Computer Applications

Chanderprabhu Jain College of Higher Studies & School of Law
Plot No. OCF, Sector A-8, Narela, New Delhi – 110040
(Affiliated to Guru Gobind Singh Indraprastha University and Approved by Govt of NCT of Delhi & Bar Council of India)
Semester: FIRST Semester
Name of the Subject:
COMPUTER APPLICATIONS
BASICS OF COMPUTERS
UNIT-I

2
What Is A Computer?
A computer is an electronic device, operating under the control of
instructions (software) stored in its own memory unit, that can accept data
(input), manipulate data (process), and produce information (output) from the
processing. Generally, the term is used to describe a collection of devices that
function together as a system.

3
Devices that comprise a computer system
Printer
(output)
Monitor
(output)
Speaker
(output)
Scanner
(input)
Mouse
(input)
Keyboard
(input)
System unit
(processor, memory…)
Storage devices
(CD-RW, Floppy, Hard
disk, zip,…)

4
What Does A Computer Do?
•Computers can perform four general operations, which
comprise the information processing cycle.
• Input
• Process
• Output
• Storage

5
What Do Computers Do?
• Input, Process, Output, & Store data
Input Process Output
Store Data

6
Data and Information
• All computer processing requires data, which is a collection of raw
facts, figures and symbols, such as numbers, words, images, video and
sound, given to the computer during the input phase.
• Computers manipulate data to create information. Information is data
that is organized, meaningful, and useful.
• During the output Phase, the information that has been created is put
into some form, such as a printed report.
• The information can also be put in computer storage for future use.

7
Why Is A Computer So Powerful?
• The ability to perform the information processing cycle with amazing
speed.
• Reliability (low failure rate).
• Accuracy.
• Ability to store huge amounts of data and information.
• Ability to communicate with other computers.

8
How Does a Computer Know what to do?
• It must be given a detailed list of instructions, called a computer
program or software, that tells it exactly what to do.
• Before processing a specific job, the computer program corresponding
to that job must be stored in memory.
• Once the program is stored in memory the compute can start the
operation by executing the program instructions one after the other.

9
What Are The Primary Components Of A Computer ?
• Input devices.
• Central Processing Unit
(containing the control unit and
the arithmetic/logic unit).
• Memory.
• Output devices.
• Storage devices.

10
Uses of Computer
PC at Home
Common uses for the computer within the home
• Computer games
• Working from Home
• Banking from Home
• Connecting to the Web

11
Uses of Computer
• Office Applications
• Stock Control
• Stock control is ideal for automation and in many companies it
is now completely computerized. The stock control system keeps
track of the number of items in stock and can automatically order
replacement items when required.
• Accounts / Payroll
• In most large organizations the accounts are maintained by a
computerized system. Due to the repetitive nature of accounts a
computer system is ideally suited to this task and accuracy is
guaranteed.

12
Uses of Computer
• Automated Production Systems
• Many car factories are almost completely automated and the cars are
assembled by computer-controlled robots. This automation is becoming
increasingly common throughout industry.
• Design Systems
• Many products are designed using CAD (Computer Aided Design)
programs to produce exact specifications and detailed drawings on the
computer before producing models of new products.

13
Uses of Computer
Computers in Daily Life
• Accounts
• Games
• Educational
• On-line banking
• Smart ID cards
• Supermarkets
• Working from home (Tele-working)
• Internet

14

15

Name of the Subject:
INTRODUCTION TO COMPUTER
SOFTWARES
UNIT-II

17
• Software is a set of electronic instructions that tells the computer how
to do certain tasks. A set of instructions is often called a program.
• When a computer is using a particular program, it is said to be
running or executing the program.
• The two most common types of programs are system software and
application software.
Bringing the Machine to Life –
What is Software?

