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Information technology (IT) is the application
of computers and telecommunications equipment to store,
retrieve, transmit and manipulate data, often in the context of a business
or other enterprise.
The term is commonly used as a synonym for computers and
computer networks, but it also encompasses other information distribution
technologies such as television and telephones.
Several industries are associated with information
technology, such as computer hardware, software, electronics,
semiconductors, internet, telecom equipment, e-commerce and
Introduction to Computer
An electronic device which is capable of receiving
information (data) in a particular form and of performing a sequence of
operations in accordance with a predetermined but variable set of procedural
instructions (program) to produce a result in the form of information or
History of Computer
2500 BC – Abacus
1614 AD – Napier’s Bones – Invented by John Napier
1633 AD – The Slide Rule – Invented by William Oughtred
1642 AD – The Rotating Wheel Calculator – Developed by
1822 AD – The Difference Engine – Built by Charles Babbage
1890 AD – Hollerith Tabulating Machine – Designed by Herman
Generation of Computers
First Generation - 1940-1956: Vacuum Tubes
Used vacuum tubes for circuitry and magnetic drums for
large in size, occupied a lot of space and produced enormous
very expensive to operate and consumed large amount of
operated only on machine language
Input was based on punched cards and paper tape
It could solve only one problem at a time.
The Universal Automatic Computer (UNIVAC) and the
Electronic Numerical Integrator And Calculator (ENIAC)
Generation of Computers
Second Generation - 1956-1963: Transistors
The transistor was far superior to the vacuum tube, allowing
computers to become smaller, faster, cheaper, energy-efficient and more
Second-generation computers moved from the use of machine
language to assembly languages, 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.
IBM-1620, IBM 1401, CDC 3600, UNIVAC 1108
Generation of Computers
Third Generation (1964-1971 ): Integrated Circuits
Jack Kilby, an engineer with Texas Instruments, developed
the Integrated circuit (IC) The third generation computers was announced in
1964 by IBM with its 360 line of computers
IC on silicon chips were used for internal operations
increased the speed and efficiency of computers.
In this generation, keyboards and monitors were used instead
of punched cards and printouts.
The computers were interfaced with an operating system which
allowed to solve many problems at a time.
Thousands of integrated circuits were built onto a single
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.
In 1981 IBM introduced its first computer for the
home user, and in 1984 Apple introduced the Macintosh.
Microprocessors also moved out of the realm of desktop
computers and into many areas of life as more and more everyday products began
to use microprocessors.
Fourth generation computers also saw the development
of GUIs, the mouse and handhelddevices.
Generation of Computers
Fifth generation computing devices
Based on artificial intelligence, are still in
development, though there are some applications, such as voice recognition,
that are being used today.
The use of parallel processing and superconductors
is helping to make artificial intelligence a reality.
Quantum computation and molecular
and nanotechnology will radically change the face of computers in
years to come.
The goal of fifth-generation computing is to develop devices
that respond to natural language input and are capable of learning
Components of a Computer
to all the physical items associated with a computer system.
set of instructions, which enables the hardware to perform a specific task.
Classification of computer
Computations are carried out with physical quantities such
as voltage, length, current, temperature
Its work on the principle of measurement
Volt meter, ammeter and thermometer
The combination of features of analog and digital computer
is called Hybrid computer. Having both digital & analog features.
Used in various areas of engineering, space vehicle
simulation and training of astronauts, passenger flight radar system, also used
to control robots. Used in hospitals, weather forecasting
are specialized in counting, the digital computer handles values that are in a
discrete (binary 1 or 0).
It converts the data into digits and all operations carried
out on these digits at extremely fast rates
Size and performance wise
Digital Computer - Classification according to purpose
Designed to handle variety of different problems and to meet
Normally weak in speed & efficiency as compared to
Special purpose computer.
Use for applications such as payroll, accounts, inventory
control, budgeting and sales analysis.
Designed to handle specific problem or to perform special
Use for specific task like Satellite tracking, industrial
process, house hold devices. blood pressure monitoring system
Digital Computers-Size wise
The invention of microprocessor (single chip CPU) gave birth
to the micro computers
Also known as a PC, the first PC was built by IBM
Laptop- are portable
computers that fit in a briefcase. Laptop computers, also called notebook
computers when its is even smaller.
Palmtops- Pen-based computers use a pen like stylus and
accept handwritten input directly on a screen. Pen-based computers are also
called Personal Digital Assistants (PDA). Special engineering and
hardware design techniques are adopted to make the portable, smaller and light
These are also small general purpose system. They are
generally more powerful and most useful as compared to micro computer. Mini
computer are also known as mid range computer or Child computer.
