Tm 1st mod

MODULE 1: Introduction
N.Nagasubba Reddy, Assistant Professor, R.V.Institute of Management Page 1
Introduction
Introduction and definition of computer, Functional components of a computer system,
functioning inside a computer, Hardware and Software with examples, Introduction to
languages, compiler, interpreter and assembler. Operating System: Definition, Functions,
Types and Classification, Elements of GUI based operating system-Windows-Use of menus,
tools and commands of windows operating system, Linux and free and open software;
Computer Networks: Overview and Types (LAN, WAN and MAN), Network topologies,
Internet; Data representation and computer security
Computer: a computer is an electronic device which accept a data process it according to
the instructions given to it and produces meaningful information.
Functional components of computer:
 Input devices: for entering data and instructions into the CPU. Key board, mouse,
touch screen, optical scanner, voice recognition etc.
 Central processing unit: control unit and arithmetical unit
 Control unit: interprets instructions and direct processing.
 Arithmetic and logical: perform arithmetic and logically operations.
 Output devices: communicates and records information, visual displays unit, printer,
audio response devices etc.
 Primary storage devices: stores data and program instructions during processing.
 Secondary storage: stores data and programs for processing, magnetize disk, tape
units, optical disk etc.
Input devices Output devices
Control unit
Arithmetical
logic unit
Primary storage
Secondary storage

Generations of computers
First Generation (1940-1956) Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and
were often enormous, taking up entire rooms. They were very expensive to operate and in
addition to using a great deal of electricity, generated a lot of heat, which was often the
cause of malfunctions.
First generation computers relied on machine language, the lowest-level programming
language understood by computers, 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.
The UNIVAC and ENIAC computers are examples of first-generation computing devices.
Second Generation (1956-1963) Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers. The
transistor was invented in 1947 but did not see widespread use in computers until the late
1950s. The transistor was far superior to the vacuum tube, allowing computers to become
smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation
predecessors. Though the transistor still generated a great deal of heat that subjected the
computer to damage, it was a vast improvement over the vacuum tube. Second-generation
computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or
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. These were also the first computers that stored their instructions
in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.
Third Generation (1964-1971) Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on silicon chips, called
semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers
through keyboards and monitors and interfaced with an operating system, which allowed
the device to run many different applications at one time with a central program that
monitored the memory. Computers for the first time became accessible to a mass audience
because they were smaller and cheaper than their predecessors.

Fourth Generation (1971-Present) Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of integrated
circuits were built onto a single silicon chip. What in the first generation filled an entire
room could now fit in the palm of the hand. 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.
As these small computers became more powerful, they could be linked together to form
networks, which eventually led to the development of the Internet. Fourth generation
computers also saw the development of GUIs, the mouse and handheld devices.
Fifth Generation (Present and Beyond) Artificial Intelligence
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.
Categories / classifications of computer systems or classes:
1. Micro-computers: personal computers (pcs), network computers technical work
stations, personal digital assistants, information appliances etc.
2. Mid-range computers: network servers, mini computers, web servers, multiuser
systems.
3. Mainframe computers: enterprise systems, super servers, transaction processors,
super computers.
Microcomputers:
These are the most important category of computer system for business people and
consumers, the availability of micro-computers are based on size, shape, and purpose.
A micro-computer is the smallest category of the computer.

