A personal computer that was purchased in the early 1980s probably included a
keyboard as the only input device. Today, every new PC includes a pointing device
as standard equipment, as shown in Fig. 1
Fig. 1: Most modern personal computers are equipped with a mouse.
Full-size PCs usually include a mouse as the pointing device
A mouse is an input device that you can move
around on a flat surface (usually on a desk or keyboard tray) and controls the
(also called the mouse pointer) is an on-screen object, usually
, that is used to select text; access menus; and interact with programs,
files, or data that appear on the screen. Fig. 2
shows an example of a
pointer in a program window.
Fig. 2: An example of a pointer as it might appear on a computer screen.
Types of computer mouse
The mechanical mouse is the most common type of pointing device. A mechanical mouse contains a small rubber ball that protrudes through a hole in the bottom of the mouse's case (see Fig. 3
). The ball rolls inside the case when you move the mouse around on a flat surface. Inside the mouse, rollers and sensors send signals to the computer, telling it the distance, direction, and speed of the ball's
motions. The computer uses this data to position the mouse pointer on the screen.
Fig. 3: The parts of a mechanical mouse, seen
from the top.
Another popular type of mouse, the optical mouse
, is nonmechanical
type of mouse emits a beam of light from its underside; it uses the light's reflection
to judge the distance, direction, and speed of its travel (see Fig. 4).
Fig. 4: Optical Mouse.
Benefits of mouse over keyboard
The mouse offers two main benefits.
, the mouse lets you position the cursor anywhere on the screen quickly without using the cursor-movement keys. You
simply move the pointer to the onscreen position you want and press the
mouse button; the cursor appears at
, instead of forcing you to
type or issue commands from the keyboard, the mouse and mouse-based
operating systems let you choose commands from easy-to-use menus and
dialog boxes (see Fig. 5
result is a much more intuitive way to
use computers. Instead of remembering
obscure command names, users can
figure out rather easily where commands and options are located.
Fig. 5: Using the mouse to choose a command from a menu.
If you use a drawing program, you can use the mouse to
create graphics such as lines, curves, and freehand shapes
on the screen. The mouse has helped establish the computer as a versatile tool for graphic designers, starting
what has since become a revolution in the graphic design field.