Computer Applications
Computer Applications
Computer Applications
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7.5 Module Design Requirements
7.6 Summary
7.7 Keywords
7.8 Review Questions
7.9 Further Readings
Unit 8 Presentation Graphics 184
8.1 Introduction
8.2 Creating a Presentation on PC
8.3 Creating a New Presentation
8.4 PowerPoint Views
8.5 Creating a Presentation Using a Template
8.6 Creating a Blank Presentation
8.7 Opening an Existing Presentation
8.8 Displaying the Slides
8.9 Saving a Presentation
8.10 Closing a Presentation
8.11 Summary
8.12 Keywords
8.13 Review Questions
8.14 Further Readings
Unit 9 Data Communication and Networking 196
9.1 Introduction
9.2 Data Communication
9.3 Multiplexing
9.4 Components of Computer Network
9.5 Local Area Network (LAN)
9.6 Uses of a Network
9.7 Topology
9.8 Networking Cables
9.9 OSI Layout and IEEE
9.10 Popular Types of LAN
9.11 Inter Networking
9.12 Public Networks
9.13 Client/Server Vs. Peer to Peer Networking
9.14 Network Operating Systems
9.15 Network Management
9.16 LAN in Business Environments
9.17 Summary
9.18 Keywords
9.19 Review Questions
9.20 Further Readings
5
Further Readings
UNIT-1
• Computer Software Applications in Chemistry; Peter C. Jurs; Wiley-IEEE
• Information Technology for ‘O’ Level; Manoj Kumar, M. Shamir Bhudookan;
Editions De L’Ocean Indien
UNIT-2
• Computer Aided Management (Using MS-Office 2003 Tools); Sanjeev Gupta,
Shameena Gupta; Excel Books
• Information Technology for ‘O’ Level; Manoj Kumar, M. Shamir Bhudookan;
Editions De L’Ocean Indien
UNIT-3
• Data Processing for Business and Management; Robert J Thierauf; John Wiley &
Sons
• Business Systems; Ramesh Bangia; Laxmi Publication
UNIT-4
• A Practical Handbook for Software Development; N.D.Birrell, M.A.Ould;
Cambridge University Press
• An Integrated Approach to Software Engineering; Pankaj Jalote; Springer
UNIT-5
• Computer Aided Management (Using MS-Office 2003 Tools); Sanjeev Gupta,
Shameena Gupta; Excel Books
• Information Technology for ‘O’ Level; Manoj Kumar, M. Shamir Bhudookan;
Editions De L’Ocean Indien
UNIT-6
• Programming Concepts - A Brief Tutorial for new Programmers; Richard
Holowczak; http://cisnet.baruch.cuny.edu/holowczak/classes/programming/
• Information Technology for ‘O’ Level; Manoj Kumar, M. Shamir Bhudookan;
Editions De L’Ocean Indien
UNIT-7
• Concepts, Techniques, and Models of Computer Programming; Peter Van Roy
and Seif Haridi; MIT Press
• Programming Concepts - A Brief Tutorial for new Programmers; Richard
Holowczak; http://cisnet.baruch.cuny.edu/holowczak/classes/programming/
UNIT-8
• MS-Office; K.K.Shahjahan; Excel Books
• Computer Aided Management (Using MS-Office 2003 Tools); Sanjeev Gupta,
Shameena Gupta; Excel Books
UNIT-9
• Data Communications Principles; Richard D Gitlin, Jeremiah F Hayes, Stephen B
Weinstein; Springer
• Data and Computer Communications; William Stallings; Prentice Hall
• Data Communications and Networking; Behrouz A. Forouzan, DeAnza College;
McGraw-Hills
UNIT
1
COMPUTER – AN INTRODUCTION
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z Define a computer and its various parts.
z Classify computer according to purpose, technology used, size and capacity.
z Describe various characteristics of computer.
z Describe various Input and output devices.
z Understand the concept of Office Automation.
z Describe various components of a computer system.
z Describe various generations of the computer.
U N I T S T R U C T U R E
1.1 Introduction
1.2 What is a Computer?
1.3 Importance of Computers (Man vs. Machine)
1.4 Classification of Computers
1.5 Popularity of Personal Computers (IBM PC vs. Apple Mac PC)
1.6 Architecture of a Computer System
1.7 Computers in Business
1.8 Facilities Available in Computerised System
1.9 Indian Computing Environment
1.10 Office Automation
1.11 Components of a Computer System
1.12 Hardware Components of Micro Computer
1.13 Classification of Software
1.14 Generation of Computers
1.15 Computer Languages
1.16 Language Translators
1.17 Summary
1.18 Keywords
1.19 Review Questions
1.20 Further Readings
1.1 INTRODUCTION
Nothing has revolutionized modern life the way rapid progress of computers has. For better or
worse, computers have infiltrated every aspect of our society. Today, computers do much
more than simply compute. They make airline or railway reservation and teach on-line; some
super store scanners calculate our grocery bills while keeping the store inventory; computerised
telephone switching has greatly improved the telephone system and Automatic Teller Machines
(ATM) let us conduct banking transactions from virtually anywhere in the world.
As computers become more widespread in the workplace, new ways to harness their potential
developed. As smaller computers become more powerful, they could be linked together, or
networked, to share memory space, software, and information and communicate with each
other.
Computer Application
in Management 1.2 WHAT IS A COMPUTER?
In a laymans language, a computer is a fast calculating device that can perform arithmetic
operations. Although the computer was originally invented mainly for doing high speed
and accurate calculations, it is not just a calculating device. The computer can perform any
kind of work involving arithmetic and logical operations on data. It gets the data through an
input device, processes it as per the instructions given and gives the information as an
output. We can define computer as follows:
Definition
A computer is a fast electronic device that processes the input data according to the
instructions given by the programmer/user and provides the desired information as an
output.
According to Purpose
According to the utilization of computer for different uses, computers are of following two
types:
1. General Purpose Computers: Computers that follow instructions for general
requirements such as sales analysis, financial accounting, invoicing, inventory,
management information etc. are called General Purpose Computers. Almost all
computers used in offices for commercial, educational and other applications are
general purpose computers.
2. Special Purpose Computers: Computers designed from scratch to perform special
tasks like scientific applications and research, weather forecasting, space applications,
medical diagnostics etc. are called Special Purpose Computers.
Student Activity 1
1. What is a computer?
2. What are the main characteristics of computer?
3. What are general purpose computers?
4. What are analog computers? Give examples.
5. What are hybrid computers?
Some of the examples of mainframe computers are IBM 3090, IBM 4381, IBM 4300 and IBM
ES-9000.
3. Minicomputer: Minicomputers are medium-scale, smaller and generally slower than
mainframe computers. Like mainframes, they have many terminals which are connected
with one CPU and can support many users. The cost of minicomputer is very less as
compared to mainframe. Therefore, it is mainly used in applications where processing
can be distributed among several minicomputers rather than using a mainframe
computer.
Some of the examples of minicomputers are PDP-1, IBM AS/400 and DEC Micro VAX.
IBM AS/400, which is actually a midicomputer (computer with performance between a
mainframe and minicomputer) is becoming very popular among minicomputers.
4. Microcomputer: A microcomputer is the smallest digital computer, which uses a microprocessor
as its CPU. Microprocessor is a single chip (Integrated Circuit) CPU. Microcomputer is popularly
called as Personal Computer (PC). It can be used both as a stand-alone machine and a terminal
10 in a multi-user environment. Microcomputers are becoming very popular nowadays due to
very high processing power and memory. Today, a powerful microcomputer may be used as a Computer – An Introduction
substitute for mini or mainframe computer.
Microcomputers are either of desktop or portable model. Portable computers can be
carried from one place to another. Some of the models are called as laptops while others
as notebook computers. Notebook computers are smaller, lighter and costlier than laptops.
Desktop computers fit on a desktop and are used widely in offices and homes. The
pictures of some of the desktop and portable computers are shown in Figure 1.2.
Input/Output Unit
We know that the computer is a machine that processes the input data according to given
set of instructions and gives the output. Before a computer does processing, it must be
given data and instructions. After processing, the output must be displayed or printed by
the computer. The unit used for getting the data and instructions into the computer and
displaying or printing output is known as an Input/Output Unit (I/O Unit).
The Input Unit is used to enter data and instructions into a computer. There are many
peripheral devices which are used as input/output units for the computer. The most common
form of input device is known as a terminal. A terminal has a electronic typewriter like
device, called keyboard along with a display screen, called Visual Display Unit (VDU) or
monitor. Keyboard is the main input device while monitor can be considered both as an
input as well as an output device. There are some other common input devices like mouse,
punched card, tape, joystick, scanner, modem etc., which are explained in later part of this
unit. Monitor, printer and plotter are the main peripheral devices used as output units for
the computer.
Memory Unit
Memory Unit is that component of a computer system, which is used to store the data,
instructions and information before, during and after the processing by ALU. It is actually
a work area (physically a collection of integrated circuits) within the computer, where the
CPU stores the data and instructions. It is also known as a Main/Primary/Internal Memory.
It is of following three types:
(a) Read Only Memory (ROM pronounced as “Ra-om”)
(b) Random Access Memory (RAM pronounced as "R-aem")
(c) Complementary Metal Oxide Semiconductor Memory (CMOS)
(a) Read Only Memory: Read Only Memory is an essential component of the memory
unit. We know that the computer, being a machine, itself has no intelligence or memory
and requires the instructions which are given by man. Whenever the computer is
switched on, it searches for the required instructions. The memory, which has these
essential instructions, is known as Read Only Memory (ROM). This memory is
permanent and is not erased when system is switched off. As appears with its name, it
is read type of memory i.e. it can be read only and not be written by user/programmer.
The memory capacity of ROM varies from 64 KB to 256 KB (1 Kilobyte = 1024 bytes)
depending on the model of computer.
ROM contains a number of programs (set of instructions). The most important program
of ROM is the Basic Input Output System (BIOS, pronounced as "bye-os") which
activates the hardware (physical components of computer) such as keyboard, monitor,
floppy disk etc. in communicating with the system and application software (set of
instructions or programs).
Types of ROM: There are many types of ROM available for microcomputers like Mask
ROM, PROM, EPROM, EEPROM and EAPROM.
Definitions
Mask ROM: Mask ROM is the basic ROM chip. In this type of ROM, the information is stored
at the time of its manufacturing. So, it cannot be altered or erased later on.
PROM: PROM stands for Programmable Read Only Memory. In this type of ROM, the information
is stored by programmers after its manufacturing. It cannot be altered or erased later on.
EPROM: EPROM stands for Erasable Programmable Read Only Memory. It is similar to PROM,
but its information can be erased later on by ultra violet light and it can be reprogrammed.
EEPROM: EEPROM stands for Electrically Erasable Programmable Read Only Memory. It is
similar to EPROM, but its information can be erased by using a high voltage current.
EAPROM: EAPROM stands for Electrically Alterable Read Only Memory. As compared to EPROM
and EEPROM, the information stored in EAPROM can be altered later.
(b) Random Access Memory: Random Access Memory (RAM) is another important
component of Memory Unit. It is used to store the data and instructions during the
14
execution of programme. Contrary to ROM, RAM is temporary and is erased when Computer – An Introduction
computer is switched off. RAM is a read/write type of memory and, thus can be read
and written by user/programmer. As it is possible to randomly use any location of this
memory, therefore, this memory is known as random access memory. The memory
capacity of RAM varies from 640 KB to several megabytes (1 Megabyte = 1024 KB)
with different models of Pc.
Types of RAM: There are two types of RAM used in PCs - Dynamic and Static RAM.
Definitions
Dynamic RAM (DRAM): The information stored in Dynamic RAM has to be refreshed after
every few milliseconds, otherwise it is erased. DRAM has higher storage capacity and is cheaper
than Static RAM.
Static RAM (SRAM): The information stored in Static RAM need not be refreshed, but it
remains stable as long as power supply is provided. SRAM is costlier but has higher speed than
DRAM.
Student Activity 3
1. State the basic units of a computer.
2. What are the various parts of CPU?
3. What is the function of ALU and CU?
4. What are registers?
5. What is the function of clock in CPU?
6. Define memory. Describe its various types.
7. Define CMOS.
On-line Mode
Following devices are used to capture data on-line.
Keyboard
z A computer keyboard is a sophisticated electromechanical component designed to
create special standardized electronic codes when a key is pressed.
z The codes are transmitted along the cable that connects the keyboard to the computer
system unit or terminal, where the incoming code is analyzed and converted into the
appropriate computer usable code.
Light Pen
z It is a pointing device, used to select a displayed menu option on the CRT. Light pens
are frequently used by graphics designers, illustrators, and drafting engineers.
z It is capable of sensing a position on the CRT screen when its tip touches the screen.
z A user can draw directly on the CRT screen with the light pen if the computer system
is provided with Computer Aided Design (CAD) package such as AutoCad 14.
Mouse
z A mouse is also a pointing device.
z As the mouse is rolled across the desktop, the cursor moves across the screen.
z The user can select menu or command by pushing a button on the mouse once or
twice.
Scanners
Scanners are a kind of input device. They are capable of entering information directly into
the computer.
The main advantage of direct entry of information is that users do not have to key in the
information.
Optical Scanners
Terminals
Terminals can be "dumb", "smart", or "intelligent", and are used mainly by those who do
their work on mini or mainframe computers (or supercomputers).
A variety of computer terminals are used to enter data, including the following popular
types:
z Point-of-Sale (POS) terminals
z Financial transaction terminals
16
z Executive workstations Computer – An Introduction
z Portable terminals
z Microcomputers used as terminals
Smart Cards
z It contains a build-in microcomputer chip.
z In case of smart cards, there are less chances of fraud.
z How much cash a customer has to his credit is stored in the chip before it is issued to
him.
z When the customer uses the card to make purchases, the required amount is deducted
from the balance by a special electronic machine used by merchants.
z The electronic machine used by merchants communicates with the card issuing
company's computer from time to time for money transactions. Thus, a card holder has
the facility of keeping electronic money with him.
z When his electronic money is used up, he can replenish electronic money by depositing
money at automated banking machine of card-issuing company.
z A record of purchases made by the customer can also be stored in a smart card.
Off-line Mode
Off-line data entry involves devices through which data are recorded on some media and
then into the computer later.
In almost 90% of the applications, data entry is done off-line. This saves the precious
computer processing time.
Key-to-tape
A Key-to-tape device, also known as magnetic tape encoder, is designed to record keyed
data directly onto magnetic tape.
Key-to-floppy
These data entry machines are used to store data directly on flexible disks, called diskettes
or floppies.
Key-to-disk
Used as data recording stations in systems where data from different points has to be
recorded for processing at one point.
When business transaction occurs, it is noted down and calculated at the point of transaction
(by clerk) and the same transaction data is entered by the computer operator in the computer
system.
The data entered by the operator are totalled by the computer. If the two entries do not
match, then it is a clear indication that there is a mistake.
17
Computer Application In this manner only correct data will be passed to the machine before processing is done.
in Management
Using Built-in Checks by the Computer Program
There should be some control to make sure that no data are entered which is beyond a
certain value.
For example, the salary cheques for a particular organization may not exceed Rs. 20,000.
If so, then if a cheque is made for an amount more than Rs. 20,000, then computer will point
an error.
For Output
There are two basic categories of computer-produced output:
z Output for immediate use by people, and
z Output that is stored in computer-usable form for later use by the computer. Output
can be in either hardcopy or softcopy form.
Printers
These are the most popular commonly used output devices.
z Capable of printing characters, symbols, and sometimes graphics on paper.
z Printers are categorized according to whether the image produced is formed by physical
contact (impact printers) or not (non-impact printers) of the print mechanism with the
paper.
Plotters
z A plotter is a specialized output device designed to produce high-quality graphics in
a variety of colors.
z There are two basic types of plotters: those that use pens and those that do not.
Drum plotters and flatbed plotters both uses pens. Electrostatic plotters do not.
Microfilm and Microfiche
z In this technique the output from the computer is recorded on a microfilm as microscopic
film images. The information recorded on the microfilm can be read with the help of a
microfilm reader.
z A microfiche (pronounced as fish, French word, which means card) is a 4 x 6 inch film
sheet.
z It can store up to 270 pages of information.
z It is easier to read a microfiche as compared to a microfilm.
Definition
Office automation is the application of computer and related technologies like communication
and networking to integrate the general office tasks so that the efficiency of office work is
improved.
Office automation does not mean just to install computers and communication devices in an
office, but it is much more than that. We will discuss in later part of this unit, how an office
can be automated in a real sense.
All these hardware devices except motherboard are called peripheral devices, as they are
connected to the motherboard.
Motherboard
Motherboard, also called as System Board, is the most important hardware component of a
microcomputer. Motherboard is so called as all the other boards (printed circuit boards
having chips or other electronic components) of the computer are connected to this board,
hence it is like mother of all other boards.
Notes
Components of Motherboard
A motherboard contains the CPU chip, Memory chip (ROM and RAM chips), I/O interface,
expansion slots and many other logic circuits. It may also contain a maths co-processor chip. CPU
or processor chip is the main component of motherboard. The types of CPU chip (8088/80286/
80386/80486 etc.) vary from one model of PC to another. The function of maths coprocessor
chip (8088/80287 etc.) is to support the CPU chip in processing of mathematical calculations.
Memory chips are physically installed on the motherboard by different packing methods. There
are three different types of packing of RAM chips DIP, SIMM and SIPP. DIP (Dual Inline Package)
is the most common packing, having a small rectangle box with leads on both sides. SIMM (Single
Inline Memory Module) packing contains a number of chips soldered on an expansion board
having an edge connector. SIPP (Single Inline Pin Package) is similar to SIMM, but uses pin rather
than an edge connector. Expansion slots are connectors on motherboard where expansion cards
like display card, hard disk controller card etc. can be connected. I/O interface is the channel
between the CPU and a peripheral devices (keyboard, monitor etc.).
21
Computer Application Input Devices
in Management
Input devices are used to input data, information and instructions into the RAM, The
common input devices of a PC are described below and shown in Figure 1.4.
Keyboard: Keyboard (similar to a typewriter) is the main input device of computer. It contains
3 types of keys - alphanumeric keys, special keys and function keys. When a key is pressed,
an electronic signal is produced. This signal is detected by a keyboard encoder that sends
a binary code corresponding to the key pressed to the Cpu. There are many types of
keyboards but 101 Keys Keyboard is the most popular one.
Mouse: Mouse (similar to a mouse) is another important input device. It is a pointing device used to
move cursor, draw sketches/diagrams, selecting a text/object/menu item etc. on monitor screen while
working on windows (graphics based operating environment of computer). Mouse is a small, palm
size box containing 3 buttons and a ball underneath, which senses the movement of the mouse and
sends the corresponding signals to CPU on pressing the buttons.
Trackball: A trackball looks like a mouse, as the roller is on the top with selection buttons
on the side. It is again a pointing device used to move the cursor and works like a mouse.
Light Pen: Light pen (similar to a pen) is a pointing device which is used to select a displayed
menu item or draw pictures on the monitor screen. It consists of a photocell and an optical
system placed in a small tube. When its tip is moved over the monitor screen and pen button
is pressed, its photocell sensing element detects the screen location and sends the
corresponding signal to the CPU.
Touch Screen: Touch screen is sensitive to human fingers. Using this device, the user can
point to a selection on the screen instead of pressing keys.
Joystick: Joystick is also a pointing device which is used to move cursor position on a monitor
screen. It is mainly used in Computer Aided Designing (CAD) and playing computer games.
Mouse
A 101 keys keyboard
Optical Mark Reader (OMR): It is a special type of optical scanner used to recognize the
type of mark made by pen or pencil. It is used where one out of a few alternatives is to be
selected and marked. It is specially used for checking the answer sheets of examination
having multiple choice questions.
Optical Character Reader (OCR): It is also an optical scanner, which is capable of detecting
alphanumeric characters typed or printed on paper using an OCR font. OCR devices are
used for large volume applications like reading of passenger tickets, computer printed bills
of credit card companies and reading of ZIP codes in postal services.
Bar Code Reader: This device is an optical scanner used for reading bar-coded data (data in
form of light and dark lines). Bar-coded data is generally used in labelling goods, numbering
the books or encoding ID or A/c numbers.
Magnetic Ink Character Recognition (MICR): MICR is used to recognize the magnetically-
charged characters, mainly found on bank cheques. MICR is used by the banking industry
for the processing of cheques. A special equipment is used to encode, decode and process
the cheques.
Voice-Input Devices: These devices can recognize the human voice. They seem to be very
useful but are not popular due to storage of limited vocabularies and variations in way of
pronouncing words by different persons.
Student Activity 5
1. What do you mean by office automation?
2. List various office functions needed to be automated.
3. Describe Teleconferencing Systems.
4. Define hardware and software.
5. Define : (a) Motherboard (b) Input device (c) Output device.
6. Describe any five input devices.
7. What is a Digitiser?
8. Define OMR and OCR.
Output Devices
Output devices are hardware components which are used to display or print the processed
information. The common output devices are described below and shown in Figure 1.5.
Monitor: Visual Display Unit (VDU), commonly called as monitor is the main output device
of computer. It consists of a Cathode Ray Tube (CRT), which displays characters as an
output. It forms images from tiny dots, called pixels, that are arranged in a rectangular form.
The sharpness of the image (screen resolution) depends upon the number of the pixels.
Types of Monitors: There are different kinds of monitors depending upon the number of
pixels. Depending upon the resolution, monitors can be classified as follows:
(a) CGA (Color Graphics Adapter) .
(b) MDA (Monochrome Display Adapter). 23
Computer Application (c) HGA (Hercules Graphics Adapter)
in Management
(d) EGA (Enhanced Graphics Adapter)
Controls
Paper
Drum
Laser Printer
Depending upon color of display, monitors can be classified as Monochrome (with single
color black/white display) and Color (with all colors display) Monitors.
Printer: Printer is the most important output device, which is used to print information on
papers. Printers are essential for getting output of any computer based application.
Types of Printers: There are many types of printers which are classified on various criteria
24 as illustrated in Figure 1.5 Printers can be broadly categorized into two types.
Computer – An Introduction
(a) Impact Printers: The printers that print the characters by striking against the ribbon
and onto the paper, are called Impact Printers. These printers are of two types
(i) Character Printers: These printers print one character at a time. These printers
are again of two types Daisy Wheel and Dot Matrix Printers. Daisy Wheel Printers
these printers print the characters by a mechanism that uses a plastic or metal hub
with spokes, called daisy wheel. The characters are embossed on the radiating
spokes and printed by striking these spokes against the ribbon and paper. Daisy
Wheel printers give a good quality but they are expensive than Dot Matrix printers.
Dot Matrix Printers these printers print the characters by putting dots onto the
paper. They do not give better printing quality than daisy wheel printers, but are
faster in speed. The printing speed of a dot matrix printer can be upto 360 cps
(characters per second). They are widely used with microcomputers in most of the
offices.
(ii) Line Printers: These printers print one line at a time. Their printing speed is
much more than character printers. They are again of two types Drum Printers and
Chain Printers. Drum Printers these printers print the line by a rotating drum
having a ring of characters for each print position. The hammers strike each
character of the drum simultaneously, so that entire line is printed for one full
rotation of the drum. These printers are also called as Barrel Printers. The printouts
obtained from these printers, have even character spacing but uneven line height.
Chain Printers these printers print the line by a rotating chain having ring characters
for each print position. Their printing mechanism is similar to drum printers. The
printouts obtained from these printers, have uneven character spacing but even
line height.
(b) Non-Impact Printers: The printers that print the characters without striking against
the ribbon and onto the paper, are called Non-Impact Printers. These printers print a
complete page at a time, therefore, also called as Page Printers. Page printers are of
three types
(i) Laser Printers: These printers look and work like photocopiers. They are based
on laser technology, which is the latest development in high speed and best
quality printing. In these printers, a laser beam is used to write the image on a
paper. First, the image is formed by electrically charged thousands of dots on a
paper by laser beam. Then, the paper is sprayed with a toner having the opposite 25
Computer Application charge and is passed over a heated roller to make the image permanent. Laser
in Management
printers are very popular and have become an essential part of Desk Top Publishing
(DTP). Although laser printers are costlier than dot matrix, they are generally
preferred in all offices due to their best quality of printing. There are many models
of laser printers depending upon the speed and number of dots printed. The latest
model of laser printer is 1200 DPI (Dots Per Inch), which can print 10 pages/
minute. Some high speed laser printers give a speed of upto 100 pages/minute.
(ii) Inkjet Printers: These printers print the characters by spraying the paper with
electrically charged ink. These printers give better quality than character printers
but not better than laser printers. They are cheaper than laser printers, hence
used widely in many offices. They also offer an option of using color cartridges
for multi-color printing.
(iii) Thermal Printers: These printers print the characters by melting a waxbased ink
off a ribbon onto a special heat sensitive paper. They give letter-quality printing
but are relatively expensive in maintenance than other printers.
Plotter: Plotter is an important output device, used to print high quality graphics and
drawings. Although the graphics can be printed on printers, the resolution of such printing
is limited on printers. Plotters are generally used for printing/drawing graphical images such
as charts, drawings, maps etc. of engineering and scientific applications. Some important
types of plotters are discussed below:
(i) Flatbed Plotters: These plotters print the graphical images by moving the pen on
stationary flat surface material. They produce very accurate drawings.
(ii) Drum Plotters: These plotters print the graphical images by moving both the pen and
the drum having paper. They do not produce as accurate drawings as printed by flat
bed plotters.
(iii) Inkjet Plotters: These plotters use inkjets in place of pens. They are faster than
flatbed plotters and can print multi-colored large drawings.
Student Activity 6
1. What are output devices? Give examples.
2. Write the full form of the following:
(a) CGA (b) MDA (c) HGA (d) EGA (e) VGA (f) SVGA
3. What is the difference between character printers and line printers?
4. Describe laser printer.
5. What are plotters? Describe its various types.
26
Storage Devices Computer – An Introduction
In preceding part of this unit, we have discussed about the primary memory of computer. Primary
memory (especially RAM) stores the data, instructions and informations temporarily during processing
by CPU. When computer is switched off, this memory gets erased. How does a computer store the
data, information and software permanently, so that they can be retrieved whenever required? Certainly,
there must be some storage devices in computer. Now, we will discuss about different Storage
Devices, sometimes also called as Secondary Memory Devices.
CD ROM Drive
Magneto Optical
(MO) Disk.
Figure 1.8: Common Storage Devices
There are many storage devices used with microcomputers. Some of the common storage
devices are explained below and shown in Figure 1.8.
(i) Winchester Disk (Hard Disk): Winchester Disk is the most common storage device
of present day microcomputers. It is popularly called as Hard Disk Drive (HDD) or
sometimes as Fixed Disk Drive. It is fixed inside the computer and is not easily
removable. It is used for storing the software and data inside computer. It is known as
'Winchester Disk', probably because this drive was first made by IBM at Hursley
Laboratory, located near Winchester in England.
Winchester Disk consists of one or more disk platters, an access mechanism and read/
write heads which are sealed in a case. Hard disk size depends upon the disk platter's
diameter. There are many different platter sizes (such as 51/2, 31/2 , 21/2 inch etc.). The
31/2 inch size platter is common with PCs and 21/2 inch with laptop/ portable computers.
Read/ write head is used to write any information on the disk surface or to read it back.
There are different types of hard disks depending upon their storage capacities. Storage
capacities of hard disks range from 10 MB to 6.3 GB, but 4.3 GB are nowadays a
common part of Pentium computers
(ii) Floppy Disk: Floppy Disk (FD) is another common storage device which is small,
flexible and easily removable. It is made of a plastic disk coated with magnetic material,
which is sealed inside a square plastic jacket. It is called as 'Floppy' because it is soft
having flexible physical property. Data can be written on or read from this floppy by a
drive, called Floppy Disk Drive (FDD), which is fixed inside the computer.
* DS stands for Double Sided, LD for Low Density and HD for High Density
27
Computer Application There are many types of floppies depending upon their sizes and storage capacities as
in Management
illustrated in Table 1.3. The original floppy, developed by IBM, is an 8" floppy, but the
most popular sizes available for present day PCs are 51/4" and 31/2". The storage
capacity of floppies vary from 360 KB to 1.44 MB. The floppies can store data on both
sides (Double-sided Floppies) or on single side (Single-sided Floppies) depending
upon the floppy drive. Double sided floppy drives are most frequently used in present
day PCs. The latest floppy drive, that packs two high density floppy drives (5.25 & 3.5
inch) into a single package, is known as Combo Drive.