Now the term is not in use, once it was between mainframe
& personaal computer category, this category was defeated by PC or desktop
computers because of reduce price and better performance in speed.
Mini Computers are now replaced with Servers.
Application :- Departmental systems, Network Servers, work
Main Frame Computer
Mainframe computers are those computers that offer faster
processing and grater storage area. It is also known as Father computer.
Designed for Multiple user interfaces. Different people can
operate these computers at the same time for complex intensive tasks.
For Non Stop reliable operation, to upgrade these systems
you don’t have to switch off.
Using Multiple Processors 2-24 etc., Memory in GB’s, storage
Application – Host computer, Central data base server.
Use in Large Business, Airlines, Banks, E-Commerce Sites,
Military, Industrial organizations.
Super computer are those computer which are designed for
scientific job like whether forecasting and artificial intelligence etc.
A super computer contains a number of CPU which operate in
parallel to make it faster. It also known as grand father computer.
Ultra-high performance tasks
IBM’s deep blue, which defeated world Chess Champion Gary
Examples of such applications are stock analysis, special
effects for movies, weather forecasting, weapons research and development. and
even sophisticated art works.
Computer designed as….
A computer is designed using four basic units.
Arithmetic and Logic Unit (ALU)
Components of a computer
Input unit allows the user to enter the program and
data and send it to the processing unit. The common input devices are keyboard,
mouse and scanners.
Memory Unit provides space to store input data,
intermediate results and the final output generated. Secondary storage devices
are additional memory devices such as floppy disks, magnetic tapes, hard disks,
and compact disks
Output Unit is used to print or display the results,
which are stored in the memory unit. It converts the data from binary form to
the human understandable form. The devices are normally a monitor and printers.
The input unit, output unit and secondary storage
devices are together known as Peripheral devices
Central Processing Unit (CPU)- is known to be heart or brain
of the computer system as it follows the instructions of the software/program
to manipulate data in information
Control Unit – fetches an instruction, decode the
instructions, executes the instructions and it stores the results
Arithmetic and Logic Unit (ALU)-the place where the actual
execution of the instructions takes place. It performs arithmetic and logical
operations and controls the speed of these operations
Registers- are high speed storage areas that temporarily
store data during processing to enhance computer’s performance
Input devices allows the user to enter the program and
data and send it to the processing unit. The common input devices are
keyboard, mouse and scanners.
more formally known as the central processing unit (CPU), has the
electronic circuitry that manipulates
input data into the information as required. The central processing unit
actually executes computer instructions.
Output devices show the processed data – information –
the result of processing. The devices are normally a monitor and
Memory from which the CPU fetches the instructions and
data is called main memory. It is also called as primary memory and is
volatile in nature.
Computers can accept input from a microphone.
An expansion card called a sound card records and
plays back sound files.
Speech recognition is a type of input in which the
computer recognizes words spoken into a microphone.
Special software and a microphone are required.
The most common output device is the monitor or VDU.
A monitor is a peripheral device which displays computer
output on a screen.
Screen output is referred to as soft copy
Modern monitors, where the case isn’t more than a few
centimeters deep, are usually Liquid Crystal
Displays (LCD) or Thin Film
Transistors (TFT) monitors.
Older monitors, where the case is likely to be around 30 cm
deep, are Cathode Ray Tube (CRT) monitors.
Resolution – The sharpness of the image determined by
the number of horizontal and vertical dots (pixels) that the screen can display
(800 x 600, 1024 x 768, 1600 x 1200)
A printer is a peripheral device that produces a physical
copy or hard copy of the computer’s output.
Types of printer-Impact printers
Line printers are high-speed printers capable of printing an
entire line at a time. A line printer can print 150 lines to 3000 lines per
The limitations of line printer are they can print only one
font, they cannot print graphics, the print quality is low and they are noisy
The most popular serial printer is the dot matrix printer.
It prints one line of 8 or 14 points at a time, with print
head moving across a line. They are similar to typewriters. They are normally
The printing speed is around 300 characters per second.
Types of Printers-Non impact printers
Inkjet printer, also called a bubble-jet, makes
characters by inserting dots of ink onto paper
Cost of printer is inexpensive but ink is costly
Laser printer works like a copier
Quality determined by dots per inch (dpi) produced
Color printers available
Expensive initial costs but cheaper to operate per page
A plotter is a printer that uses a pen that moves over a
large revolving sheet of paper.
It is used in engineering, drafting, map making, and
The computer can also give produce voice output(audio data).