18

19
• System software exists primarily for the computer itself, to help the
computer perform specific functions.
• One major type of system software is the operating system (OS). All
computers require an operating system.
• The OS tells the computer how to interact with the user and its own
devices.
• Common operating systems include Windows, the Macintosh OS,
OS/2, and UNIX .
Bringing the Machine to Life –
System Software

20
• Application Software consists of programs that tell a computer how
to produce information
• Application software tells the computer how to accomplish tasks the
user requires, such as creating a document or editing a graphic image.
• Some important kinds of application software are:
Word processing programs Spreadsheet software
Database management Presentation programs
Graphics programs Networking software
Web design tools and browsers Internet applications
Communications programs Utilities
Entertainment and education Multimedia authoring
Bringing the Machine to Life - Applications

What is an Operating System?
• A program that acts as an intermediary between a user of a computer
and the computer hardware.
• Operating system goals:
– Execute user programs and make solving user problems easier.
– Make the computer system convenient to use.
• Use the computer hardware in an efficient manner.

Computer System Structure
• Computer system can be divided into four components
– Hardware – provides basic computing resources
• CPU, memory, I/O devices
– Application programs – define the ways in which the system
resources are used to solve the computing problems of the
users
• Word processors, compilers, web browsers, database
systems, video games
– Users
• People, machines, other computers

Four Components of a Computer System

Operating System Definition
• OS is a resource allocator
– Manages all resources
– Decides between conflicting requests for efficient and fair
resource use
• OS is a control program
– Controls execution of programs to prevent errors and improper
use of the computer

Operating System Definition (Cont.)
• No universally accepted definition
• “Everything a vendor ships when you order an operating system” is
good approximation
– But varies wildly
• “The one program running at all times on the computer” is the kernel.
Everything else is either a system program (ships with the operating
system) or an application program

Computer Startup
• bootstrap program is loaded at power-up or reboot
– Typically stored in ROM or EEPROM, generally known as firmware
– Initializates all aspects of system
– Loads operating system kernel and starts execution

Computer System Organization
• Computer-system operation
– One or more CPUs, device controllers connect through common bus
providing access to shared memory
– Concurrent execution of CPUs and devices competing for memory
cycles

Computer-System Operation
• I/O devices and the CPU can execute concurrently.
• Each device controller is in charge of a particular device type.
• Each device controller has a local buffer.
• CPU moves data from/to main memory to/from local buffers
• I/O is from the device to local buffer of controller.
• Device controller informs CPU that it has finished its operation by causing
an interrupt.

Common Functions of Interrupts
• Interrupt transfers control to the interrupt service routine generally, through
the interrupt vector, which contains the addresses of all the service routines.
• Interrupt architecture must save the address of the interrupted instruction.
• Incoming interrupts are disabled while another interrupt is being processed
to prevent a lost interrupt.
• A trap is a software-generated interrupt caused either by an error or a user
request.
• An operating system is interrupt driven.

30
Computer Software
•Computer software is the key to productive use of computers. Software can be
categorized into two types:
• Operating system software
• Application software.

31
Operating System Software
Operating system software tells the computer how to perform the
functions of loading, storing and executing an application and how to
transfer data.
Today, many computers use an operating system that has a graphical user
interface (GUI) that provides visual clues such as icon symbols to help
the user. Microsoft Windows 98 is a widely used graphical operating
system. DOS (Disk Operating System) is an older but still widely used
operating system that is text-based.

32
Application Software
•Application Software consists of programs that tell a computer how to
produce information. Some of the more commonly used packages are:
•
• Word processing
• Electronic spreadsheet
• Database
• Presentation graphics

33
Word Processing
• Word Processing software is used to create and print documents. A key
advantage of word processing software is that users easily can make
changes in documents.

34
Electronic Spreadsheets
• Electronic spreadsheet software allows the user to add, subtract, and
perform user-defined calculations on rows and columns of numbers.
These numbers can be changed and the spreadsheet quickly
recalculates the new results.

35
Database Software
• Allows the user to enter, retrieve, and update data in an organized and
efficient manner, with flexible inquiry and reporting capabilities.

36
Presentation Graphics
• Presentation graphic software allows the user to create
documents called slides to be used in making the presentations.
Using special projection devices, the slides display as they
appear on the computer screen.