(iii) Compact Disk: Compact Disk (CD) is the latest storage device, used to store data,
information and software, which can be read only and not be changed or erased. It is
an optical read only memory, made up of a resin. Therefore, it is actually called as
Compact Disk Read Only Memory (CD-ROM). However, the information is stored on
CDs by using an expensive drive, called CD-ROM drive.
Nowadays compact disks are very popular storage devices for microcomputers because
a large number of software including multimedia, audio and graphics software are
available only on these disks. Compact Disks can store a large volume of data (upto
680 MB), which is almost same a storage capacity of 630 MB Hard Disk.
WORM (Write Once Read Many) is a type of compact disk which can be recorded
only once and not erased. It can store more data than CD-ROM, generally measured in
gigabytes.
(iv) Magnetic Tape: Magnetic tape is the oldest storage device available for
microcomputers. It is generally used to store a large volume of data that is needed to
be sequentially accessed and processed. The tape is made up of a plastic ribbon
coated with an iron-oxide material, which can be magnetized. The data stored on tape
can be read as well as erased and written again.
Magnetic tape is a sequential access storage device, hence it is not possible to read
the data randomly or directly. Therefore, magnetic tapes are suitable only for storing
data for backups and batch mode applications and not for on-line applications. On the
other hand, magnetic disks (floppy and hard disks), which are discussed above, are
considered best storage devices for on-line applications.
(v) Video Disk: Video disk is used to store text, video and audio data. It is widely used for
training applications as it can be played like a phonograph record.
(vi) Magneto Optical Drive: Magneto Optical (MO) drive is the latest of all storage devices.
This drive uses both a laser and an electromagnet to record data on a removable
cartridge. The surface of the cartridge contains tiny embedded magnets The unique
feature of MO drive is that it has a very high storage capacity. Although MO drive is
costlier and slower than HDD, it has a long life and is more reliable.
(vii) DVD ROM/RAM Disk: DVD ROM and DVD RAM disks are optical disks having a
storage capacity of 4.7 GB and 5.2 GB respectively. These disks are becoming the next
generation's new standard for higher capacity removable media. They are ideal for
storage of huge amount of information required for multimedia applications. One can
put 133 minutes of high quality of video with digital sound on a DVD RAM Disk.
Cards
Cards are the printed circuit boards used to hold the chips (integrated circuits). There are
many types of cards used in PC, the important ones are Video Card, Sound Card, I/O Card,
Controller Card and Memory Card. Video card (Display Card) generates the text and graphic
images for monitor while sound card generates the sound. Pentium computers, generally,
use a PCI (Peripheral Component Interconnect) video card to speed up graphics. I/O Card
provides a place for connecting mouse and printer. Cables of hard disk and floppy disk are
connected to controller cards. Memory Card provides a place for memory chips.
Cords are the cables used to plug into the ports. There are different types of cables for
connecting different types of input, output and storage devices. The important cords used
in a PC are keyboard cords, power cords, monitor cords and printer cords.
Power Supply
Power supply is considered as the 'Heart' of a Pc. Computer requires a clean and steady
power source for working properly. Power supply is that important hardware, which provides
the power source to a computer. It provides a voltage range of 4.95 to 5.25 volts for the
highest performance of the system. Power supplies vary in size and power (in watt).
Notes: An Uninterrupted Power Supply (UPS) keeps the computer running for few minutes even
when the electricity supply goes off. UPS is not a part of computer and is purchased separately.
It is optional but mostly preferred to CVT (Constant Voltage Transformer) and is always
recommended for computerised applications like MIS.
Student Activity 7
1. Define Winchester Disk.
2. Define floppy disk.
3. Define CD-ROM and WORM.
4. What is the function of magnetic tape?
5. What is magneto optical drive?
6. Define cards.
System Software
Software, which are required to control the working of hardware and aid in effective execution
of a general user's applications are called system software. These software perform a variety
of functions like file editing, storage management, resource accounting, I/O management,
database management, etc. Some of the examples of system software are DOS (Disk Operating
System), Windows, BASIC, COBOL and PC TOOLS. These software are developed by System
Programmers.
Application Software
Software which are required for general and special purpose applications like database
management, word processing, accounting etc. are called as application software. Some of
the examples of application software are dBASE, Word Star, Tally etc. Application software
are developed using system software by Application Programmers.
29
Computer Application (i) General Purpose Application Software
in Management
(Database Management Packages, Word Processors, Spreadsheets, Office Automation
Packages)
(ii) Special Purpose Application Software
(Desktop Publishing, Multimedia, Business Applications)
Examples:
z ENIAC (Electronic Numerical Integrator and Calculator) It was the first electronic
computer using vacuum tubes. - 1946
z EDSAC (Electronic Delay Storage Automatic Calculator) It was the first stored-program
computer. - 1949
z EDVAC (Electronic Discrete Variable Automatic Computer) It was successor of EDSAC.
- 1951
z IAS machine (Princeton's Institute of Advanced Studies) It was a new version of the
EDVAC, built by von Neumann. - 1952
30
The basic design of IAS machine is now known as von Neumann machine, which had five Computer – An Introduction
basic parts the memory, the arithmetic logic unit, the program control unit, the input and the
output unit.
Examples:
z PDP-l, developed by DEC was the first minicomputer.
z NCR 304 (National Cash Register), was first all-transistorized computer.
They still had less storage capacity, relatively slower performance and thus could not fulfil
the requirements of the users and programmers. The third generation computers became
out-dated around the year 1978 when it was found that thousands of ICs could be integrated
onto a single chip, called LSI (Large Scale Integration).
Examples:
z IBM 360, developed by IBM in 1964 was the first product line designed as a family.
z PDP-8, developed by DEC in 1965 was the first mass-market minicomputer.
z PDP-ll, developed by DEC in 1970 was the first highly successful minicomputer.
z CRAY-l, developed by Cray in 1974 was the first supercomputer.
z VAX, developed by DEC in 1978 was the first super minicomputer.
Example:
z Yet to develop but ROBOTS have few features of fifth generation computers.
Student Activity 8
1. What are system software? Give example.
2. What are application software? Give example.
3. What are first generation computers?
4. What are the limitations of third generation computers?
5. Describe fourth generation computers.
These languages were widely used for applications development, but most of them are
outdated nowadays due to popularization of 4GLs. The uses of different 3GLs are summarized
in Table 1.4.
Table 1.4: Uses of 3GLs (Third Generation Languages)
Language Uses
BASIC (Beginner's All Purpose Used for all purposes (Commercial, Scientific, Educational,
Graphics Symbolic etc.) by beginners.
Instruction Code)
PASCAL (Name of a Scientist) Used for both commercial and scientific applications.
C (No full form) Very powerful language for development of both system
and application software.
(c) User-friendly Languages: Although high-level languages are simpler to codify than
low-level languages, they still require a lot of time to learn their programming syntax.
Hence, these languages are beyond the reach of many computer users (including MIS
professionals), who do not want expertise in programming. Therefore, a new category
of languages have been developed which are user-friendly, very easy to codify and
simplest to learn. These languages are called as User-friendly Languages and popularly
known as 4GLs (Fourth Generation Languages). Some of the common 4GLs are dBASE,
Foxbase, Foxpro, MS Access, Oracle, Sybase and Ingres. The uses of different 4GLs
are summarized in Table 1.5.
(d) Object-oriented Languages: We have discussed that the object-oriented programming
is the latest approach in programming. The languages which are based on Object-
Oriented Programming (OOP) approach, are called as Object Oriented Languages.
They may be classified into Fifth Generation Languages. Object Oriented Languages
are specially useful for development of GUI (Graphical User Interface) applications.
These languages also offer a unique feature of Reusable Code. Some of the popular
object-oriented languages are Smalltalk, C++ and Object COBOL, Object Pascal, Simula,
Eiffel, Java & Visual J++. C++ and Visual J++ are widely used nowadays for development
of windows-based applications. The uses of different object-oriented languages are
summarized in Table 1.6. 33
Computer Application Table 1.5: Uses of 4GLs (Fourth Generation Languages)
in Management
Language Uses
dBASE Used for development of mainly single user DOS based database appliactions.
Foxbase Used for development of both single and multiuser DOS based database applications.
Foxpro Used for development of both DOS and Windows based database opplications.
Oracle Used for development of relational database applications on any operating environment.
Sybase Mainly used for development of on-line applications such as Decision Support Systems
and Transaction Processing.
Object COBOL Used for development of object oriented applications on mainframe computer.
Notes: There are certain languages which support most of the features of object-oriented programming
except inheritance. These languages are not pure object-oriented languages and are known as object-
based languages. For example, Ada, a high level language designed for process control, is an object-based
language.
Student Activity 9
1. Which language is understandable by computer?
2. What are high-level languages?
3. What are object-oriented languages?
4. What is the function of language translators?
5. Describe the following:
(a) Assembler (b) Interpreter (c) Compiler.
1.17 SUMMARY
A computer is an electronic device that can perform a variety of operations according to the
instructions given by the programmer/user and provides the desired information as an
output. Computers are fast, accurate, diligent, having high memory, but no intelligence.
Computer are classified as general purpose or special purpose computers according to the
purpose of their requirement. According to the technology used, computers are classified
as analog which are used for scientific and engineering application, digital which are
considered as general purpose computers or hybrid computers. Which incorporate the
technology of both analog and digital computers. According to their size, computer can be
classified as super computer, mainframe computer, minicomputer and micro computer.
The main components of computer are input/output units central processing unit and memory
unit. Input unit is used to enter data and instructions into a computer. CPU performs all the
processing of input data: Memory is used to store the data, instructions and information
before during and after the processing by ALU. Output unit makes available output to the
users.
CPU consists of ALU (Arithmetic Logic Unit) which is responsible for all arithmetic and
logical operations, CU (Control Unit) which controls the transfer of data and instructions
among other units of computer Registers, which are used to store data, instructions and
memory addresses when ALU performs arithmetic and logical operations, Buses which are
used to transfer data between registers and clock which measures and allocates a fixed time
slot for processing each and every micro operation.
Memory is the internal storage area, which holds the data and instructions during processing.
The three types of main memory or Internal memory are RAM (Random Access Memory),
ROM (Read Only Memory) and CMOS (Complementary Metal Oxide Semiconductor
Memory).
Computers are used in business for data capturing in on-line as well as off-line mode, for
storage and retrieval of information, for output and for transmission. Offices are needed to
be automated to reduce cost of administrative overhead and to increase efficiency of office
tasks and staff. The hardware components of microcomputer can be classified into
motherboard, Input devices, output devices, storage devices, cards, ports and cords and
power supply. Various Input devices are keyboard, mouse back ball, light pen, touch screen,
Joy stick, digitizer, Scanner, Optical Mark Reader (OMR), Optical Character Reader (OCR)
Bar Code Reader (BCR), Magnetic Ink Character Recognition (MICR) and voice input devices
various output devices include monitor printer plotter and computer output micro file. Storage 35
Computer Application devices include hard disk, floppy disk, compact disk, Magnetic tape, video disk, Magneto
in Management
optical drive, DVD ROM/RAM disk, etc.
Computer software as classified as system software which are required to control the working
of hardware, and software which are required for general and special purpose applications.
Computers are classified into six types based on their historical advancement and electronic
components used, from fourth generation to fifth generation computers. Computers languages
are categorized into four types, low level, high-lever, user friendly and object oriented
language.
Language translators are used to convert are codes of other languages into machine code.
Various categories of language translators include Assemblers, compilers and Interpreters.
1.18 KEYWORDS
z ALU: Arithmetic Logic Unit of a computer which is used to perform arithmetic and
logic operations.
z Assembler: A program which translates an assembly language program to its machine
language equivalent.
z Assembly Language: A low-level language for programming a computer in which
mnemonics are used to code operations and alphanumeric symbols are used for
addresses.
z Cache Memory: A small high speed memory which is used to temporarily store a
portion of a program or data from the main memory. The processor retrieves instructions
or data from the cache memory. Instruction and data caching speeds up computation.
z Chain Printer: A printer in which the characters to be printed are embossed on a
chain or a band. The chain is fashioned as a loop and print heads are activated to print
specified characters.
z Communication Channel: A medium through which (electric) signal are transmitted
and received.
z Compiler: A system program to translate a high level language program to machine
language.
z Computer: This is a machine which executes an algorithm stored in its memory to
process data fed to it and produces the required results.
z Control Bus: A set of wires used to transmit signals to control the operation of
various units of a computer.
z CPU: Central processing unit of a computer. It consists of circuits to perform arithmetic
and logic and also has circuits to control and co-ordinate the functioning of the
memory and I/O units of a computer.
z Data Entry Unit: A system which a keyboard to enter data and a magnetic medium
such as a floppy disk to store the entered data.
z Data (Digital Audio Tape): User 4 mm wide magnetic tape in a cartridge to store
around 4 GB of data (1994).
z Digital Channel: A communication medium through which information in binary
(digital) form is transmitted.
z Disk Memory: A back up or peripheral memory in which information is stored as
magnetized spots on the surface of disks coated with magnetic material. In hard disks
the disks are not flexible. In floppy disks the disks is a circular platter made of flexible
magnetic coated plastic sheet.
z Floppy Disk: A circular magnetic disk made of flexible plastic sheet coated with magnetic
material.
36
z Fourth Generation: Fourth Generation computers:- Computers built between 1975 Computer – An Introduction
and now. They use large scale integrated circuits, semiconductor memories and powerful
high level languages and operating systems.
z High Level Languages: Computer language in which each statement is translated into
many machine language statements.
z I C: Integrated circuit. An electronic circuit fabricated on a single chip of silicon.
z Input Unit: A part of a computer used to feed programs and data.
z Joy Stick: A stick mounted on a spherical ball which moves in a socket. Used to more
the cursor on the screen of a display device.
z Laptop: A portable computer which weighs around 2 kg and runs all PC applications.
It used a liquid crystal display and is usable by the person while traveling.
z Light Pen: A pen shaped devices which has a lens assembly. It is pointed towards an
image displayed on a cathode ray screen. It picks up the right and determines the
position of the picture element picked up.
z Machine Language: A language which users numeric codes to represent operations
and numeric addresses of operands. Each model of a computer has a unique machine
language.
z Memory: An organized collection of cells used and programs in a computer.
z Microcomputer: A computer which is fabricated using a microprocessor, and other
integrated circuits, namely, a ROM, RAM and I/O interface chips.
z Output Unit: A unit of a computer used to print or display computed results.
z Printer: An output unit to print the results of computation. Line printers print one full
line at a time using a character, chain or drum. Character printer print one character at
a time serially.
z Processor: A unit of a computer which interprets instructions, executes them using
arithmetic and logic circuits and controls the operation of all the other units of the
computer (also known as CPU).
z RAM: Random Access memory. A memory used as the main memory of a computer in
which the time to retrieve stored information is independent of the address where it is
stored.
z ROM: Read only Memory. A memory in which information is permanently written. The
information can be read quickly but not change.
z Second Generation Computer: Computer built during the period 1956-65 which used
transistors in CPU, magnetic core main memories and high level language FORTRAN
and COBOL for programming.
z Software: Programs for a computer.
z System Software: General programs written for a computer. These programs written
for a computer. These programs provide the environment to facilitate the writing of
application programs.
z Third-generation Computer-Computer built between 1966 and 1975 which used
integrated circuits in CPU, high speed magnetic core main memories, powerful high
level languages and saw the advent of time sharing operating system.
z VDU: A Video Display Unit. An I/O device which consists of a television tube for
presenting outputs and a keyboard for entering inputs.
z Volatile Memory: A memory in which the information stored is lost unless energy is
continuously fed to it.
Detailed Questions
1. What is the difference between general purpose and special purpose computers?
2. What is the difference between analog and digital computers?
3. Classify computers on the basic of their technology.
4. What do you mean by the term diligence' respect to computers?
5. List some application areas of super computers.
6. What is the difference between minicomputer and microcomputer?
7. Write a short note on personal computer?
8. Describe the architectural of computer system.
9. State the basic units of computer. Name the submits that make up the CPU, and give
the function of each of the units.
10. What is the function of memory? What are its measuring units?
11. What are the major strengths and weaknesses of computer?
38
12. What is the difference between RAM and ROM? Computer – An Introduction
39
Computer Application
in Management UNIT
2
PC-SOFTWARE PACKAGES
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z Disk operating system, its internal and external commands.
z Windows, its working and windows accessories.
z MS-Word as a word processor.
z MS-Access a data base management package.
z MS-Excel as a spread sheet package.
U N I T S T R U C T U R E
2.1 Introduction
2.2 Disk Operating System (DOS)
2.3 Windows
2.4 Word Processor
2.5 Starting Word 2000
2.6 Editing Documents in Word 2000
2.7 Formatting Documents
2.8 Clip Gallery
2.9 Page Setting
2.10 Application of a Word Processor in Corporate Sector
2.11 Database Management Packages
2.12 Starting Access 2000
2.13 Working with Tables
2.14 Working with Forms
2.15 Working with Reports
2.16 Spreadsheet Packages
2.17 Starting Excel 2000
2.18 Working with Documents
2.19 Data Entry and Editing
2.20 Types of Cell Entries
2.21 Commonly Used Functions
2.22 Absolute and Relative Cell Referencing
2.23 Number Format
2.24 Charting with Excel
2.25 Macros
2.26 Importing and Exporting Files
2.27 Printing a Workbook
2.28 Application of a Spreadsheet in Corporate Sector
2.29 Summary
2.30 Keywords
2.31 Review Questions
2.32 Further Readings
2.1 INTRODUCTION
In this unit, we are discussing all the important software concepts and providing you the latest
knowledge of all the software available in the market. Many types of software are available for
40
various applications. The software development field is so advanced that day by day existing PC-Software Packages
software are becoming outdated and new software are coming in the market. So we must get aware
of the latest developments in the software industry.
Here, we discuss following software packages which are required for general and special purpose:
z Disk Operating System
z Windows
z Word Processor
z Database Management Packages
z Spreadsheet Packages
Loading DOS
The booting happens automatically when the computer is switched on, provided DOS is available
to it. DOS can be present on both hard disk as well as the floppy disk. So, when the system is
turned on, a search for DOS is done on floppy drive first. If it is not present on the floppy drive,
the DOS is searched for on the hard disk. Thus, for booting to happen, the DOS must be present
either on the floppy or on the hard disk. So, if DOS is not present on the hard disk, insert the
floppy carrying DOS software in the A drive before switching on the system. If the system boots
from floppy, the following prompt comes on the screen:
A:\>
where underscore character '- ' indicates the cursor (blinking mark) of the screen. However, if
booting has been done from the hard disk, then the following prompt will come:
C:\>
C:\> or A:\> is the DOS Prompt. Looking at DOS Prompt, you can easily make out the currently
active drive. If you want to switch yourself over to the another drive, then simply type its drive
letter after the prompt and hit the <Enter> key as shown below:
C:\>A: <Enter>
A:\>
Now again if you want to go back to the C drive, then type in C: and hit the <Enter> key.
41
Computer Application Files and Directories in DOS
in Management
File is a collection of related information. Any kind of text, data or program that is entered, is
stored in a file. Now, it is very essential to organize your files in an ordered manner. This makes file
search easier otherwise, it can really be a difficult and time consuming job to search for a particular
file out of the whole lot of files stored on the disk. An example of library can make the explanation
of the concept more clear. As you must have already observed, the books in a library are put in big
cabinets. Each cabinet is divided into many shelves and sub-shelves. Each shelve or sub-shelve
contains books on a particular subject. So, the required book on a particular subject can be found
out very easily without wasting much time and effort.
On similar grounds, all the files that are related to each other are clubbed at one place. This is
known as a Directory Structure or simply a Directory. A directory structure resembles an inverted
tree. The main directory becomes the Root directory. The directories and files become the branches
of this directory tree. Any number of files and directories can be added to it thus, making the tree
grow big downwards. Let us take an example:
Suppose we wish to store two kinds of files on our disk: ACCOUNT and EXPENSE. Further, we
wish to keep two more kinds of files (say CASHSALE and CREDSALE) under ACCOUNT sub-
directory. DOS can very much help you in organizing your files through directory structure which
is shown in Figure 2.1.
1. On the top of the directory structure, there is a Root directory. This directory is always
present and is shown by \(backslash) for referencing. Any file or directory that is created is
always under the Root directory.
3. ACCOUNT is the parent directory of the directories CASHSALE and CREDSALE. It can
also be said that the CASHSALE and CREDSALE are the sub-directories of the ACCOUNT
directory. Thus, a directory under a directory is called a sub-directory.
It can be clearly seen that the files relating to a particular subject can be put under a directory. For
example, all the files relating to expenses can be put under EXPENSE sub-directory whereas all the
files relating to cash sales can be stored under the sub-directory CASHSALE.
Referencing Files
It's time to learn, as to how to locate a file? The directory structure shown in Figure 2.2 has two
sub-directories under the Root directory. The sub-directory EXPENSE has two files under it.
42
PC-Software Packages
DOS allows you to go from one directory to another by following a certain path. In the beginning,
the user is always resident in the Root directory. While travelling from one directory to another,
certain rules have to be followed. A user cannot go directly from ACCOUNT sub-directory to
EXPENSE sub-directory. To go from one sub-directory to another, you have to first go to its
parent directory or the Root directory. Thus, for going from ACCOUNT sub-directory to EXPENSE
subdirectory, you first have to go to Root directory. Similarly, for going from the file EAST.TXT to
WEST.TXT, you have to go to the EXPENSE sub-directory first. Thus, in other words, while
moving from one directory to another, you have to go to its parent directory first.
Now, in order to reach out to the file WEST.TXT the following path has to be followed:
C:\>Expense\ West.txt
1 3 4 5
Here,
1 is the drive name where the file is resident in;
2 is the path which DOS takes to reach for a file;
3 is the directory under the Root;
4 is the primary name of the file that is to be accessed; and
5 is the extension name of the same file.
The backslash (\) has to be used for tracing out the path. The first backslash takes you to the
Root directory. The subsequent backslashes separate the directories, sub-directories and the
filename that are given in the whole path.
File Naming Conventions
There are certain rules that have to be followed while giving names to your files. A file name has
two parts Primary Name and Extension (Secondary Name). A dot (.) separates a primary name from
an extension. Let as see the two parts of the file named DRAGON.TXT.
DRAGON.TXT
Primary Extension
Name
A primary name cannot have more than eight characters and an extension cannot have more than
three characters. A file name having only the primary name and no extension is absolutely valid
because it is optional to give an extension to a file name. An extension is generally given by the
language or software used. For example, if you are entering a BASIC or PASCAL program, its file
name would have extension BAS or PAS respectively. A file name can contain the following
characters:
1. An Alphabet (A-Z) or (a-z) 43
Computer Application 2. A number (0-9)
in Management
3. Special characters such as: $, #, &, @, !, %, (, ), -, { , }, " A, etc.
except *, ?, full stop (.) and space ( ).
It is a good practice to give meaningful names to your files. However, no two files can have exactly
the same name on the disk. Thus, a name given to a file on a disk has to be unique.
VALID INVALID
MYHUNT MY BOOK.DOC
Dragon.Txt B.R. Arora
Uphill.up S?JAIN.BAS
VIJAYA EXCELBOOKS
Employee.Emp ANARAG.**
157.IN VICKY.MEHTA
The rules for naming a directory are the same as that of naming files.
Student Activity 1
1. What is an operating system?
2. Define MS-DOS.
3. What is booting?
4. What is a file and a directory?
5. Describe the file naming conventions in MS-Dos.
DOS Commands
DOS offers a variety of commands to perform various functions. With the help of DOS commands,
you can display the list of files and directories that are present on the disk, create new files and
directories, remove unwanted files and directories and much more. DOS commands can be entered
either in uppercase or lowercase letters. The format of a DOS command is called syntax. All DOS
commands begin with command name. When DOS carries out the instructions given by you, it is
called the execution of DOS command. Let us discuss some of the DOS commands in detail. (The
commands which you should issue, are written as bold letters throughout this unit).
The directory commands help you to create new directories and remove existing ones. They also
allow you to travel from one directory to another. You can also view the listing of files and
directories that are present on the disk.
This particular DOS command helps you in displaying a list of files or directories that are present
on hard disk as well as floppy disk. Thus, to see the contents of your hard disk, issue the
following command:
C\>DIR <Enter>
The above command displays the primary name, extension and size of files in bytes. It also
displays the date and time when the file was created or modified last. If you wish to view the
contents of the floppy drive, then you first switch yourself to the floppy drive and then issue the
DIR command as shown below:
C\> A: <Enter>
44 A:\>DIR <Enter>
Figure 2.2 shows two sub-directories ACCOUNT and EXPENSE. If you wish to view the contents PC-Software Packages
of the sub-directory EXPENSE, then issue the following command:
Let us assume that there is one more sub-directory by the name BUSINESS existing under EXPENSE.
To view the contents of this sub-directory, issue the following command:
If you have a large number of files on the disk, then on issuing, DIR command, the screen scrolls
up and only a few file names are shown. In such a case, issue the following command:
C:\>DIR/P <Enter>
The above command will show the contents of the disk pagewise or screenwise. Now, if you are
interested only in seeing the file names, then issue the following command:
C:\>DIR/W <Enter>
The above command shows the names of files and directories widthwise. So, in one line only five
names of files and directories are shown. The other details like the size of file, the date and time of
each file creation are not shown. The directories are shown in square ([]) brackets.
In the earlier part of this unit, we discussed that all the related files should be clubbed at one place,
called a directory or sub-directory. So, to club all the related files under one head, new directories
and sub-directories have to be created. Let us create a new sub-directory by the name INCOME
under the Root directory.
where MD stands for Make Directory. Further, let us create another sub-directory by the name
HOSPITAL under the sub-directory Income.
With time, certain directories grow old and are no more needed. It is better to delete such directories
because they can save us many precious bytes on the disk. So, let us delete the sub-directory
HOSPITAL with the following command:
A directory or a sub-directory has to be essentially empty before removing it. For example, in
order to remove the sub-directory HOSPITAL, there should not be any directories and files under
it. So, you must first delete all the files and remove all the sub-directories present under the sub-
directory HOSPITAL before removing it. We will discuss the method for deleting files in subsequent
part of this unit.
Let us again refer to the Figure 2.2. Suppose you are under the EXPENSE sub-directory and you
want to access the files or directories in the ACCOUNT sub-directory. This would involve the
changing of directory from EXPENSE to ACCOUNT. This will make the ACCOUNT directory
active. The task of changing directories can be accomplished with the help of CD command.
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Computer Application Look at the following example:
in Management
C:\>CD ACCOUNT <Enter>
where CD stands for Change Directory
The above command will take you to the sub-directory ACCOUNT as shown by the following
prompt:
C: \ACCOUNT>
If you want to go to the sub-directory CASHSALE straight from the sub-directory EXPENSE,
issue the following command:
C:\>CD ACCOUNT\CASHSALE <Enter>
After the above command, the following prompt will come:
C:\ACCOUNT\CASHSALE>
The command for going to the root directory from the above prompt is:
C:\ACCOUNT\CASHSALE>CD\ <Enter>
But, the command for going to the parent or previous directory (whether it is root or sub-directory)
is:
C: \ACCOUNT\ CASHSALE>CD.. <Enter>
If you are in the sub-directory CASHSALE, the above command will take you to ACCOUNT sub-
directory as shown below:
C: \ACCOUNT>
Let us assume that you have a file by the name NORTH.TXT in the root directory and you wish
to copy this file in the newly created Area sub-directory. The following command will do this:
C:\>COPY NORTH.TXT \AREA <Enter>
Similarly, you can copy files from any directory to any other directory. DOS only needs the
specification of full path from you. Let us copy a file OLD.TXT which exists under the sub-
directory DATA to the sub-directory INFO which is resident in the floppy disk.
