IGNOU BCS011 NOTES
BASIC OF COMPUTER
First Generation Computers: Vacuum Tubes (1940-1956)
First generation computers are characterized by the use of vacuum tube.
A vacuum tube was a fragile glass device, which used filaments as a source of electronics.
These vacuum tubes were used for calculation as well as storage and control.
The Example of First Gen of Computer is Electronic Numerical Integrator and Computer (ENIAC)
and Universal Automatic Computer (UNIVAC)
The ENIAC was 30-50 feet long, weighed 30 tons, contained 18,000 vacuum tubes, 70,000
registers, 10,000 capacitors and required 150,000 watts of electricity
First generation computers were too bulky in size which required large room for installation.
Second Generation Computers: Transistors (1956-1963)
Solid-State components (transistors and diodes) and magnetic core storage formed the basis for
the second generation of computers
Transistor is a device composed of semiconductor material that amplifies a signal or opens or
closes a circuit.
Transistor replaced the bulky electric tubes in the First generation computer.
They also allowed computers to become smaller and more powerful and faster at the same
time.
The Example of Second Gen is FORTRAN (1956), ALGOL (1958) and COBOL (1959)
Third Generation Computers: Integrated Circuits (1964-1971)
The Third Generation computers were introduced in 1964
Transistors were miniaturized and placed on silicon chips, called semiconductors, which
drastically increased the speed and efficiency of computers.
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
Computers of this generation were small in size, low cost, large memory and processing speed is
very high.
Examples: NCR 395, B6500, IBM 360,370
Fourth Generation Computers: Microprocessors (1971-Present)
Fourth generation computers started around 1971 by using large scale of integration (LSI) in the
construction of computing elements
LSI circuits built on a single silicon chip called microprocessors.
microprocessor contains all the circuits required to perform arithmetic, logic and control
functions on a single chip.
this period, high speed vector processors changed the scenario of high performance computing.