Advantages:
 Small and portable relatively inexpensive, used for household management
entertainment and in small business.
 Good graphic capacities
 Works as soon as they are switched on
 Do not occupy much space
 Do not consume much power
Disadvantages:
 Limited memory storage capacity
 Limited processing capacity.
Popular microcomputers are:
1. Personal computers
2. Work stations: high end computers
3. Laptops
4. Notebooks
5. Hand held computers
6. Information appliances: TV setup box
7. Wearable’s: watches.
Mid-range computers systems / MINI computers:
Mini computers are small general purpose computers and consists of a CPU, several disk
drivers and Printers, more primary storage, CPU speed is 100 MIPS to 500 MIPS.
 Smaller COU than main frames
 Word lengths are usually 16-32 bits
 Supports between 15 to 25 terminals
 Most popular mini computers are Data general, IBM series/ 8100, Texas instruments.
Main frame computers: these are the larger computers built to a conventional architecture
the cost performance has now improved as compared earlier but their underlying
philosophy is unchanged.
These can process several millions instructions per second, larger organizations use these
machines to handle wide array of data such as banks, insurance companies, airlines ,
railways reservations, space research organizations etc.
The computers are often called as “corporate work horses”
Example: IBM system/ 370 ranges from smaller model 115, to medium sized model 168 to
very large model 3033.

Super computers: these are the largest mainframes computers they have huge primary
memory and the most advanced capabilities through fastest computers they are not used
for commercial data processing.
They are used in specialised areas such as in defence, aircraft design and computer
generated movies, weather research etc.
Super computer of large size costs from 5 million dollars to 50 million dollars range.
Example: param 8000, and param 10,000 were developed by C-DAC a government
organization.
Computer software:
Computer programs and procedures concerned with the operations of an information
system, the detailed set of instructions that control the operations of the computer
systems.
Program: a series of statements or instructions to the computers.
Computer software is set of instructions and decisions roles gives life to computers, they
give the way to CPU how to manipulate data.
The functions of software are:
 Manage computers resources of organization
 Provides tools for human being to take advantage of these resources
 Act as an intermediary between organizations and stored information.
Computer software
Application software System software
General purpose
application program
Applicationsspecific
program
System
management
programs
System
development
program
System support
program

Application software:
It consists of programs that are written for the users for specific tasks they are called so
because they direct the processing required for a particular use or application.
1. General purpose program: MS-OFFICE, E-mail, DB packages, graphic package etc.
2. Application specific program: ASP are designed to meet information processing
needs for specific business or scientific application such as project planning and
monitoring, inventory management etc.
These application programmes are internally developed by outsiders to meet specific
needs, the package consists of modular structure that is each module is made up of
sub module (programs) with many options to the user.
Example: Inventory management, CRM, ERP.
System software: system software comprises programs designed to co-ordinate the
operations of the computers systems, it manages hardware, software and data resources
of the computer.
Software that executes routine tasks. Example: operating systems, utility programs,
languages translators, communication software also called as support software.
1. System management program: operating system, DBMS, Telecommunication
software.
o Operating system: it is an integrated systems of complex program that
manages the resources of the computer and provides user interface,
operating system can be DOS, UNIX, MS Windows.
The functions of OS are resources management, data management, job
management, input-output management, maintaining security conflict
resolution etc.
o DBMS is a set of programs that controls creation, maintenance and use of
database, it allows different applications to share data and programs, it also
secures data in the database from misuse. Example: oracle, MS SQL.
2. System support program: system utilities, performance monitors, security monitors
o System utilities software consists of programs that are very frequently
requested by application programs like transferring data from one medium
to another formatting disk, backing up and sorting of files.

o Security and performance monitors provides variety of support services to
users such as error control message, restricting unauthorised entry priority
allocation for critical application etc.
3. System development programs:
Programming languages translators, programming editors and tools, CASE (computer
aided software engineering packages)
These programs helps users and system developers in designing and building
systems.
These help in developing programs for computer processing, these include language
translators, programming tools and computer aided software engineering.
Language translators is a piece of system software that translates application into machine
language, the translators may be assemblers, compilers, interpreters, it has made
programming easier and portable.
Language Translators: (Assembler, compiler and interpreter)
Assemblers:
Programming in machine language is very difficult so programmers began to use certain
mnemonics which is called as assembly language.
These mnemonics are translated into machine language for execution the input to the
assemblers program is called source program and the output in machine language is called
OBJECT CODE.
Assemblers are similar to interpreters except that interpreters each instruction is
translated into many instructions.
Compilers:
The development of high level language made computer programming more easily but the
computer does not understand instructions in High Level language (HLL).
To overcome this a software is developed compiler to translate high level language source
code into machine language instructions object code.
Interpreter: an interpreter does a similar job but in a different styles. It converts high level
language in to low level language that is it converts user understandable language into
machine understandable language; it translates one statement at a time, and if error-free
executes it. This continues till the last statement.