C:\>COPY DATA \OLD.TXT A:\INFO <Enter>
With time, certain files grow old which are no longer required. So, it is desirable to delete such files
because unwanted files occupy precious space on the disk. Suppose there is a file on the hard
disk by the name TRYPRG which is no longer required. The following command deletes this file:
C:\> DEL TRYPRG <Enter>
If the file SALE.PRG exists on the floppy disk, first you go to the A: prompt and then delete the file
as shown below:
C:\>A: <Enter>
A:\>DEL TRYPRG <Enter>
While deleting any file of a sub-directory, its full path should be given as illustrated in the
following example. Let us assume that the TRY.PRG file exists under a subdirectory MANAGE on
the hard disk. To delete this file-issue one of the following commands:
C:\>DEL C:\MANAGE\ TRYPRG <Enter>
OR
C:\>DEL MANAGE\TRYPRG <Enter>
You can also delete the IMT.PRG file by first changing to that sub-directory and then issuing the
DEL command as given below:
C:\>CD\MANAGE <Enter> C:\MANAGE>DEL TRY.PRG <Enter>
DOS allows you to give new names to your files. Assume that there is a file by the name OLD.TXT
and now you wish to give a new name NEW.TXT to it. Carry out one of the following commands
to get your work done.
C:\>REN OLD.TXT NEW.TXT <Enter>
OR
C:\>REN DATA \OLD.TXT NEW.TXT <Enter>
The file OLD.TXT which resides under the sub-directory DATA now has a new name
NEW.TXT. 47
Computer Application Wildcards
in Management
Often you may need to do a similar kind of job on a number of files. If these files have something
in common, then we can save the effort of performing repetitive job. So, these files can be referred
collectively by using the wildcard facility provided by DOS. The use of wildcards in a DOS
command gives greater flexibility when using similar type of file names. DOS offers two wildcards
: ? and *. Each? can be replaced by exactly one character or none, if it is given at the end of the
filename. As and when the? wildcard is specified in the middle of a filename, it has to necessarily
match one character. The * wildcard can match eight or less characters in the primary name and
three or less characters in the extension part.
Let us take an example to make the concept of wildcards clear. Suppose the following files are
present onto your disk:
screen:
Are you Sure (Y /N)? _
Press 'Y' if you really want to delete all files otherwise press any key. Never try the above command
on root directory of hard disk, otherwise your most important DOS file COMMAND. COM will
also be deleted and thereafter you will not be able to boot the system from the hard disk. Therefore,
wildcards with DEL command should be used with great caution.
Student Activity 2
1. List some directory commands of DOS.
2. What is the difference between RD and MD command?
3. What is the function of CD Command?
4. How will you copy files in Ms-Dos?
5. How will you rename a file in MS-Dos?
6. What is the advantage of wild cards?
So, key in the new date in 'month-date-year' format. However if you do not want to change this
date simply hit the <Enter> key. The current date will be taken as new date.
(B) Displaying and/or changing the current time: The TIME Command
The TIME command is used to display and change the current time.
C: \> TIME <Enter>
Enter the new time in hours: minutes: seconds format. Hit the <Enter> key if you do not want to
change the time. The new time can also be specified along with TIME command.
You will find a blinking cursor in the second line. Enter the text and terminate : each line by
pressing <Enter> key as illustrated below:
My first DOS file. The name given to this file is Hello.Txt.<Enter>
Once all the required text is entered, hit the <Ctrl+Z> keys together to mark the end of Text.
<Ctrl+Z> keys tell DOS that no more text is going to be entered now. Again hit the <Enter> key.
The contents of any file can be viewed very easily by giving the TYPE command followed by the
file name. Let us see the contents of file HELLO.TXT that we have just created by issuing the
following command.
C:\>TYPE HELLO.TXT <Enter>
You can also send the output of a file to the printer. The following command starts the printing job
provided the printer is on.
C:\>TYPE HELLO.TXT >PRN <Enter>
At times, you may require to display a text on the screen while executing a set of commands. The
ECHO command helps you to display a meaningful message on the screen. This command is
issued as illustrated below:
C:\>ECHO Please insert floppy in drive A: <Enter>
The ECHO command is a special DOS command used exclusively in batch files (the files containing
a set of DOS commands). There is one more form of ECHO command i.e., ECHO OFF as shown
below:
C:\>ECHO OFF <Enter>
The above command tells DOS not to display other commands in the batch file.
Users always prefer to see the prompt for currently logged sub-directory. The PROMPT command
tells DOS to include the sub-directory, greater than (>) sign or any text as a part of the prompt. The
various forms of PROMPT command are discussed below:
(i) To display the path designation (e.g., \ACCOUNT\EXPENSE) and the greater than sign as
a DOS prompt, issue the following command:
C:\> PROMPT $p$g <Enter>
After giving the above command, if you are logged to EXPENSE sub-directory of ACCOUNT
sub-directory in the root directory, then the following prompt will come on the screen:
C: \ACCOUNT\EXPENSE>_
(ii) To display a text “1 Love India” along with path designation and greater than prompt, issue
the following command:
C:\>PROMPT I Love India $p$g <Enter>
The above command will display the following prompt:
I Love India C: \>_
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(iii) To display just greater than sign without path designation, you can give the following PC-Software Packages
command:
C:\>PROMPT <Enter>
The command will display the following prompt:
C >_
By this time, you must be familiar with the directory structure of DOS. Suppose your program (say
PRINCE.COM file) lies on the GAME sub-directory of the root directory and you want to execute
it from any other sub-directory (say WINDOWS). To execute PRINCE.COM file, first you will
have to make GAME as the currently active sub-directory and then issue the following command:
C:\GAME>PRINCE <Enter>
DOS provides a shortcut way to locate and run the above program from any other sub-directory
by specifying the path as illustrated below:
C:\ WINDOWS> PATH C:\GAME <Enter>
The above command tells DOS that GAME sub-directory is in the current search path of DOS.
DOS will first search the required program file in the currently logged drive and then GAME sub-
directory. Thus, the PRINCE.COM file can be executed directly from WINDOWS or any sub-
directory as shown below:
C:\WINDOWS>PRINCE <Enter>
Student Activity 3
1. How will you set date and time of system in Ms-Dos?
2. What is the function of CLS command?
3. How will you create a new file in MS-Dos?
4. What is the function of Type command?
5. What is the function of path command?
Internal Commands
The commands which are a part of the main files of DOS (i.e., COMMAND. COM and two hidden
files) are known as Internal Commands. They are loaded in the RAM as soon as the computer is
switched on. The important internal commands are: DIR, COPY, DEL, REN, MD, CD, RD, TYPE,
COPY CON, DATE, TIME, CLS, ECHO, PROMPT and PATH. We have already discussed all these
commands quite in detail. These commands are very frequently used.
External Commands
External commands are those commands which are stored on disks as separate program files.
These files have the same primary name as the command name. The extension of these files is
either COM or EXE. So, at the time of execution of these commands, the corresponding program
file should be present in the DOS sub-directory of the harddisk and DOS sub-directory should
also be in the path search. The commonly used external commands are: FORMAT, DISKCOPY,
CHKDSK, XCOPY and LABEL. Let us learn about these commands.
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Computer Application 1. Making the disk usable: FORMAT Command
in Management
Before discussing the format command in detail, let us first see what is meant by the term 'Formatting'.
Generally when you purchase a diskette from the market, it is unformatted. It can be compared
with a notebook which has blank pages without any ruler lines. You would prefer to put lines,
write page numbers and categories the pages into equal parts so that an index can be made and
the required topic can be searched very easily. Similarly, DOS organizes the disk into concentric
circles which are called tracks. Tracks are further divided into triangular regions. Each such region
is called a sector. The organization of disk into tracks and sectors is called Formatting. The Figure
2.3 makes the formatting concept more clear.
FORMAT command is used for formatting a hard disk or floppy disk. As FORMAT is an external
command, a file by the name FORMAT. COM should be present on your disk. In order to format
the floppy disk, issue the following command:
C: \> FORMAT A: <Enter>
Insert a floppy disk in drive A and hit the <Enter> key. When the formatting of the disk is done,
the following message appears on the screen.
Enter Volume Label (upto 11 characters):_
Here, you can give a name to the disk for its easy identification. A label upto 11 characters can be
given to the disk after it is formatted. If you don't want that your disk should carry any label,
simply press <Enter> key. Now, the following message will come:
Format Another (Y/N)?_
Now, if you want to format another disk, then hit 'Y' (for Yes) and insert that disk in the drive
otherwise type in 'N' (for No) or press any key to end the format program.
New disks should always be formatted for using them. But old disks can also be formatted.
Formatting will make the disk blank by erasing all its data. You may require to format an old disk
if it has bad sectors and is needed again for usage. However, the FORMAT command should be
used with extreme caution. Any disk whether hard disk or floppy disk will lose all data stored on
it once the formatting operation is done. Therefore, you should not try the FORMAT command
for formatting the hard disk. If you format the hard disk, all the contents stored on it are going to
be removed permanently and new tracks and sectors will be created.
FORMAT command also provides a method for making your disk bootable. The following command
is used for this purpose:
C:\>FORMAT A:/S <Enter>
With the help of above command, all the operating system files (COMMAND. COM and two
hidden files) are copied from the hard disk to the floppy disk. This floppy can now be used to load
52
DOS in the computer's memory if you are unable to boot the system from the hard disk. The COPY PC-Software Packages
command cannot serve the above purpose because it cannot copy the two hidden files of DOS in
the boot sector.
The command CHKDSK helps to check the status of the disk. After checking the disk, CHKDSK
displays several items of information. However to get executed, this command needs the program
file CHKDSK.COM. Let's check the status of the disk in drive A through the following command:
C:\>CHKDSK A: <Enter>
On successfully checking the disk, the following status is shown on the screen:
If no drive letter is specified with CHKDSK command, then the currently active drive is checked
for.
Although, you have seen that a volume label to the disk is given at the time of formatting the disk,
DOS also provides LABEL command to change, delete or give new label. This command needs a
program file LABEL.COM. Let us give a label to the floppy disk by the following command:
C:\>LABEL A: <Enter>
So hit the <Enter>key if you want to delete the volume label without typing in anything. You can
also provide volume label directly with the following command.
C:\>LABEL A:MANOJ <Enter>
4. Copying contents of one the floppy disk to another: The DISKCOPY Command
The DISKCOPY command helps you to copy all the contents of one disk onto the other in such
a way that both disks become identical. It copies the contents of the floppy disk present in source
drive onto the disk present in the destination drive. If you have a single drive on your computer,
then the same drive can act as source as well as the destination drive. The command to copy the
contents of one floppy onto the other is given here:
C:\>DISKCOPY A: A: <Enter>
When you issue the above command a screen like the one shown below appears:
Insert SOURCE diskette in Drive A
Press any key to continue
53
Computer Application At this point, insert the diskette whose contents are to be copied and then hit any key. Another
in Management
message appears on the screen as shown below:
Insert TARGET diskette in drive A
Press any key to continue
So, after this message appears, insert the diskette into which the files are to be copied. Thereafter,
press any key to continue the process. Once the process of copying is completed, the following
screen appears:
Copy Complete
Copy Another (Y/N)?_
Press the 'Y' (for Yes) key if you want to copy the contents of some other diskette. DOS will again
prompt you to enter the source diskette. However, if you want to stop the DISKCOPY process,
press 'N' (for No). DISKCOPY command first formats the target diskette if it is unformatted and
then copies files onto it. So, if any contents exist on the target diskette, they are all going to be
removed. The DISKCOPY command needs the program file DISKCOPY.COM for execution.
The XCOPY command is used to copy the files present in sub-directories. The command 'COPY
*.*' copies the files of the currently working directory and DISKCOPY command copies the entire
contents from one floppy to another. So, they are not helpful in copying files selectively. The
XCOPY command offers three special advantages:
a) It prompts you to specify the files that you want to copy.
b) It can also copy directories and other lower level directories.
c) It can be used to copy files from the hard disk to the floppy disk.
Now, let us explore the XCOPY command. If you wish that DOS should ask for your confirmation
for copying a file, then use the /P option along with the XCOPY command. Consider the following
example:
C:\>XCOPY C:ACCOUNT A:ACCOUNT /P <Enter>
If you want to copy the directories and lower level directories, then use the /S option alongwith
the XCOPY command. Look at ,the following example:
C:\>XCOPY C: ACCOUNT A:ACCOUNT /S <Enter>
This command will copy the directory and all the sub-directories onto the A disk. However, if the
/S option is not specified, then the XCOPY command works within the single directory. You can
also use /P and /S option simultaneously with the XCOPY command as shown below:
C:\>XCOPY C:ACCOUNT A:ACCOUNT /P/S <Enter>
The whole path can be specified with the XCOPY command. This command again needs the
program file XCOPY.EXE in order to get executed.
BATCH Files
Very often, you keep keying in the same sequence of commands to do a repetitive job. For
example, everyday, when you start your work on the computer, you first see the listing of files
present on the hard disk. Then, you copy all the files with extension EXE and TXT from the floppy
disk to hard disk. Thus, for achieving your task, you have to issue the following commands
everyday.
C:\>DIR/P <Enter>
C:\>COPY A: *.EXE C: <Enter>
C:\>COPY A: *.TXT C: <Enter>
54
DOS can really simplify your task. All the sequence of commands can be put in a file which is PC-Software Packages
called a batch file. This file offers a great advantage. Any number of commands given in a batch
file can be executed by just giving a single command at the DOS prompt. DOS executes all these
commands one by one. All the batch files can have any primary name but the extension given to
these kinds of files is BAT. The method of creating a batch file is exactly similar to that of creating
any other file on DOS. Let us see it, through an example:
C: \>COPY CON MY. BAT <Enter>
DIR/P <Enter>
COPY A: *.EXE C: <Enter>
COPY A: *.TXT C: <Enter>
<CTRL+Z> <Enter>
In the above example, a batch file by the name MY.BAT has been created. If you want to execute
this file, simplify type in the name of the file at the DOS prompt as shown below:
C:\>MY.BAT <Enter>
or C:\>MY <Enter>
The commands given in this batch file are going to be executed one by one in the sequence
specified.
Enter the above commands on the root directory of bootable floppy disk. Reset your system. You
will notice the above created batch file being executed automatically.
Student Activity 4
1. What are Internal and external DOS commands?
2. What is the function of FORMAT commands?
3. What is the function of CHKDISK command?
4. What is the difference between DISKCOPY and XCOPY?
5. What are batch files?
6. Describe AUTOEXEC.BAT file.
2.3 WINDOWS
Windows is an another popular software. Windows 98, a product of Microsoft is the latest upgrade
of its earlier versions (Windows 3.0, 3.1, 3.11 and 95). It is a Graphical User Interface (GUI) which has
been designed to make your work more intuitive and easy. There is no more need of remembering the
exact syntax of commands to get your work done. Everything is provided in the form of pictures and
55
Computer Application graphics. Windows 98 is a full fledged operating system. The program files and other resources are
in Management
generally accessed with the help of mouse. The Windows 98 desktop acts as the primary media for
organizing your programs, files and resources.
Hardware Requirements
Features of Windows 98
We will briefly discuss some of the features of Windows 98:
1. It provides a graphical operating environment. All the programs and other resources are
provided in the form of Icons.
2. It is a full fledged operating system with an in-built copy of DOS. DOS programs can be
safely run on Windows 98.
3. It is a multi-threaded and preemptive multi-tasking operating system which means that
more than one application can be made to run simultaneously and more smoothly.
4. It supports long file names upto 255 characters, thus, breaking the DOS naming convention
where you can give primary file name upto 8 characters.
5. The plug and play feature of Windows 98 automatically adapts itself to the hardware it is
running on. It can detect hardware and then install all the proper drivers without taking any
help from you.
6. It gets you organize all your work on the desktop or in folders. You can safely click at any
folder to open it up.
7. It is more effective in cleaning up after crash of a faulty application. At any time, if a program
crashes, you can remove it safely from the tasklist without disturbing other running
application. The memory and other resources that the application was using are altogether
freed.
8. It contains a disk compression program which can essentially double your hard disk space,
thus, preventing you from buying a new hard disk.
Now, to open the folder 'My Computer' just double-click it. All the resources on your computer are
shown in it as can be seen in Figure 2.5. Now, if you want to see the files and folders present on
your floppy disk, click the object 3 1/2 Floppy (A:) Icon.
The Taskbar
Taskbar is located at the bottom of the Windows 95 desktop. It contains a start button on the left
side. On the extreme right side, the taskbar shows the current time. The taskbar also shows all the
applications that are currently opened. You can switch between applications using the taskbar.
The Figure 2.6 shows that Paint and Aldus Pagemaker 5.0 are the applications that are currently
running, The button of the application that is running in the foreground appears depressed. The
button that appears raised tells us that the application is running in the background. However, if
you want to run any particular application in the foreground, then simply click at that button
appearing on the taskbar.
This menu shows you the document that you recently opened or worked upon. This offers a
short way of opening a document. It launches the application in which the document was created.
The document menu keeps tracks of the latest fifteen documents that you have used and it puts
them in an alphabetical order.
This menu is used for changing the default system setting. You can fiddle with the control panel,
printer folder and taskbar setting from here.
The Find option of the start menu helps in locating a particular file or a folder. It offers a quick way
of finding a file. In the 'Named' box type in the file name you want to search. Accordingly,
Windows 98 will return you the full details about the file.
Windows 98 has got very smart help to offer. In case you find yourself stuck on any issue simply
select the Help option from the Start Menu. Above all, you can type in your query in your own
words. Windows 98 will display you the related information.
The Run option of the Start Menu helps you to run your file or application straightway. Simply
type in the full path and the filename in the 'Open' box and click at 'OK' button. You can also make
use of the 'Browse' button in order to locate appropriate files.
58
7. The Shutdown Command PC-Software Packages
This command is used for shutting down the system. It offers three options. You can shut down
your system, restart your system in windows mode itself or you can switch yourself to DOS mode
temporarily. Select appropriate option depending upon your requirement.
Student Activity 5
1. Why is windows called GUI based operating system?
2. What are the minimum hardware requirements to run windows 98?
3. What are the features of windows 98?
4. What is a desktop?
5. What is the taskbar? What does it hold?
Windows Explorer
The File Manager of Windows 3.x is replaced with Windows 95 explorer. It helps you to manage
and organize your files and folders. In order to start explorer click at the start menu. Select
Programs and then the Windows Explorer option. The 'Windows Explorer' windows comes up on
the screen as shown in Figure 2.9. This screen lets you to explore anything on your desktop. The
left part of the explorer screen shows the desktop at the highest level. All the components of the
desktop like 'My Computer' ,'Network Neighbourhood', 'Recycle Bin', etc., are shown under it. You
must have observed that some components of the desktop have a plus sign (+) before them. It
shows that there are deeper level of components under it. On clicking at the plus sign, the next
level of the hierarchy is shown.
This layering of components continues as long as there is deeper level of folders or components
underneath. The right side of the Explorer Screen shows the contents of the folder or the
components that are selected in the left part of the explorer window. In the right part of window
only, the major actions are performed. Now, we will learn some of the important functions that are
performed frequently.
A file or a folder can be safely deleted by following the steps given below:
1. Select the file or folder that has to be deleted. 59
Computer Application 2. Hit the <Del> key or from the File menu, select the Delete option.
in Management
3. Windows 98 will confirm before deleting the file.
Windows 98 allows you to move files from one place to another. A file can be moved from one
folder to another by simply performing the following drag and drop procedure:
1. Select the file that you want to move from the right pane.
2 Click the file or the folder on the left pane and drag it in the new destination.
In order to copy a file to the floppy disk, follow the steps mentioned below:
1. Select the file that has to be copied to the floppy disk.
2. Right click the mouse button and select the Send To option.
3. Select the floppy disk to which the file has to be copied.
In Windows 98, deleting a file is a two step process. Once the file is deleted, it is put in the 'Recycle
Bin'. The 'Recycle Bin' appears on the desktop. It is of immense use if you have accidently deleted
your files. The files once deleted can be restored from the 'Recycle Bin'. However, if the file is
deleted from the 'Recycle Bin' also, then you cannot in any case recover your file. So, the Recycle
Bin helps you to retrieve deleted files. In order to restore a file from the 'Recycle Bin', follow the
steps given below:
1. Double Click the 'Recycle Bin' icon available on the desktop. A dialog box opens up as
shown in Figure 2.10.
2. This window shows all the files that have been deleted. Select the file that you wish to
restore.
3. From the File menu, select Restore option.
If you wish to delete all the files from the Recycle Bin also, then follow the steps given below:
1. Double-click the 'Recycle Bin' icon on the desktop.
2. From the File menu, select the Empty Recycle Bin option.
3. Windows 98 will ask you to confirm before deleting all the files.
Windows 98 Accessories
Windows 98, like its predecessors, contains several built-in accessories which make your computer
easier and more convenient to use. In order to access Windows 98 accessories, click on the Start
button, move the mouse cursor to programs and then click at the Accessories option of the
cascading menu. We will learn a few of the commonly used built-in accessories of Windows 98.
(A) WordPad
Microsoft WordPad for Windows 98 is a very simple word processing program which allows you
to create, read and modify simple documents. It is more or less similar to Windows 3.x Notepad
program but contains more features and is capable of opening a wider variety of documents. It
contains basic file manipulation, editing, viewing and formatting tools that are essential for creating
simple documents. It contains standard menu items. The Wordpad can be seen in Figure 2.11.
The Microsoft Fax program of Windows 98 helps you to send and receive faxes. It can help you
to send the documents that have been created on your computer. You can also send documents
directly from compatible applications without ever leaving the application e.g., using Word for
Windows, you can use the File menu's Send command to direct the output of that application
directly to a fax telephone number rather than a printer.
Windows 98 contains a number of useful system tools to help you see and configure your
system. Let us briefly discuss a few system tools.
Backup: This program helps you to perform backups of your computer system.
Disk Difragmenter: This system tool reconfigures files on your hard disk so as to speed up disk
access times.
Scan Disk: This utility is more or less similar to the old DOS checkdisk utility. It scans your disk
and gives you the disk status by finding out the used, unused and bad sectors.
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Computer Application Drive Space: This utility is a disk compression program that can double up the space on a disk
in Management
drive. If you need some extra space on your disk, you can use this facility.
(D) Multimedia
Windows 98 contains utilities that can control your CD-ROM player and multimedia abilities. You
can use it to control various aspects of your multimedia system.
(E) Calculator
Windows 98 has a desktop calculator that can perform simple calculations. It contains both the
standard as well as the scientific calculator. The calculator has been shown in Figure 2.12.
(F) Paint
If you are a graphics lover, Windows 98 can fulfil your desire. It contains 'Paint' utility which can
create simple graphics. You can create, open, view and edit graphics files such as bitmaps, PC
Paintbrush files, etc. A typical Paint can be seen in Figure 2.13.
There is absolutely no end to what a word processor can do. By now you must have realized that
the word processing applications have become much more sophisticated than before.
This would bring up Word with a new document opened up for you. Your computer screen will
match closely to the Figure 2.16. This blank page is nothing but an empty file created automatically
by WORD. This file by default gets the name - Document l. The extension given to a Word
document is 'doc'.
64
Screen Elements PC-Software Packages
When Word opens up, you will notice two windows on the screen, one nested closely within the
other. The larger among these is called the Application Window, which frames the entire screen. The
smaller window is called the Document Window, which fits in the application window. Both these
windows serve a different purpose. The application window helps the user to communicate with the
Word program, whereas, the document window is used for creating as well as modifying the Word
documents. So, as you keep typing, the words displayed on the monitor or screen, are actually shown
in the document window. The different elements of the screen are shown in Figure 2.16. The different
elements of this screen are outlined in Table 2.1.
Text Area
Menu Bar It shows menu options of Word and is located under title bar.
Standard Located exactly below the menu bar and gives access to WORD's most
Toolbar frequently used commands and utilities.
Formatting Lies below the standard toolbar; it offers commonly used formatting
Toolbar commands.
Ruler Line Located below the formatting toolbar and provides ongoing page measurement
and quick access to margins, tabs and indents.
Status bar Located at the bottom of the screen; it displays important and varied
information about the currently opened document like page number, column
number, line number, etc.
View Buttons Located towards the left side of the horizontal scroll bars(above status bar);
they show the documents in different views like normal view, page layout view,
outline view etc.
Horizontal Help the user to move in the left or right side of the document.
Scroll Bars
Maximise Located in the upper right corner of the screen; it controls the size of the
Button application window.
Minimise Located in the upper right corner of the screen, towards left of maximise
Button button; it helps to mini mise the whole application and show it in the reduced
form on the taskbar.
Close Button Located in the upper right corner of the screen, towards right of maxi mise
button; it helps to shut down the opened application; it also allows the user to
save the opened files before quitting Word. 65
Computer Application Contents of Menu Bar
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All the menu pads located on the menu bar can be pulled down by clicking at them or by pressing
<Alt + key> where 'key' is the underlined character of the menu name. At one time only one menu
pad can be activated and pulled down. From the pull down list, any entry can be selected with the
help of mouse. In all the pull down menus, you would find that a few entries are shown in light
color. These entries are called 'ghosted' entries and are inaccessible, These ghosted entries
become solid only when the features they support become accessible. For example, the cut, copy,
paste entries become active from the 'Edit' menu only when some text is selected and is made
available on the clipboard. When the text is no more selected, these entries again become inactive.
5. Format: The 'Format' menu is basically used for enhancing the look of the document. It can
make your document’s look beautiful by adding a variety of font types and sizes, paragraph
formats, tabs, borders and columns, drop caps, bulleted and numbered lists and style
settings. The 'Format' menu can be seen in Figure 2.21.
8. Window: The 'Window' menu allows you to add, arrange and select document windows in
a case where more than one document is open. The 'Window menu can be seen in Figure
2.24.
9. Help: The 'Help' menu can be used to look for specific information. It also gives some
knowledge about Microsoft Word itself. If you find yourself in a difficult situation anytime,
then do not hesitate taking help from Word through this particular menu. The ‘Help’ menu
68 has been shown in Figure 2.25.
PC-Software Packages
Student Activity 7
1. List some Windows 98 accessories.
2. What is a word processor? Name some words processing packages.
3. What is the use of word processing?
4. How will you start MS-Word?
5. Describe various screen elements of MS-Word.
6. Describe various menus available on Menu bar.
This is not end of the road. The enhancements done to Word 2000 as discussed above are just a
small chunk. 69
Computer Application Working with Documents
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It's time to familiarize ourselves with the various important concepts like creation of new files,
opening existing files, saving and finally closing them.
At times, you might need create a new document from scratch. So, for creating a new document,
click at the 'File' menu and then select the 'New' option as shown in Figure 2.27. Now, Word is
ready to accept text as well as other related commands from you.
You can also open a new document by clicking at the 'New' button available on the standard
toolbar. Look for the 'New' icon in Figure 2.29 shown on the next page. Remember to save your
document before quitting. ('Saving a Document' is being discussed in the subsequent part).
Opening a Document
If your document is stored on any of the storage devices like hard disk or floppy disk, then it
becomes possible to retrieve that document and the user can manipulate it the way he/she wants.
Word offers a variety of ways to open your document which are discussed below:
Click here
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Computer Application Click at the Start button. Point at 'Open Office Document' and click it as can be seen in
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Figure 2.28. Alternatively, click at the option 'Open Office Document' of the Office shortcut bar
available on the desktop.
Click at the 'File' menu and select the option 'Open' as can be seen in Figure 2.30.
Alternatively, for opening a document, just doubleclick at the 'Open' button from the standard
toolbar. This icon looks exactly similar to a file folder and has been shown in Figure 2.30.
One very important thing to observe here is that - an 'Open' dialog box appears on the screen after
employing any of the above mentioned methods of opening a document. The 'Open' dialog box
has been shown in Figure 2.31. In this 'Open' dialog box you would notice a 'look in' box which is
used for selecting the drive as well as the folder where your required document is resident in.
Then, there is 'Files of Type' box which helps you to select the kind of file that you want to open.
Suppose you want that only the Word documents should be shown in the file list, then click at the
pull down arrow and from the drop down list, select 'Word Documents' option. In case you want
to see all the files in the selected drive, then select' All Files' option from the drop down list. Finally
click the filename in the file list and click at the <Open> button or double click the filename to open
up the file.
For future retrieval of the document, it needs to be saved on hard disk or floppy disk. Once all the
text is entered, save the document with any of the following methods:
Method 1
Click at the 'File' menu and then select 'Save' option. You would notice a screen that looks like the
Figure 2.32. When the file is being saved for the very first time, the 'Save as' dialog box comes up
because Word needs some additional information from you.
