UNIT 7 - Information Technology Notes- Part 1

Information Technology
Introduction to Computer
v  Hardware  (CPU, Input / Output devices, Storage)           
v   Software (System / Application Software)
v  Transmission Medias
v  Switching Systems
Computer Networks & Technologies
v  Networking Topologies
v  Network Types                
Internet & Other Technologies
Integrated Service Digital Network (ISDN),
Open Systems Interconnections (OSI)

Information Technology
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 computer services

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 signals.

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 Blaise Pascal
1822 AD – The Difference Engine – Built by Charles Babbage
1890 AD – Hollerith Tabulating Machine – Designed by Herman Hollerith

Generation of Computers

First Generation - 1940-1956: Vacuum Tubes

Used vacuum tubes for circuitry and magnetic drums for memory.
large in size, occupied a lot of space and produced enormous heat.
very expensive to operate and consumed large amount of electricity.
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 reliable

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.

Generation of Computers

Fourth Generation - 1971-Present : Microprocessors

Thousands of integrated circuits were built onto a single silicon 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.

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 and self-organization

Components of a Computer

                refers to all the physical items associated with a computer system.
                is a set of instructions, which enables the hardware to perform a specific task.

Classification of computer

Analog 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

Hybrid Computer

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

Digital Computers

     Digital computer 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

                                - Special purpose
                                - Special purpose
Size and performance wise

Digital Computer - Classification according to purpose 

General Purpose

Designed to handle variety of different problems and to meet different needs.

Normally weak in speed & efficiency as compared to Special purpose computer.

Use for applications such as payroll, accounts, inventory control, budgeting and sales analysis.

Special purpose

Designed to handle specific problem or to perform special task.

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 weight computers.

Mini Computer

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 group system.

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 in TB’s

Application – Host computer, Central data base server.

Use in Large Business, Airlines, Banks, E-Commerce Sites, Military, Industrial organizations.

Super Computer

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

Large, expensive

IBM’s deep blue, which defeated world Chess Champion Gary Kasparov

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.
They are:
 Input unit
 Central Processing Unit
                                a. Control Unit
                                b. Arithmetic and Logic Unit (ALU)
                                c. Registers
 Memory Unit
 Output Unit

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

CPU Unit
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.

 The Processor, 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 printers.

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.

Audio Input

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.

Output devices-Monitor

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)

Output devices-Printers

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 minute.

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 to operate

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 slow.

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 
Letter-quality printouts
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 seismology.

The computer can also give produce voice output(audio data).
Speaker serves as a voice output device.
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