UNIT I

LESSON – 1
INTRODUCTION TO COMPUTER SYSTEM

1.2 CHARACTERISTICS OF COMPUTERS

The main characteristics of computers are:
a) Speed
b) Storage
c) Accuracy
d) Versatility
e) Automation
f) Diligence
g) Reliability

a) Speed :
Computers are capable of carrying out the task with enormous speed. Today’s computers,
according to their class, can perform from 4 MIPS (Millions of instructions per second) to 100
MIPS. What may take days for manual calculations may take only a few hours for computers to
perform. Inside the computer the information signal travels at incredible electronic speed.
b) Storage:
Computers can store enormous quantity of information. Which is expressed in terms of
Kilobytes (or) Mega Bytes (MB) or Gega Bytes (GB). It is achieved through its ‘Main memory’ or
‘Primary storage’ and through ‘auxiliary storage’ or ‘Secondary storage’. The Hard disks Floppy
disk, Compact Disc(CD) and Magnetic Tape storage are examples of secondary storages.
These large volumes of storage occupy much lesser space compared to paper documents and
this aspect of computers makes them more powerful.
c) Accuracy:
The accuracy of a Computer is consistently high. In fact, this quality of the computers make
them indispensable in various fields such as Scientific Research, Space Research, Weather
Predictions and many other areas where precision of a high order is required. The accuracy of
the computer is best achieved by programming them in the most efficient manner. When it
comes to very complex mathematical or scientific problem the computer’s accuracy has no
substitute.
d) Versatility:
Computers are versatile in that they can perform almost any task, provided they are given the
appropriate logical steps. For example, they are capable of performing wide ranging tasks such
as construction of a payroll, inventory management in a factory, hotel billing, hospital
management, banking applications and any imaginable task in every walk of life.
e) Automation:
The biggest advantage of computers is that it is automatic in its operation. Once a programming
logic is initiated the computer performs repeated operations without human interventions until
program completion.
f) Diligence:
Computers are machines and that do not get tired or ‘lose concentration’ like human beings. If a
large number of calculations say million calculations are to be performed the resultant output will
remain exactly the same even if operations are repeated any number of times. But when a
human being is asked to do the same job this consistency cannot be achieved. Thus for those
who want consistent and continuous standard output, computer’s ‘diligence’ is of great help.
g) Reliability:
The computers give very accurate results with predetermined values. They correct and modify
the parameters automatically, giving suitable signals. They give formatted results with high
degree of precisions.