First, Word wants you to give a name to your file. This has to be given in the 'Filename 'box.
Secondly, the kind of file you are trying to save, should be given in the 'Save as type' box. Thirdly,
the place where you want to save your document should be given in the 'Save in' box. After giving
all this information, click at the <Save> button. Your file is finally saved onto the disk.
The 'Save as' dialog box is displayed only once till the time you don't give a name to your
document. Once the document has a name, next time if you try to save your file after making a few
changes in it, then the 'Save as' dialog box will not appear on the screen.
Save Button
The other way of saving your files is by clicking at the 'Save' button available on the standard
toolbar. You can see the 'Save' button in Figure 2.32.
It's a good idea to keep saving your documents after every few minutes. The reason is if the
computer goes down or a power failure occurs, then the chances of recovering some contents in
the document are high. Unsaved new documents are the most vulnerable.
Closing a Document
Word offers a very handy method of closing documents. Like, you would prefer to close and
remove the office files that are no more required on your table, in the similar manner you may want
to close Word documents too. So, for closing a file, click at the 'File' menu and select the 'Close'
option as shown in Figure 2.33. This will close the file that is recently opened. As many documents
are opened in WORD, you are required to issue 'File - Close' commands for those many times to
close all the files one by one.
Word will also prompt you to save your files before closing them as shown in Figure 2.34. If you
want that your file should be saved before it is closed, then click at <Yes> button otherwise hit the
<No> button. A case may arise when you want to continue working in the same document after 73
Computer Application issuing 'File Close' command. Select the <Cancel> button. It will allow you to work again in your
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document thus cancelling the issued command.
To quit Word or to close the Word application program, click at 'File\Exit' options as shown in
Figure 2.35. With this command, all the currently opened documents are also closed automatically.
Word will again prompt you to save your files before quitting.
Student Activity 8
1. How will you create a new document in MS-Word?
2. How will you open a pre-exiting file in MS-Word?
3. How will you save a document in MS-Word?
4. How will you exit from MS-Word?
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PC-Software Packages
2.6 EDITING DOCUMENTS IN WORD 2000
Editing means modifying or making changes in your document. It would involve:
z Inserting new text
z Copying text from one part of the document to another part
z Moving text from one part of the document to another part
z Deleting unwanted text.
Before exploring all these editing features of Word 2000 in detail let us discuss the word-wrapping
feature first. Incomplete words or the words that exceed right margin look very clumsy. With the
help of word wrap feature, Word automatically wraps around the word in next line, when the
cursor reaches the right margin. So, every time when you reach at the end of line, you don't need
take care of hitting the <Enter> key. The only time, you need press the <Enter> key is, when you
want to end a paragraph or insert a blank line.
Selecting Text
Text needs be selected for performing various block operations (like Copying/ Moving/ Deleting)
on it and for easing our work. Selection of text can be done both by mouse as well as by keyboard.
First of all, let's learn how to select text using a mouse. The various methods of selecting text by
mouse are discussed below:
1. Hold your mouse button from where you want your selection to start and drag the mouse
either rightways or downwards. Release the mouse button at the place where you want
your selection to end up.
2. If you want to select a single word, then take your mouse pointer at that word and double
click it.
3. Paragraphs can be very easily selected by triple clicking anywhere within the paragraph.
Keyboard can also be used to select text. The method of selecting text by keyboard is discussed
below:
1. Take the cursor at a place where you want your selection to start.
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Computer Application 2. Hold down the <Shift> key and move the cursor with arrow keys in the direction required.
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Release the keys at a place where you want your selection to end up. In this way, your text
would be highlighted.
Inserting Text
Generally, when you startup WORD, it is in the Insert Mode, which means as text is typed in, the
following text is pushed towards the right side. So, wherever you need put in new text in your
document, take your cursor at that particular location and start typing in. The method is exactly
the same for inserting either a single character, word, line or a couple of lines.
At times, you also might need overwrite the pre-written text. For that matter, press the <INS> key
from the keyboard once. This would put Word in overwrite mode and the word 'OVR' will be
displayed on the status bar at the bottom of the screen. Now, when the new text is typed in, the
existing contents at the current cursor location are going to be overwritten by the new text. If you
want to put yourself back in the insert mode, press the <INS> key once again.
Copying Text
Copying means duplicating the contents of the document at some other desired place. The
procedure for copying text is almost the same as that of moving text with a little difference which
is being discussed in the following steps:
1. Select the text that has to be copied.
2. Press <Ctrl + C> keys. Alternatively, select the 'Copy' option from the 'Edit' menu.
3. Take the cursor wherever you want the text to be pasted.
4. Hit <Ctrl + V> keys. Alternatively select the 'Paste' option from the 'Edit' menu.
You can also use the 'Copy' and 'Paste' button (shown in Figure 2.29) available on the standard
toolbar for copying and pasting text. With the above procedure, you would notice the same text
appearing at two places in the same document.
Moving Text
Moving text means removing text from one portion of the document and placing it at some other
location. For moving text, do the following steps:
1. First, select the text that you want to move.
2. Then, click at the 'Edit' menu and select the 'Cut' option. Alternatively you can also cut the
selected text by pressing <Ctrl + x> keys. Once the text is cut, you will notice that the marked
text disappears from the screen. Don't feel worried, your text is put on the windows clipboard
(temporary portion, of memory) from where it can be pasted anywhere.
3. Look for the place, where you want your text to be placed. Take the cursor at that location and
hit the <Ctrl + v> keys or alternatively select the 'Paste option from the Edit menu.
You can also make use of the 'Cut' and 'Paste' button (shown in Figure 2.29) from the standard
toolbar for cutting and pasting the selected text respectively.
Deleting Text
A passage of text can be very easily erased off by selecting it and pressing <Del> key on the
keyboard. A single character can also be deleted very easily by positioning the cursor at that
particular character and hitting the <Del> key.
If you want to scrap off only a single word from your document, select the word by double
clicking it and hit the <DEL> key. You can also delete words by following commands:
z Press <Ctrl + Del> keys to delete next word
z Press <Ctrl + Backspace> keys to delete previous word.
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Student Activity 9 PC-Software Packages
1. What do you mean by editing a document?
2. How will you insert text in a document?
3. How will you make the duplicate of some portion of text in a document?
4. How will you delete text in a document?
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Computer Application Using Formatting Toolbar
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The formatting toolbar is designed very artistically as shown in Figure 2.36. It contains most of
tools that need be used to give a complete and wholesome look to your document. The toolbar
also shows you the font type and size as applied to your text. It also displays the effects (Bold,
Italic or Underline) as given to the text. For applying a font type and size to your text, use the
formatting toolbar in following steps:
1. Select the text.
2. Click at the arrow beside the font type box and select a font type of your choice from the
drop down list.
3. Again, click at the arrow beside the font size box and select an appropriate font size from the
drop down list.
The required font type and size can also be applied to the text by using 'Formal menu as described
in following steps:
1. Select the text.
2. From the 'Format' menu, select the 'Font' option. The 'Font' dialog box appears on the screen
as shown in Figure 2.37.
3. Choose appropriate font type from the 'Font' box. You can move up or down in the 'Font' box
with the help of up and down arrow keys.
4. Similarly, choose the required font style and size for your text from the 'Font style' and 'Size'
boxes respectively.
You will find the look of your text changing with the application of new font type, style and size.
If you have given a keen look at the formatting toolbar: then you must have observed three
buttons showing the letters B, I and U. The letter 'B' stands for Bold, 'I' for Italic and 'U' for
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Underline (Refer Figure 2.36). In order to make your text look a bit darker than the rest of the PC-Software Packages
document, concentrate on the following steps:
1. Select the text.
2. Click at the 'B' button.
On carrying out these steps, the 'B' button becomes depressed or lightened. If you do not want
the text to be bold select the text again and click at the 'B' button. This button on the toolbar again
becomes prominent and your text is not bold anymore.
At times you would like to see your text in italics or would like to underline it. To do this, do the
following steps:
1. Select the text.
2. Click at 'U' button to underline and 'I' button to italicise it.
Alternatively, the same work can also be done using the 'Format' menu by following steps:
1. Select the text.
2. Click at the 'Font' option of the 'Format' menu.
3. In the 'Font' dialog box, activate the 'Bold' option or 'Italic' option from the 'Font style' box
to show your text in bold or italics. (Refer Figure 2.37)
4. In order to underline the text, select the required option from the 'Underline' box drop down
list.
If you are a keyboard person, you can also use one or more of the following key sequences to
achieve the same, after selecting the text:
z Press <Ctrl + B> keys to bold the text
z Press <Ctrl + 1> keys to italics the text
z Press <Ctrl + U> keys to underline the text
Alignment of Text
Text alignment means placement of text between the margins. Your text can be left, right, centre
aligned or it can be justified within the margins. Left alignment of text would mean the arrangement
of text evenly in a straight line at the left side of the document but with uneven edges on the right
side. Right aligned text is just the opposite of left aligned text with text evenly arranged at the right
edge of the document but uneven from the left side. Justified text would involve even edges of
text along both margins. Centre aligned text means that the text is placed exactly in the centre of
the page. Centre aligned text is most suitable for giving titles, headings etc. Generally and most
frequently the text is left aligned because then the text becomes easily readable and understandable.
Now, let us find out how text can be aligned using the formatting toolbar.
1. Select the text (it could be a single line or a paragraph or the whole document).
2. Click at any of the alignment buttons from the formatting toolbar to get the desired result.
(Refer Figure 2.36).
If you are more in the habit of using keyboard, then give the following keyboard shortcuts after
selecting the text:
z Press <Ctrl + L> keys to left align the text
z Press <Ctrl + R> keys to right align the text
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Computer Application z Pres8 <Ctrl + J> keys to justify the text
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z Press <Ctrl + E> keys to show the text in the centre
Formatting Paragraphs
Formatting means deciding alignment of the paragraph. It also includes the spacing that is to be
put in between the lines. In order to carry out formatting on Paragraph, it needs be selected first.
Then go to the 'Format' menu and do the lowing steps:
1. From the 'Format' menu, select 'Paragraph' option. A 'Paragraph' dialog box shoots up on
the screen as shown in Figure 2.38.
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Using Formatting Toolbar PC-Software Packages
In case you decide that you don't require 'numbers' or 'bullets', you can very easily put them off
by repeating the above steps.
This method perhaps offers a wider choice of symbols other than the typical black circle. Let us
discuss this method:
1. Select the text.
2. Select the 'Format Bullets and Numbering' option.
A 'Bullets and Numbering' dialog box appears on the screen as shown in Figure 2.39. Select the
'Bulleted' tab in case you want bullets in your document. If you wish to put numbers then select
the 'Numbered' tab. Choose any of the bullets or numbers and apply it onto your document by
clicking <OK> button. You see how easy it is to place bullets and numbers in your document.
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Computer Application
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Inserting Clips
To place clips in your document, go about performing the following steps:
1. Select Insert/Picture/Clipart'. A dialog box by the name 'Microsoft Clipart Gallery' is shown
on the screen as shown in Figure 2.44. Now, from this dialog box, select the 'Clipart' tab. You
will notice that your clipart gallery is indexed on major keywords. If you scroll down in the
window under the head 'All categories', you would find a fairly long list of clips. So, in order
to make our search easier, select any particular category in the category list. In the adjoining
window, you would find all the clips relating to that category together.
2. Search through the clips and decide an appropriate clip for your document. Select anyone
desired clip and click at the <Insert> button. You will find that particular picture placed in
your document at the current cursor position.
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2. Take your pointer at any of these handles. The pointer will change into a double headed
arrow.
3. Click and drag the handle in the direction desired to make your clip big or small.
4. Release the mouse pointer when the required size of your clip is achieved.
3. Similarly, change the settings in the Bottom, Left and Right boxes as well.
At times, you might want that the changes that have been made recently should apply to the
current document only, then click at <OK> button. But in case, you want that the current document
as well as any other new document that you open should have these page settings, then click at
the <Default> button. The next step would be to click at the <Yes> button in which case Word is
trying to seek your permission in changing the default settings for page setup.
Now, let us learn how to set the top and bottom margins using the vertical ruler line. This vertical
ruler line appears only in the Page Layout view. So, in a case if your vertical ruler line is not
apparent on the screen, then first switch yourself to Page Layout view by selecting 'Page Layout'
option from the 'View' menu. To set the top margin:
1. Take your mouse pointer on the thin gray line that appears between the darkened and white
areas on the top side of the vertical ruler line.
2. As soon as your mouse pointer takes the shape of a double headed arrow, click and drag it
either upwards or downwards to attain the desired top margin.
3. Release the mouse button.
When you are trying to play with the margins, a line is shown across the page which keeps
moving up or down according to the movement of your mouse pointer. This gives you the exact
location of your margin on the page.
Student Activity 10
1. What do you mean by formatting text?
2. How will you make the text bold and Italic?
3. What do you mean by text alignment? What are the various types of alignments available
86 in MS-word?
4. When do we use bullets and numbering feature of MS-Word? PC-Software Packages
5. How will you find a group of words in MS-Word? How will you replace them with some
other words?
6. How will you give numbers to you pages?
7. How will you insert clip-art in MS-word?
8. How will you set margins using ruler?
9. What is the application of MS-word in corporate sector?
What is a Database
A database is a collection of related information. An example of a typical database is a private
telephone directory. It contains related information about each person like his name, address and
telephone number. Other examples of a database include list of customers and suppliers,
maintenance of stock in warehouses, collection of tapes in libraries, maintenance of members in a
country club, etc.
Components of a Database
All the information stored in an Access database is kept in tables as illustrated in Table 2.2.
Table: A table is a collection of some specific kind of data. It is the basic element of the database.
Data put in a table is organized in rows and columns.
Record: Each row is called a record and it contains the complete information about one particular
item, e.g., in a telephone directory all the essential details about a single person like his name,
address and city form one record.
Column: Each column is called a field. It holds information about a certain type for all records. A
field could be a name, address, telephone number, etc.
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Computer Application In the example shown in Table 2.2, the table contains four records and five fields. Thus, each
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record contains a complete and wholesome information about one item. Each column contains the
same type of information for all the records like S.No., Name, Address, etc. The field 'Name'
contains the information related to 'Name' for all records. So, you can have any number of records
as well as fields in your table. You can add more records to your table. In the similar manner, you
can also expand the field list. Your database can have any number of tables. The 'Relational'
concept allows to build relations between different tables.
Opening a Database
In order to access any table form or report created in a database, it has to be opened first. A
database can be opened by the following methods:
The different parts of an Access Window are shown in Figure 2.50. You are already familiar with
most of the components of this window. You have already been introduced to title bar, minimize
button, maximize button, close button, control menu button, menu bar, toolbars and status line.
The term 'Database Window' has been brought up for the very first time before us.
Toolbar
Database
window
Status
line
1. Click at the Blank Database option to create a new database. Finally, click at the <Ok>
button. The Figure 2.52 appears on the screen.
ruby
2. Access wants you to give a name to your database. So, in the 'Filename' box, type in the
name of the database. Here, the name given to an Access database is 'Ruby'. Then, click at
the <Create> button. Now, the Figure 2.53 appears on the screen.
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The 'Table Wizard' contains some sample tables as shown in Figure 2.55. Select the table in the
'Sample Tables' window according to your requirement. The corresponding fields of the table are
shown in the adjacent window. You can put all the fields from the sample table. You can also
decide and put a few fields in your table from the fieldlist. So, for putting the fields selectively,
select the field and click at the single arrow pointing towards the right side. However, if you wish
to put all the fields from the sample table into your table, click at the double arrow pointing
towards the right side. In case, if you have accidentally put a wrong field into your table, then
select that field and click at the single arrow pointing towards the left side. This will clear the field
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Computer Application from your table. The double arrow facing towards the left side will remove all the fields from your
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table. However, if you wish to give a new name to your field, then click at the <Rename> button.
A 'Rename' dialog box comes up on the screen. Simply, type in the new name. Finally, click at the
<Next> button.
The Figure 2.56 appears on the screen. The 'Table Wizard' appears on the screen. You can give a
name to your table. The name given to the table in the example is 'Mailing List'.
Click at the <Next> button. Figure 2.57 appears on the screen. Access allows you to create a
temporary form for entering data through the 'Enter data directly into the table' option. However,
if you wish that the form should also be saved for future use, then click at the option <Enter data
directly into the table> using a form the wizard creates for me'. In the latter case, the wizard will
automatically create a new form for you according to the fields that you have decided to put in
your table. Finally, click at the <Finish> button. Figure 2.58 appears on the screen.
Click in the <First Name> box and enter the first name of the person. In a similar manner type in the
rest of the appropriate details by clicking in respective box. Once all the details of a single record
are entered, click at the <Next Record> button. It will take you to the next record and there you can
type in the details of the second record. The 'Next Record' button is also used for seeing the
contents of the next record of the table. The 'Last Record' button shows you the details of the last
record. The <Previous Record> button will take you to the previous record. The very first record
of the table can be seen with the help of the 'First Record' button. Once all the records are entered,
click at the Save As option of the File menu to save the form and give an appropriate name. Click
at the <Close> button appearing on the extreme right of the screen to get back to the Database
Window.
The contents of the table can be seen by going back to the 'Database Window'. Click at the
<Forms> tab and select the form name whose contents are to be seen. Lastly, click at the <Open>
button. You can navigate between different records to see their details.
Student Activity 11
1. Define DBMS.
2. What are the various components of a database?
3. How will you start MS-Access?
4. What are the features of a database window?
5. How will you create a table in MS-Access?
6. How will you view the contents of the table?
7. How will you exit from MS-Access?
In order to move around the datasheet, you can make use of either the keyboard or the mouse.
You can select any data element by clicking it with the help of mouse pointer. Using the keyboard,
press the <Shift + Tab> keys together to move from one field to another. Once you have reached
the last field in the current row, press the <Tab> key again to go to the first field of the next record.
However, if you are in the first field, pressing the <Shift + Tab> keys will take you to the last field
of the preceding record. You can also use the up and down arrow keys to move from one record
to another. In order to select the entire record, click in the left most column of that particular
record's row.
A table is opened in the Design view in order to examine its structure. It shows the fields present
in the table as well as the data type and properties for each field.
The grid at the top of the Design view window shows all the fields, their data types and some
description about the field. The lower part of the window shows the other properties of the field
that has been selected in the upper grid. At one time, the properties of only one field that is
selected is shown in the lower window.
You can very easily view the details of another field by simply clicking anywhere in the grid row
on which it appears. The information in the lower window changes to match the properties for the
newly selected field. Access shows the currently selected field by putting an arrow on the row in
the left most column of the upper window.
If the left most column of the grid displays. a key icon, then that field is being used as the primary
key for the table. This means that this particular field is being used as a unique field. This field can
never contain repetitive entry. All the data for this field is uniquely identifiable. Therefore, this
field is said to be the 'primary key' of the table. Now, let us study the basic structure of a table in
detail.
1. Field Name: The Field name column present in the upper window specifies a name for the
field. No two fields in the table can carry the same name. You can provide any name to your
field. However, the Field name cannot have more than 64 characters. It can contain any
combination of letters, numbers, spaces and special characters except periods, exclamation
marks or square brackets. Field names can never start with a space.
2. Data Types: The Data Type column is present next to the Field name column. It signifies the
type of information stored in the field. The edit box for this column is a drop-down list box
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Computer Application which contains all the available data types. Let us briefly explore all the available data
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types:
(a) Text: It stores the alphanumeric data which contains a string of characters.
(b) Number: Any kind of numeric data is held by this data type.
(c) Date/Time: It stores the date and time.
(d) Currency: It is a special numeric data type used for holding monetary values.
(e) Autonumber: This kind of data type is mostly used for primary key fields. Fields of this
data type are read only. Access automatically inserts the next number in the sequence.
(f) Yes/No: This data type can hold only one of the two values such as Yes/No or True/
False.
(g) Memo: This data type is used for storing long text fields upto a limit of 64,000 characters.
This data type is used, to store long comments or notes.
3. Description: The Description column is present adjacent to the Data type column. This is
used to give a short description about the field. The Description column provides complete
explanation of the purpose the field serves.
4. Properties: Each field has got its own set of properties. It further defines the fields and how
it is used in the database. So, as you move from one field to another in the upper window,
the corresponding properties in the lower window also change. Now, let us look at some of
these properties:
(a) Field Size: The Field size property appears only for the Text and Number data types.
This property specifies the maximum number of characters that can be stored in the
field for a single record for a text value. For Number fields, field size specifies the type
of number that will be stored in the field. The available choices are Byte (a. number from
0 to 255, whole numbers only), Integer (-32,768 to 32, 767, whole numbers only), Long
Integer (-21, 47, 483, 648 to 2147, 483, 647, whole numbers only), Single (can hold a very
large number and fractional numbers) and Double (stores numbers larger than single).
The choice made here does affect the amount of space Access uses to store the field.
Therefore, you should be very careful in deciding the field size.
(b) Caption: The Caption property specifies a string that has to be displayed as the column
heading whenever the field is displayed in the Datasheet view.
(c) Default Value: The Default value specifies a value that will be put into the field if it is
not given by the operator at the time of entering the record.
(d) Validation Rule and Validation Text: The Validation rule property specifies a test that
is performed on any data that is entered into the field. If the data does not pass the rule,
then a message is shown on the screen. However, if any message is typed in the
Validation text property, then that message is displayed, otherwise some system error
message is shown on the screen. For example, for a price field if you specify the
validation rule as '>100', then any data below 100 will not be accepted and the computer
will prompt you to re-enter.
(e) Required: The Required property forces you to enter a value if it has been set to 'Yes'.
You cannot leave that particular field empty at the time of entering record in your table.
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Opening a Form PC-Software Packages
First of all, open the database that contains the required form. Now, in the database window, click
at the forms tab. All the forms of the currently active database are shown in the window. Select the
Form name with the help of the mouse pointer and finally click at the <Open> button. Figure 2.61
appears on the screen. Using the arrow keys, you can view the other records of the table.
Creating a Form
A form can be very easily created using the Form wizard. The form wizard is the quickest and the
easiest way to create a form that is bound to a table. You can use the form immediately or you can
make changes to get the form look exactly the way you want. Thus, in order to create a form using the
form wizard, first of all, select the Forms tab in the Database window. Finally, click at the <New>
button. A 'New form' dialog box appears on the screen as shown in Figure 2.62.
This Form wizard dialog box wants you to select the fields from the table that need be added to the
form. By clicking the single arrow pointing towards the right side, you can add fields one by one
to your form. You can add all the fields into your form by clicking at the double-arrow pointing
towards the right side. After you have decided and put the fields, click at the <Next> button. You
will find Figure 2.64 coming up on the screen.
Creating a Report
A simple report can be created using the ‘Auto Report' feature of Access. ‘Auto Report’ creates
a report automatically containing all the fields and records from the selected table. Each field on
the report appears in a single line carrying a label on the left side of the page. You can create a
report by first going to the main window and then clicking at the Reports tab. Click at the <New>
button present on the main database window. Finally, click at the 'Auto Report' option. 'Auto
Report' creates a single-column or tabular reports. 'Auto Report' is the quickest and the easiest
way of creating reports.
Printing a Report
Most of the times, a hard copy of the report is taken out and put in record file. It helps in taking
very useful and quick decisions. To print a report select it from the Report tab in the main database
window and then choose 'File/Print' option from the Database window. A 'Print' dialog box appears
on the screen. Use this dialog box to choose the printer that will print the report, which pages to
100 print, what range of pages to print, how many copies and other print properties.
Saving and Closing Reports PC-Software Packages
A report can be saved by choosing the File/Save option. When the report is being saved for the
very fist time, a dialog box appears before you which asks you the name of the report. By default,
the name 'Report l' is given to your report. In order to close a report, click at the Close box available
at the right corner of the screen.
Moreover, it becomes very handy for a manager to maintain data and prepare reports based on
these data. A variety of reports can be generated depending upon the precise and specific
requirements of the managers. It also allows you to create queries and provides you an answer to
the manager's most difficult decision oriented questions.
Student Activity 12
1. What is the difference between design view and datasheet view?
2. What is a form? How will you create a form?
3. How will you edit records in a form?
4. What is a report? How will you open and view reports in MS-Access?
5. How will you print a report?
6. What are the application of a database in corporate sector?
EXCEL 97 is a very powerful and easy to use spreadsheet package which is being commonly used
these days. It is basically an end user application package. It works very well with numbers and
their complex calculations. EXCEL 97 helps to put and prepare your data in an organized, orderly
and meaningful fashion. EXCEL 97 finds its major contribution in creating reports, using formulas
and performing calculations. It is best suited for scientific and statistical analysis. EXCEL 97 can
also be used to prepare Profit and Loss accounts, Balance Sheet and other Tax statements. It
works well for both simple and complicated numbers. EXCEL 97 can do anything for you. Your
imagination can be the only limit. It can be used for preparing analytical reports including statistical
analysis, forecasting and regression analysis. Good looking and attractive charts can be created
which depict data in clearer and meaningful fashion. EXCEL 97 can also be used to create
relationships between different types of data. EXCEL 97 can do all the work of a full fledged word-
processor but it lacks the advanced features of desktop publishing. It also supports the high level
features of object linking and embedding which means data from Word can be safely and easily
put and linked with data in EXCEL and vice versa is also true.
An Electronic Spreadsheet can do a great job with mind crunching numbers. Any kind of complex
calculation can be done in a matter of few seconds.
To startup EXCEL in Windows 98, the steps given below can be followed:
1. Click on the Start button at windows taskbar.
2. Select Programs option
3. Select Microsoft Excel option.
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Figure 2.69: Starting Microsoft Excel
You will find that the given menu options are very much similar to Figure 2.69. As stated in the PC-Software Packages
previous lesson also, the menu options shown to find out in this figure might not exactly resemble
those seen on your computer. So, you need do a bit of exploring job where actually MS-EXCEL
is installed on your computer.
Alternatively, MS-EXCEL can also be started up through the following steps:
1. Click at the Start button.
2. Select 'New Office Document'. A 'New Office Document' dialog box appears on the screen.
Double-click at the blank workbook option or select one of the other tabs, such as spreadsheet
to start EXCEL 2000.
Once EXCEL 2000 is loaded in the computer's memory, a blank workbook shoots up on the screen.
A typical name given to a file in EXCEL is Workbook. The terms Excel Document, Excel Workbook
and Excel File carry the same meaning and can be used interchangeably. This blank file by default
gets the name - Book l. The extension given to a file in Excel is 'XLS'. A typical Excel screen
resembles Figure 2.70.
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Figure 2.71: Screen Elements of Excel
Computer Application Table 2.3: Description of Screen Elements
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A workbook has got three worksheets in it by default. New worksheets can be added to it. It is a
good idea to keep all the related work in different worksheets of the single workbook. So, it can be
safely said that a workbook is a binder and the worksheets are its sheets. A worksheet can be
moved from one workbook to another.
Student Activity 13
1. What is an electronic spreadsheet?
2. Name some popular spreadsheet packages.
3. How will you start MS-Excel?
4. Describe various screen elements of MS-Excel.
5. Differentiate between a workbook and a worksheet.
If your document is stored on any of the storage device like hard disk or floppy disk, then it
becomes possible to retrieve that document. EXCEL offers a number of ways to open your
document which are discussed below:
1. Click at the 'File' menu and select the option 'Open'.
2. Alternatively, for opening a document, just double click at the 'Open' button available on
the standard toolbar.
An 'Open' dialog box appears on the screen as shown in Figure 2.72. In this 'Open' dialog box you
would notice a 'Look in' box which is used for selecting the drive as well as the folder where your
workbook has been stored. Double-click the folder to see the workbooks under it. From the 'Files
of type' box, select the kind of file that you want to open. Suppose you want that only the EXCEL
documents should be shown in the file list then click at the pull down arrow and from the drop
down list, select 'Microsoft Excel Files' option. Finally click the workbook name in the file list and
click at the <Open> button or double click the workbook name to open it up.
Saving a Workbook
A workbook should be saved properly before closing it or quitting EXCEL for its future retrieval.
Once all the text is entered, save the document with any of the following methods:
1. Click at the 'File' menu and then select 'Save' option.
2. The other way of saving your files is by clicking at the 'Save' button available on the
standard toolbar.
