4.0 INTRODUCTION

In the previous unit, we have discussed the history of computer systems and methods to store data in computers. In this unit we shall discuss something about input/output devices and their functions. Input/output devices constitute a major part of a computer system. These are also called peripheral devices. Without I/O devices, a user cannot communicate with the computer. They are required to enter data and instructions in a computer so that the computer can process that data and provide the result to the user through output devices. In computer, inputs are the signals and data received by the system and outputs are the signals and data which are generated from the system. 

First we will discuss briefly about input/output devices and then move on to the function and structure of input and output devices. And finally, we will discuss about recent trends in input devices such as digital camera, barcode reader, magnetic ink character recognition and magnetic stripe reader such as ATM machines and Electronic Point of Sale (EPOS).

4.1 OBJECTIVES

After studying this unit you should be able to understand:
  • the basic concepts of input/output devices;
  • functions of input/output devices;
  • types of input/output devices;
  • types of Ports;
  • types of monitors, printers, scanners and graphics tablet; and
  • newer technologies in computer hardware. 

4.2 INPUT OUTPUT (I/O) DEVICES

The computer will be of no use if it is not communicating with the external world. Thus, a computer must have a system to receive information from the outside world and must be able to communicate results to the external world. Thus, a computer consists of input/output devices. Input and output devices can also be written as I/O devices.

Input and output devices of a computer system are the devices that connect you to computer. Input devices let you to transfer data and user command into the computer system. I/O devices are used to interact with the computer system. For example, you can type in data by using a keyboard, or you can input data in picture form by using a scanner in computer system.

Notes-
Inputs are data or signals received by the computer system. An Input unit takes the input and converts it into binary form, so that it can be understood by the computer  

On the other hand, output devices display the result of input data or signals after processing it. Examples of these could be your computer’s monitor, which displays all the programs which are running on the computer, as well as the printer, which will print out a hard copy of the information which is saved in your computer.

Input and output devices allow the computer system to interact with the outside world by moving data into and out of the computer system.

Examples of some input devices are:

 Keyboard 
 Mouse 
 Joystick
 Microphone 
 Bar code reader 
 Graphics tablet 
 Pen drive
 CD/DVD
 Digital Camera

An output device is used to send data out of the system. The user sees the result after processing of data by the computer through output devices. Examples of some output devices are: 

 Monitor  Printer  Plotter  Speaker

Input and output devices are also called I/O devices. They are directly connected to an electronic module called I/O module or device controller. For example, the speakers of a multimedia computer system are directly connected to a device controller called an audio card, which in turn is connected to the rest of the system.

Input and output devices are similar in operation but perform opposite functions. It is through the use of these devices that the computer is able to communicate with the outside world. 

Input data for the computer system could be in any of the following forms :

 Manual inputs from a keyboard or console.
 Analog inputs from instruments or sensors.
 Inputs from a storage device, such as pen-drive, CD’s and Floppy Drives.

The speed of a processor is far more than the input devices, such as the keyboard of computer system. Computer systems can process hundreds or thousands of computer words or characters per second. Thus, a study of the first method, i.e. manual input.

reflects the inability of human-operated keyboards or keypunches to supply data at a speed that matches the speed of digital computers.

👉Check Your Progress - 1 
Part I: State True/False

1) Keyboard is an input device.                   True / False
2) Monitor is an input device.                     True / False
3) Printer is an input device.                       True / False
4) Graphic Tablet is an input device.          True / False
5) Joy-stick is an output device.                 True / False
6) Speaker is an output device.                  True / False
7) Microphone is an input device.             True / False

Part II: Short answer type questions 

1) What do you mean by input devices? …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. 
2) What do you mean by output devices? …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………….
 3) Name some input and output devices? …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………….