1.3 HISTORY OF COMPUTERS

In the early days of mankind, man used to count the head of cattle by putting lines on trees.
Slowly these lines changed to numbers. To do calculation on numbers he started inventing
machines.
1. Abacus
Abacus was probably the earliest of counting devices. It consists of rectangular wooden frame
with two compartments and beads sliding along the steel wires for counting. Multiplication and
divisions are done using repeated additions and subtractions. Even today in which cross strings
are fixed. Beads are inserted on to the strings. There are a number of rows of beads.
2. Napier’s logs and bones:
John Napier, a Scottish mathematician invented logarithms. The use of logarithms enabled him
to transform multiplications and division problems of addition and subtractions. In the beginning
he called logarithms as artificial numbers. But later he named them logarithms. Napier also
invented a computing device consisting of sticks with numbers carved on them. These sticks are
called bones as they were made of bones. These bones helped a lot in multiplication involving
large numbers.
3. Slide rule
As the name indicates, the slide rule has one scale sliding within the other. Suppose you want to
add two numbers 3 and 5, set 3 on the fixed scale and slide the moving scale. So that its “0’
coincides with”5” of sliding scale. This is the sum of 3 and 5. The process of reading could be
quick if you are trained in the use of slide rule.
4. Calculating machines and Pascal’s calculator:
A French mathematician, Blaise Pascal invented a machine based on gear wheels. He was the
son of tax collector who had to do lot of calculations as part of his job. Blaise Pascal wanted to
make his job easier by inventing a calculator. You might be familiar with gear wheels in use in
your bicycle which meshes with a driving chain. He used similar gear wheels with ten teeth for
each digit position. He fixed them together so that one wheel drives the other. When the wheel
corresponding to units position rotated by ten teeth, it drove the wheel corresponding to the next
higher position by one tooth. Thus one could make calculations. Pascal provided dials, which
indicated numbers stored on each wheel. He also used suitable “dialing system” to operate the
gear wheels. Other people also made a number of such calculators. Computer scientists
honoured Pascal by naming a programming language Pascal after him.
5. Babbage difference and analytical engines.
 Babbage, a British National and the son of a wealthy banker wanted to correct the errors in the
logarithm tables being used during his time. In 1822, he made a machine which calculated the
successive difference of exprressions (X2 + ax + b is an example of an expression) and
prepared table which helped him in his calculations. The royal Astronomical society awarded a
gold medal to him for his invention and granted a large sum of money to carry out further work.
He wanted to make an accurate calculating machine called “Babbage’s Analytical Engine”. The
analytical Engine was supposed to be very accurate. So it needed lot of parts made with
precision. Babbage could not make such parts. He conceived that his machine would use input
devices, would have a processing part called “mill” where you can perform calculations, would
also incorporate It consists of rectangular frame in which cross strings are fixed. Beads are
inserted on to the strings. There are a number of rows of beads .Since he was about 100 years
ahead in his ideas, he could not get parts needed for his machine. This is because there were
no tools to make such precision parts. He did lot of work related to making precision parts and
spend all the grants (and lot of his money too) but failed in his attempt to make a machine. He
ultimately died as a frustrated man.
6. Lady Ada Lovelace Lovelace
is the daughter of the famous English poet Lord Byron. She was a mathematician. She studied
the works of Babbage and wrote about them. From her account only, we can see the close
resemblance of the modern day computers and Babbage’s work. Lady Ada Lovelace’s
contributions are very important. Since she predicted that computers can be programmed, a
language, Ada used widely in America’s Department of Defence Computers was named after
her.
7. Herman Hollerith’s Machine
Governments all over the world collect details about the number of people living in their
countries. This information helps the Government in planning for the future, Sometimes you find
enumerators (people taking such details) coming to your house with forms to collect such
details. This operation is called “census” which is normally done once in 10 years.
In the United States a census was carried out in 1880 and the U S Government was processing
the census data. Even as this was going on, the next census was due in 1890. To process the
census of 1890 fast, the Government announced a competition.
Dr. Herman Hollerith Produced cards out of special paper pulp, designed punching machines to
punch holes in the card to count census figures and invented sorting machines to read such
punched card and collect data. He could complete the job within three years, achieving a
speedup of about three times.
8. ABC Computer:
In 1937, Dr. John Atanstoff with the help of his assistant Berry designed the Atanstoff Berry
Computer (ABC). The machine laid the foundation for the development of electronic digital
computer.
9. ENIAC- Electronic Numerical Integrator and Calculator
In 1947 john Mauchly and Eckart completed the first large scale Electronic Digital Computer,
ENIAC. In this computer, each time a program was changed, the wiring had to be completely
rearranged. It weighed 30 tons, contained 18,000 vacuum tubes and occupied a space of 30 50
feet.
10. EDSAC-Electronic Delay Storage Automatic Calculator:
 Maurice V.Wilkes of Cambridge University completed EDSAC in 1949. EDSAC was the first
computer to operate on the stored program concept.
11. UNIVAC-I – Universal Automatic Computers: In 1947, after ENIAC became operational
Mauchly and Eckart formed their own Company- The Eckart-Mauchly Computer Corporation”.
Immediately after this they started the design of UNIVAC-I. This was purchased by US bureau of
Census. UNIVAC was the first computer dedicated to business applications

