones shown here). Menus are an efficient way of presenting all the important commands that the application (or operating system) thinks you may need. You don't have to remember all the commands - since they are listed for you. Also, you can use either a mouse or a keyboard to select your menu items.

	The operating system used by the range of personal computers from Apple (eg iMac, iBook, etc.) has an easy to use graphical interface. You can run new programs by moving the arrow (cursor) over one of the small pictures (icons) and double clicking the mouse button. The output of the program is shown in a rectangle (window) on the computer screen. The windows open on the screen are meant to represent pieces of paper on a desk - in fact the screen is often referred to as the desktop. Many other operating systems use this windows style interface. For example, operating systems from Microsoft (eg. Windows XP) also use windowed programs, icons, menus and pointers.
UNIX is an operating system that was around before personal computers became popular. It too has a graphical user interface called X-Windows. Lynux, the free UNIX clone, has a number of GUIs. Two popular interfaces are KDE and Gnome. Apple's latest operating system, OS X, is based on UNIX. Linking a very new operating system with one of the oldest. Most modern computers offer some sort of GUI. These interfaces are easy to understand and most people can use them without having to read a large, complicated manual. The job of the GUI is to make the computer easier to use.

The Command-Line Interface

It wasn't very long ago (well, during the 1980s anyway) that most PC owners used an operating system called either MSDOS (from Microsoft) or DRDOS (from Digital Research). The screen allways looked a bit like the one shown here. To run a program you had to type in its name and press enter. To do anything more complicated (like change directory, copy a file, or format a disk) you had to type in a number of commands (which you just had to memorise) usually at the bottom of the screen. These interfaces evolved from the computers that used printers for output instead of VDUs. Each command and its response was typed on a new line on the printer.

The good thing about graphical user interfaces is that they are much easier to use than the command-line interfaces. However, you don't need a fast, powerful computer to run a command-line interface as they use little memory or processing power.
In the end, though, the job of the user interface is to make the computer easier to use. For this reason the command-line interface has become much less common and the windows-style GUI is the normal way to interact with a computer.

Now answer these questions:

1. What does the W in WIMP stand for ? - Window Windy Wide-Area
2. What does the I in WIMP stand for ? - I can do it Intel Icon
3. What does the M in WIMP stand for ? - Mainframe Menu MSDOS
4. What does the P in WIMP stand for ? - Program Pocket Pointer
5. What does GUI stand for ? - Give Up Interest Graphical User Interface Graphically Unusual Interface
6. What is the name for the little arrow in a GUI ? - Bob Pointer Clippy
7. What is the name for the little pictures in a GUI ? - Icons Pictures Error messages
8. What is the name for the lists of commands shown in a GUI ? - Command List Menu
9. What is the main advantage (good thing) of a GUI ? - They cost a lot of money They are easy to use They make the computer go faster
10. What is the main disadvantage (bad thing) of a GUI ? - It uses a lot of memory / processing time It uses too little memory / processing time People liked it too much

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