Difference between Interpreter and complier:
 Interpreter translates and executes the first instruction before it goes to the second,
while complier translates the whole program before execution.
 Error correction is much simpler in the case of the interpreter because it is done
instates, the complier produces an error list for the entire program at the end.
 Interpreter take more time for the execution of a program compared to compliers
because a statement has to be translated every time it is read.
Programming languages:
First generation: Code of the first generation programming language [G1] was entered
through physical switches on the computer. A sequence of such commands is known as
code. Specifically, code that a machine can read and understand according to its logical
design is called machine code [M1], which is in contrast to human readable code. The first
generation of programming languages is all about machine code.
Second generation: Improves on first generation by providing code as human readable
source code with logically structures. The source code must be assembled into machine
code before it can be executed by a CPU. This assembly step is done by an assembler.
Third generation: Improves on second generation by making language architecture
independent, i.e. no longer tailored to the processor or environment, which requires a
compiler to make machine code for the CPU. Some, like Java, make use of an intermediate
code which is run by a virtual machine, reaching further architecture independence.
Another aspect of third generation is that they are more programmer-friendly.
(E.g. no longer needing to state the length of multi-character (string) literals in FORTRAN).
High level language is a synonym for third-generation programming language. The
computer takes care of non-essential details, not the programmer.
Early language examples: Algol, Cobol (business), Fortran (scientific)
Structured language examples: C
Object oriented examples: C++, C#, Java, Python
Fourth generation: Improves on 3GL and their development methods with higher
abstraction and statement power, to reduce errors and increase development speed by
reducing programming effort.
A 4GL is designed with a specific purpose in mind. This offers a high potential. 4GL are not
always successful, sometimes resulting in inelegant and UN maintainable code. However,
given the right problem, the use of an appropriate 4GL can be spectacularly successful. (This
refers to an example with 8 times productivity gains over COBOL).

In some senses, software engineering supports 3GL, while 4GL are more oriented towards
problem solving and systems engineering.
Some argues that 4GL is a subset of the so-called DSL or domain-specific languages.
Examples: Oracle Forms, PL/SQL, Revolution language, SAS, SPSS, SQL
Fifth generation: Improves on the previous generations by skipping algorithm writing and
instead provide constraints. While 4GL are designed to build specific programs, 5GL are
designed to make the computer solve a given problem without the programmer. This way,
the programmer only needs to worry about what problems need to be solved and what
conditions need to be met, without worrying about how to implement a routine or
algorithm to solve them.
Examples: Prolog, OPS5, Mercury
On a critical view, Prolog kind of systems has a high performance penalty. With better
implementation techniques, this penalty has been shown to be 25%-50% of conventional
programming languages.
Operating system:
An operating system is a set of programs that schedule tasks, allocates storage and
presents a default interface to the user between applications.
Types of operating systems
Operating systems are classified into different types they are:
1) Single user, single tasking operating system - Single user single tasking operating systems
are those operating systems which can be used by a single user at a time. Also we can only
do a single task at a time in such operating systems. Example of single user single tasking
operating systemis MS DOS. In Microsoft DOS only one program can be executed by a user
at a time.
2) Single user multi tasking operating system - Single user multi tasking operating systems
are those operating systems which can be used by a single user to do multiple
operations/tasks at a time. Microsoft Windows is an example of such operating system. In
Windows only one user can log in at a time but that user can do many tasks at a time.
3) Multi user, multi tasking - In multi user multi tasking operating systems more than one
user can log in at a time and do as many tasks they want. Linux is an example of such
operating system. This is the main difference between a windows and Linux operating
system. In Linux there are 7 terminals, in which 6 are non graphical terminals and 1 is
graphical terminal. So 7 users can use a Linux machine at a time.