1.4 COMPUTER SYSTEM

A computer system is a combination of various components. It performs the system functions
such as input, processing, output, storage and control. A computer system consists of the
following components:
1. Hardware
2. Software
3. Human ware
4. Firmware
5. Bridge ware
1. Hardware
The physical components of the computer, such as electrical, electronics and mechanical unit
are known as the hardware of the computer. That is, the input units, output units and CPU are
called hardware. Thus hardware is the equipment involved in the function of a computer. It
consists of the components that can be physically handled. The function of these components is
typically divided into three main categories: input, output, and storage. Components in these
categories connect to microprocessors, output and storage. Components in these categories
connect to microprocessors, specifically, the computer's central processing unit (CPU), the
electronic circuitry that provides the computational ability and control of the computer, via wires
or circuitry called a bus.
2. Software:
The computer performs operations like addition, subtraction, multiplication and division only
when the user instructs it to do so. The user issues instructions and the CPU acts in accordance
with the instructions. The sets of instructions, which control the sequence of operations, are
known as programs, and collectively programs are called software. The software can be
broadly classified into two types. They are:
a. System Software
b. Application software
3. Human ware:
The man-machine interface is called a human ware. The people who work with the computer
are collectively called the human ware or livewire.
4. Firmware:
The computer programs permanently stored in ROM or PROM are called firmware. These
programs are provided by hardware manufacturer along with the computers. Generally these
are booting programs which help in the starting of a computer. Such programs cannot be erased
or overwritten.
5. Bridge ware:
The computer components and programs used to translate instructions and information written
for one type of computer into a format that another type of computer can understand is called
bridge ware. This is necessary because different computers are made by different
manufacturers.

1.5 IMPORTANCE OF COMPUTERS IN BUSINESS

Computer plays an important role in business environment as every organisation adopts it in
some form or the other to perform the tasks in effective manner. In the past few years’ rapid
development in IT, particularly in communications, electronic service networks, and multimedia
have opened up new opportunities for corporates. All these are contributing towards new and
effective ways of processing business transactions, integrating business processes, transferring
payments and delivering services electronically. It has affected the business in the following
ways:
1. Office Automation
Computers have helped automation of many industrial and business systems. They are used
extensively in manufacturing and processing industries, power distribution systems, airline
reservation systems, transportation systems, banking systems, and so on. Computer aided
design (CAP) and computer-aided manufacture (CAM) are becoming popular among the large
industrial establishment.
2. Stores large amount of date and information
Business and commercial organizations need to store and maintain voluminous records and
use them for various purposes such as inventory control, sales analysis, payroll accounting,
resources scheduling and generation of management reports. Computers can store and
maintain files and can sort, merge or update as and when necessary.
3. Improves Productivity
With the introduction of word processing software, Computers have recently been applied to
the automation of office tasks and procedures. This is aimed at improving the productivity of
both clerical & managerial staff.
4. Sharing of data and information
Due to networking of computers, where a number of computers are connected together to share
the data and information, use of e-mail and internet has changed the ways of business
operations.
5. Competitiveness
Computers offer a reliable and cost-effective means of doing business electronically. Routine
tasks can be automated. The customers can be provided support round the clock, which is 24
hours a day. With advancement in IT sector, corporates are spreading business around the
world thus, increasing their presence and entering new markets.
6. Security
To provide security to data and important computer programs, almost every organisation has
some security programs to avoid the illegal access of the company’s information by
unauthorized persons. The three fundamental attributor of a security program are confidentially,
integrity and availability which allow access to only authorized persons in an organization.
7. Cost Benefits The extensive availability of internet based information means that companies
have a wider choice of suppliers which leads to a more competitive pricing. Due to the presence
of internet the role of the middleman becomes less important as companies can sell their
product or services directly to the customer.
8. Marketing
Corporates engaged in e-business can take help of their respective websites to create brand
awareness of their products, thus, creating new avenues of promotion of their products. In
addition, companies’ websites can also provide better services such as after sales service to the
customer.

