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By Anne Perera
The first man-made computing device is the Abacus The abacus,
also called a counting frame. The Chinese abacus was developed
about 5000 years ago. Addition, subtraction, division and
multiplication can be performed on a standard abacus.
John Napier, a Scotland national, found the Logarithms to the
world in 1617. Using John Napiars logarithm concepts, the slide
rule was designed in England in 1632.
Around 1642, a French mathematician called Blaise Pascal
invented the adding machine that helped mathematical calculations.
Additions and subtractions could be done easily by using it.
Pascals machine was one of the first mechanical calculating
An Englishman called Charles Babbage designed the first model
required for a mechanical computer in 1822.
Charles Babbage designed the 'Analytical Engine' in 1833.
Components required for data input, storage, processing and output
had been designed inside. Computers designed later were greatly
influenced by these concepts of Babbage and that is why Babbage is
considered to be the Father of computers.
A friend of Babbage called Ada Augusta Lovelace was keen on
preparing programmes required for his engine. Such programmes are
considered to be the first attempt of computer programming. Ada
Augusta Lovelace is considered to be the first computer programmer
in the world. The computer language which was used later for
military purposes was named Ada to pay respect for her.
Herman Hollerith adopted the punched card concept. Early method
of data storage used with early computers. Punch cards also known
as Hollerith cards and IBM cards.
A computer can be classified as follows: 1) Based on the
generations 2) Size 3) Purpose 4)Design technology / Computational
1. First Generation Computers (1939-1958) Vacuum tubes
Based onVacuumTubes Used magnetic drums for main memory.
Can solve one problem at a time. Input was based on punched
cards and paper tape, and output was displayed on printouts. First
generation computers based on machine language, the lowest-level
programming language understood by computers
Disadvantages Very large in size. Consumed a large amount of
energy. They heated very soon due to thousands of vacuum
Disadvantages They were not very reliable. Constant maintenance
was required. Very slow in speed. Used magnetic drums which provide
very less data storage.
ENIAC (Electronic Numerical Integrator and Computer) - worlds
first electronic digital computer in 1946
UNIVAC (Universal Automatic Computer) -The first commercial
2. Second Generation Computers (1954-1959) Transistors
The second generation of computers used transistors for the
internal operations. They used magnetic core for the memory Still
based on punched cards for input and printouts for output.
The first computers that stored their instructions in their
memory, which moved from a magnetic drum to magnetic core
technology. Used symbolic, or Assembly language, which allowed
programmers to specify instructions in words. High-level
programming languages were also being developed at this time, such
as early versions of COBOL and FORTRAN.
Advantages: Smaller in size as compared to the first generation
computers. Computers were more reliable Used less energy and were
Advantages: Better portability as compared to the first
generation computers. Used faster peripherals like tape drives,
magnetic disks, printers etc. Used Assembly language instead of
Machine language. Accuracy improved.
Disadvantages Cooling system was required Constant maintenance
was required Commercial production was difficult
Disadvantages Only used for specific purposes Expensive Punch
cards were used for input.
These computers used integrated circuits on silicon chips. A
single IC chip may contain thousands of transistors. Eg:- IBM 370,
IBM System/360, UNIVAC 1108 and UNIVAC AC 9000
Advantages Smaller in size as compared to previous generations.
More reliable. Used less energy Produced less heat as compared to
the previous two generations. Better speed and could calculate data
in nanoseconds. Used fan for heat discharge to prevent damage.
Advantages Totally general purpose Could be used for high-level
languages. Good storage capacity. Less expensive Better accuracy
Commercial production increased. Used mouse and keyboard for
Disadvantages Air conditioning was required. High technology
required for the manufacturing of IC chips.
Use microprocessor chips. The Microprocessor contains thousands
of ICs. The technology of integrated circuits improved rapidly. The
LSI (Large Scale Integration) circuit andVLSI (Very Large Scale
Integration) circuit was designed. Reduced the size of
The size of modern Microprocessors is usually one square inch.
It can contain millions of electronic circuits. Examples :- Apple
Macintosh & IBM PC. Can be linked together to form networks,
which led to the development of the Internet. Introduced GUIs and
Advantages More powerful and reliable than previous
generations. Small in size Fast processing power with less power
consumption Fan for heat discharging and to keep cold. Totally
Advantages Commercial production Less need of repair. Cheapest
among all generations All types of High level languages can be used
in this type of computers
Based on the technique of Artificial Intelligence (AI).
Computers can understand spoken words & imitate the human. Can
respond to its surroundings using different types of sensors.
Scientists are constantly working to increase the processing
power of computers. IBM Watson computer is one example for a 5th
generation computer. There are some applications, such as voice
recognition, that are being used today.
Computers can be classified according to their sizes too.
Mainframe computers Mini computers Micro computers
There are different types of Micro computers. Some of them are,
Personal Computers (PC) Laptop Computers Palmtop computers
Workstations Server computers Super computers
Computers can be categorized into two types based on their
purpose. 1)General Purpose Computers Computers used for usual and
day - to - day activities. 2) Special Purpose Computers Computers
used for special purposes such as scientific experiments, air
traffic control systems etc.
1) Digital computers Computers designed by using the binary
/digital number system are called digital computers. A digital
computer can count and accept numbers and letters through various
2) Analog computers Computers which are designed considering
the physical data such as temperature, sound, and pressure etc.
Analog computers process data input in a continuous form.
2) Analog computers Data such as voltage, temperature are
represented in the computer as a continuous, unbroken flow of
information. Analog computers are used in engineering and
3) Hybrid computers A combination of the above two types of
computers. Example: In Process Control Computer Systems, the inputs
comes from devices like pressure, thermometers etc.
3) Hybrid computers The inputs from analog devices are sent to
a digital computation unit that runs the mathematical model for
controlling the process.