When the workbook is being saved for the very first time, the 'Save as' dialog box comes up
because EXCEL needs some additional information from you. EXCEL wants you to give a name to
your workbook. If you want to save your workbook with a name that is already given by EXCEL,
simply click at the <Save> button. However, if you want to give some other name, then erase off
the existing name from the 'Filename' box and give a new name to the workbook.
The 'Save as' dialog box is displayed only once till the time you don't give a name to your
workbook. Once the workbook has a name, next time if you try to save your file after making a few
changes in it, then the 'Save as' dialog box will not appear on the screen. So, if you intentionally
want to change the name of your workbook, select the Save as 'option from the File' menu.
Replace the name of the workbook with a new name in the 'Filename' box. It will create two copies
of the same workbook—one with an old name and the other with a new name that you have just
given. It's a good idea to keep saving your workbooks after every few minutes. The reason is if the 105
Computer Application computer goes down or a power failure occurs, then the chances of recovering something in the
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document are high. Unsaved new documents are the most vulnerable.
Closing a Workbook
It. is extremely easy to close workbooks in EXCEL. So, for closing a workbook, click at the File
'menu and select the Close' option. If you have made any changes in your workbook after saving
it, then EXCEL prompts you to save your workbook before closing it. Thus, if you want that your
workbook should be saved before it is closed, then click at <Yes> button otherwise hit the <No>
button in the dialog box that appears next. A case may arise when you want to continue working
in the same document after issuing 'File\Close' command. Select the <Cancel> button. It will allow
you to work again in your document thus cancelling the issued command.
Exiting Excel
EXCEL offers a large number of methods for shutting itself down. You can follow any of the below
mentioned approaches:
1. Click at 'Close' button present in the upper right corner of the title bar.
2. Select 'Exit' option from the 'File' menu.
3. Press <Ctrl + W> keys together.
EXCEL will close all the currently opened workbooks on its own. EXCEL wants you to play a safe
game. It will again prompt you to save your files before quitting like it did while closing your
workbook.
Inserting Text
Generally, when you startup EXCEL, it is in the Insert Mode, which means as text is typed in, the
following text is pushed towards the right side. So, if you are only interested in putting new text in the
cell then, take your cursor at that particular location of the cell and start typing in.
Sometimes, old text has to be replaced with new text. Take your cursor at a place wherever any
change has to be effected. Type in the new contents and erase off the existing contents with the
help of <Del> key. However, if the EXCEL is in the 'Typeover' mode, then the old contents are
automatically replaced with the new contents. If you want to put yourself back to the insert mode,
press the <INS> key once from the keyboard.
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Moving and Copying Text PC-Software Packages
The contents of a cell or range of cells can be moved as well as copied to some other location in
the worksheet. Copying cells mean duplicating the contents of a cell or range of cells at some
other desired place. Moving text means removing text from one portion of the worksheet and
placing it at some other location. The procedure for copying and moving text is almost the same
with a little difference. For copying cell contents, follow the steps given below:
1. Select a cell or range of cells.
2. Press <Ctrl + C> keys. Alternatively, select the 'Copy' option from the 'Edit' menu.
3. Take the cursor to the cell wherever you want the text to be pasted.
4. Hit <Ctrl + V> keys. Alternatively, select the 'Paste' option from the 'Edit' menu.
You can also use the 'Copy' and 'Paste' button available on the standard toolbar for copying and
pasting text. On similar grounds, for moving the cell contents, select the 'Cut' option instead of
'Copy' from the 'Edit 'menu. Rest of the steps are the same as that of copying cell contents.
Deleting Text
A passage of text can be very easily erased by selecting it and pressing <Del> key from the
keyboard. You can also delete a single character by positioning the cursor at that particular
character and hitting the <Del> key.
If you want to scrap off only a single word from your document, select the word by double
clicking it and hit the <Del> key. You can also delete words by following commands:
l Press <Ctrl + Del> keys to delete next word.
l Press <Ctrl + Backspace> keys to delete previous word.
Inserting a Row
In order to insert a new, blank row in between two rows, follow the steps given below:
1. Take the cursor where a new row has to be inserted.
2. Select ‘Rows’ option from the ‘Insert’ menu. A blank row will be inserted above the current
row.
Inserting a Column
To insert a blank column, the steps given below can be followed:
1. Take the cursor where a new column has to be inserted.
2. Select ‘Columns’ option from the Insert menu. You will find a new blank column inserted to
the left of the current column.
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Computer Application Clearing the contents of a single cell or range of cells is different from deleting them. When you
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clear a cell or range of cells, the contents are erased, leaving the cells blank. However, when a cell
or cell range is deleted, the other cells re-adjust themselves to fill in the empty space created by
deleting them.
You can change the overall look of the whole workbook. You may require to change the height of
a row for adjusting text in case a larger font size than default is applied onto it. So, if the font size
is made larger than the cell height, then some part of the text might be hidden. Now, to change the
height of rows, the steps given below can be applied:
1. Select the row whose height has to be changed. This can be done by either clicking in any
cell of that particular row or by clicking at the row header.
2. From the ‘Format’ menu, select the 'Row' option. Then, choose 'Height’.
3. Enter the height of the cell that you want to achieve.
In order to change the height of a group of rows, select all those rows. From the 'Format' menu,
select the 'Rows' and then the 'Height' option. Key in the desired row height. All the selected rows
will have the same row size.
Text Values
We can put both text and numbers in a cell. Any entry that contains text, numbers or any special
character is recognized as a text entry. A text purely in alphabets is mostly used for giving titles
and identifying information such as Salesman Name; Sales (pieces); etc. Generally, a text entry is
given at the top and left side of the worksheet. A number entry can be formatted to text in a case
when no mathematical calculation is required on it. By default, a text entry is left aligned. Looking
at the alignment of the entry, you can easily make out the category in which EXCEL has placed
your data. In order to apply any particular type of format on your data, select the cells and activate
"Cells" option from the "Format' menu. Choose any of the formats to apply it on the selected text.
Numeric Values
Any entry is treated as a numeric value if the first character entered, is a number or a mathematical
operator such as + or –. Numbers are typed directly. A numeric value can contain any of the
following characters:
108 0 1 2 3 4 5 6 7 8 9 + - ( ) , / $ % . E e
By default numeric values are right aligned. These numbers can also be formatted depending PC-Software Packages
upon the kind of presentation you require. EXCEL has some pre-defined formats for each kind of
numeric value.
Formulae
EXCEL offers a very powerful tool to use existing data values to calculate new values. Formulae
establish relationship between two or more cells. It performs a mathematical or arithmetical
operation on these data values. The formula can contain numbers as well as cell addresses and
can be created using the arithmetic operators like + (addition), – (subtraction), *(multiplication),
/ (division) and ^ (exponent). The formula entry can be made by beginning the entry with a +, @
or = sign. While entering a formula, key in an opening bracket followed by cell address. It must
end with a closing bracket.
Let us now create a simple worksheet and learn how to put labels, values and formulae in it. Follow
the steps given below:
1. Take your mouse pointer to the cell C2 and type in "RUBY BAKERY PRODUCTS". Then,
press the <Enter> key.
2. Go to the cell D3 either with the help of arrow keys or by clicking it with the mouse pointer.
Thereafter, enter "Jun-98". Press the <Enter> key. Similarly, typein "Jul-98" in the cell E3 and
again hit the <Enter> key.
3. Similarly, enter all the data as shown in Figure 2.73.
4. Now, we want to find out the total sale for the month of Jun-98. This requires the entering
of a formula in the cell D9. So, take your cell pointer to the cell D9. The formula entry shall
begin with a + sign or an opening parenthesis.
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Computer Application
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FUNCTION-NAME is the name of the standard in-built function as offered by EXCEL and <range
of cells> specifies the cell range on which the action of the function has to be performed. Let us
discuss some of these functions one by one. We will take the example of the workbook as shown
in Figure 2.76 in explaining these functions.
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The @SUM( < range of cells> Function PC-Software Packages
This function adds the values of the cells specified in the range. For example:
@SUM(D4:D8)
It would show the added up value of the cells D4,D5,D6,D7 and D8 as 210.
It will give the result 13 because this is the smallest value contained in cells D4 through D8.
It will give back the answer as 5 since there are five entries in the above specified range. This
function can be useful if you want to find out the number of entries made in a particular range
especially when the worksheet is very big.
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Computer Application manner, column letter can also be preceded with a dollar sign e.g. $D5. This will make the column
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fixed while copying but row is going to take the new reference.
Any of the above mentioned formats can be applied to either a single cell or range of cells before
or after typing in the value. In case, any specific format is applied to blank cells, then any entry
that is typed in those cells will be automatically converted to the selected format. Let us proceed
further and learn how to apply a few formats. In order to format numbers, follow the steps given
below:
1. Select the cells that need be formatted.
2. From the 'Format' menu, choose cells option. A 'Format Cells' dialog box appears on the
screen.
3. Click at the 'Number' tab.
4. Select the format that you want to apply.
5. Finally, click at the <OK> button.
Autofill
Autofill tool offered by EXCEL helps you to repeat a cell entry. It looks at the series entered by
you in adjacent cells and tries to complete it for you. For example, if you want to enter the labels
for all the twelve months of a year simply, type in first two entries, i.e., Jan. and Feb. in two
adjacent cells. Then, highlight both the cells by selecting them. Take your mouse pointer at the
bottom right corner of the selected cells. Your mouse pointer is going to take the shape of a +
(plus) sign. This plus sign is called Autofill handle. Drag your mouse pointer either across or
downwards for those many cells till you wish to continue the series. Autofill keeps filling the
series till the time the mouse pointer is dragged. So, you are saved the effort of keying in the labels
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of the rest of the months. The output given by Autofill is shown in Figure 2.77. While using PC-Software Packages
Autofill, you can drag the mouse pointer up, down, right or left. Look at some of the examples of
sequences that the Autofill feature can identify:
Student Activity 14
1. How will you create a new workbook in MS-Excel?
2. How will you save a workbook in MS-Excel?
3. How will you edit a cell entry?
4. How will you delete text from a cell?
5. How will you insert a row or a column in a worksheet?
6. Describe various types of cell entries.
7. List some commonly used functions in MS-Excel.
8. Describe absolute and relative cell referencing.
9. What is the function of Auto fill option in MS-Excel?
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Computer Application
in Management 2.24 CHARTING WITH EXCEL
As the common saying goes 'A picture is worth a thousand words' is found true by almost all of
us. Any kind of message can be best said and understood through its representation in pictorial
form. A chart or a picture gives a bird's eyeview of the entire scenario in a single look. So, let us
see how we can utilize the EXCEL's power of making charts. EXCEL supports many different
kinds of charts according to the vast and varied needs of the user. EXCEL also allows you to link
your charts with your data. So, as and when some changes are made to the data, these are
automatically reflected in your chart.
A typical worksheet showing data arranged in rows and columns can be safely used for creating
charts. Thus, enter data in a tabular form with proper row and column headings. EXCEL is very
good at figuring out an appropriate chart on its own.
Let us first of all create a worksheet with the data given in Figure 2.78. This figure gives the
number of sales made by each salesman in a particular month.
To create a chart, select one of the cells in the table and press F11 key. EXCEL would automatically
create a chart for you as shown in Figure 2.78. This is the easiest way of creating a chart.
Let us find out how to create charts using Chart Wizard. A wizard is a tool offered by EXCEL
which takes you through a series of steps to complete a particular process. So, while working
through a wizard, it shows a dialog box which asks for more information. You can either accept the
default settings or you can give in your own information according to your requirement. Thus, to
create a chart using the data given in Figure 2.78, let us begin by selecting a cell within the table.
Select the 'Standard Types' tab. Now, select the kind and type of chart into which the data has to
be converted from the 'Chart Type' box. Then, select the chart sub-type from the adjacent window.
Finally, click at <Next> button.
Data range included in the chart can be changed very easily. Click at the 'Collapse' dialog icon
which appears at the end of the 'Data Range' text box. A collapsed dialog box appears on the
screen as shown in Figure 2.81. This will make your worksheet apparent again. The data that has
been selected for creating a chart is shown by dashed lines. In case, you want to use a different
data range, then you can select that particular data from here. Click at the 'Expand' dialog icon
which is located at the right corner of the collapsed dialog box to go back. Now, you have the
desired range and orientation. Click at the <Next> button.
You can change the overall look of the chart by making other changes in the default settings. Hit
the 'Axes' tab to control the labels for the value on the axes. The 'Gridlines' tab can be used to get
rid of gridlines entirely. This will make your chart free from any gridlines. You can make the grid
look finer or show it in any one direction. The 'Legend' tab can help you in deciding the placement
of legend box on the screen. With the 'Data Labels' tab, you can decide whether the actual data
numbers (in our example Sept, Oct, Nov, ) and the corresponding data labels (like Salesman Name)
are to be displayed or not. The 'Data Table' tab helps you to specify whether or not a formatted
table of the data is to be included along with the actual chart or not. Finally, click at the <Next>
button after making all those desired changes.
1. Embedded Charts: These charts can be linked to the data based on which the chart is
created. So, if any changes are made to the data, the corresponding chart also changes.
2. Chart Sheets: These charts can also be linked to the data. The only difference is that these
charts are placed in separate worksheets. The chart is put in the middle of the new worksheet.
It leaves very little scope of moving the chart.
Finally, click at the Finish.
The different components of a chart are shown in Figure 2.84.
2.25 MACROS
The very word 'Macro' gives the impression of a huge big giant. Macro is not the hero of a horror
movie but a small program that carries out pre-defined and prerecorded series of steps by giving
a few keyboard shortcuts. So, we can state that a macro is like a recorded movie which can be run
any number of times. Macro is just a way of doing your work in a series of steps which it carries
out automatically once it is triggered. It can be very easily said that a macro is like a batch fie
created in DOS. It contains a series of commands. So, as and when a macro is called and run, the
instructions given in it are executed one by one.
A macro automates your tasks, thus saving a lot of your precious time. ‘Macro’ can just do
anything for you. Your imagination can be the only limitation to it. EXCEL offers macros in two
languages, Excel Visual Basic and Excel 4.0 Macro language. You can use either language to
create macros but Excel Visual basic is more difficult to use. Moreover, you also need know Excel
Visual Basic language itself. So, throughout our session, we would concentrate on learning how
to create macros using Excel 4.0 macro language.
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The macro is now ready to be executed. This macro is by default made available to all the PC-Software Packages
worksheets of the current workbook. However, if you want this macro in other workbook, then
select 'New workbook' option in the 'Record Macro' dialog box. Don't forget to click at the 'Stop
Recording' button once all the necessary steps to be included in the macro are over. Otherwise
your macro is going to become unnecessarily big with unwanted steps in it.
Using a Macro
Till this time, we were on our path of creating a new macro. Now, let us learn how to run or execute
a macro. You can run your macro in any of the following ways:
1. If a shortcut key has been assigned to your macro, then it can be activated by pressing
<Ctrl+'key'> or <Shift+Ctrl+'key'> depending upon the case of the 'key'.
2. A macro can also be run by selecting 'Tools\Macros\Macros' from the main menu. Then,
click at the macro name that you want to execute. Once the macro starts running, you can
stop it abruptly in between by pressing the 'Esc' key.
Deleting a Macro
If a macro is no longer needed, then it is advisable to delete it. In order to delete a macro, click at
the 'Tools\Macro\Macros' option from the main menu. A 'Macro' dialog box appears on the
screen. Select the macro that has to be deleted. Finally, click at the <Delete> button to complete
the process.
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1. Open the file 'Shruti.txt' by selecting 'Open' option from the 'File' menu. Figure 2.86 appears
on the screen.
2. Click at the <Next> button.
3. A dialog box by the name 'Text Import Wizard Step 2 of 3' appears on the screen. It guesses
where the columns should be put as shown in Figure 2.87.
4. In case you want the columns to appear at some other place, then move the line by clicking
it and then dragging it. You can also remove a line in case you do not require it by double-
clicking at that particular line. Then, click at the <Next> button.
5. A 'Text Import Wizard Step 3 of 3' is shown on the screen as can be seen in Figure 2.88. This
dialog box allows you to set the Data Format for each column. You can also leave the data
120 as it is without changing the data format. Finally, click at the <Finish> button.
PC-Software Packages
Student Activity 15
1. What is a chart?
2. How will you create a chart using chart wizard?
3. What is a chart sheet?
4. What are embedded charts?
5. What are MACROS?
6. How will you create and record a macro?
7. How will you import an access file in a worksheet?
8. How will you print a workbook?
9. How will you save a micro?
10. What are the applications of a spread sheet in corporate sector?
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2.29 SUMMARY
An operating system is an integrated set of specialized programs that is used to control and
manage the resources and overall operation of a computer system.
DOS is the most commonly used operating system. Loading of DOS into the main memory is
known as booting. DOS commands are of mainly two types: internal and external. Internal commands
are directly interpreted by the command processor, command.com. External commands are
interpreted with help of external files (with extensions.com or .Exe)
Storage areas on a disk are known as directories. A directory may contain files and/or sub-
directories inside it. The full name of a file or a directory (including path) is called pathname.
Wildcards special characters carrying special meaning. Two MS-DOS wildcards are‘?’ and ‘*’
The '?' can replace exactly one or none characters in a name. The '*' can replace number of
characters in a name.
Some DOS internal commands are copy, DEL/ERASE, REN, TYPE, DIR, CHDIR/CD, MK, DIR/
MD, RMDIR/RD, BREAK,CLS, DATE, PATH, TIME, PROMPT, etc. Some external commands are
DISK COMP, DISKCOPY, FORMAT, LABEL, PRINT, XCOPY, etc.
Batches of MS-DOS command stored under a filename with extension. BAT are known as Batch
files. The batch files with the name AUTOEXEC.BAT is automatically executed by
MS-DOS at the time of booting.
MS-windows is a GUI based operating system. In windows operating system, multiple applications
can be simultaneously run in different windows. In MS-windows, the screen upon which icons,
windows, etc., are displayed is known as desktop.
You can explore you computer through start button and taskbar, my computer and window
Explorer. The taskbar is a bar, which is usually located at the bottom of the screen. The start
button is located at taskbar. By clicking at start button, start menu appears wherefrom you can
start program, open document, customize you system, get help, search for items on your computer
and more.
Windows Explorer is another way of seeing what is on your computer. Windows explorer shows
the computer's contents as a hierarchy. The programs available under Programs section of start
menu can be started by clicking at start, then at programs and then at the desired program or
group. To quit an open program, just check at close button (X). A folder is a location in which you
can store files and other folders.
To create new folders start→find→folder commands are clicked in my computer window. To find
files or folders, start→find→files or folder commands are clicked. To rename a file, firstly the file
icon or name is selected and then file-Rename commands are clicked. To move a file, the file icon
or name is firstly selected, then edit→cut commands are clicked. Then the destination folder is
opened in a My computer windows and there Edit→paste commands are clicked.
To copy a file, firstly, the file icon or name is selected, then Edit→Copy Command is clicked the
destination folder is opened in a My computer window, and there Edit→paste commands are
clicked. To delete a file, a folder, firstly select the file icon or name and then either click Delete key
or click File→Delete commands. To create a shortcut to a file, firstly select the file or folder,
whose shortcut is to be created. Then drag the file icon through right mouse button to desired
location where shortcut is to be placed. And then select create shortcut. To shut down the
computer, Start→Shut down commands are clicked.
A database refers to the collection of interrelated data and database management systems (DBMS)
is a computer program that manager a database effectively and efficiently. MS-Access offers
many features like tables, forms, queries, reports and data access pages to manage data, A new
database can be created either through wizard or by clicking File→New command or New button
or by pressing ctrl+N. While designing tables, you have to decide about field names, field types,
field size, field properties and primary key. 123
Computer Application At field level these validation techniques maybe used: Input mask, validation Rule and Text,
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Default Value, Allow Zero Length, Required and Lookup values. The input Mask property specifies
and controls how data is entered and displayed.
A word processor is a package that processes textual matter and creates organized and flawless
documents. The word processor offers very useful features like speed, powerful editing and
formatting features, permanent storage, Graphics, object linking and embedding spell check and
mail merge etc.
Tables can be inserted in a word document through Table button of Standard toolbar and can be
manipulated through the Table drop down menu. Also word provides quite many drawing features
that can be used to include the desired graphics in the document.
A spreadsheet is a software tool that lets one enter, calculate, manipulate, and analyze set of
numbers. A worksheet is a grid of cells made up of horizontal rows and vertical columns. A
worksheet is a group of worksheets. Three types of data can be entered in a Worksheet (i) Number
(ii) Text, (iii) Formulas, charts are the pictorial representation of worksheets data. Various chart
types in MS-Excel are: areas chart, column chart, bar chart, line chart, pie chart, XY (scatter) chart.
Chart in MS-Excel are saved in two ways: (i) embedded chart (ii) Chart sheet. Embedded chart is
a chart object that is placed on a worksheet and saved with that worksheet. Chart sheet is a sheet
in a worksheet that contains only a chart.
2.30 KEYWORDS
Alignment: It refers to the way the right and left edges of a paragraph line up along the right and
left margins of your document.
Autocorrect: It is a feature of the MS-Office package that corrects automatically when a word is
typed with wrong or nearly wrong spellings. The correction is made according to the list of
correct and incorrect words is provided.
Bullet: A paragraph marker, usually indented to list paragraphs point wise.
Clipboard: Space in the memory where an MS-Office application stores data, objects etc.,
originating from cut and/or paste actions.
Cursor: Cursor is a pointer, which tells where on the document the action will appear or affect. The
cursor can be moved and placed anywhere on the document using pointing device like mouse.
Font: It is a set of a typeface and its style.
Indentation: It is the space left within the margin of a page.
Scroll Bars: They are sliding narrow bars with arrows at the ends and a slider in between, used
to scroll through an active pane of a window. Two types available, according to their orientation
- Horizontal Scrollbar and Vertical Scrollbar.
Status Bar: It displays the positioning of the cursor, displays the status of some important keys
of keyboard, shows the messages for the toolbar mouse points to it, displays messages for menu
option when a menu option is selected or pointed out by a user.
Style: It is a set of formatting characteristics that can be applied to text in document to quickly
change its appearance.
Title Bar: Title bar shows the name of the document and is situated in the top of the window
application.
View Buttons: View buttons are shortcuts of various views in the View Menu, placed adjacent to
the horizontal scroll bar. These buttons select different ways the document can be viewed.
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MS-Word 2000 PC-Software Packages
Block: It is a selected piece of text, graphics and other objects to be treated as a unit.
MS-Excel 2000
Absolute Reference: Address of a cell or a range of cells with no reference to other cell in terms
of row and column addresses.
Cell: A Cell is a box at the intersection of a row and a column in a worksheet where data is stored.
There are 65536 x 256 = 16777216 cells in a single worksheet.
Column: Columns are combination of all the vertical cells joined together in a single vertical line.
Fill Handle: The small black square in the corner of the selection of a cell or range, which changes
to a black cross pointer when placed at the corner of selection.
Formula Bar: Formula bar shows the formula instead of the result, if there is one present in the
current cell.
Formula: It is an expression that performs operations on worksheet data. Formulas can perform
mathematical operations, such as addition and multiplication.
Full Screen View: A view in which the entire desktop space is occupied by the current worksheet.
Headers and Footers: They are text, page numbers, date, document’s title or file name, or the
author’s name that are usually printed at the top and bottom of each page in a worksheet
respectively. A header is printed in the top margin, footer is printed in the bottom margin.
Name Box: This box shows the name or the address of the currently active cell.
Normal View: A view of a worksheet in which no reference to pagination is displayed and print
area is not specified.
Range: A group of cells, optionally having a name taken as one unit of cells.
Relative Reference: It is address of a cell or range of cell with respect to a given cell.
Row: Rows are combination of all the horizontal cells joined together in a single horizontal line.
Worksheet: It is the working area of MS-Excel. Each worksheet of a single workbook has its own
identity and is separate from other worksheets.
Workspace: It is the working area of MS-Excel where workbooks, worksheets and other related
objects may be opened and manipulated.
MS-Access 2000
Action Query: It is used to perform an action on records that meet the criteria specified in the
query object.
Application Programmers: Computer professionals who interact with the system through Data
Manipulation Language calls, which are embedded in a program written in a host language (for
example, COBOL, PL/I, PASCAL, C). The programs are referred to as application programs.
Attribute: Piece of information describing a particular entity. These are mainly distinguishing
characteristics of the individual entity.
Auto Number Data: A data type that stores an integer that is incremented or decremented
automatically as records are added and/or deleted.
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optional arguments. These functions are already created for the users and they do not have to
create them.
Detailed Questions
1. What do you mean by booting up?
126 2. What is the full form of ROM-BIOS?
3. What do you mean by default drive? PC-Software Packages
4. How many parts are there in a file name under MS-Dos? What are file naming conventions?
5. What are volume labels? How many characters can a volume label contain?
6. What are wild cards? What is the use of '?' and '*' wild card in MS-DOS?
7. What is the purpose of copy command?
8. To view a directory listing width wise, which command is used?
9. Which commands lets you create directories? Give example.
10. What is the use of switch /w in DIR command?
11. How is X COPY a better copy command than COPY?
12. What are batch files? What is the significance of AUTOEXEC.BAT file?
13. Give some of the advanced features of window 98.
14. What is the difference between copying and moving files and folders?
15. When a folders is copied to another place, do the sub-folders in the folder also get copied?
16. What is windows Explorer and give some of its functions?
17. Differentiate between notepad and WordPad.
18. What do you mean by dialog box? Also discuss its various components.
19. What is the start Group? What are the different functions that can be done through this?
20. Discuss some advance features of windows 98.
21. (i) Give procedure to create a new folder in windows 98.
(ii) Give procedure for closing down the windows 98.
22. What is the function of taskbar and recycle bin?
23. Describe the functions of the Control Panel.
24. What are the advantages of a word processor over typewriters?
25. What is meant by text alignment? In how many ways can you align you text?
26. What is meant by page margins? Which option will you choose to set the margins of your
document?
27. What are the advantages of find or replace features of word processor?
28. Write your Bio-Data in MS-Word.
29. Prepare a business letter to you customer promising to attend to his complaint immediately.
Use page setup, formatting features, etc.
30. Prepare a table in which the budget comparison of three years is made.
31. What is data and why is it required?
32. What is information and how it differs from data?
33. Differentiate between a query and a report.
34. Differentiate between a form and the datasheet view.
35. Describe various ways of creating a table in access. Differentiable between a formula and a
function.
36. Differentiate between a formula and a function.
37. Differentiate between a table and a query.
38. What are the purposes of forms in Access 2000? Explain with appropriate examples.
39. Can an Excel chart be inserted into an Access report? How?
40. How many rows and columns are there in MS-Excel Worksheet?
41. What do you mean by range of cells? 127
Computer Application 42. What do you mean by cell referencing and what are different types of referencing?
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43. Why is formatting necessary?
44. What are the different types of data that can be entered in MS-Excel?
45. What is the difference between copying and moving a range?
46. What is the different components of chart? Explain.
47. Define embedded chart.
48. Define chart sheet.
49. Explain various types of charts available in MS-Excel.
50. Which types of files can be imported and exported from MS-Excel?
128
Data Processing
UNIT
3
DATA PROCESSING
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z Various modes of data processing.
z Basic functions carried out in data processing.
z Data hierarchy and data structure.
z Application portfolio of business organization.
z Computerized financial accounting system, inventory control system payroll system and
invoicing system.
U N I T S T R U C T U R E
3.1 Introduction
3.2 Modes of Data Processing
3.3 Basic of Data Processing
3.4 Data Hierarchy
3.5 Data Structure
3.6 Application Portfolio Development
3.7 Management of Data Processing Systems in Business Organizations
3.8 Computerised Financial Accounting System (FAS)
3.9 Computerised Inventory Control System
3.10 Computerised Payroll System
3.11 Computerised Invoicing System
3.12 Summary
3.13 Keywords
3.14 Review Questions
3.15 Further Readings
3.1 INTRODUCTION
The computer processes the data to give information. Processing of data is done by the CPU in
various ways. In this unit we will discuss various types of data processing techniques, their
functions, data hierarchy and structure, At last some computerized system models are discussed
for your ready reference.