4) Real time operating systems - Real time operating systems are operating systems used in
real time applications like embedded systems, robots, automobile engine controllers etc.
Windows CE is an example for real time operating system.
User interface:
An operating system provides an interface through which the user interacts with the
system; there are two fundamentals approaches for users to interface with the operating
system.
We have two types of user interface:
1. Command line interface (CLI)
2. Graphical user interface ( GUI)
Command line interface operating system: a command line interface also as command line
user interface, console user interface and character user interface (CUI) is a means of
interacting with a computer program where the user or client issues commands to then
program in the form of successive lines of text (command lines).
Examples: command line operating systems are DOS (Disk operating system) and UNIX etc.
Graphical user interface: GUI operating system presents commands in graphical form, for
example, application programs, commands, disk drives, files etc, are presented in the form
of icons, usually a command is given to the computer by clicking with mouse on the icon,
GUI also provides menus, buttons, and other graphical object to the user to perform
different tasks, GUI is very easy to interact with the computer.
Functions, elements & features of operating system in a computer:
An operating system has lot of functions to do in a computer. Some of them are listed
below:
1) Provide user interface - As said earlier without a proper user interface it’s difficult to
manage a machine. It is possible to interact with a machine using the commands, but it's
easy to learn all the commands used in an OS.
2) Input/output management - We can add additional hardware's to a computer and
configure them easily with the help of an operating system. Printer, external hard disk,
scanner, USB drives are some of the external devices we can connect with a computer.
3) Memory and CPU management - Operating system allocates the memory and other
resources for the other programs in a computer. The memory allocation and CPU usage of
each program is controlled by OS and you can check them from the 'Task Manager'.
4) Multitasking - Multitasking is another feature of operating systems (not in DOS). We can

do more than one tasks at the same time in an operating system. For example you can listen
to music in media player while typing a note.
5) Networking - It’s easy to do networking with the help of operating systems. You can
share files, folders or even hardware resources like printer through a network with the help
of operating systems.
6) Icons: the graphical representations of the applications files, and folder which when
clicked immediately open up a window is called icons, these are actually sort cut to the
applications.
7) Command button: buttons like cancel, ok, save which when clicked perform an action
immediately are called commands buttons.
8) Window: in a GUI when an application is open, it appears in the form of a window when
user is working on number of applications number of windows is open together.
9) Task bar: a bar commonly located at the bottom of windows operating system that
displays the programs that are currently running, this bar also displays the time, and the
start button.
10) Menu: it displays a list of command options out of which one can be selected as desired.
Linux and free and open software:
What is Linux, Free Software and Open Source?
Linux (also known as GNU/Linux) is a computer operating system, like Microsoft Windows or
Apple Mac OS. Unlike those two, however, Linux is built with a collaborative development
model. The operating system and most of its software are created by volunteers and
employees of companies, governments and organisations from all over the world.
The operating system is free to use and everyone has the freedom to contribute to its
development. This co-operative development model means that everyone can benefit.
Because of this, we like to call it Free Software, or Socially Responsible Software. Closely
related is the concept of Open Source Software. Together, Free and Open Source Software
is collectively abbreviated as FOSS. This contrasts with the proprietary (or closed source)
development model used by some software companies today.
Loaders and linkers:
Once assembler’s produces object code it must be placed into memory and executed.
This loading of object code is done by the loaders it is a program that places programs into
memory for execution.

