What is a computer? Basic concepts

Definition of what is a computer.

A computer is a versatile, fast operating machine that can be used for home and business-related task to enhance productivity. This means, a computer is a collection of electronic parts, or hardware, that incorporates a set of instructions called software. All computers perform the same basic functions: they enable you to store, manipulate and communicate information.


Hardware refers to all physical parts of a computer. These are the parts that can be seen and touched. The hardware components include the part that are used to input, process, output and store information. Examples include the mouse, monitor, hard drive, and printer. In other words, any type of device, even the computer as a whole, which consist of physical parts is seen as hardware.

What is a computer used for?

Computers can be used to perform various functions. Some of the most common tasks include.
  • Creating documents such as memos, reports etc.
  • Budgeting and performing accounting tasks.
  • Analyzing numeric information.
  • Searching through lists or reports for specific information.
  • Scheduling and planning projects.
  • Creating illustrations.
To perform a computer task, two components are needed: a computer (hardware) and programs (software). The computer works with information called data. Data refers any type of information that is entered into the computer. For example, data can be text in a letter, pictures and calculations etc.

Main parts of a computer

  • Central processing unit (the brain of the computer)
  • The main memory (RAM and ROM)
  • The hard drive (hard disk)
  • Input and Output devices, such as the mouse, keyboard, scanner, printer, monitor or screen.
  • Storage devices, such as the hard drive, flash drive, CD-ROM, DVD-ROM.
  • System unit or System case. It is the plastic or metallic outer box in which the CPU, memory, hand drive and all other internal devices are held.

Input Devices

The data instructions that a computer receives are called input. The hardware, through which this data is sent, is called input devices. Common input devices include the mouse and keyboard.
  1. Keyboard
The most general way to enter data is through a keyboard. The keyboard is a direct line of communication between the user and the computer. Keyboards can be used to enter letters, numeric characters and instructions to other parts of the computers to processing. The keyboard consists of between 82 and 108 keys, depending on what type of keyboard is used. The number of keys can also vary between countries, as the alphabets of various countries differ.There are two main types of keyboards, mechanical key switch keyboards and capacitive keyboards.

Maintaining the keyboard

Keyboards can get dirty very easily, but cleaning the keyboard is easy. You will need the following:
  • Clean cloth
  • Cotton buds
  • Suitable cleaning fluid (isopropyl alcohol or spirits)
  • Can of compressed air or a vacuum cleaner
Make sure the computer is switched off and unplug the keyboard. Hold the keyboard upside down to release any debris between the keys. If you have a can of compressed air, use it to blow any debris from around and under the keys. The hose of the vacuum cleaner can also be used to suck the debrisTake a cotton bud, put a few drops of the cleaning fluid of it and use the cotton bud to clean the sides of the keys. Take a cloth and dampen it with cleaning fluid. Give the surface of the keyboards a good wipe-over, using the cloth to trace the counters of the keys.
  1. Mouse

A mouse
A mouse
A mouse is a pointing device that is used to point, click, drag and select items on the screen. It  allows you to quickly move around on the screen by the means of a mouse pointer. The mouse pointer (cursor), usually takes the space of a small arrow. The mouse pointer will move in the same directions as the mouse. A mouse is usually made of plastic and it is usually connected to the computer via a cable. Some devices use some infrared signals instead of the cable to perform the normal mouse functions. The mouse is moved around by hand, on a mouse pad or any flat, clean surface. Underneath the mouse is a rolling ball or infrared beam that transmits the mouse movements to the PC.Most mouse devices will have two buttons on top and scroll wheel between the two buttons. Both buttons are used for clicking and selecting functions. The wheel is used to scroll up and down on the screen. The main purpose of scowling is to move quicker up or down in a document.
  • Scanner

A scanner is able to copy graphics, lines and text directly from paper to the computer.
  1. Web Camera (Webcam)

Webcams are small cameras producing images which can be accessed using the Internet, instant messaging or PC video conferencing application.
  1. Microphone

A microphone is used to record voice, music or sound into the computer. Special sound is used to convert the recorded sound, music or human speech into digital signals.
  1. Barcode Reader

Striped barcodes can be found on most products in shops. The width of the different lines of the bar corresponds with different numbers. The lines carry information on price, production, codes, etc.
A visa card slotted in a barcode reader
A visa card slotted in a barcode reader

Output Devices

Output is the information that is produced by the computer. The information in the computer is in the form of binary cone. Output device change computer code to a format that can be read and understood by the user or other devices.
  1. Monitor, Screen or VDU (Visual Display Unit)
A monitor is the most used computer output device. The display provides instant feedback by showing you text and graphics images as you work or play.
  1. Printers
A printer produces paper copies (hard copies) of the documents or data that can be viewed on screen.
  1. Speakers
Speakers are output devices that transmit sound from the computer. Sound can be generated from various devices, for example, the CD-ROM or an application.

Characteristics of Computer

Computers play a big role in our day-to-day activities. Below are a list of computer characteristics: -
  • Speed − Normally, a computer can perform 3 to 4 million instructions per second.
  • Accuracy − A Computer can give a high degree of accuracy. Any errors that can occur is due to wrong fed data by human keying in the data.
  • Reliability − A Computer can repeatedly perform same kind of work without resorting toerrors as would be a human because of boredom and tiredness.
  • Versatility − A Computer can do large work spectrum ranging from data entriess, booking of travel tickets, to more complex numeric calculations etc. A computer will process any necessary data that is keyed in hence the need to observance of the rule of the thumb, GIGO, (garbage in garbage out). If you input wrong data, you get wrong output (results).
  • Storage Capacity − Computers do store large amounts of data at a less fraction of cost of traditional file storages. Data is safer from wear and tear that comes with paperwork.

Advantages of Using Computer

  • Computers can do repetitive tasks with accuracy.
  • Computers don't get bored or tired as human being would
  • For routine work, computers perform well, hence humans can focus more on intelligent functions and tasks.

Disadvantages of Using Computer

  • A Computers lacks the intelligence a human has, so they rely on human without looking at the final outcome
  • Electricity supply is required hence a big challenge to nations with less or no connectivity.


The process of switching on a computer for use is what is called booting.The process involved includes: -
  • putting on power supply (switching on)
  • Loading of the operating system.
  • Keeping the applications in a standby mode in case the user needs to use any.
The initial set of instructions that run when a computer is powered on is known as Basic Input Output System or BIOS. BIOS is a software programmed into the hardware of the computer hardware.If a system is running but needs to be restarted because of one reason or another, rebooting is initiated.There are two types of booting −
  • Cold Booting − Starting the system on from the power supply. The next procedure under cold booting is is for the system to load BIOS.
  • Warm Booting − Performed when the system is running but needs to be restarted. It is a faster booting than cold booting because BIOS is by stepped.
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