Batch Processing
Also referred as serial or off-line or sequential processing.
This type of processing requires the data to be initially grouped (as a batch) before it is processed
serially, and the results obtained periodically.
129
Computer Application The batch might be a group of sales orders or purchase orders, etc., collected off-line.
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The batch is processed at definite period of time in stipulated frequency, and each transaction in
batch is processed in serial order.
The method of batch processing reduces the idle time of a computer system because transition
from one job to another does not require operator intervention.
It is the most appropriate method of processing for many types of applications, such as payroll or
preparation of customer statements, where it is not necessary to update information (records) on
daily basis.
On-line Processing
On-line processing is that type of processing where the result of data processing transaction is
available immediately.
It permits transaction data to be fed under CPU control directly into secondary on-line storage
devices from the point of origin without sorting it first.
It also permits users to enter into a conversation with the computer to send and receive messages,
within a fraction of a second after the enquiry message has been transmitted.
This conversation permits the user to process transactions one after the another with greater
assurance that the actions taken by the computer are correct. This type of processing also
provides a satisfaction to the users that they are able to command the machine. However, this
type of processing can not be used in all circumstances as otherwise the processing time will
increase. Examples of online applications include:
Banking, stock exchanges, stock control, work progress control in plants, inventory status, etc.
The characteristic of real time data processing that truly distinguishes it from the more common
batch and on-line processing systems is the immediacy of its response on receipt of a message.
Thus, all on-line systems are not necessarily real time data processing systems. The application
areas of real time systems are:
l Enquiries about customer's account status can be answered in seconds.
l Credit appraisal can be carried out immediately.
l Sales analysis master file can be updated on-line. This file provides a ready information to
the sales manager regarding sales trends, etc.
Real time system also finds extensive application in airlines booking, banking system, air and
ground traffic control, automatic radar connected defence and space programs.
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Distributed Data Processing Data Processing
Often, each computer in the system is chosen to handle a specific workload with the network
supporting the system as a whole. When distributed processing is used, it requires that databases
be located at different sites for efficient functioning.
The database is broken up into logical cooperating parts and situated at a different location. User
can access data from any location, easily accessing the local as well as the remote databases.
This form is most convenient for organizations with many branch offices located over great
distances. Each branch stores data elements relating to its daily operations at its own site. A
major part of processing can be taken care of at the local level.
A typical application is in banks where all the branches have intelligent terminals linked to a big
computer at the head office. Data from the branches is sent to the master where it is processed.
Student Activity 1
1. What is the aim of any processing system?
2. Define Batch processing system.
3. What are the disadvantages of batch processing system.
4. Define on-line processing.
5. What are the essential requirements of a real time processing system?
6. Describe distributed data processing.
Following are the basic functions carried out in any data processing:
Origination
The first function involved in the processing of data is the origination of the data to be processed.
Specifically, the nature, type and origin of the source documents must be determined, such as
sales orders, purchase orders, etc.
Data Capture
Data must be recorded or captured in some form or the other before they can be processed. What
data are important and should be collected for input and processing depends upon the organization
and the system.
Data maybe captured in paper forms using source documents and in paperless forms through:
l Keyboards
l Automated teller machines
l Other direct input devices that accept input data in machine readable form
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Computer Application Sorting
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Normally, it is easier to work with data if they are arranged in a logical sequence. e.g., First to last
time sequence.
Biggest to smallest.
Oldest to newest, etc.
These are the few of the many of computer generated graphics that are used to view data at a
glance.
Output
After the various operations on the data have been completed, the delivery or communication of
the information or results must be carried out by:
(a) Reporting, which is the format presentation and distribution of processed data.
(b) Issuance of documents, such as cheques, invoices, and reports.
(c) Retrieval, which is the fetching of a specific item or items of stored information at the
request of a user.
(d) Analysis, which encompasses all of the ways in which the receivers utilize output, i.e., use
the information provided by the system.
(e) Communicating and reproducing (transmission).
Transferring data from one location or operation to another, for use or further processing, is data
transmission, a process that continues until information in a usable form reaches the final user.
Sometimes, of course, it is necessary to copy or duplicate output documents.
Storage
Finally, the results of the processing of data must be retained for future use of reference. This
function is called storage.
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Data Processing
3.4 DATA HIERARCHY
Listed below are the components of the data hierarchy in the ascending order of complexity:
Simple Bit
Byte
Field or item
Recod
File
Most Complex Database
This is called a data hierarchy because databases are composed of files, files are composed of
records, and so on.
Bit
The term bit is short for binary digit. It can assume either of the two states, representing numeric
value 0 or 1.
Byte
In a computer system, basic unit of information is called a byte. A byte of information is generally
stored by using 8 bits in a specified combination.
Field or Item
A field or item of data is one or more bytes that contain data about attributes of an entity.
Record
File
A file is a collection of related records. The concept of a computer file is very similar to the manual
file in a filing cabinet.
Database
A database consists of all the files of an organization, structured and integrated to facilitate
updation. of files and retrieval of information from them.
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Computer Application
in Management 3.5 DATA STRUCTURE
Data maybe organized in various ways; the logical or mathematical model of a particular situation
using data is called a data structure.
A data structure is a class of data that can be characterized by its organization and the operations
that are defined on it.
Student Activity 2
1. What are the basic functions of data processing?
2. What is the difference between data capturing and data merging?
3. What are various ways to summarize data.
4. Describe data hierarchy.
5. What is a data structure?
The approach has its origin to 1996 Washington State Strategic Plan and includes the foundational
policies, procedures, and processes necessary to make informed decisions about IT alternatives
and achieve a very high rate of project success.
The portfolio concept is grounded in the management principle that any significant investment
134 requires careful monitoring to maximize its value and insulate it from threats to its integrity. This
principle is well understood with respect to traditional investment categories real property, Data Processing
commercial paper, and equity investments all of which are commonly managed in portfolios.
These portfolios allow decision-makers to view the range of investments as a whole but also
consider discrete investments in context.
The need for an application portfolio is less well understood with respect to investments but no
less important. Organization investments on applications involve significant taxpayer funds; are
often mission-critical; and are increasingly interrelated in a digital, networked environment.
Investments in applications can be leveraged with great effect if the portfolio is sufficiently
flexible to adapt to changing business and service needs. Their value, on the other hand, can be
undermined by rigid design, unsubstantiated claims about capabilities or performance, and neglect.
Portfolio-based IT management organizes information about all IT resources into the perspective
of an investment portfolio. The portfolio is responsive to the needs of a variety of decision-
makers, including agency executives, agency technical managers, agency program managers and
the like. Information is structured to facilitate recognition of trends, analysis of problems and
opportunities, and the evaluation of alternatives within the context of an organization's overall
investment.
Student Activity 3
1. What do you mean by application portfolio?
2. What are the characteristics of portfolio-based IT management?
3. What information is included in the application portfolio of an organization?
4. Who belong to the organization of the data processing system?
5. List the responsibilities of the data processing manger.
Financial accounting is an art of recording and processing all transactions within an organization
with outsiders and includes events affecting the financial position of the organization. It results
in preparation of the annual profit and loss account as well as balance sheet for the organization.
A great volume of accounting data is numerical and is always processed with the same method.
This makes computerization relatively easy.
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Data Processing
3.9 COMPUTERISED INVENTORY CONTROL SYSTEM
What is Inventory?
l Inventory refers to buffer stock of items of use being maintained by the organization to
prevent losses resulting from non-availability of materials.
l Different levels of stocks of different items will be maintained depending upon their
consumption level, cost, and other characteristics.
137
Figure 3.1: An Overview of Inventory Control/Material Management
Computer Application
in Management 3.10 COMPUTERISED PAYROLL SYSTEM
Payroll system is concerned with accurate and timely computation of compensation to each
individual employee.
In addition, the payroll system generates relevant information inputs to budgetary control and
financial accounting systems.
The objective of the payroll system is wages calculations and associated record keeping.
Description
Each organization has an employee compensation/wage policy. In addition, employee compensation
is also subject to certain statutory provisions like Income Tax regulations. The processing logic
of the payroll system has to take into account all relevant provisions.
In the process, all the relevant databases and the files will also be updated.
System Outline
l Invoice Generation
Once the invoice is generated, accounts receivable system takes over. File containing newly
generated invoices becomes an input to the accounts receivable system.
System Outline
Processing Steps
Sales orders from customers received in variety of ways in the form of order form, through fax,
over phone are entered into the computer system.
Orders are validated through checking of item prices and customer credit rating. Valid orders are
stored in the Order File.
Orders are processed after checking the availability of items from the finished goods inventory
file. This step generates three outputs, namely, Picking List, Packing Slip, and Sales Ledger.
Once the order has been processed, corresponding invoice is prepared by referring to price
master file. In this step, the required number of invoice copies are generated and an invoice ledger
is produced. Newly generated invoices are copied to the invoice master file.
System Outputs
Packing List: is a document generated to help warehouse staff assemble all items included in
one customer order quickly and conveniently. It contains the Order No., Item
No., Quantity and the location of an item in the store.
Packing Slip: is a document accompanying the order consignment to the customer. It contains
customer order number and the list and quantity of items in a particular
consignment along with forwarding address.
Invoice: is a bill or a claim made by the supplier on the customer for the goods supplied.
It contains customer order reference, list and quantity of items supplied, prices,
total amount payable, payment date, and discounts as applicable along with
payment instructions.
Sales Ledger: is daily listing of all sales made showing sales order number and order value.
139
Invoice Ledger: is daily listing of all invoices prepared during the day.
Computer Application Student Activity 4
in Management
1. Why does an organization need computerized FAS?
2. What is Inventory? What are its objectives?
3. What is a payroll system?
4. What is invoicing system? Describe its processing step.
5. What are the various outputs of a system?
3.12 SUMMARY
Various types of data processing systems followed by the organization to optimize their efficiency
are batch processing, online processing, real time processing and distributed data processing.
The basic functions carried out in any data processing include the origination of the data to be
processed, capturing of data be fore processing, sorting the data, merging the multiple files,
performing calculations and summarizing it. Then the results of processing of data are stored for
future reference.
The smallest unit of data is bit. 8 bits form one byte. One or more bytes that contain data about
attributes of an entity is a field. A collection of fields relating to a specific entity forms a record,
collection of related records forms a file and the collection of all files of an organization form a
database.
An application portfolio of a business organization is a compilation of information about the
organizations investments in its IT-based application infrastructure. The portfolio approach
recognizes the maturing capabilities of the organizations. The portfolio concept is grounded in
the management principle that any significant investment requires careful monitoring to maximize
its value and insulate it from threats to its integrity. The portfolio is responsive to the need of a
variety of decision-makers, including agency executives, agency technical managers, agency
program managers and the like.
Financial accounting is an art of recording and processing all transactions within an organization
with outsiders and includes events affecting the financial position of the organization. This
system is computerized to do more accurate calculations and faster and frequent supply of
reports.
Some other systems that can be computerized in an organization include inventory control system,
payroll system, Invoicing system, etc. The outputs of the system includes packing list, packing
slip, Invoice, sales ledger and Invoice ledger.
3.13 KEYWORDS
Batch Processing: Processing that requires the data to be initially grouped (as a batch) before it
is processed serially, and the results obtained periodically.
Online Processing: Processing where the result of data processing transaction is available
immediately.
Real Time Processing: Data processing system in which the time interval required to process
and respond to input is so small that the response itself is useful for controlling the physical
activity of a process.
Distributed Data Processing: Data processing which involves a computer system linked by a
communication network where processing is performed by separate computers.
Sorting: Arranging the data in a local sequence.
Bit: Representing numeric value 0 to 1.
Byte: Basic unit of information, generally stored by using 8 bits.
Field: One or more bytes that contain data about attributes of an entity.
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Record: A collection of fields relating to a specific entity. Data Processing
Detailed Questions
1. Describe various modes of data processing system.
2. What is the difference between on-line processing and Real-time processing?
3. What do you mean by the terms merging and summarizing of data?
4. How does the information communicated?
5. Why is storage of information required?
6. Describe the hierarchy of data.
7. Describe computerized pay roll system. Also draw its system model.
8. Describe the objective and scope of Inventory control system.
9. Describe various system outputs of an organization in its Invoicing system.
4
SOFTWARE DEVELOPMENT
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to:
z Describe software development process.
z Understand various phases of software development.
U N I T S T R U C T U R E
4.1 Introduction
4.2 Computer Software Systems
4.3 Software Development Process
4.4 Summary
4.5 Keywords
4.6 Review Questions
4.7 Further Readings
4.1 INTRODUCTION
Computer software has become a driving force. It is the engine that drives business decision
making. It is a key factor that differentiates modern products and services. Software is virtually
inescapable in a modern world.
The software development process has been the focus of considerable attention over the last
decade. It is a frame work for the tasks that are required to blind high-quality software.
When we consider the payroll problem, it is obligatory on the part of every employer to pay the
wages to employees within a prescribed time limit. When the number of employees is large, it is
preferred to have a computerized system of preparing the pay bills rather than manual ones. A
computer software package on payroll thus becomes an integral part of a large business
organization.
Similarly, financial accounting is another field where computerization can play an important role.
The financial accounting package is one which helps the organization in preparing various financial
reports, ledgers, and journals of monetary transactions.
2. Systems Analysis: When the systems analyst decides that the requested system is feasible
and the management agrees to continue the development process, the next phase of SDLC
is determination of systems requirements. This phase includes studying of existing system
in details and collecting data in order to find out the requirements of the users.
3. Systems Design: After collecting and studying user's requirements, the system is designed.
This phase involves identification of inputs data, output reports and the procedures to
process the data.
4. Development of Software: When the design (properly documented) is accepted by the
requested department, the programmers start designing of data structures and writing of
program. The programmers test their individual programs and integrate them into a single
system.
5. Systems Testing: Testing is the most vital phase of SDLC. In this phase, the system as a
whole is tested with different techniques to ensure that the software is bug free. 143
Computer Application 6. Implementation: The tested system is installed at the user's place and implemented. This is
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generally considered the last phase of SDLC. However, the systems development work
continues until the users of requested department accepts the candidate system.
7. Maintenance: After implementation, the systems need be maintained in order to adapt the
changing business needs. Maintenance is sometimes not considered as a phase of SDLC,
but it is an essential part of a software project that never ends.
The different phases of Software Development Life Cycle (SDLC) are illustrated in Figure 4.1.
It maybe possible that the candidate system fails due to any major mistake occurred in any of the
development phase. In that case, any or all of the phases are needed be reviewed again, so that
the system is completely accepted by the requested department. This is the reason, why 'life
cycle' term is used in software development phases. We will discuss about each phase in detail in
subsequent sections.
4.4 SUMMARY
For development a large a software for any business application, many people are involved and
many months or even years are spent. Whether a system is small or large, software development
revolves around a life cycle that with the recognition of user's needs and understanding their
problem. The various phases involved include feasibility study, system analysis, system design,
development of software, system testing, Implementation and maintenance. If the candidate
system fails due to any major mistake occurred in any of the development phase, any or all of the
phases are needed be reviewed again, so that the system is completely accepted by the requested
department.
4.5 KEYWORDS
System Analysis: Study of existing system in detail and collecting data in order to find out the
requirements of the users.
System Design: Identification of input, output and procedures to process the data.
System Testing: Testing of the whole system with different techniques to ensure that the software
is bug free.
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Answers (Unsolved Questions) Software Development
1. (a) Feasibility study (b) Feasible, development, (c) System design (d) Maintenance.
2. (a) False (b) True (c) False (d) True.
Detailed Questions
1. What is a computer software system?
2. Describe the various phases of software development process.
3. What are the seven phases of SDLC? Draw diagram?
4. What is system testing? Why is it required?
5. What will happen if a system fails?
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Computer Application
in Management UNIT
5
FILE SYSTEM AND DATABASE
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z Various types of files.
z Various file organizations.
z Master and transaction file.
z File design.
z Designing and generating reports.
z Relevance of database management system.
U N I T S T R U C T U R E
5.1 Introduction
5.2 Various Types of Files
5.3 Files Organization
5.4 Master File
5.5 Transaction File
5.6 File Design
5.7 Designing Reports
5.8 Relevance of Database Management Systems
5.9 Integration of Application
5.10 Introduction to a Micro Database Manager
5.11 Summary
5.12 Keywords
5.13 Review Questions
5.14 Further Readings
5.1 INTRODUCTION
Files and database have become an essential component of everyday life in modern society. In the
course of a day, most of us encounter several activities that involve some interaction with a
database, like in banks to deposit and withdraw funds; if we make a hotel or airline reservation; if
we access computerized library catalog; or if we order a magazine subscription from a publisher,
chances are that our activities will involve someone accessing a database.
To understand the basics of database, we must start with files and its various types and organization
which together form the database.
Data Files
l A data file is used to store the data records. These data files are well defined data structures
that contain related data organized in convenient groupings (records) of data items.
l Each data file has two additional types of records: Header record, and types record.
l Header records contain file identification information and keep apart different groups of
records in a file.
l Trailer records contain codes to mark the end of a set of data records. These also record file
usage information.
l Categories of data files:
Depending upon the nature of data, data files can be categorized as:
1. Master file
2. Transaction file
3. Work file
4. Audit file
5. Backup file
l File organization:
Data in files can be organized in different ways. These data records can be organized in
anyone of the following ways:
1. Serial
2. Sequential
3. Indexed Sequential
4. Directly Accessible/Random
Program Files
Program files are used to store programs in different languages provided by different software
vendors. These files have different extensions depending on the language used to write a program.
e.g.: 1. A program file written in 'C' language has extension. C.
2. A program file written is C++ language has extension. CPP.
Executable Files
These files store ready to execute programs. These files may have extension.EXE.COM or .BAT.
These programs can be directly executed from the command prompt.
Student Activity 1
1. What are the various types of files depending on the type of content?
2. What are data files? What are its various categories?
3. What is a program file?
4. Which files are said to be executable files?
5. What is the difference between unformatted and formatted text files?
The four file organization methods that are commonly used in business data processing
applications are:
1. Serial
2. Sequential
3. Direct or Random
4. Indexed Sequential
The selection of a particular file organization depends upon factors like, the type of application,
the method of processing for updating files, size of file, etc.
Examples are: memory dumps, archival files, records of events, transaction files.
Each record is written after the last record in the current file. The order of records in the serial file
is according to the time when the data was generated.
To access these records, the computer must read the file in sequence from the beginning.
The retrieval search ends only when the desired key matches with the key field or the currently
read record.
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On an average, about half the file has to be searched to retrieve the desired record from a sequential File System and Data Base
file.
Sequentially organized files are normally created and maintained on storage media such as magnetic
tape, cartridge tape, magnetic disks, etc.
Advantages
1. Easy to organize, maintain, and understand.
2. There is no overhead in address generation locating a particular record requiring only the
specification of the key field.
3. Relatively inexpensive I/O media and devices can be used.
4. It is the most economical and efficient file organization where the activity ratio (the ratio of
the total number of records in transaction file and the total number of records in master file)
is very high. That is why this file organization is most suitable for transaction files.
Disadvantages
1. It proves to be very inefficient and uneconomical for applications in which the activity ratio
is very low.
2. Since an entire sequential file may need be read to retrieve and update few records,
accumulation of transactions into batches is required.
3. Transactions must be stored and placed in sequence prior to processing.
4. Timeliness of data in the file deteriorates while batches are being accumulated.
5. Data redundancy is typically high since the same data maybe stored in several files,
sequenced on different keys.
6. Random enquiries are virtually impossible to handle.
Applications
Payroll System
Billing and customer statement preparation
Bank cheque processing
Financial accounting
For mapping the key fields to the locations, an arithmetic procedure called hashing algorithm is
frequently used.
This address generating function is selected in such a manner that the generated addresses
should be distributed uniformly over the entire range of the file area and a unique address must be
generated for each record key.
A Direct Access Storage Device (DASD) such as drum, disk, etc., are essential for storing a direct
file.
Advantages
1. The access to and retrieval of a record is quick and direct (within a fraction of a second).
2. Transactions need not be sorted and placed in sequence prior to processing.
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Computer Application 3. Accumulation of transactions into batches is not required before processing them. They
in Management
maybe processed as and when generated.
4. It can also provide up-to-the minute information in response to enquiries from
simultaneously usable on-line stations.
5. If required, it is also possible to process direct file records sequentially in a record key
sequence.
6. A direct file organization is most suitable for interactive on-line applications.
Disadvantages
1. These files must be stored on a direct access storage device. Hence, relatively expensive
hardware and software resources are required.
2. File updation (addition and deletion of records) is more difficult as compared to sequential
files.
3. Address generation overhead is involved for accessing each record due to hashing function.
4. May be less efficient in the use of storage space then sequentially organized file.
5. Special security measures are necessary for on-line direct files that are accessible from
several stations.
6. System design around it, is complex and costly.
Applications
A direct file organization is most suitable for interactive on-line applications such as:
1. Airline/Railway reservation systems
2. Teller facility in banking applications
Advantages
1. Permits the efficient and economical use of sequential processing techniques when the
activity ratio is high.
2. Permits direct access processing of records in a relatively efficient way when the activity
ratio is low.
Disadvantages
1. These files must be stored on a direct access storage device. Hence, relatively expensive
hardware and software resources are required.
2. Less efficient in the use of storage space than some other alternatives.
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Applications File System and Data Base
This file organization is a compromise approach that combines some of the advantages of both
the sequential and direct approaches, and therefore used in almost all the applications, like
Material A/C, Banking Industry, etc.
e.g.: The master file could contain records having the following fields:
A transaction file is a temporary file containing all relevant data about all transactions of one type.
e.g.: Daily sale transaction file
Daily stores issue file
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Computer Application Student Activity 2
in Management
1. What do you mean by file organization? What are the various methods of file organization?
2. What are the advantages of sequential file organization?
3. List some application of direct file organization.
4. What is index sequential file organization?
5. Define master file and transaction file.
To design a file, there are four methods that are commonly used in business data processing
applications. They are:
1. Serial
2. Sequential
3. Direct or Random
4. Indexed Sequential
The selection of a particular file organization depends upon factors like, the type of application,
the method of processing for updating files, size of file, etc.
Serial File
In serial file, records are stored without any consideration of their order or sequence.
Examples are: memory dumps, archival files, records of events, transaction files.
Each record is written after the last record in the current file. The order of records in the serial file
is according to the time when the data was generated.
Sequential File
In a sequential file, records are arranged in the ascending or descending order or chronological
order of a key field.
To access these records, the computer must read the file in sequence from the beginning.
The retrieval search ends only when the desired key matches with the key field or the currently
read record.
On an average, about half the file has to be searched to retrieve the desired record from a sequential
file.
Sequentially organized files are normally created and maintained on storage media such as magnetic
tape cartridge tape, magnetic disks, etc.
Advantage
1. Easy to organize, maintain, and understand.
2. There is no overhead in address generation locating a particular record requiring only the
specification of the key field.
3. Relatively inexpensive I/O media and devices can be used.
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4. It is the most economical and efficient file organization where the activity ratio (the ratio of File System and Data Base
the total number of records in transaction file and the total number of records in master file)
is very high. That is why this file organization is most suitable for transaction files.
Disadvantages
1. It proves to be very inefficient and uneconomical for applications in which the activity ratio
is very low.
2. Since an entire sequential file may need be read to retrieve and update few records,
accumulation of transactions into batches is required.
3. Transactions must be stored and placed in sequence prior to processing.
4. Timeliness of data in the file deteriorates while batches are being accumulated.
5. Data redundancy is typically high since the same data maybe stored in several files,
sequenced on different keys.
6. Random enquiries are virtually impossible to handle.
Applications
Payroll system
Billing and customer statement preparation
Bank cheque processing
Financial accounting
For mapping the key fields to the locations, an arithmetic procedure called hashing algorithm is
frequently used.
This address generating function is selected in such a manner that the generated addresses
should be distributed uniformly over the entire range of the file area and a unique address must be
generated for each record key.
A Direct Access Storage Device (DASD) such as drum, disk, etc., are essential for storing a direct
file.
Advantages
1. The access to and retrieval of a record is quick and direct (within a fraction of a second).
2. Transactions need not be sorted and placed in sequence prior to processing.
3. Accumulation of transactions into batches is not required before processing them. They
maybe processed as and when generated.
4. It can also provide up-to-the minute information in response to enquiries from
simultaneously usable on-line stations.
5. If required, it is also possible to process direct file records sequentially in a record key
sequence.
6. A direct file organization is most suitable for interactive on-line applications.
Disadvantages
1. These files must be stored on a direct access storage device. Hence, relatively expensive
hardware and software resources are required. 153
Computer Application 2. File updation (addition and deletion of records) is more difficult as compared to sequential
in Management
files.
3. Address generation overhead is involved for accessing each record due to hashing function.
4. Maybe less efficient in the use of storage space then sequentially organized file.
5. Special security measures are necessary for on-line direct files that are accessible from
several stations.
6. System design around it, is complex and costly.
Applications
A direct file organization is most suitable for interactive on-line applications such as:
1. Airline/Railway reservation systems
2. Teller facility in banking applications
The contents (which serve as an index) help us to locate (page of the desired topic) so that one
can turn directly to that page to begin reading instead of searching each page. .
In an indexed sequential file, records are stored sequentially on a direct access device (i.e.,
magnetic disk) and data is accessible either randomly or sequentially.
The sequential access of data occurs as one record at a time until the desired item of data is found.
The records of the file can be stored in random sequence but the index table is in sorted sequence
on the key value.
Advantages
1. Permits the efficient and economical use of sequential processing techniques when the
activity ratio is high.
2. Permits direct access processing of records in a relatively efficient way when the activity
ratio is low.
Disadvantages
1. These files must be stored on a direct access storage device. Hence, relatively expensive
hardware and software resources are required.
2. Less efficient in the use of storage space than some other alternatives.
Applications
This file organization is a compromise approach that combines some of the advantages of both
the sequential and direct approaches, and therefore used in almost all the applications, like
Material A/C, Banking Industry, etc.
Student Activity 3
1. What do you mean by file design? What are the objectives of file design?
2. Differentiate between serial file and sequential file.
3. What is a direct file?
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4. What are the disadvantages of an Indexed sequential file?
File System and Data Base
5.7 DESIGNING REPORTS
Systems analysts specify reports when they need a record of data or a report of information, or
circulate a large volume of information to several persons simultaneously.
Only those reports whose printing is absolutely necessary should be printed. One well designed
report may sometimes replace several poorly designed ones. Providing unnecessary details assists
no one, so analysts should be alert to avoid producing extraneous data.
Printed Reports
Printed reports vary in size, although analysts often use these standard sizes:
l 91/2 by 11 inches
l 11 by 14.7/8 inches
l 8 by 14.7/8 inches
These sizes are for continuous forms (sometimes called pin-fed or fan-fold forms)–connected
sheets of papers that feed into the printer one after the other.
All the features of printed output are available in microfilm and microfiche, the two film output
methods. Film output reduces output cost by approximately one-third. After developing in the
microfiche machine, film can be stored and retrieved when needed. For reference data used only
sporadically, such as private saving account balance that changes infrequently and can have
interest pasted every three months, microfilm could be a useful output option.
A page of output takes so little space when stored on microfilm. One square inch of a film can
store as much information as several pages of paper report. A 3.5 inch card stores the equivalent
of hundreds of pages.
The time taken to locate the film reel or card containing the information wanted the user must
maintain an index and to load the film into a microfilm or microfiche reader for viewing is a real
disadvantage.
Special Forms
Reports could be printed on simple paper. But usually, when an organization sends a report to its
customer, the logo and the name of the organization is also printed on it. Sometimes, the report is
printed on a paper which is "pre-printed". Recall your high school marksheets. The name of the
board, the year and logo of the board as well as the name of examination passed were printed on
the paper. The marks, name, school name, date of birth, etc., were printed afterwards. Another
example is your electricity bill. The titles of various labels are preprinted. The values against them
are printed by the information system.
As we discussed earlier, the layout is a blueprint that will guide the construction of programmes
later in the development process. Each variable in the layout must be accounted for in programme
instructions.
l All pages should have a title and page number and show the date on which the output was
produced.
l All columns must be labelled.
l Abbreviations must be avoided.
Some organizations specify standards that guide design practices in addition to the above
guidelines. A sample report format is shown in Figure 5.1.