The software that links these objects modules into a load module is called linkers, these are
called library routines that is the linker’s programs links to library and enables it to use
during execution.
Multi programming:
CPU is very fast but I/P devices are slow, multi-programming is a technique develop to
minimise the effect of this mismatch between CPU and Input devices so that CPU is used
efficiently.
Multi-programming requires sophisticated operating systems, multi- programming runs one
program at a time, when that program requires Input operation which is slow process. The
CPU switches to another job, if the 2nd job requires Input operation, the CPU is allotted a
third job and so on, always a program will be in any one of the 3 states ready running and
block.
It is execution of 2 or more independent and separate program by the same computer.
Multi- processing:
This has 2 or more CPUs which have ability to execute 2 or more jobs simultaneously, if one
of the CPU fails another takes over and carriers on with processing.
The differences between multiprocessing and multiprogramming are as follows:
Multi –programming executes different jobs by single CPU but multi-processing executes
different jobs by different CPUs at the same time.
Time sharing/ multi – tasking: it is a logically extension of multi-programming, it refers to
the simultaneously use of computers by many users, the computer time is divided and each
user is allotted a small division of time in turn it switches between users so fast that every
users thinks that he is getting CPU fully, a number of applications that can be runned
depends on the memory and processing power.
Hardware: in information technology hardware is the physical aspects of computers,
telecommunications and other devices, hardware is a collective term, Hardware includes
not only the computer proper but also the cables, connectors, power supply unit, and
peripheral devices such as key board, mouse, speaker and printers.

Hardware
Input Devices: can read data and convert them to a form that a computer can use.
 Keyboard: is most common input device is used today. The data and instructions are
input by typing on the keyboard. Apart from alphabet and numeral keys, it has other
function keys for performing different functions.
 Mouse: It’s a pointing device. The mouse is rolled over the mouse pad, which in turn
controls the movement of the cursor in the screen. We can click, double click or drag
the mouse.
 Scanner: Scanners are used to enter information directly in to the computers
memory. This device works like a Xerox machine. The scanner converts any type of
printed or written information including photographs into digital pulses, which can
be manipulated by the computer.
 Track Ball: Track ball is similar to the upside- down design of the mouse. The user
moves the ball directly, while the device itself remains stationary. The user spins
the ball in various directions to effect the screen movements.
 Light Pen: This is an input device which is used to draw lines or figures on a
computer screen. It’s touched to the CRT screen where it can detect raster on the
screen as it passes.
 Optical Character Rader: It’s a device which detects alpha numeric characters
printed or written on a paper. The text which is to be scanned is illuminated by a low
frequency light source. The light is absorbed by the dark areas but reflected from the
bright areas. The reflected light is received by the photocells.
 Bar Code Reader: This device reads bar codes and coverts them into electric pulses
to be processed by a computer. A bar code is nothing but data coded in form of light
and dark bars.
 Voice Input Systems: This devices converts spoken words to M/C language form. A
micro phone is used to convert human speech into electric signals. The signal pattern
is then transmitted to a computer when it’s compared to a dictionary of patterns
that have been previously placed in a storage unit of computer. When a close match
is found, the word is recognized.
Inputdevices
Memory
Outputdevices

 Digital Camera: It converts graphics directly into digital form. It looks like an ordinary
camera, but no film is used therein, instead a CCD (changed coupled Divide)
Electronic chip in used. When light falls, on the chip though the lens, it converts light
waves into electrical waves.
Output devices:
Computer output devices get information out of the computer, delivering data that has
been processed by the computer to the user. Output devices produce data in different
forms including audio, visual and hard copy.
 Monitor: The most common computer output device is the monitor or computer
screen. Monitors create a visual display for you to view from processed data. They
come in a variety of screen sizes and visual resolutions. There are two common types
of modern computer monitors, cathode ray tube and flat panel screens. CRT
monitors use phosphorescent dots to create the pixels that make up displayed
images. Flat panel monitors usually use liquid crystals or plasma to create output.
 Printer: Printers produce a hard copy version of processed data such as documents
and photographs. The computer sends the image data to the printer, which then
physically recreates the image, usually on paper. There are three types of computer
printers: ink jet, laser and dot matrix. Inkjet printers spray tiny dots of ink on a
surface to create an image. Laser printers use toner drums that roll through
magnetized pigment and then transfer the pigment to a surface. Dot matrix printers,
common in the 1980s and 1990s, use a print head to embed images on a surface,
using an ink ribbon.
 Audio Output: Computers produce audio data that requires output devices such as
speakers and headphones to deliver the sound to you.
 Projector: Projectors are display devices that project a computer-created image. The
computer sends the image data to its video card, which then sends the video image
to the projector. They are typically used for presentations or for viewing videos.
 Plotter: Plotters create a hard copy of a digitally rendered design. The design is sent
to the plotter via a graphics card and creates the design using a pen. Generally
used with engineering applications, plotters basically draw an image using a series
of straight lines.

