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Explain generations of computer in detail.

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First-generation computers

Period Component used Access time Cost
1949 - 1959 Vacuum Tube Milli second Very expensive

The first computers used vacuum tubes for electronic circuitry and magnetic drums for memory. They were very expensive to operate their electricity consumption was high and they generated a lot of heat, which was often the cause of malfunctions. First-generation computers were communicated through machine language to perform operations, and they could only solve one problem at a time.

Input was based on punched cards and paper tape, and output was displayed on printouts. UNIVAC and ENIAC computers are examples of first-generation computing devices.


  • For Calculation and computation.
  • Payroll Processing
  • Record keeping


  • Required a huge space
  • Too big in size
  • Very slow in speed
  • Low level of accuracy and reliability
  • Low storage capacity
  • High power consumption
  • High heat generation
  • Used machine language
  • Difficult to maintain
  • Fault finding was very difficult

Second Generation Computers

Computer Model Manufacturer
ENAIC Moore's School of Electrical
UNIVACI Engineering University, University of Pennsylvania.
Period Component used Access time Cost
1959 - 1965 Transistor Micro second Less cost

1. In second-generation computers symbolic or assembly languages were used.

2. High-level programming languages were also in use at this time, such as the early versions of COBOL and FORTRAN.

3. The memory storage used magnetic core technology.

4. Second-generation computers still relied on punched cards for input and printouts for output.


  • Smaller in size
  • Better speed
  • Low power consumption
  • No heat was generated.
  • Better storage capacity
  • More reliability
  • Compact Design
  • Faster than I Generation Computers.


  • Needed Air conditioning environment
  • Constant maintenance needed.
  • No operating system
Model Manufacturer
IBM 70, 1400, 1600 IBM
Honeywell 400,800
UNIVAC 111,5590, 1107

Third Generation Computers

Period Component used Access time Cost
1965 - 1970(Mini computer was introduced) Integrated Circuits (IC's) Nano second Loss Cost

1. The development of the integrated circuit was made use of in the third generation of computers.

2. Transistors were miniaturized and were placed on silicon chips, called semiconductors.

3. The processing speed and efficiency of computers increased.

4. Keyboards and monitors were used as input and output devices.

5. The computer system had an operating system and helped to run multiple applications simultaneously. Computers gained a lot of popularity because of small size and low cost.


  •  Better than first and second-generation computers
  • Used high-level language
  • Size got reduced further
  • Speed got increased
  • Much better performance 
  • Much more reliability


  • Initial problem with Manufactures.
Model Manufacturer
IBM 70, 1400, 1600 IBM
PDP 8 Series
Spectra 70
UNIVAC 1108,9000

Digital Equipment
Series RCA

Fourth Generation Computers

Period Component used Access time Cost
1970 - 1985 LSIC,VLSIC Nano second  Very low cost

1. The microprocessor was used in fourth the generation computers, as thousands of integrated circuits were built onto a single silicon chip.

2. 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.

3. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.

4. Network technology was introduced at this time. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.


  • Speed and Reliability are more
  • Computer occupies every walks of life.
  • More superior to earlier computers.
  • Computer-aided Design introduced (CAD)
  • LAN (Local Area Network) and WAN (Wide area network) got introduced
Model Manufacturer
Apple Series Apple
M 68000
8086, Z 8000
DEC 10, STAR 1000
Digital Equipment


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