Chapter 5. Input Devices

Input Devices

An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system (such as a computer). Input and output devices make up the hardware interface between a computer and the user or external world.

Types of Input

Data is the raw facts given to the computer.

Programs are the sets of instructions that direct the computer.

Commands are special codes or key words that the user inputs to perform a task, like RUN "ACCOUNTS". These can be selected from a menu of commands like "Open" on the File menu. They may also be chosen by clicking on a command button.

User response is the user's answer to the computer's question, such as choosing OK, YES, or NO or by typing in text, for example the name of a file.


Some Common Computer Input Devices:

Keyboard :The first input device we will look at is the Keyboard. The image used on the next page to illustrate the various keys may not look like the keyboard you are using. Several variations are popular and special designs are used in some companies. The keyboards shown below put the function keys in different places. The Enter and Backspace keys are different shapes and sizes. One has arrow keys while the other doesn't. It's enough to confuse a person's fingers!!
The backslash key has at least 3 popular placements: at the end of the numbers row, above the Enter key, and beside the Enter key. We also have the Windows keyboards which have two extra keys. One pops up the Start Menu and the other displays the right-click context sensitive menu. Ergonomic keyboards even have a different shape, curved to fit the natural fall of the wrists.
Mouse - Most modern computers today are run using a mouse controlled pointer. Generally if the mouse has two buttons the left one is used to select objects and text and the right one is used to access menus. If the mouse has one button (Mac for instance) it controls all the activity and a mouse with a third button can be used by specific software programs.
One type of mouse has a round ball under the bottom of the mouse that rolls and turns two wheels which control the direction of the pointer on the screen. Another type of mouse uses an optical system to track the movement of the mouse.

Pointing Devices :
Pointing devices move some object on the screen and can do some action
Common pointing devices

Track ball -

basically an upside down mouse
Joystick
Game controller
Scanner :
A scanner allows you to scan documents, pictures, or graphics and view them on the computer. You can also use software to edit the items you scan.Used to put printed pictures and text into a computerConverts an image into dots that the computer can understandTo scan text, optical character recognition (OCR) software is needed
Digital Camera :
Used to take electronic pictures of an object
The pictures taken by a digital camera can be used directly by a computer
CD-ROM/DVD-ROM:
Can be used to put both sound and images into a computer
Use a laser to read a Compact Disk (CD) or a DVD disk