Computer Memory
Computermemoryisresponsibleforstoringdataand applicationsonatemporaryor a permanent
basis.It enablesapersontoretainthe informationstoredonthe computer.Withoutamemory
device/arrangementinplace,the processorwouldnotbe able tofindaplace whichisneededto
store the calculationsandprocesses.
Computermemorycanbe primarilyclassifiedintotwotypes:PrimaryMemoryandSecondary
Memory.
Primary memory:
Random Access Memory (RAM): RAM stands for Random Access Memory. It write data into
RAM and also read data from RAM. RAM is a volatile memory. It holds data as long as the
computer is switched on.
ROM: ROM stands for Read Only Memory. It is a non-volatile memory. It read data from
memory.
Secondary storage:
Secondary memory is available on mass storage devices for permanent data storage. Data
stored on a secondary device is retained even when it is not supplied any power. This data
can be transported in most cases.
Secondary storage consists of punch cards, hard disk, flash drives (USB), optical drives,
floppy disk, and magnetic tapes.

Computer networks: Computer networks are interconnected hardware, software and
telecommunication resources that share multiple facilities for their optimal use.
Types of Communication Networks:
 Local Area Network (LAN) connects computers within a limited physical area, such
as an office, a classroom, a building, a manufacturing plant, or a work-site. LAN is
usually confined within a spread of 1.5 to 2 km of space, using ordinary telephone
wiring or coaxial cable or wireless radio system.
 Metropolitan Area Network (MAN) connects computers over a large city or
metropolitan area, often included in the category of wide area network. These fairly
large networks are needed for carrying out day to day activities of many business
and government organizations and their end-users.
 Wide Area Network (WAN) covers a large geographical area, often a whole country.
In order to transmit and receive information among their employees, customers,
suppliers and other organizations across cities, regions and countries, many
multinational companies use WANs. Three categories of WANs are operational in
India: special-purpose (related to a single organization on proprietarily basis) or
general-purpose (catering to multiple organizations on a service-provider basis) or
dual-purpose (serving both special-purpose and dual-purpose roles) these undergo
planning and modification all the time.
NETWORK TOPOLOGY: specifically refers to the physical layout of the network, especially
the locations of the computers and how the cable is run between them. Four most common
topologies are:
• Bus
• Star
• Ring
• Mesh
Bus Topology:
Bus topologies

All the devices on a bus topology are connected by one single cable. When one computer
sends a signal up the wire, all the computers on the network receive the information, but
only one accepts the information. The rest rejects the message. One computer can send a
message at a time. A computer must wait until the bus is free before it can transmit.
Advantages and disadvantages of BUS network topology:
1. The bus is simple, reliable in small network, easy to use and understand
2. Requires the least amount of cable to connect the computers and less expensive
3. Easy to extend the bus
Disadvantage of network topology
1. Heavy network traffic can slow a bus considerably
2. Each barrel connector weakens the electrical signal
3. Difficult to troubleshoot a bus
Star Topology:
All the cables run from the computers to a central location, where they are all connected by
a device called a hub. Each computer on a star network communicates with a central hub
that resends the message either to all the computers or only to the destination
computers.
Advantages:
• Easy to modify and add new computers to a star net
• Center of a star net is a good place to diagnose network faults
• Single computer failure do not necessarily bring down the whole net
• Several cable types can be used with the hub
Disadvantages:
• Central hub fails, the whole network fails to operate