Name of the Subject
DESKTOP COMPONENTS
UNIT-III

Spreadsheets Basics
• Excel is a “spreadsheet” which holds different kinds of information
• It performs calculations with mathematical and statistical functions
• Constants - entries that do not change
• Formulas - combination of constants and functions

Using Functions in Excel
• Use spreadsheets in decision making; use Goal Seek and Scenario Manager
to evaluate multiple conditions
• Use financial functions (PMT, etc.)
• Use fill handle and AutoFill capability
• Use pointing to create a formula
• Statistical Functions — MAX, MIN, AVERAGE, COUNT
• Use functions over arithmetic expressions
• Decision making functions (IF and VLOOKUP (vertical lookup))

SUM(number1, number 2,…)
• Example
=SUM(3, 2) equals 5
• If cells A2:E2 contain 5, 15, 30, 40, and 50: =SUM(A2:C2) equals
50 =SUM(B2:E2, 15) equals 150

AVERAGE(number 1, number 2,…)
• Examples
If A1:A5 is named Scores and contains the numbers 10, 7, 9, 27, and 2,
then:
=AVERAGE(A1:A5) equals 11
=AVERAGE(Scores) equals 11
=SUM(A1:A5)/COUNT(A1:A5) equals 11

SIN(number)
• IMPORTANT NOTE:
– Angle (number) must be provided in radians If your argument is in
degrees, multiply it by PI()/180 to convert it to radians.
=SIN(PI()) equals 1.22E-16, which is approx. 0
=SIN(PI()/2) equals 1
=SIN(30*PI()/180) equals 0.5, the sine of 30 degrees

COUNT
• COUNT counts the number of cells that contain numbers & numbers
within the list of arguments.
• Value 1, 2,…, are 1 to 30 arguments that can contain or refer to a variety of
different types of data, but only numbers are counted.

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given criteria.
Suppose A3:A6 contain "apples", "oranges", "peaches", "apples", respectively:
COUNTIF(A3:A6,"apples") equals 2

(A4:A130,1)
(A4:A130,2)
(A4:A130,3)
(A4:A130,4)
(A4:A130,5)
=COUNTIF(A4:A130,1)
=D4/D9*100

Some Useful Functions
• IF
• TIME
functions

Conditional Functions
• Conditional functions allow the software to perform conditional tests and
evaluate a condition in your worksheet. Depending on whether the
condition is true or false, different values will be returned to the cells.
• =IF is the most important conditional function

If
=IF(condition, action if true, action if false)
This tests the “condition” to determine if specific results or cell contents are
true or false.
The instructions to be executed can return cell contents that are labels as well
as values.

Logical Operators
• To perform conditional tests, logical operators are required.
= Equal
< Less than
> Greater than
<= Less than or Equal to
>= Greater than or Equal to

Logical Functions
And(logical1, logical2) Returns true if each
condition is true
Or(logical1, logical2) Returns true if either
condition is true
Not(logical) Returns true if the
condition is f

Examples
=IF(AND(B11<>0,G11=1),10,0) means that if the value in B11 is not equal to 0
and the value in G11 is equal to 1, assign the number 10. Otherwise, assign
the number 0.
=IF(OR(E13=“Profit”,F15>G15),”Surplus”,”Deficit”) means that if either E13
contains the word “Profit” or the contents of F15 are greater than or equal to
the contents of G15, assign the label “Surplus”. Otherwise, assign the label
“Deficit”.

VLOOKUP Function
• Searches for a value in the leftmost column of a table, and then returns a
value in the same row from a column you specify in the table. Use
VLOOKUP instead of HLOOKUP when your comparison values are
located in a column to the left of the data you want to find.
Syntax:
=VLOOKUP(lookup_value,table_array,
col_index_num,range_lookup)
– If range_lookup is TRUE, the values in the first column of table_array
must be placed in ascending order: ..., -2, -1, 0, 1, 2, ..., A-Z, FALSE,
TRUE; otherwise VLOOKUP may not give the correct value. If
range_lookup is FALSE, table_array does not need to be sorted.

