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Generations of Computers

Generation of computers is the developmental stages that the computer has gone through. There are 5 generations of computers and their accompanying innovations.

First Generation – Vacuum Tubes (1940 – 1956)

First generation computers were those manufactured between 1940s and 1950s. The computers used the stored program concept. First generation computers were associated with the vacuum tubes or valves technology as circuitry and magnetic drums for memory.

Characteristics of the First Generation of Computers

  1. They were very bulky and heavy.
  2. They measured between 50 – 100ft long and about 80ft high.
  3. The computers weighed up to 200 tons and occupied 3000 cubic ft.
  4. They used vacuum tubes to store and process data.
  5. Examples of first generation computers are ENIAC, EDSAC, and UNIVAC.
  6. It generates a lot of heat
  7. It relies on machine language
  8. These computers were limited to solving one problem at a time

Problems of First Generation of Computers

  1. The vacuum tubes also generated a lot of heat hence, they needed a cooling system.
  2. They were very bulky and heavy and are not mobile.
  3. It occupies excess space.
  4. It consumes a lot of energy.


Second Generation – Transistors (1956 – 1963)

The replacement of vacuum tubes by transistors saw the advent of the second generation of computing. They were a big improvement over the vacuum tube, despite still subjecting computers to damaging levels of heat. However they were hugely superior to the vacuum tubes, making computers smaller, faster, cheaper and less heavy on electricity use. They still relied on punched card for input/printouts.

The language evolved from cryptic binary language to symbolic (assembly) languages. This means, programmers could create instructions in words. About the same time high level programming languages were being developed (early versions of COBOL and FORTRAN). Transistor-driven machines were the first computers to store instructions into their memories – moving from magnetic drum to magnetic core-technology. The early versions of these machines were developed for the atomic energy industry. Examples of second generation computers are NCR, 315, International Business Machine (IBM), 7030.

Characteristics of the Second Generation of Computers

  1. They were smaller in size than first generation computers.
  2. They occupied smaller space than the first generation computers.
  3. Second generation computers used less electricity and generated less heat.
  4. The transistors could do all that the vacuum tubes did.
  5. The computers were faster and lighter in weight than first generation computers.
  6. It uses assembly language
  7. It uses punch cards for input and output


Third Generation – Integrated Circuits (IC) (1964 – 1971)

By this phase, transistors were reduced and put on silicon chips (called semiconductors). This led to a massive increase in speed and efficiency of these machines.  These were the first computers where users interacts using keyboards and monitors used an operating system. This enabled these machines to run several applications at once using a central program which functioned to monitor memory. As a result of these advances which again made machines cheaper and smaller, a new mass market of users emerged during the 1960s. They were first used in space ships and electronic military equipment.

 Characteristics of Third Generation of Computers

  1. The computers used integrated circuits.
  2. They were faster than second generation computers.
  3. They were smaller in size and also more powerful.
  4. The computers had fast memory access.
  5. It runs several applications at a time.
  6. They were first used in space ships and electronic military equipment.

Fourth Generation – Very Large Integrated Circuits (1972 – 1984)

Intel The chip-maker developed the Intel 4004 chip in 1971, which positioned all computer components (CPU, memory, input/output controls) onto a single chip. What filled a room in the 1940s now fit in the palm of the hand. The Intel chip housed thousands of integrated circuits. The year 1981 saw the first ever computer (IBM) specifically designed for home use and 1984 saw the Macintosh introduced by Apple. Microprocessors even moved beyond the realm of computers and into an increasing number of everyday products.


The increased power of these small computers meant they could be linked, creating networks which ultimately led to the development, birth and rapid evolution of the Internet. Other major advances during this period have been the Graphical user interface (GUI), the mouse and more recently the astounding advances in lap-top capability and hand-held devices.


A microprocessor is a central processing unit fabricated on a chip. This generation of computers had optical readers and graphic display terminals. The use of floppy diskette as a storage facility was introduced in this generation. Examples are Intel 4004, Intel 8085, Pentium 1, 2, 3, etc 

Characteristics of Fourth Generation of Computers

  1. The computers were smaller in size
  2. They were very powerful computers
  3. They had high processing speed
  4. They had high storage capacity
  5. They use Graphical User Interface (GUI)
  6. They use mouse


Fifth Generation – Artificial Intelligence (AI) (1980s to Date)

Computer devices with artificial intelligence are still in development, but some of these technologies are beginning to emerge and being used such as voice recognition. Artificial Intelligence (AI) is a reality made possible by using parallel processing and superconductors. Leaning to the future, computers will be radically transformed again by quantum computation, molecular and nano technology.


The essence of fifth generation will be using these technologies to ultimately create machines which can process and respond to natural language, and have capability to learn and organize themselves. They also have the capacity of making decisions and judgments. This generation is witnessing the influx of super microcomputers through artificial intelligence whose main attraction over previous computers is speed and power.


These are computers that will be able to mimic many things that so far can only be done by human beings. For example, fifth generation computers will be able to accept spoken word instruction (voice recognition) and assist doctors in carrying out diagnosis.



  1. The fifth generation computers made use of …………..
  2. The means by which a computer receives spoken word instruction is called ………….
  3. The 3rd generation computers were manufactured between …………. and …………
  4. List two characteristics of 3rd generation computers.
  5. First generation computers were manufactured between ………… and …………
  6. One of the problems of the first generation computers was that they generate a lot of ………….
  7. …………. was used for storage in the 2nd generation computers.
  8. List two examples of 2nd Generation computers.
  9. What is a microprocessor?


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