Classifications, generations, applications and limitations of digital computers

Computer Classification: By Size and Power

Computers differ based on their data processing abilities. They are classified according to purpose, data handling and functionality.

According to functionality, computers are classified as:

  • Analog Computer: A computer that represents numbers by some continuously variable physical quantity, whose variations mimic the properties of some system being modeled.
  • Personal computer: personal computeris a computer small and low cost. The term”personal computer” is used to describe desktop computers (desktops).
  • Workstation: A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user’s machine (client machine) in contrast to a “server” or “mainframe.”
  • Minicomputer: minicomputer isn’t very mini. At least, not in the way most of us think of mini. You know how big the personal computer is and its related family.
  • Mainframe: It refers to the kind of large computer that runs an entire corporation.
  • Supercomputer: Itis the biggest, fastest, and most expensive computers on earth.
  • Microcomputer: A personal computer is a

According to purpose or functionality, computers are classified as general purpose and special purpose computers. General purpose computers solve large variety of problems.They are said to be multi purpose for they perform a wide range of tasks. Examples of general purpose computer include desktop and laptops.
On the other hand,special purpose computers solve only specific problems.They are dedicated to perform only particular tasks.Examples of special purpose computers can include calculators and money counting machine.

Generation of Digital Computers

According to age,computers are grouped in terms of generations. They include;1st generation computers,2nd generation computers,3rd generation computers,4th generation computers, and finally 5th generation.

1st  generation computers.This is a generation of computers that were discovered between the years 1946 and 1957.These computers had the following characteristics: They used vacuum tubes for circuiting.They used magnetic drums as memory for data processing.Their operating system was quite low as compared to the later generations.An operating system can be defined as a collection of programs designed to control the computer’s interaction and communication with the user. A computer must load the operating system like Microsoft into memory before it can load an application program like Ms Word.These computers required large space for installation.They were large in size and could take up the entire room.They consumed a lot of power.They also produced huge amounts of energy and power which saw machines breaking down oftenly. Using the computers,programming capabilities was quite low since the computers relied on machine language.Machine language can only be understood by the computer but not human beings .Their input was based on punched cards and paper tapes.

2nd  generation computers. These computers existed between the years 1958 and 1964.They possessed the following features:These computers used transistors for circuitry purposes.They were quite smaller in size compared to the 1st generation computers. Unlike the 1st generation computers, they consumed less power. Their operating system was faster.During this generation, programming languages such as COBOL and FORTRAN were developed.This phase of computers relied on punched cards too for input and printouts.

3rd generation computers.These are computers that existed between 1965 and 1971.The computers used integrated circuits(ICs) for circuitry purposes.The computers were smaller in size due to the introduction of the chip.They had a large memory for processing data. Their processing speed was much higher.The technology used in these computers was small scale integration (SSI) technology.

4th generation computers. The computers under this generation were discovered from 1972 to 1990s. The computers employed large scale integration (LSI) technology.The size of memory was /is high/large,hence faster processing of data.Their processing speed was high.The computers were also smaller in size and less costly in terms of installation.This phase of computers saw introduction of keyboards that could interface well with processing system.During this phase, there was rapid internet evolution.Other advances that were made included the introduction of GUI(graphical user interface) and mouses.Other than GUI, there exist other user interfaces like natural-language interface,question-and-answer interface,command line interface(CLI).


5th generation computers.These are computers that are still under development and invention. There development might have began in 1990s and continues in to the future. These computers use very large scale integration (VLSI) technology. The memory speed of these computers is extremely high.The computers can perform parallel processing. It is during this generation that Artificial Intelligence (AI) concept was generated e.g voice and speech recognition. These computers will use quantum computation and molecular technology.They will be able to interpret data and respond to it without direct control by human beings.

Applications and Limitations of Digital Computers

In a very general way, it can be said that the advantages of the digital computer compared to the analog computer,I are its greater flexibility and precision, while its disadvantages are its higher cost and complexity.

Information storage can be easier in digital computer systems than in analogue ones. New features can often be added to a digital system more easily too.

Computer-controlled digital systems can be controlled by software, allowing new functions to be added without changing hardware. Often this can be done outside of the factory by updating the product’s software. So, the product’s design errors can be corrected after the product is in a customer’s hands.

Information storage can be easier in digital systems than in analog ones. The noise-immunity of digital systems permits data to be stored and retrieved without degradation. In an analog system, noise from aging and wear degrade the information stored. In a digital system, as long as the total noise is below a certain level, the information can be recovered perfectly.

Digital computers play an important role in life today as they can be used to control industrial processes, analyse and organize business data, assist in scientific research and designing of automobiles and aircraf, and even help making special effects in movies. Some Main Applications of Digital Computers are as follows –

Recording Information

Official statistics keepers and some scouts use computers to record statistics, take notes and chat online while attending and working at a sports event.

Analyzing Movements

The best athletes pay close attention to detail. Computers can slow recorded video and allow people to study their specific movements to try to improve their tendencies and repair poor habits.


Many sportswriters attend several sporting events a week, and they take their computers with them to write during the game or shortly after while their thoughts are fresh in their mind.

The main disadvantages are that digital circuits use more energy than analogue circuits to accomplish the same tasks, thus producing more heat as well. Digital circuits are often fragile, in that if a single piece of digital data is lost or misinterpreted, the meaning of large blocks of related data can completely change.

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