• The evolution of computer started from 16th century and resulted in today’s modern machines.
  • The present day computer, however, has also undergone rapid change over the years. 
  • Each new generation of computers is not only superior from their predecessor in processing and capabilities but also differs in looks and sizes.
  • Each generation phase is distinguished from others on the basis of the type of switching circuits used.


  • The time period, during which the evolution of computer & its related things took place is called generation of computers.

Generation of Computers

Generation of Computers can be divided into five distinct phases for the simplicity of study of development. These are –

  • First Generation Computers (1940 -1956)
  • Second Generation Computers (1956 -1963)
  • Third Generation Computers (1964 -1971)
  • Fourth Generation Computers (1972 – 2010)
  • Fifth Generation Computers (2010 – Present)

First Generation Computers : Vacuum Tubes (1940-1956)

  • The first generation computers were introduced in 1940.
  • First generation computers are mainly characterized by the use of vacuum tube.
  • Processing speed – Slowest.
  • Size of Computer – Largest.
  • Reliability – Unreliable.
  • Operating System – None.
  • Language support/use – Machine.
  • Vacuum Tube –
    • A vacuum tube was a fragile glass device, which used filaments as a source of electronics.
    • The vacuum tube can switch electricity on or off, or It could control and amplify electronic signals/current.
    • These vacuum tubes were used for calculation as well as storage and control.
    • First generation computers were too bulky in size which required large room for installation and they used to emit large amount of heat, so air-condition was must for the proper working of computers. 
    • The vacuum tube replaced by the transistor in next generation, this is because of several reasons i.e. the vacuum tube looks and behaves very much like a light bulb; it generates a lot of heat and has a tendency to burn out. Also, compared to the transistor it is slow, big and bulky. When engineers tried to build complex circuits using the vacuum tube, they quickly became aware of its limitations.When the transistor was invented in 1947 it was considered a revolution. Small, fast, reliable and effective, it quickly replaced the vacuum tube.
  • Examples – ENIAC, EDVAC, UNIVAC-1 etc.

Second Generation Computers : Transistors (1956-1963)

  • The second generation computers were introduced in 1956.
  • Second generation computers are characterized by the use of transistors.
  • Solid-State components (transistors and diodes) and magnetic core storage formed the basis for the second generation of computers.
  • Processing speed – Slow.
  • Size of Computer – Large.
  • Reliability – Less Reliable.
  • Operating System – None.
  • Language support/use – Assembly.
  • Transistor –
    • The transistor is the most important one for the development of modern computers.
    • It is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit.
    • It is Invented in Bell Labs, America.
    • Transistors have become the key ingredient of all digital circuits, including computers.
    • The transistor acts like a switch. It can turn electricity on or off, or it can amplify current.
    • It is used for example in computers to store information.
    • Transistor replaced the bulky electric tubes in the first generation computer.
    • Transistors perform the same functions as a vacuum tube, except that electrons move through solid materials instead of through a vacuum.
    • Transistors were made of a semi-conducting material and controlled the flow of electricity through the circuit.
    • They also allowed computers to become smaller and more powerful and faster at the same time.
    • They are also less expensive, required less electricity and emitted less heat than vacuum tubes.
    • Manufacturing cost was also very low.
  • It is in the second generation that the concept of Central Processing Unit (CPU), memory, programming language and input and output units were developed.
  • Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words.
  • These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
  • During the second generation many high level programming languages were introduced, including FORTRAN (1956), ALGOL (1958) and COBOL (1959).
  • Examples : – PDP-8, IBM1400 series, IBM 1620, IBM 7090, CDC 3600 etc.

Third Generation Computers : Integrated Circuits (1964-1971)