Name of the Subject
COMPUTER NETWORKS
UNIT-IV

Networking
• Computer network A collection of computing devices that are connected in
various ways in order to communicate and share resources
Usually, the connections between computers in a network are made using
physical wires or cables
However, some connections are wireless, using radio waves or infrared signals

15-58
Networking
• The generic term node or host refers to any device on a network
• Data transfer rate The speed with which data is moved from one place
on a network to another
• Data transfer rate is a key issue in computer networks

15-59
Networking
• Computer networks have opened up an entire frontier in the world of
computing called the client/server model

15-60
Networking
• File server A computer that stores and manages files for multiple users on
a network.
• Web server A computer dedicated to responding to requests (from the
browser client) for web pages

15-61
Types of Networks
• Local-area network (LAN) A network that connects a relatively small
number of machines in a relatively close geographical area

15-62
Types of Networks
• Various configurations, called topologies, have been used to administer
LANs
– StarRing topology A configuration that connects all nodes in a closed
loop on which messages travel in one direction
– topology A configuration that centers around one node to which all
others are connected and through which all messages are sent
– Bus topology All nodes are connected to a single communication line
that carries messages in both directions

Types of Networks
Various network topologies
15-10

15-64
Types of Networks
• Wide-area network (WAN) A network that connects two or more local-
area networks over a potentially large geographic distance
– Often one particular node on a LAN is set up to serve as a gateway to
handle all communication going between that LAN and other networks
• Communication between networks is called internetworking
– The Internet, as we know it today, is essentially the ultimate wide-
area network, spanning the entire globe

15-65
Types of Networks
Metropolitan-area network (MAN) The communication
infrastructures that have been developed in and around large cities

15-66
Internet Connections
• Internet backbone A set of high-speed networks that carry Internet traffic
These networks are provided by companies such as AT&T, GTE, and IBM
• Internet service provider (ISP) A company that provides other
companies or individuals with access to the Internet

15-67
• There are various technologies available that you can use to connect a
home computer to the Internet
– A phone modem converts computer data into an analog audio signal
for transfer over a telephone line, and then a modem at the destination
converts it back again into data
– A digital subscriber line (DSL) uses regular copper phone lines to
transfer digital data to and from the phone company’s central office
– A cable modem uses the same line that your cable TV signals come in
on to transfer the data back and forth

15-68
• Broadband A connection in which transfer speeds are faster than 128 bits
per second
– DSL connections and cable modems are broadband connections
– The speed for downloads (getting data from the Internet to your home
computer) may not be the same as uploads (sending data from your
home computer to the Internet)

Packet Switching
• To improve the efficiency of transferring information over a shared
communication line, messages are divided into fixed-sized, numbered
packets
• Network devices called routers are used to direct packets between networks
Figure 15.4
Messages
sent by
packet
switching
15-18

15-70
Open Systems
• Proprietary system A system that uses technologies kept private by a
particular commercial vendor
– One system couldn’t communicate with another, leading to the need
for
• Interoperability The ability of software and hardware on multiple
machines and from multiple commercial vendors to communicate
– Leading to
• Open systems Systems based on a common model of network architecture
and a suite of protocols used in its implementation

15-71
Open Systems
• The International Organization
for Standardization (ISO)
established the Open Systems
Interconnection (OSI)
Reference Model
• Each layer deals with a
particular aspect of network
communication
The layers of the OSI Reference Model

15-72
Network Protocols
• Network protocols are layered such that each one relies on the protocols
that underlie it
• Sometimes referred to as a protocol stack
Layering of key network protocols

15-73
TCP/IP
• TCP stands for Transmission Control Protocol
TCP software breaks messages into packets, hands them off to the IP
software for delivery, and then orders and reassembles the packets at
their destination.
• IP stands for Internet Protocol
IP software deals with the routing of packets through the maze of
interconnected networks to their final destination

15-74
TCP/IP (cont.)
• UDP stands for User Datagram Protocol
– It is an alternative to TCP
– The main difference is that TCP is highly reliable, at the cost of
decreased performance, while UDP is less reliable, but generally faster.

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