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INTRODUCTION

Definition of a computer

 

  • A computer can be define as an electronic device that process  a user’s input usually referred to as data to a desired output, also known as information.
  • This is made possible by a set of instructions called computer programs stored in a computer.
  • Data can be defined as raw facts that do not have much meaning to the user and may include: numbers, letters and symbols.
  • Information is the processed data that is meaningful to the user.
  • A computer is said to be electromagnet because it utilizes electrical signals to process information.
  • The integration of computers and telecommunication facilities for the purpose of communication is what is referred to as Information and Communication Technology (ICT).
  • Computers come in different sizes and designs but the most common is personal computer (PC). Used in offices, home, schools and business.

 

Physical part of a computer

 

  • A desktop computer is made up of a collection of different components that are interconnected in order to function as a single entity.
  • A typical desktop computer is basically made up of a system unit and other devices connected to the system unit called peripheral devices.
  • Examples of peripheral devices include;
  • monitor also known as screen,
  • keyboard and

 

System Unit

  • This is the part that houses the brain of a computer called the central processing unit (CPU).
  • The system unit also houses other devices called drives. Drives are used to store, record and read data.

 

Peripheral devices

  • Peripheral devices are connected to the system unit using special cables Called interface cables that transmit data and information to and from the devices.
  • The cables are attached to the system unit through connectors called ports.

 

 

Keyboard

  • A keyboard is the most common peripheral device that enables a user to enter data and instructions to a computer.

 

Mouse

  • A mouse is a pointing device that enables the user to execute commands.
  • It is used to control an arrow displayed on the screen. To execute a command the user moves the mouse which consequently moves the pointer on the screen.

 

Monitor

  • A monitor or simply the screen is a television- like device used for displaying information. It is called a monitor because it enables the user to monitor or see what is going on in the computer.

 

Classification of computers

  • Computers can be classified according to physical size, purpose and functionality.

 

Classification according to physical size

 

  • Based on physical size, computers can be classified into four main groups namely

 

  • supercomputers,
  • mainframe computers,
  • minicomputers and

 

 

Supercomputers

 

  • Supercomputers are the fastest, largest, most expensive and powerful computers available. They are to perform many complex operations in a fraction of a second. Because of its weight; a supercomputer is kept in a special room. Due to their huge processing power, super computers generate a lot of heat. Special cooling system is therefore required. Sometimes the whole CPU is immersed in an aquarium like tank containing liquid fluorocarbon to provide cooling.
  • Supercomputers are mainly used for scientific research, which requires enormous calculations. Applications that justify use of computers include aerodynamic design and simulation, petroleum research, defense and weapon analysis among others.
  • Supercomputers are mostly found in main developed countries such as USA and Japan where they are used for advanced scientific research such as nuclear physics.

 

Mainframe computers

 

  • Mainframe computers are less powerful and less expensive than supercomputers.
  • While supercomputers may be described as giant computers, mainframes are said to be big in size. They are used for processing data and performing complex mathematical calculations. They have a large storage capacity and support a verity of peripherals.
  • Mainframe computers handle all kinds of problems whether scientific or commercial.
  • They are mostly found in government agencies, big organization and companies such as banks, hospitals, and airports etc; which have large information processing needs.

Minicomputers                                                                                                                                              

 

  • A minicomputer resembles the mainframe but slightly smaller. Thus it is referred to as small-scale mainframe computer. Although it supports fewer peripheral devices and is not as powerful and fast as the mainframe computer, it was developed as a cheaper alternative to the mainframes for smaller organizations.
  • They are used mainly in scientific laboratories, research institutions, engineering plants and places where processing automation is required.
  • They well adapted for functions such as accounting, word processing, data base management and specific industry applications.

 

Microcomputers

 

  • A microcomputer is the smallest, cheapest and relatively least powerful type of computer. It is called a microcomputer because; its CPU is called a microprocessor, which is very small compared to that of microcomputers, mainframe and supercomputers.
  • Microcomputers are commonly used in training and learning institutions, small business enterprises, and communication centers, among others.
  • Today, the power of microcomputers has grown tremendously, closing the gap that formerly existed and reserved for the minicomputers and the mainframes.
  • Technology advancement has seen the development of smaller minicomputers.
  • Types of minicomputers in operation today;
    1. Desktop computers: is designed to be placed on top of an office desk.
    2. Notebook or laptop computers: portable convenient for mobile users.
    3. Personal Digital Assistant (PDA): is small enough to fit in the pocket.