  • The third generation computers were introduced in 1964.
  • Third generation computers are characterized by the use of integrated circuits (ICs).
  • Processing speed – Medium.
  • Size of Computer – Medium.
  • Reliability – More Reliable.
  • Operating System – Yes.
  • Language support/use – High Level Language.
  • Integrated Circuits (ICs) –
    • The integrated circuit is nothing more than a very advanced electronic circuit.
    • Integrated circuits is semiconductor devices with several transistors built into one physical component.
    • It is an electronic circuit which involves thousands or millions of interconnected components like transistors, diodes and resistors.
    • They are popularly called ICs. We can find several of them in computers/other electronic devices.
    • The microprocessor is actually an integrated circuit that processes all information in the computer.
    • The first integrated circuits (ICs) were based on small scale integration (SSI) circuits, which had around 10 devices per circuit (or chip), and evolved to the use of medium-scale integrated (MSI) circuits, which had up to 100 devices per chip.
    • Integrated circuits are also found in almost every modern electrical device such as cars, television sets, CD players, cellular phones, etc.
    • The main benefits of ICs are lower costs, high reliability and smaller space requirements. 
    • Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
    • The development of ICs proved to be a milestone in the field of computer and electronics.
    • These ICs are popularly known as chips. Silicon is the basic material used to make computer chips, transistors, silicon diodes and other electronic circuits and switching devices because its atomic structure makes the element an ideal semiconductor. Silicon is commonly doped, or mixed, with other elements, such as boron, phosphorous and arsenic, to alter its conductive properties. A typical chip is less than ¼-square inches and can contain millions of electronic components (transistors). Computers consist of many chips placed on electronic boards called printed circuit boards. There are different types of chips. For example, CPU chips (also called microprocessors) contain an entire processing unit, whereas memory chips contain blank memory.
    • A single IC, has many transistors, registers and capacitors built on a single thin slice of silicon.
    • Development in ICs ranges from small scale integration (SSI) to medium scale integration (MSI).
    • Multilayered printed circuits were developed and core memory was replaced by faster, solid state memories.
    • The IC technology was also known as “Microelectronics” technology, since large number of circuit could be integrated on a single chip.
  • Computers of this generation were small in size, low cost, large memory and processing speed is very high.
  • Higher level language such as BASIC (Beginners All purpose Symbolic Instruction Code) was developed during this period.
  • Integrated solid-state circuitry, improved secondary storage devices, and new input/output devices were the most important advantages in this generation.
  • The new circuitry increased the speed of the computer. Arithmetic and logical operations were now being performed in microseconds or even nanoseconds.
  • The development of mini computers also took place during this generation.
  • Examples : – NCR 395, B6500, IBM 360,370 etc.

Fourth Generation Computers : Microprocessors (1972-2010)

  • Fourth generation computers started around 1972.
  • Fourth generation computers are characterized by the use of microprocessor.
  • Processing speed – Faster.
  • Size of Computer – Smaller.
  • Reliability – More Reliable.
  • Operating System – Yes.
  • Language support/use – High Level Language.
  • Microprocessor –
    • LSI circuits built on a single silicon chip called microprocessors.
    • A microprocessor contains all the circuits required to perform arithmetic, logic and control functions on a single chip. 
    • The Intel 4004 chip, developed in 1971, located all the components of the computer – from the central processing unit and memory to input/output controls – on a single chip.
  • Because of microprocessors, the fourth generation includes more data processing capacity than equivalent-sized third generation computers.
  • Due to the development of microprocessor, it is possible to place computer’s central processing unit (CPU) on single chip. These computers are called microcomputers. 
  • They use large scale of integration (LSI) in the construction of computing elements. 
  • Due to use of LSI/VLSI, now computer fit in the palm of the hand.
  • The major innovations in this generation were the development of microelectronics and the different areas in computer technology such as multiprocessing, multiprogramming, time-sharing, operating speed, and virtual storage.
  • During this period, high speed vector processors changed the scenario of high performance computing.
  • Mostly microcomputers and workstations were introduced for time shared mainframe computers. Thus the computer which was occupying a very large room in earlier days can now be placed on a table.
  • The personal computer is one of the revolutionary invention is really a Fourth Generation Computer. I
  • It is the period when evolution of computer networks also took place.
  • Examples : Apple II, Alter 8800 etc.

Fifth Generation Computers (2010 – Present)

  • Fifth generation computers are based on Artificial Intelligence.
  • Processing speed – Fastest.
  • Size of Computer – Smallest.
  • Reliability – More Reliable.
  • Operating System – Yes.
  • Language support/use – High Level Language.
  • Artificial Intelligence(AI) –
    • Artificial Intelligence is the branch of computer science concerned with making computers behave like humans and allow the computer to take its own decision.
    • Currently, no computers exhibit full artificial intelligence (that is, are able to simulate human behavior).
    • The greatest advances have occurred in the field of games playing.
    • The best computer chess programs are now capable of beating humans.
    • Today, the hottest area of artificial intelligence is neural networks, which are proving successful in an umber of disciplines such as voice recognition and natural-language processing.
    • There are several programming languages that are known as AI languages because they are used almost exclusively for AI applications. The two most common are LISP and Prolog.
  • The speed is extremely high in fifth generation computer.
  • In the development of Fifth generation computers, parallel processing attended the main focus of developers.
  • Until this time, parallelism was limited to pipelining and vector processing.
  • This generation introduced machines with hundreds of processors that could all be working on different parts of a single program.
  • Developments of more powerful computers are still in progress using AI.
  • It has been predicted that such a computer will be able to communicate in natural spoken language with its user, store vast knowledge databases, search rapidly through these databases, making intelligent inferences, drawing logical conclusions, image processing and see objects in the way that humans do.

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