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Report Generation File System and Data Base
Commercial outputs need formatted output. These formatted outputs are known as reports. A
formatted report may have the following:
1. Report heading
2. Page heading
3. Page numbering
4. Footers
5. Some remarks
6. Date, month, and year of printing
Commercial outputs may also extend over multiple pages. In that case, one will have to keep a
provision in his program so that certain details get printed on every page.
Report maybe of
1. Single page
2. Multiple page
Report Heading
It represents the title of the report and appears, only on the first page of the report.
Page Heading
Page Footer
It is printed at the bottom of each page. It is generally the total number of records on the page, sum
of the numeric data, etc.
Report Detail
This constitutes the main body of report. The output details or the information of the main
consequence are listed in this group.
Label Generation
Creating Labels means to generate address slip in computer. Creating mailing labels is a two step
process:
(1) Designing Label Form
(2) Production of Labels
Production of Labels
When you have designed and label form you want, you can print the labels at any time. At this
time, label is ready to use.
Logical data independence implies that application programs need not be changed if fields are
added to an existing record nor do they have to be changed if fields not used by application
programs are deleted.
According to a recent survey, a typical global company has 30 to 50 enterprise applications and
spends 25 to 40 per cent of its Information Technology (IT) budget on application integration.
And integration requirements are intensifying with the current wave of acquisitions and mergers.
Custom point-to-point solutions and other e-band-aids can solve pieces of the problem in the
short term, but they are typically expensive to produce and difficult to maintain. Application
integration aims at creating a cost-effective integration architecture and infrastructure to promote
interoperability among applications. And interoperability is the key to agility for the accelerating
change that rules today's global marketplace.
Cross-functional business processes through integration enable the open flow of information
between systems, across organizations, between enterprises and among trading partners. Several
technologies are available to integrate web-based applications, front-and-back-office systems,
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Computer Application ERP systems, and package software applications. Some of the most popular application integration
in Management
solutions are PeopleSoft, Oracle, SAP, and other leading ERP systems, as well as all leading
database management systems (DBMSs). A typical application integration looks similar to the
one depicted in the figure given below:
The database manager module is responsible for all these tasks in the following way:
1. Interface with the file manager: Database manager interacts with the file manager of the
operating system by storing raw data on disk using the file system usually provided by a
conventional operating system. The database manager would translate a DML (Data
Manipulation Language) statement into sequence of low-level file system commands for
storing, retrieving and updating data in the database.
2. Integrity enforcement: It enforces integrity by checking that updates in the database do
not violate consistency constraints. For example, in a bank database, it is the task of the
database manager to see that no bank account balance is below Rs. 1000 as otherwise it
would violate consistency constraint.
3. Security enforcement: By defining security checks and constraints, the database manager
ensures that the database is safe. The database manager is endowed with the power of
letting the users use the database and also deny it. It is the sole responsible person to
provide access rights to a user like - read only, read-write etc.
4. Backup and recovery: Database is such a valuable asset that the database manager must
ensure that it is not damaged or lost. Therefore, it regularly takes backup of the database. In
case of any failure it initiates suitable recovery procedure to resurrect the database. It must
also do it in the least amount of time.
Student Activity 4
1. What is a printed report? Describe its layout.
2. Give the necessary guidelines to design a printed report.
3. What are labels? How you generate them?
4. What are the features of DBMS?
5. List some issues related to integration of application.
6. What is a micro database manager?
5.11 SUMMARY
l A file is a collection of related records.
l A file is made up of record, which are made up of fields, which in turn are made up of
characters.
l Fields within logical records are normally called "data items".
l A record is recognized or identified by the record KEY.
l Data files can be broadly classified as master files, transaction files, and references files.
l The physical nature of the storage device will have a direct bearing on the way files are
organised on it and also on the method of access.
l There are three main types of file design: sequential, indexed sequential and direct access.
l System analysts specify reports when they need a record of data or a report of information. 161
Computer Application l Printed reports vary in sizes. Its all the features are available in microfilm and microfiche.
in Management
l The layout is a blueprint that will guide the construction of programmes later in the
development process.
l A formatted report may have Report heading, Page heading, Page numbering, Footers,
some remarks, date, month and year of printing.
l In control break report, one need group information bared on some common criterion.
l DBMS reduces data-redundancy, allows to share data, assures data integrity and security,
resolves the conflicts among various users and supports data independence.
l The database manager module is responsible for managing interface with the file manager,
integrity enforcement, security enforcement, and backup and recovery of data.
5.12 KEYWORDS
File: A collection of related records.
Data File: Well defined data structures that contain related data organized in convenient groupings
of records.
Direct File: A file which consists of records that can be directly located without having to search
through any other records.
Index Sequential Access Method (ISAM): The technique where the records of the file can be
stored in random sequence but the index table is in sorted sequence on the key value.
Master Files: Files which include some information of permanent nature and are updated by
recent transactions.
Transaction Files: Files in which the data relating to business events recorded, prior to further
stage of processing and are created from source documents used for recording events or
transactions.
Serial File: File where records are stored without any consideration of their order or sequence.
Sequential File: File where records are arranged in ascending or descending order or chronological
order of a key field.
Data Integrity: Implies that the data contained in the database in both accurate and consistent.
Database Manager: A program module which provides the interface between the low level data
stored in the database and the application programs and queries submitted to the system.
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(f) ———are files of a fairly permanent nature. File System and Data Base
Detailed Questions
1. What is the difference between a data file and an executable file?
2. What is the difference between a program file and an object code file?
3. What is a formatted text file?
4. Describe various types of file organizations.
5. Compare sequential and Index sequential file organization?
6. What are the advantages and disadvantages of random file organization?
7. What is a master file? Describe its various types.
8. What is the purpose of having a transaction file.
9. Describe various file design methods.
10. List some applications of sequential file.
11. Why do we require printed report?
12. Describe the layout of a printed report?
13. What should a formatted report contain?
14. Describe the reports with control break?
15. What do you mean by data redundancy and Integrity?
16. How does DBMS support security of data?
17. What are the issues related to integration of an application ?
18. What are the responsibilities of a database manager module?
163
Computer Application
in Management UNIT
6
PROGRAM AND DEVELOPMENT
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z How to define a program.
z Various steps in program development.
z Characteristics of a good program.
z Flow charts and rules for drawing flow charts.
z Input-process-output analysis.
U N I T S T R U C T U R E
6.1 Introduction
6.2 Program Definition
6.3 Steps in Program Development
6.4 Characteristics of a Good Program
6.5 Data Handling and Declaration
6.6 Introduction to Flow Charts
6.7 Input Process Output Analysis
6.8 Summary
6.9 Keywords
6.10 Review Questions
6.11 Further Readings
6.1 INTRODUCTION
A program is a series of instructions that perform a particular task and is recorded in some form on
a computer disk. Simply, program is an abstract collection of instructions for computers to perform
specific tasks. It is variously known as a program or software program.
Systematic notations for the specification of such sequences of computation steps are referred to
as programming languages.
The task of developing programs for the solution of computation problems is referred to as
programming.
Variables
z Data which may change or be assigned different values as the program runs is known as
variables.
z Limitations imposed by language on maximum number of characters used to form variable
names.
Variable Types
Each type occupies different storage in RAM and contains values within limits specified for
constants of the same type.
z Integer or fixed point
z Real or floating point
z Character or string
Student Activity 1
1. What is a program?
2. What are the various steps involved in development of a program?
3. What are the characteristics of a good program?
4. What are the various data types involved in a program?
The beginning, end of a point of interruption in a program, is represented by the terminal box.
e.g.: END
Input/Output Box
Any function of an input/output device (marking information available for processing, recording,
processing information, etc.) is represented by input/ output box.
e.g.: Input A
166
Processing Symbol Program and Development
A group of program instructions that perform a processing function of the program is represented
by this symbol.
Calculate
e.g.:
Gross Pay
Decision Box
This box is used to document points in the program where a branch to alternate paths is possible
based upon variable conditions.
e.g.: A≥B
Connector
An entry to, or an exit from another part of the program flow chart is represented by this symbol.
(C)
Flow Lines
← ↑ ↓ →
Predefined Box
A group of operations not detailed in the particular set of flow charts are represented by the
predefined box.
Rule 2
The logic of a program flow chart should flow from top to bottom and from left to right.
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Computer Application Good Logic
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Bad Logic
Rule 3
Each symbol should have one entry point and one exit point.
Rule 4
Rule 5
168
Advantages of Flow Charts Program and Development
Flow charts are used for a broad variety of applications in different types of work. These give a
clear graphical/pictorial representation of the various paths that must be followed to perform the
acts to accomplish the goals of the program.
Flow charts are invaluable at the time when modifications must be made to the original program to
perform additional services not planned originally.
Flow charts are language independent. Flow charts are a visual representation, and hence provide
a convenient alternative to the usual narrative description for a program of system.
Flow charts offer a controllable level or detail. They are usable from the most summary systems
level to the most detailed programming level.
Flow charts may not reveal significant steps to be followed in actual coding. Flow charts are often
cumbersome to use and costly to produce. Flow charts do not constitute a programming language,
they are person-to-person means of communication, not person-to-computer. Flow charts are
difficult to produce at a summary level.
Sequential Logic
The instructions are executed in order from top to bottom.
↓
Instruction 1
↓
Instruction 2
↓
Instruction 3
↓
Instruction 4
Selectional Logic
This employs a number of structures called if structures, each of which is essentially a selection
of one, out of several alternatives. This is equivalent to the code:
IF test
THEN A;
ELSE B;
end if
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Computer Application
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Iterative Logic
This involves the structures involving loops. Iterative construct is further categorized as: Do
While-End do, Repeat-Until, and For-Next loops.
While test
do process;
end do;
repeat process;
until test;
Example 1. Draw a flow chart to print first 100 numbers using Do While-End do logic.
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Example 2. Draw a flow chart to print the greater among two numbers. Program and Development
Example 3. Draw a flow chart to allow the user to enter a non-blank name and display a welcome
message for the user on the screen.
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Computer Application Types of Flow Charts
in Management
The two major varieties of flow charts used presently in practice are:
z System flow charts
z Program flow charts
Input(s) Output(s)
Process
Student Activity 2
1. What is a flow chart?
2. Describe various flow chart symbols.
3. Describe the rules for drawing flow charts.
4. What are the draw backs of flow charts?
5. Describe the logical constructs used in flow charts.
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6. Describe various types of flow charts. Program and Development
6.8 SUMMARY
A program is a series of instruction that perform a particular task. The task of developing programs
for the solution of computation problems is referred to as programming. The steps involved in
writing computer programs are problem identification, task and data analysis, output identification,
designing the solution data validation, Implementation, debugging final documentation and
maintenance. A good program should be accurate, reliable, efficient, robust, reusable, maintainable
and readable. The main function of a computer program is data processing. Various types of data
include constants and variables.
Flow charts are the pictorial description of program logic. The symbols used in a flow chart
include terminal box-to represent the beginning and end of a program; Input/output box-to
represent any function of an input/output device; processing symbol-to represent instructions
that perform a processing function; decision box-to document those points where a branch to
alternate paths is shown; connectors-to represent an entry to, or an exit from another part of the
program flow chart; flow lines-to connect the sequence of logical setups; and predefined box-to
show a group of operations not detailed in the particular set of flow charts. Flow charts offer a
controllable level of detail but still are something strange to work with for beginners. The logical
constructs used in flow charts include sequential logic, selective logic and iterative logic. The
two major varieties of flow charts are system flow charts and program flow charts.
Every process takes some input (s) and transforms it (them ) into output (s). The input-process-
output analysis of a system is vital to understand, characterize and design a system.
6.9 KEYWORDS
Program: A series of instructions that perform a particular task and is recorded in some form on
a computer disk.
Programming: The task of developing programs for the solution of computation problems.
Programmer: A person engaged in the activity of programming.
Constant: Data which is predetermined before a program is used.
Variable: Data which may change or be assignment different values as the program runs.
Flowchart: Pictorial representation of program logic.
Detailed Questions
1. Define a program, programming and programmer.
2. What do you mean by data declaration?
3. What is a flow chart? Describe its various types.
4. What is the used of predefined box in a flowchart?
5. Describe the function of a connector in the flow chart.
6. What are the advantages of flow charts.
7. Describe various logical constructs used in flow charts.
8. Draw a flow chart to print prime numbers between 1 and 100.
9. Draw a flow chart to calculate amount using formula A= P(1+r/100)n.
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Programming Concepts
UNIT
7
PROGRAMMING CONCEPTS
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z Various techniques of program design.
z Linear and structured programming.
z Basic constructs of structured programming.
z The modular design of programs and communication between modules design.
z The requirements of module design.
U N I T S T R U C T U R E
7.1 Introduction
7.2 Program Design Techniques
7.3 Programming Techniques
7.4 Modular Design of Programs
7.5 Module Design Requirements
7.6 Summary
7.7 Keywords
7.8 Review Questions
7.9 Further Readings
7.1 INTRODUCTION
A set of program design concepts has evolved over the past three decades. Although the degree
of interest in each concept has varied over the years, each has stood the test of time. Each
provides the program designer with a foundation from which more sophisticated design methods
can be applied. In this chapter we will discuss various techniques of program design. The concept
of modularity will also be discussed.
Top down design approach is performed in a special way. The main program is written first. It is
tested before sub-programs are written. To do this, the actual sub-programs are replaced with
stubs. The stubs simply test to see if the data is passed correctly.
After the main program is written and checked, each module is written and tested in turn. This
should first be done without the main program in order to isolate a stub if an error occurs.
A simple main program is written to test the sub programs. If the modules run properly, then it is
tested with the main program.
If the module and the main program run properly then the next module is written and checked and
so on.
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Computer Application To describe the program at its highest level, we use something called the "universal program",
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and then by a process of "stepwise refinement" work out the details of each part of the program.
Example 1
Problem: How to reach Kolkata from Delhi by train?
Let us apply top-down design approach on this problem. Break this problem into smaller problem
as follows:
The problem (whole) has been broken into smaller problems each easily manageable and solvable.
If need be, these smaller tasks may be further broken into still smaller tasks. These smaller tasks
- viz. how to buy a ticket, can be solved easily than the whole problem at a time.
Advantages
1. At each stage, the sub programs are tested by themselves and then the main program is
tested. Whenever modules are added, they are tested with the main program so if any error
occurs it will probably be in a module only and this will be easy to debug.
2. It is desirable for modules to be kept small in general. As far as possible a module should be
less than 100 statement lines long.
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Bottom Up Design Programming Concepts
A bottom up approach would be to write the most basic subroutines in the hierarchy first and
then use them to make more sophisticated subroutines.
Example 2
Problem: How to reach Delhi to Kolkata by train?
The pure bottom up approach is generally not recommended because it is difficult to anticipate
which low level subroutines will be needed for any particular program. It can often be a useful first
step to produce a library of basic functions and procedures before embarking on a major project.
In the bottom up approach it is usually assumed that the basic routines created will be general
enough to be used more than once.
Using the subroutines, to construct a program, save yourself repeating the same lines of code by
reusing it.
A routine that is used many times has a very difficult status to those higher in the hierarchy. It is
more like a basic instruction in the programming language than a large scale program component.
Structured Programming
Structured programs are the ones that are divided into functional modules and arranged in an
hierarchical order instead of programs written in a sequence.
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Computer Application One of the most versatile properties of a digital computer is that it can make a "decision", thus
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creating a branching point. There are also times when it becomes necessary for a program to
"Look Back" over a set of statements, a number of times. If branching and looping can be used,
then much more complex iterative algorithms can be written, which in turn results in more complex
programs.
There are procedures that can be used for writing these complex programs that make them much
less error prone and much easier to debug. The technique for writing such programs are referred
to as Structured programming.
Structured programming refers to the process in which we break the overall job down into separate
piece of modules. The above figure shows, that how a salary program is broken down into number
of small modules.
These modules, in turn, are broken down into smaller pieces which can also be further subdivided.
Modules must be chosen in such a way that we can specify how they have to interact. In effect,
there is a contact between each pair of modules.
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Basic Constructs of Structured Programming Programming Concepts
There are three program constructs used normally in structured programs. They are:
1. Sequence
2. Selection
3. Repetition (Iteration Logic)
Sequence
Structure consists of the action followed by another till the desired result is obtained.
Statement 1
Statement 2
---------------
---------------
Statement n
Selection
z This construct indicates a decision one way, two way or multi-way selection.
In conditional execution there is a need carry out a logical test and then take some particular
action which depends upon the result of that test.
z Selection is a special kind of conditional execution in which a particular group of statements
is chosen from several available groups.
If (condition is true) then
sequence of statements
else
another sequence of statements
end if
z The selection structure consists of a test for a condition followed by two alternative paths
for the program to follow. The program selects one of the program-control paths depending
on the outcome of the test condition. After performing one of two paths, the program
control returns to a single point. This pattern can be termed as if ... else because of its logic.
Iteration
z In most cases programs require that a group of consecutive instructions be executed
repeatedly until some logical condition has been satisfied. Generally, the required number
of repetitions are not known in advance. This type of repetition is known as conditional
looping.
z Another type of repetition is unconditional looping. In this, the execution of a group of
consecutive instructions is repeated for some specified number of times, this is done by for
loop.
z The repetitive structure can also be called loop and represents an iterative process. Iterative
logic refers to structure involving loops of which, there are two types:
1. do while (condition is true)
a sequence of statements
end do
2. repeat
a sequence of statements
until (condition is true)
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Computer Application These three coding structures allow a program to be read from top to bottom, making the logic of
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the program more visible for checking and maintenance.
Student Activity 1
1. List various program design techniques.
2. Describe top down design technique.
3. Describe bottom-up design technique.
4. Define linear program and structured program.
5. What are the basic constructs of structured programming?
A program module is defined as the part of a program that performs a separate function, e.g.,
input, input validation, processing of one type of input.
A program module maybe quite large, so that it maybe further divided into logical sub modules.
The process of subdivision continues until all modules are of manageable size in terms of complexity
of logic and numbers of instructions.
The modules reflect a logical flow for a computer program. After initialization, processing proceeds
logically with input, input validation, various processing modules and output. Error handling
maybe required during execution of any module.
Basic Attributes
A module is a collection of program statements with five basic attributes.
z An input
z An output
z A function
z A mechanism
z Internal data
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Control Relationship between Modules Programming Concepts
z The structure charts show the interrelationships of modules by arranging them at different
levels and connecting modules in those levels by arrows. An arrow between two modules
means the program control is passed from one module to the other at execution time. The
first module is said to call or invoke the lower level modules.
z There are three rules for controlling the relationship between modules:
There is only one module at the top of the structure. This is called the root or boss module.
The root passes control down the structure chart to the lower level modules. However,
control is always returned to the invoking module and a finished module should always
terminate at the root.
There can be no more than one control relationship between any two modules on the
structure chart, thus, if module a invokes module b, then b cannot invoke module a.
Control items are used to direct program control and show error or end of file conditions. This
control couple is shown by a filled-in circle on the tail of arrow.
Student Activity 2
1. What is a program module?
2. What are the functional modules of a program?
3. What are the basic attributes of a program model?
4. Describe the rules for controlling relationship between various modules of a program.
5. Describe various requirements of module design.
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Computer Application
in Management 7.6 SUMMARY
In the top down design technique, the main program is written and tested before sub programs are
written, then each module is written and tested in turn. A bottom-up approach would be to write
the most basic subroutines in the hierarchy first and then use them to make more sophisticated-
subroutines. Linear program is a method for straight forward programming in a sequential manner.
Structured programs are the ones that are divided into functional modules and arranged in a
hierarchical order. Branching and looping allows much more complex iterative algorithms to be
written, which in turn results in more complex programs. Structured programming decreases the
complexity of program by breaking-down into smaller logical units, reduces debugging and program
writing time. The three program constructs used in structured programs are sequence, selection
and repetition (iteration) logic.
A program module is the part of a program that performs a separate function. The structure charts
show the interrelationships of modules by arranging them at different levels. Two types of
informations are passed between modules: Data and control.
The qualities reflected by the module design include coupling, cohesion, span of, size and shared
use.
7.7 KEYWORDS
Universal Program: The program at its highest level.
Linear Program: A method for straight forward programming in a sequential manner which does
not involve any decision making.
Structural Program: programs that are divided into functional modules and arranged in an
hierarchical order.
Structured Programming: The process of breaking the overall job into separate pieces of modules.
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(c) Branching and looping can be used to write more complex programs. Programming Concepts
(d) The iteration structure is a special kind of conditional execution of a group of statements.
(e) Functions may be duplicated in separated modules.
Detailed Questions
1. What is the difference between top down and bottom-up design approach?
2. What are the advantages of top down design?
3. Describe the top-down Implementation.
4. Give a general model of linear programs
5. Define structural programming.
6. What is a program module.
7. Define conditional looping.
8. What is Iterative logics?
9. How does two modules communicate?
10. Differentiate between coupling and cohesion.
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Computer Application
in Management UNIT
8
PRESENTATION GRAPHICS
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z How to create a presentation on PC using wizard or template. Or a blank presentation?
z Components of power point screen.
z Auto content wizard.
z Different views available in power point.
z Displaying the slides.
z Saving a presentation.
U N I T S T R U C T U R E
8.1 Introduction
8.2 Creating a Presentation on PC
8.3 Creating a New Presentation
8.4 PowerPoint Views
8.5 Creating a Presentation Using a Template
8.6 Creating a Blank Presentation
8.7 Opening an Existing Presentation
8.8 Displaying the Slides
8.9 Saving a Presentation
8.10 Closing a Presentation
8.11 Summary
8.12 Keywords
8.13 Review Questions
8.14 Further Readings
8.1 INTRODUCTION
PowerPoint is a presentation software package included in Microsoft Office suite. It is used to
create professional quality presentations. A presentation is a structured delivery of information.
Presentation can be reproduced on transparency, paper or on-screen. PowerPoint features can be
used to work on slides, organize presentation contents with outlines and generate speaker notes
and audience handouts. Teachers, professors, politicians and sales representatives make
presentations to sell their concepts. Some other notable presentation software packages are
Harvard Graphics and Lotus Freelance.
PowerPoint 2000 helps you structure the ideas and information that you may want to convey to
your audience. It lets you create the contents of your presentation by typing/inserting text,
pictures, sounds and animations. With it, you can add visual images, supporting documents and
audio recordings to enhance your presentation. PowerPoint makes the creation of any presentation
simple by providing built-in professional designs called AutoLayouts and templates. You can
also create different versions of. a presentation for different audiences and build your contents in
either a text-based outline view or a design based slide view.
z Menu Bar: It is similar to the menu bar in other Microsoft Office applications having File,
Edit, View, Insert, Format, Tools, Window, Help menus.
z Toolbars: Toolbars are collections of buttons that you can click and activate some of the
most common commands in PowerPoint. These commands can also be activated through
menus.
z Status Bar: It is located at the bottom of the PowerPoint screen. It displays the number of
the current slide and the name of the template on which the presentation is based.
z Vertical Scroll Bar: It helps you to scroll through the slides in a presentation.
z Slide Buttons: They are located at the bottom of the vertical scroll bar and help you to
display the previous and next slides.
The first option in the PowerPoint dialog box under Create a new presentation using is the
AutoContent Wizard. The AutoContent wizard is a guide composed of several screens that help
you to create a professional presentation quickly and easily. It basically takes you through series
of questions. You can choose options to create a good presentation.
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Computer Application
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The AutoContent Wizard can create 8 to 12 slides with suggested content that you can
change.
2. Click on the Next Button.
A dialog box as shown in the figure is displayed.
Press a category button for the type of presentation you are going to create and then select
the presentation that best suits your need.
3. Select the Presentation style in the Next screen as shown:
The given screen shown on next page helps choose the type of output you will be using
and the wizard will select the best color scheme for your presentation. You can change
the look of your presentation by applying other color schemes available in the format
menu.
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Presentation Graphics
4. Enter data into each text box and click on the Next Button.
The information entered by you will be put into the presentation by the wizard for you. You
can always change this information later.
5. The Next screen will end the AutoContent Wizard and in turn your presentation will be
created as shown below.
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Computer Application The Presentation Created by the wizard for you will be seen in the Normal view as displayed in the
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figure below.
Normal View
Normal view contains three panes: the outline pane, the slide pane, and the notes pane. These
panes let you work on all aspects of your presentation in one place. You can adjust the size of
different panes by dragging the pane borders.
Outline pane
Presentation in
normal view
Notes pane
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Outline Pane: Use the outline pane to organize and develop the content of your presentation. Presentation Graphics
You can type all of the text of your presentation and rearrange bullet points, paragraphs, and
slides in this pane.
Slide Pane: In the slide pane, you can see how your text looks on each slide. You can add
graphics, movies, and sounds, create hyperlinks, and add animations to individual slides.
Notes Pane: The notes pane lets you add your speaker notes or information you want to share
with the audience. If you want to insert graphics in your notes, you must add the notes in notes
page view.
These three panes are also displayed when you save your presentation as a Web page. The only
difference is that the outline pane displays a table of contents so that you can navigate through
your presentation.
At any time while you are creating your presentation, you can start your slide show and preview
your presentation by clicking Slide Show.
Slide
Sorter
toolbar
Slide view and outline view have been combined in normal view.
If you would like to use the old slide or outline view, you can add the command to a menu or
toolbar.
1. On the Tools menu, click Customize, and then click the Commands tab.
2. In the Categories box, click View.
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Computer Application 3. Drag the Outline or Slide command from the Commands box to the menu or toolbar you
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want to add it to.
If you are adding the command to a menu, when the menu displays a list of commands, point to
where you want the command to appear, and then release the mouse.
Student Activity 1
1. What is power point?
2. Describe various components of a power point screen.
3. How will you create a presentation using Auto content wizard?
4. Describe various views available in power point.
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3. Select the template and click on the OK button to activate the template. The New Slide box Presentation Graphics
is displayed as shown in the figure below.
4. Select the layout from the New Slide dialog box and click OK button.
A slide as shown in the figure below will be displayed
Template is a general term used for a pattern, which will remain same throughout the Presentation.
All the slides will have the same background as selected by you.
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Computer Application A slide as shown in the figure will be displayed.
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Table 8.1
2. Enter the File name when the Save button gets activated.
3. Click the Save button. 193
Computer Application
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To close a presentation, select the Close option from the file menu. If the current file is unsaved,
Power Point will display a dialog box with Yes/No options. Select Yes if you want to save the file,
No if you do not want to save the file or Cancel to return to your file without saving it.
Student Activity 2
1. Write a step wise procedure to create a presentation using a template.
2. Write a step wise procedure to create a blank presentation.
3. How will you open an existing presentation?
4. How will display the slides of a presentation?
5. How will you save a presentation?
6. How will you close a presentation?
8.11 SUMMARY
The application software that can professional looking visual aids is called presentation. Graphics
software. MS-Power point can be started by clicking at start→programs→Microsoft power point.
A slide can contain one or more of these component: Titles, Graphs, Drawing objects, clipart and
pictures. The slide components that are used for reference are: Handouts note, on lines. A new
presentation can be created through one of these methods: (i) Auto content Wizard (ii) Blank
presentation. A new slide can be added by either clicking at common tasks option of formatting
toolbar, and then selecting new slide option, by clicking at insert menu’s new slide option. A
presentation in power point can be viewed in any of these views. Normal, outline slide, slide
sorter, slide shows and notes page views.
8.12 KEYWORDS
Design Template: A set containing graphics design and color scheme of a presentation.
Outlines: Summarized version of slides, that contain only tiles and main text.
Presentation Graphics Software: A software that lets one create professional electronic
presentation.
Slide Show: Electronic presentation that can run on computer screen or a protection device.
(a) The two main views of power point are normal view and slides sorter view.
(b) You can preview you presentation by clicking slide show.
(c) The presentation templates does not include masters with pre-formatted fonts and
styles.
(d) The keyboard and the mouse can be used to navigate through the slides.
(e) Slide view and outline view have been combined slide-sorter view.