• Many star networks require a device at the central point to rebroadcast or
switch network traffic.
• Costs more for cabling in star net than bus.
Ring Topology:
Ring Topology
Each computer is connected to the next computer, with the last one connected to the first.
Every computer is connected to the next computer in the ring, and each retransmits what it
receives from the previous computer, the message flow around the ring in one direction.
Some ring networks do token passing. It passes around the ring until a computer wishes to
send information to another computer.
Advantages:
• No computer can monopolize the network
• The fair sharing of the network allows the net to degrade gracefully as more
user are added.
Disadvantages:
• Failure of one compute can affect the total network
• Difficult to troubleshoot
• Adding or removing Computers disrupts the network
Mesh Topology:

Mesh Topology
The mesh topology connects all devices (nodes) to each other for redundancy and fault
tolerance. It is used in WANs to interconnect LANs and for mission critical networks like
those used by banks and financial institutions. Implementing the mesh topology is expensive
and difficult.
Advantages:
• Fault tolerance
• Guaranteed communication channel capacity
• Easy to troubleshoot
Disadvantages:
• Difficulty of installation and reconfiguration
• Cost of maintaining redundant link
Internet:
The Internet, sometimes called simply "the Net," is a worldwide system of computer
networks - a network of networks in which users at any one computer can, if they have
permission, get information from any other computer (and sometimes talk directly to users
at other computers).
It was conceived by the Advanced Research Projects Agency (ARPA) of the U.S.
government in 1969 and was first known as the ARPANet. The original aim was to create a
network that would allow users of a research computer at one university to "talk to"
research computers at other universities.
A side benefit of ARPANet's design was that, because messages could be routed or rerouted
in more than one direction, the network could continue to function even if parts of it were
destroyed in the event of a military attack or other disaster.

Security issues:
1. Hacking: hacking is an unethical event, hacking consider as unauthorised access for
breaking the system or trespasses a computer system, such as these tactics can be
used to retrieve passwords, access or steal the network files, overload computer
systems or damage data and programs.
2. Cracking: the term cracking means, illegal access now access comprises the entering
of the whole or any part of computer system. (hardware, components, stored data
of the system installed, directories, traffic and content- related data).
3. Cyber theft: electronic breaking and elect ring involving the theft of the money,
more recent examples involve using the internet to access major banks computer
systems.
4. Unauthorised use at work: unauthorised use of computer systems and networks by
employees, recent surveys suggest 90% of US workers admit to using work
resources for personal use.
5. Piracy: software piracy is the unauthorised copying of software and is a violation of
federal copyright laws, such piracy results in millions of dollars of lost profits by
software publishers.
6. Internet protocol spoofing: an IP attack occurs when an attackers outside the
network pretends to be trusted computer either by using an IP address that is within
its rang or buying an external IP address that user trust and to which user wish to
provide access to specified resources on user network.
7. Fraud on the internet: the internet provides companies and individuals with the
opportunity of marketing their products on the net; it is easy for people with
fraudulent intention to make their message look real and credible.
8. Bulletin boards: this is a for sharing investor information and often fraud is
perpetrated in this zone causing loss of millions who bank on them.
9. E-mail scams: since junk mail is easy to create, fraudsters often find it easy to spread
bogus investment schemes or spread false information about a company.
10. Spam: typically harmless but always annoying spam is the electronic equivalent of
junk mail spam can be dangerous through quite often it contains links to websites.
11. Virus: a small program that can produce itself by attaching its code to another
program, this way spared quickly from one system to the next. Example: Trojan
virus, Macro virus, logic bombs etc.
Security measures:
1. Encryption: the various authorised provisions in a computer system may not confer
sufficient protection for highly sensitive data; in such cases data may be highly
encrypted.
2. Firewall: a network firewall is a computer that protects computer networks from
intrusion by serving as a safe transfer point for access to and from other networks,
hence firewalls serve as gatekeepers keeping the system safe from intrusion.

