Hardware Fundamentals
© Copyright Brian Brown, 1992-2000. All rights reserved.

INPUT/OUTPUT DEVICES CONTINUED

The mouse
The mouse, invented in 1963 at the Stanford Research Institute by Douglas Engelbart, has done much to enhance the use of the personal computer. Engelbart's prototype, made of wood, with metal disks for rollers that detected the motion of the mouse, was further developed by Xerox at it's Palo Alto Research Center in the early 1970's under the direction of Jack S Hawley.

Fig 6.29: MS Mouse

In 1982, Mouse Systems introduced the first mouse for the IBM-PC, with Microsoft introducing it's own mouse in mid-1983. When the Macintosh was released in 1984, it's friendly graphical interface relied heavily on the use of the mouse as an input device.

Most mice have two or more buttons, which users depress to select items from a menu or click on graphical objects on the computer screen, thus sending commands to the computer. The mouse is held in the hand and moved across a flat surface. As the mouse is moved, its movement is detected and translated into both X and Y movements, which updates the indicated position of the mouse pointer on the computer screen accordingly.

The position of the mouse is shown on the screen as the mouse cursor and is denoted by a number of symbols.

Standard mouse pointer

Indicates computer is busy

Mouse Construction
There are two main types of mice, mechanical and optical. The mechanical mouse, the most popular type of mouse, uses a round ball which touches the surface of the desk. As the mouse is moved, this round ball also moves. Two rollers inside the mouse case make contact with the rubber ball, and are rotated by its movements. These rollers have encoders on each end which translate the movements into electrical impulses which are sent to the computer and decoded into x and y movements.

Fig 6.30: Mouse Internals: Roller Wheels

Most mice also have two or three push buttons. These buttons are pushed to make selections or move items on the computer screen.

Fig 6.31: Mouse Internals: Push buttons

Mouse Configuration
Under Windows95 and WindowsNT, the mouse can be configured for a number of settings. These allow the behavior of the mouse to be adjusted to suit the individual. For example, the mouse pointer and shape, its blinking rate, its speed can be changed. In addition, the mouse can be configured for left hand or right hand operation.

In Windows95, the left mouse button is used for selection purposes. The right button, often referred to as the Alternate Button, is used to reveal properties or additional information about items which are selected.

The configuration parameters for altering the mouse's behavior is found under Control Panel.

Fig 6.32: Mouse Configuration

Selecting items with the Mouse

Single Click
A single mouse click refers to moving the mouse pointer over the desired item and quickly pressing the left mouse button once.

Double Click
A double mouse click refers to moving the mouse pointer over the desired item and quickly pressing the left mouse button twice in rapid succession.

Drag
A drag or move operation is performed by moving the mouse pointer over the desired item and holding the left mouse button down. The mouse is then used to move to drag the object or window to the new position, then the left mouse button is released.

Summary
The mouse has become the defacto standard for Windows based systems. As the mouse is moved in the hand across a flat surface, its relative position and movement is visually tracked on the screen by a graphic called the cursor.

Most operating systems allow the behaviour of the mouse (like its speed, icon) to be controlled by the user.

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© Copyright Brian Brown, 1992-2000. All rights reserved.