Unsolved Answers
1. (a) Presentation (b) Auto content wizard (c) The outline pane, the slide pane, the notes
pane (d) Slide sorter (e) Template
2. (a) True (b) True (c) False (d) True (e) False
Detailed Questions
1. What is a slide?
2. What is a slide show?
3. What is an outline view of slide?
4. Describe various panes of slide in normal view.
5. How will you open an existing presentation?
6. What are the basic components of a slide?
7. What is the use of slide sorter view in power point?
8. In which pane can you insert speakers notes.
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Computer Application
in Management UNIT
9
DATA COMMUNICATION AND NETWORKING
L E A R N I N G O B J E C T I V E S
After studying this unit, you should be able to understand:
z How to describe data communication and its various types.
z Approaches and modes of data transmission.
z Working of modem/fax modem.
z Multiplexing.
z Components and types of computer network.
z Network topology and cables.
z OSI model of network.
z LAN and its popular types.
z Client /server and peer to peer networking.
z Network operating system and network environment.
U N I T S T R U C T U R E
9.1 Introduction
9.2 Data Communication
9.3 Multiplexing
9.4 Components of Computer Network
9.5 Local Area Network (LAN)
9.6 Uses of a Network
9.7 Topology
9.8 Networking Cables
9.9 OSI Layout and IEEE
9.10 Popular Types of LAN
9.11 Inter Networking
9.12 Public Networks
9.13 Client/Server vs. Peer to Peer Networking
9.14 Network Operating Systems
9.15 Network Management
9.16 LAN in Business Environments
9.17 Summary
9.18 Keywords
9.19 Review Questions
9.20 Further Readings
9.1 INTRODUCTION
Today world is often referred to as global village. All thanks to today’s revolutionary technology.
Because of today’s technology, we can communicate to any portion ion any corner of the world
from anywhere in the world. And the credit for all this goes to the communication revolution that
has happened in this century, especially in the last thirty years. Advances in
the communication technology, have made possible nearly everything we dreamt of.
It is basically communication that makes you take advantage of massive mainframe processing
power if you turn your PC into a terminal of a mainframe. It is communication that lets you chat
with different people across the globe through an on-line services. It is again communication that
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allows you to access huge servers of information on virtually any subject via networks of Data Communication and
computers. And that is why this chapter is dedicated to this fascinating combination of Networking
communication, computer and networking.
This communication is possible with the approach known as protocols. The data flows between
two devices as sequential bits (0 and 1) across a transmission medium say copper wire. These bits
are grouped to form a character. A character may be a number, an alphabet or a symbol. As a
standard, generally 8 bits form a byte or a character. Each bit (0 or 1) is represented as a voltage
level on a transmission medium. As a standard, bit 0 represents a positive voltage and bit 1
represents a negative voltage. These signalling conventions are followed by most of the
communicating devices. The most common interface standards are RS232c or V5, X.21 etc. In
RS232c signalling standard, voltage level between +5V to + 15V represents bit 0 and voltage level
between -5 to -15V represents bit 1. During an idle state while the data is not being transmitted,
only the electric current flows through a transmission medium (wire). At the instance of data
transmission the current in the wireline is intercepted in a particular way to superimpose data that
is representable as the voltage levels to traverse towards receiving device.
Asynchronous Transmission
In asynchronous mode of data transmission each character (byte) is transmitted one at a time.
Each character is preceded by a start bit. The purpose of start bit is to inform the receiving device
that a character transmission has begun. The transmitted character ends with a stop bit. The stop
bit suggests that a character has been transmitted. Each bit represents a voltage level for a
specific length of time to enable the receiving device to recognize and record the incoming signal
accurately. This specific length of time determines the rate of data transfer that may be measurable
in bits per second. In asynchronous mode of transmission there is no indication of the speed at
which the character is being transmitted. Therefore, there is no perceptible method for the receiving
device to sample the incoming signal precisely to recover the transmitted data. For this lack of
synchronization of transmission this mode of transmission is called asynchronous transmission.
This anamoly of non synchronization is overcome by providing internal clocks at each end,
transmitting as well as receiving. Both internal clocks work at the same rate such that on the
receipt of start bit the receiver device starts its internal clock to instruct receiver's interface to
sample the incoming signal.
Notes: Some systems may require more than one stop bit as a character terminator. This is generally
for slower devices typically with slow mechanical components. Other important point to note is that
there are several kinds of bit representations of a character. Most commonly used are ASCII (American
Standard Code for Information Interchange) and EBCDIC (Extended Binary Coded Decimal
Information Code). In widely used ASCII representation 7 bits uniquely represent a character. The
8th bit is called parity bit and used primarily for identification of success or failure of a character
transmission device to sample the frame of information appropriately at correct signalling rate.
Synchronous Transmission
In synchronous mode of data transmission a block of characters is transmitted one at a time. Each
block of characters is preceded with a few synchronization (SYN) characters. These SYN characters
contain the timing information which is used by the receiving device clock onto the sending
device's signal. Since, in this mode of data transfer the block contains the timing information
using SYN characters that allows automatic synchronization, this process is known as synchronous
transmission. The size of blocks of characters may vary therefore there exist the ASCII control
characters termed as STX (start of text) and ETX (end of text) that are used as delimiters. The
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Computer Application to be transmitted at a higher data transfer rate. The efficiency of synchronous transmission varies
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according to the block size and dependent upon the protocol. If the block size is too small the
overheads of protocol is more due to additional SYN characters and delimiters in header although
the probability of error in transmission reduces. In case the block size is too large the general
efficiency for large data transfer may improve in terms of data transfer rate but the probability of
error in transmission increases. Therefore, for a reliable error free data transfer over a long distance
requires that a maximum block size be fixed. Frequently used block size standard in most of the
protocol is 512 bytes. Generally the level of efficiency in the synchronous mode of transmission
is higher than in the asynchronous mode of transmission. (Refer Figure 9.1)
Notes: A block of data is also referred as a packet. A sequence of blocks that is transmitted from a
sending device needs to be reassembled at the receiving device. Each packet contains a packet or block
identity number and routing address for destination for accurate reassembly as the original data. In
case of identification of error on receipt of a packet, a request is sent to the sending device for
retransmission of that packet again. (Refer Figure 9.2)
z The structure of the unit of data sent should be recognized at the receiving end;
z The representation of data (ASCII/EBCDIC) should be the same on both sides of data
communications;
z There should be a method of introducing checkpoints for recovery during large data transfer
in the event of failure;
z There should be end to end protocol in both communicating hosts to recover from errors in
a similar fashion;
z Both communicating hosts should use similar addressing techniques. Approaches for Data
Transmission
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Computer Application Modes of Data Transmission
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In the simplest form of data transmission data flows in one direction. In a half duplex system of
data transmission data flows in the forward and backward directions to the receiving and the
sending devices but not simultaneously. Most common example of a half duplex system is a radio
link or a wireless set. In a full duplex system of data transmission data flows in both directions
simultaneously. A typical example of a full duplex data transmission is the RS232c interface.
RS232c interface is typically designed to connect any digital equipment to a data communication
equipment. A modem is a typical DCE.
The criteria for selection of modem should depend upon the speed of transmission, error correction,
data compression capability and Hayes compatibility. The modems that are less than 14400 bits/
sec data rates as speed are mostly obsolete now. User should prefer a modem with speed equivalent
or greater than 28800 bits/sec. A modem should be easily configurable to be used for TCP /IP
(Transmission Control Protocol/Internet Protocol). This protocol enables a modem to communicate
with most of the other modems, use of internet and most of the networking technologies. We
would discuss more of TCP/IP in the next chapter on ‘Telecommunications’. A modem should
support V protocol. V 4.2 protocols have supplanted the old Microcom’s MNP4 protocols for
error correction. For data compression, V.42b is protocol should be preferred. MNP5, MNP10 are
data compression protocol available from Microcom. The shortcoming of MNP protocol is that
these cannot handle already compressed data. A modem should be Hayes compatible. Hayes
compatibility has become de-facto standard for modems because most modems follow Hayes
command set for their configuration. (Refer Table 9.1)
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Data Communication and
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Table 9.1 : Modern Speed and Protocol
Modem speed Basic Protocol Error correction Data compression
There are two types of modems; internal and external. Internal modems are card sized and installed
inside the computer. An external modem is box shaped powered by an external power adapter and
connected to the computer with a serial cable. For faster modems 14.4 kps and above the computer
should be fitted with 16550 UART chip based serial port. Fax modems are designed to send and
receive faxes in addition to data.. Fax software is also needed to send fax. There are fax standards
ranging from Group I to Group IV or Class 1 and Class 2. Group IV and Class 2 are faster, more
efficient and the latest standard and therefore generally preferred. Some of the modems come with
digitalized voice capability also. These modems can function as voice answering machine also
when used with appropriate software.
The popular brands of modems available today are TEK from MroTek, Boca from Boca Research/
Power Tel, Soltrix from Soltrix/Amketee, Optima, Accra from Hayes/Datamatics, Sportster from US
Robotics/Soom from Soom Telephonics, MT Series from multitech, Comsphere from AT&T,
Paradyne/Crompton Greaves, etc.
Lines of Communications
There are basically two popular lines for communications. A public telephone is the ordinary
voice grade line. This line is routed through many relay systems and electromechanical systems.
This line of communication is also referred to as PSTN (Public Switched Telephone Network). A
leased line of communications is generally not subjected to the level of switching as in PSTN.
This line of communications accommodates wider range of frequencies than the voice grade. A
leased line of communications consists of bidirectional simultaneously operating two telephone
circuits.
9.3 MULTIPLEXING
Multiplexing is a technique of channelling multiple data inputs into one connection. The approaches
used to implement multiplexing is generally based on division of communication channel into time
slots or frequency bands. This technique was developed to overcome deficiency of old mainframe
machine which had direct terminal connections access for various peripherals and other computers
connected to it. Mainframe machine served as host to these terminals. This led to poor utilization
of the system because majority of connected systems remain inactive for major period of time
whereas some of the systems were saturated with requirement of data access or processing at a
specific time. Moreover the feasibility to provide port for each terminal as requirements grew was
vague. (Refer Figure 9.5)
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1 process 1
Terminal input
1
2 process 2
2 1 2 3 1 2
3 3 process 3
Student Activity 1
1. Define data communication.
2. Differentiate between synchronous and a synchronous modes of transmission.
3. Describe error management in data transmission.
4. Describe various approaches of data transmission.
5. Describe the working of modem.
The significant feature of a LAN is that its workstations are intelligent terminals with a capability
of distributed processing. This is unlike in a mainserver or miniframe centralized server based
environment where the connected terminals are dumb without processing power of their own.
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The prominent reasons which led to development and popularity of LANs are: Data Communication and
Networking
1. Sharing of expensive resources such as disk, files, printers, plotters, modems and software
was needed.
2. Diskless nodes (workstations) of a LAN provided security and virus protection by not
allowing to download important data from server or uploading unwanted software.
3. Distributed processing for inter-user communication within an organization and information
exchange was the most suitable model for MIS development.
4. Data management in a LAN environment is more efficient than the centralized processing
systems. Since, no users directly request to server for data without resorting to file transfer
on a stored media like floppy or hard disk.
5. LANs are more flexible and modular. This implies that LANs can be expanded easily by
adding of workstation with the support of networking software. If more disk storage is
needed, another hard disk can be installed or other file server can be connected in a LAN.
More than one LAN can be bridged to share data and communicate.
6. Most LANs have fault tolerant features such that in case of power failures LANs are
capable of disk mirroring and disk duplexing to safeguard data.
Notes: The hardware components hubs, switches, repeater, bridges routers and gateways are
generally applied whenever expansion of a LAN is required beyond geographic limits of optimum
performance or when two or more LAN systems are needed to be integrated for sharing of
peripherals and data resources. Modems are used alongwith telephone lines in the following cases:
(i) WAN (Wide Area Network) is needed for communication of computers located in remote
sites of an organization.
(ii) A computer user needs to access information from remote file server.
(iii) A computer user needs to send/receive electronic mail to/from a remote computer system.
We would describe this component appropriately while discussing internet working of LANs.
9.7 TOPOLOGY
The structure or layout of the cabling in connecting devices together to form a network is called
topology of the network. The advantage of a structured topology is that it is easier to add or
delete a node in the network.
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Computer Application Bus
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The Bus consists of a single communication channel. Each connected device is attached to the
media at an interface point. Each connected device has a unique hardware address. Data transfer
takes place using these hardware addresses. The bus will have more complex arrangements with
several interconnected segments.
Advantages
z Simple layout
z Ease in connectivity
z Locating cable faults is easy
z Ideal for one to many data transmissions since all connected devices see the traffic on the
cable. The signal reaches all stations regardless of their position on the bus.
Bottlenecks
There is no automatic acknowledgement of receipt by virtue of the topology. The signals stop on
reaching the end of the cable and do not return by default to the sender. Therefore, the higher
level protocols exists which can ensure that data is successfully exchanged.
Ring
Unlike bus topology, in a ring configuration the data transmission is unidirectional. Data
transmissions are received by each station’s interface as the data passes through the interface
connection. Like bus topology, each interface only copies the data from the network. Thereafter
data communicates to the device connected to the network on basis of the packet’s destination
address. Each network interface connection has its own hardware address for identification.
Typical ring topology is generally used in the large network Fibre Distributed Data Interface
(FDDI).
In ring topology, each interface station allows data transmission to pass through the interface
with only a few bits delay. For instance, consider circulation of a data packet (say 128 bytes), the
start of data packet may well have circulated around the ring and arrived back at the originating
station before the end of the packet has left for circulation. There is always only one circulating
data packet on the ring.
Advantages
z No routing problems since everyone on the ring receives the data. The addressed node
makes copy of the data for circulation
z Every generated packet eventually returns to the node therefore the acknowledgment of
successful data transmission is trivial
z Larger networks may be constructed from a number of interconnected rings.
Bottlenecks
Star
Generally, it includes a central switching system or hub. In the figure, if station D wishes to talk to
station B, it does so via the hub. In case a new device is required to be added it interfaces with
another cable attached to the central point. And if the hub is physically close to the connected
device then the individual cable rum would not be problematic. (Refer Figures 9.6, 9.7 & 9.8)
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Computer Application Advantages
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z Better overall reliability against cable faults provided the central point which is switching
data to the destination is robust
z Only a single node will be unavailable in the event of cable failure
z LANs implemented on the star topology are sometimes based on existing telephone wiring
in the building and do not normally have high data transfer rates.
Bottlenecks
Coaxial Cable
There are many types of coaxial cables reflecting the differing number and type of protection
shield used.
Data rates, as high as 500 Mbps, are supportable, but normally it is upto 50 Mbps. Error rates may
be of the order of 10e-9. Distances up to 500m can be covered without signal degradation. Coaxial
cable support baseband as well as broadband transmission. Baseband transmission possess
digital signals from one workstation to another usually at a speed of 10 Mb/s upto distance of
nearly 10000 feet. Broadband transmission enables transmitting of voice, audio, video and data
signals (e.g., television and cable television transmission) at a speed of nearly 5 Mb/s over
distances nearly 10 Km.
The cost of cable installation is usually higher than the cost of cable itself. Flexible coaxial cable
is used in thin wire Ethernet. Therefore, it is relatively easy to install. Rigid coaxial cable is used in
the original thickwire Ethernet. Therefore it is more difficult to install for it requires more careful
handling.
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Data Communication and
Student Activity 2 Networking
1. What are the various components of a computer network?
2. Define LAN. Name its components.
3. What are the used of a network?
4. What is a topology? Name various network topologies.
5. Describe various types of cables used in networking.
Table 9.4: IEEE Established 802 Committees to Set Various LAN Standards
We discuss seven layers of OSI in a sequence, layer 1 to layer 7. We would perceive importance
of OSI layering system later in our discussion where emphasis is drawn on usage of these layers
by various components of LAN for a smooth functioning. (Refer Figure 9.9)
Application
7 File transfer, access and management document and message interchange etc. layer
Transport
4 End to end transfer management layer
Network Layer
Network layer is primarily responsible for routing of information on basis of internet address
format. This level receives packet sized data block from transport level and maps to network
addresses.
Transport Layer
Flow control and sequencing of data blocks is performed at this level. Transport layer provides
reliable end to end exchange of data. This layer is responsible for optimization of the transmission
by multiplexing.
Session Layer
Session layer provides coordination between users by selecting mutually acceptable protocols.
This layer establishes calls to exchange the data bit streams. This layer effects check points for
recovery of data.
Presentation Layer
Presentation layer maps the various data representations into an external data format enabling
correct interpretation of the information received. This layer implements the confidentiality or
security of data. This layer enables the compression of data.
Application Layer
Application layer provides a range of service interfaces for application programs such as e-mail,
directory services, file transfer, etc. This effects the interchange of information amongst various
application processes.
The types (d), (e), (f), (g) and (h) are the latest developments in the LAN types. The development
of these LANs was necessitated due to increase in demand of network's bandwidth. The discussion
on these LANs would be followed after we define the term 'bandwidth' and seek reasons for its
increased demand in the modem corporate world. We initiate our discussion with explanation of
the first three LAN types.
Ethernet
Ethernet network was designed and developed by Xerox and DEC. It was initially designed to use
coaxial cable though later development enabled it to use other cabling systems. The methodology
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of communication for ethernet is CSMA/CD (Carrier Sense Multiple Access/Collision Detection). Data Communication and
Networking
In the protocol CSMA/CD, the physical layer of user's workstation generates a carrier sense
signal. This signal is listened to by the other workstation. This other workstation waits and
begins communication only if such a signal is not detected. Popular cable connections for ethernet
are thick ethernet coaxial and thin ethernet coaxial.
ARCNet
ARCNet network was designed and developed by Datapoint Inc.,United States. ARCNet is a
baseband token passing network system. In an ARCNet network transmission speeds are nearly
2.5 Mbps. Generally, ARCNet LAN is on a hybrid topology that is combination of liner bus and
star.
Token Ring
Token ring network is physically a star and electrically a ring. It is based on IEEE 802.5 standard.
In a token ring network token passing scheme is used. It involves a hardware known a MAU
(Multistation Access Unit) that is used to connect upto 8 stations in a network.
Notes: All LAN connections need a network interface card and a networking operating software such
as Novell Netware, Vines, etc. A LAN has a particular cabling system such as coaxial, thin or thick
ethernet, twisted pair, etc. A LAN uses hubs, switches and connectors through the cabling system
and networking topologies. A hub is a centralized distribution point for all traffic on a network just
like a warehouse distribution centre. In bound data traffic from NIC (Networking Interface Card)
arrives at the hub. The hub receives and rebroadcasts it's copy to all workstations connected to the
hub. Stackable hubs are stacked and connected through a proper interface port such that they appear
as single hubs. These are also called Active hubs. Nonstackable hubs are not connectable. Active hubs
split and relay network signals and amplify the signal strength whereas Passive hubs only split and
relay network signals without strengthening signals. Active hubs are connected to the network
backbone. Passive hub is generally connected to the active hubs. Intelligent hubs include a pooling
protocol SNMP (Simple Network Management Protocol) that obtains network performance and the
status data from network. Dumb hub needs management from MIS and networking department.
Notes:
Bandwidth
Bandwidth of a communication network can be described as the amount of data that can be fit through
a network connection. In broadcasting, bandwidth is the measure of the spectrum between the highest
frequency and the lowest. Unit of bandwidth is hertz (Hz.). The evolution of more network capacity
bandwidth in terms of computing efficiency and network speed in data communication has gained
momentum owing to:
z Advent of Internet and Intranet access; and availability of Web servers and browsers.
The corporate is demanding high bandwidth networks to boost quality of their data communication
and management information systems. More users, file servers, application servers, workstations
and peripherals of high performance capabilities has contributed to increase in network traffic. The
aim of the corporate to improve the sharing of information by consolidating multiple LANs into one
shared LAN has necessitated the search for high speed networking technologies.
Switched Ethernet
Switched Ethernet 10 Mbps uses switch to segment a large LAN into smaller LANs. This ensures
dedicated 10 Mbps connection to a particular PC at all times. Though the switched Ethernet hub
is inexpensive and effective solution, it has a drawback. In some of situations it can move the
bandwidth bottleneck to another point in the network.
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Computer Application 100VG any LAN
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This LAN was developed by Hewlett Packard and IBM and standardized under IEEE 802.12
specifications. This is based on DPAM (Demand Priority Access Method) which is somewhat
similar to Token ring or FDDL This LAN has not become much popular because other technologies
like ATM and Fast Ethernet provide better compatibility with existing networks.
Fast Ethernet
Fast Ethernet or 100BaseT is an extension of Ethernet specification as approved under IEEE 802.3.
These networks provide higher bandwidth with data rate as high as 100Mbps. These networks
preserve core Ethernet protocols CSMA/CD and are compatible with existing ethernet wiring
types, media and applications.
Notes: The user workstations are connected to servers. Servers are connected to a network
backbone. Generally backbone networks use broadband network system. The advantage
of this system is that it provides large bandwidth and is capable of transmitting across very
large distances.
AIM
Asynchronous transfer mode is promoted by ITU (International Telecommunication Union) as
high speed communication link for desktops as well as a high performance backbone for LANs
and WANs. The most salient feature of ATM is its scalability in speed varying from 25 Mbps to
multiple Gigabits per second. The other feature of ATM is that it allows simultaneous transmission
and receipt of data without interruption (duplex mode). ATM also allows simultaneous transmission
of video, image, audio and data over a single line. Despite the high potential of ATM technology
for high bandwidth networking, the prevalence of ATM is currently severely restricted due to
several factors. Firstly, ATM is considerably expensive technology. Secondly, many of the
applications need alteration to be successfully run on high bandwidth provided by ATM. ATM
may be considered if volume of transactions on a network is very high and a seemless integration
of LANs and WANs is required.
Bridges are the devices that link two distinct LANs. Bridges may also be used to divide a overloaded
LAN with great data traffic into two separate trunks. A router is bridge like device that interconnects
several types of LANs. The main function of router is to provide the best route for the packets of
information through the interconnection of LANs. Bridges can direct data to different segments
of a network using physical addresses but they cannot direct data traffic to another network. A
router directs data using logical addresses therefore it can send data to traffic bounds to unknown
destination, to another router, which knows the destination. A Switch is a high speed bridge that
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segments a LAN traffic such that it switches packets from one segment of LAN to another in a
matter of milliseconds. This switching is done so efficiently that it appears that the whole and Data Communication and
Networking
each segment of LAN has full access to the entire bandwidth of the network.
A Gateway is used to interconnect two dissimilar LANs. Since, a sort of translation is needed for
two dissimilar networks therefore gateway is more sophisticated, slower in performance and
expensive relay device. For example, if a Novel netware network which is running IPX/SPX protocol
is connected to a VAX host running VMS operating system, the data from netware LAN has to be
correctly interpreted by the VAX host. The Gateway relay device is extremely useful for
communication of LANs as distinct as running on SNA and DECnet protocols. The Gateway
operates on network layer and above. Besides the already described internetworking devices,
there is another internetworking device known as Brouter which functions as a bridge as well as
a router.
One of the popular vendors marketing Brouters is Bay Networks. Brouter routes when routing is
possible and if unable to do so it bridges. Refer Figure 9.10 (A,B,C,D,E,F) to get a better
understanding of the functionality of the internetworking devices.
Figure 9.10 (d): A Bridge Joins two Similar Networks for Network Expansion and Increase
Performance by Reducing Network Traffic
Figure 9.10 (e): A Bridge also Connects Dissimilar LANs such as Ethernet and Token Ring
Applications Primarily a large database. Can also include Primarily productive software such
standard productivity software as spread sheets, graphics, etc.
Security Data is sensitive and requires full authentication Password is appropriate for most
of user for each application. Security data users who determine security
administrator is required to make changes needs for themselves
Novell Netware
Novell Netware (current version 4.1) is presently one of the most popular NOS (Networking
Operating Systems). Netware is compatible both with IBM compatible PCs and the Macintosh
range of Apple computer systems. Netware is a very open system because it operates across
multiple platforms and multiple protocols such as IPX/SPX (Internetwork Packet exchange/
Sequenced Packet exchange), TCP /IP (Transmission Control Protocol/Internet Protocol),
Appletalk, X.25 and so on. Netware fileserver provides a common file system implemented through
NCP (Netware Core Protocol). The facilities provided by NCP are:
1. File access in read, write, open, close modes.
2. File locking that protects file and enables only one user to modify a file at a time.
3. Security levels that determine rights of file for users, groups and everyone. Rights may be
executable, read only, read and write, etc.
4. Network security that is maintained by assigning a login name and password to every
individual LAN users. The LAN administrator has supervisor login name that gives him all
rights for LAN maintenance such as creating groups, changing passwords or login names,
etc.
5. Print server and queue management.
6. Network management.
7. Resource allocations to users/groups such as disk space, networking time and accounts,
etc.
8. The netware include SFT (System Fault Tolerance) level 1, level 2 security. In case of server
failure, in level 1 of SFT duplexing of FAT and directory entry table takes place. In similar
cases, SFT level 2 provides disk mirroring and provides an object oriented approach in
managing resources and users on internetwork. Other salient features are:
z Login through windows;
z Graphical network analysis;
z WAN connectivity;
z Multiple language capability of success or failure of a character transmission;
z Imaging services using HCSS (High Capacity Storage System) that enables transfer or
migration of image document and other files. HCSS also provides support for mounting
optical devices and juke boxes as Netware server volumes;
z Management capability through NetView or SNMP (Simple Network Management,
Protocol).
Netware 4.1 is available in packs of ten users and above. For small scale implementation of LAN,
Novell offers Netware Lite, a Peer to Peer networking system. Novell netware is a client server
based networking operating system.
Student Activity 3
1. Describe OSI layer model of a network.
2. Name some popular LANS.
3. Define token ring network.
4. Define ATM.
5. Describe Internetworking.
6. What are public networks?
7. Write a short note on Novell network.
8. Write a short note on Lane in Business environment.
9.17 SUMMARY
Flow of information for purpose of efficient management and business process control requires
effective use of computer systems and networking technologies. This communication is possible
with the approach known as protocols. The data flows between two devices as sequential bits
(0 and 1) across a transmission medium say copper use. In asynchronous mode of data transmission
each character (byte) is transmitted one at a time.
The data transmission can be asynchronous or synchronous. CRC (Cyclic Redundancy Check) is
the most common error detection technique in synchronous transmission.
A modem is used to convert the digital output of a computing device into analog signals and vice
versa. The communicating device (computers) connected with modems are also known as DTE
(Data Terminal Equipments).
Multiplexing is a technique of channeling multiple data inputs into one connection. Mainframe
machine served as host to these terminals.
LAN is a network of computers that are interconnected in a particular fashion and contained
within a limited area say a building. It has two components-A host and workstations.
The network provides an intelligent switching capability between the devices for the purpose of
sharing. The structure of layout of the cabling in connecting devices together to form a network
is called topology of the network. Various LAN topologies include BUS, RING, and STAR. The
transmission media used in LANs are twisted pair curial cable and fabler optic. The seven layers
of OSI model include Physical layer, link layer, network layer, transport layer, session layer,
presentation layer and application layer.
Some popular LANs include Ethernet, AR (net token ring, Switched Ethernet, 100 VG and LAN,
and Fast Ethernet.
9.18 KEYWORDS
Modem: A modulation and demodulation device which converts the digital signal into analog and
vice versa.
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LAN: A network of computers that are interconnected in a computers that are interconnected in
a particular fashion and contained within a limited areas say a building.
Topology: The structure or layout of the cabling in connecting devices together to form a network. Data Communication and
Networking
Gateway: A device used to connect two or more dissimilar networks.
Detailed Questions
1. Differentiate between asynchronous and synchronous modes of transmission.
2. What are the advantages of asynchronous mode of transmission?
3. What are the various modes of data transmission?
4. What is the difference between serial and parallel transmission?
5. Give reason that led to the development and popularity of LANs.
6. What is a topology? Describe various types of topology? Describe various types of
topologies?
7. What are the advantages of Bus topology?
8. What are the bottle necks of Ring topology?
9. Differentiate between twisted pair and coaxial cable.
10. Write a short note on fiber optic cables.
11. Describe the function of transport layer in OSI model.
12. Write short notes on the following:
(i) Ethernet
(ii) ARC net
(iii) Token ring
(iv) Switched Ethernet
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(v) 100 VG any LAN
Computer Application (vi) Fast Ethernet
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(vii) Fiber Distributed Data Interface
(viii) Peer to peer networking
(ix) Client server networking.
(x) Network management.
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