3. Monitor E-mail: while there is a considerable debate about violation of employees
privacy it is also true that e-mail is one of the favourite avenues of attack by hackers
for spreading viruses or breaking into networked computers.
4. Security codes/password: multilevel passwords can be used to control access to
information assets, for example, a user might be required to have one password for
logging on to the system, another password to gain access to a particular application
and still another password to access a particular file. Passwords can also be
encrypted to avoid theft or improper use.
5. Back up files: duplicate or back up files are an important security measures, files can
also be protected by file retention measures that involve storing copies from
previous periods.
6. Security measures: these are programs that monitor the use of computer systems
and networks and protect them from unauthorised use, fraud, and destruction,
security monitors can control the use of hardware, software, and data resources of a
computer, they also be used to collect statistics on any attempt of misuse.
7. Biometric security controls: biometric controls include such detection devices as
voice recognition and fingerprinting which must correspond to the authorised
person before admitting and allowing the personnel to the system.
Data representation:
Data Representation refers to the methods used internally to represent information stored
in a computer. Computers store lots of different types of information:
 numbers
 text
 graphics of many varieties (stills, video, animation)
At least, these all seem different to us. However, ALL types of information stored in a
computer are stored internally in the same simple format: a sequence of 0's and 1's
Binary Numbers
Normally we write numbers using digits 0 to 9. This is called base 10. However, any positive
integer (whole number) can be easily represented by a sequence of 0's and 1's. Numbers in
this form are said to be in base 2 and they are called binary numbers.
Text
Text can be represented easily by assigning a unique numeric value for each symbol used in
the text. For example, the widely used ASCII code (American Standard Code for Information
Interchange) defines 128 different symbols (all the characters found on a standard
keyboard, plus a few extra), and assigns to each a unique numeric code between 0 and 127.

Graphics
Graphics that are displayed on a computer screen consist of pixels: the tiny "dots" of colour
that collectively "paint" a graphic image on a computer screen. The pixels are organized into
many rows on the screen.
Case study: (2010)
You are the owner of a shop selling hardware like paints, nails, nuts, bolts etc; you do not
have a computer based information system and have great difficulty in maintaining
inventory and sales. Suggest appropriate information system that will suit your business,
you may use suitable examples.
Important questions:
Section A:
1. Define computer.
2. What are the basic components of computer?
3. What do you mean by super computer?
4. Define micro computer.
5. What is CPU, components of CPU?
6. What do you mean by CU?
7. Define memory.
8. What is RAM, ROM?
9. What do you mean by Flash memory, Magnetic Disk?
10. Define Secondary memory.
11. What are the Input and Output devise?
12. Expand OCR and OMR.
13. Define Hardware.
14. Define software.
15. Define linker and Loader.
16. Define operating system.
17. Differentiate between complier and interpreter.
18. Define computer network.
19. Define Internet.
20. What is E-mail?
21. Define Hacking.
22. Define cracking.
23. What is IP address spoofing?
24. What is Cyber theft?
25. What is encryption?
26. Define virus.
27. Define Anti-virus.

Section B and C:
1. What do you mean by computer? Explain in detail.
2. Explain the generation of computer (History).
3. Discuss the various components of computer.
4. Explain the classifications of computer.
5. Write a short notes on
 Micro computer
 Super computer
 Mini computer
 Main frame computer
6. What are the Input and output devices of computer?
7. Define Memory. Explain the types of memory.
8. Explain the classifications of Software.
9. Explain the types of Operating system.
10. Explain the types of Language Translators.
11. Explain the following concepts.
 Multi programming
 Multi processing
 Time sharing
12. Explain LAN, WAN, MAN.
13. Explain network topologies.
14. Explain Data representation.
15. Define Internet. Explain the security issues (ethical issues) involved.
16. What is the Security measures involved?
17. Explain the various generations of Programming Languages.

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