LESSON- 2
HARDWARE AND SOFTWARE
2.1 INTRODUCTION:
A computer system consists of hardware, the physical unit (parts) of the computer that are
capable of computing and manipulating information and software (set of instructions or
programs) that carries out predefined tasks to complete a given job. The computer performs
operations like addition, subtraction, multiplication and division only when the user instructs it to
do so. The user issues instructions and the CPU acts in accordance with the instructions. The
sets of instructions, which control the sequence of operations, are known as programs, and
collectively programs are called software.
We can equate hardware and software with human body and human intelligence, respectively.
All human physical actions such as walking and eating are based on the thoughts and feelings,
which is raised by the brain. If the brain does not raise thoughts and feelings, we do not perform
any physical activity. Similarly, the actions and functioning of every hardware equipment is
driven by software. The combination of physical equipment (hardware) and logical instructions
(software) gives modern computing system their power and versatility.

2.2 COMPONENTS OF HARDWARE

I. Input unit: This unit accepts instructions and data.
II. Output unit: This unit communicates the results to the user.
III. Storage unit: This unit stores temporary and final results.
IV. Central Processing Unit (CPU): This unit performs processing of instructions and data inside
the computer.
The CPU has three components:
a) The Control Unit
b) The Arithmetic Logic Unit (ALU) and
c) The Memory Unit.

a) Control Unit:
It controls the overall operation of the computer system. It is considered as the heart of the
computer system. It controls all the other units, directs them to operate in a proper way and
co-ordinates various operations performed.
It instructs the input device to transfer the data and instructions to the main memory and then to
the arithmetic and logic unit (ALU). Then, it sends the processed result from ALU to the memory
unit for storage and transfers it to the visual display unit or to the ' printer.
The control unit coordinates the various parts of the computer system - the arithmetic logic unit,
the memory unit and the peripheral units. Besides, it controls the flow of data into, from and
within the main storage as per the program instructions.
To perform its control operations effectively and quickly, the control unit has four basic
components. They are
(a) Instruction Register
(b) Decoder
(c) Address Register and
(d) Instruction Counter
The instruction register receives one by one the instructions to be executed in the required
sequence. Then, the operation code of the instructions is transferred to decoder, which decodes
the operation code. And it activates the appropriate circuits of the arithmetic and logic unit to
perform the operation. The address register enables the data in the location specified in the
instruction to be transferred to a specified accumulator for the arithmetic and logic unit
. b) Arithmetic Logic Unit (ALU)
This unit performs two kinds of operations, the arithmetic processing and logical processing. In
arithmetic processing it performs all mathematical operations such as addition, subtraction,
multiplication and division. In logical processing, it performs the relational and logical operations
such as comparing larger or smaller values, true or false statements, etc.
c) Memory Unit
This unit holds the intermediate results during the course of calculations and provides the data
as and when required. This internal storage is also called primary memory or main memory.
This memory takes the data from an input device and stores it until the computer is ready to
process it. It also stores processed data and intermediate results. When the processing is
finished, it transfers the results to an output device.

2.3 SOFTWARE
Software is a generic term for organized collection of computer data and instructions. It is
responsible for controlling, integrating, and managing the hardware components of a computer
and to accomplish specific tasks. In other words, software tells the computer what to do and
how to do it. For example, software instructs the hardware what to display on the user’s screen,
what kinds of input to take from the user, and what kinds of output to generate. Thus, software
communicates with the hardware by organizing the control sequences, and the hardware carries
out the instructions defined by the software.

A computer needs to be instructed to perform any task. These instructions are given in the form
of computer programs, which are written in computer programming languages. A program
controls the activity of the processor. The moment the hardware (processor, memory, etc.), acts
as per the instructions of a program, the program is said to be in running or executing state.

A set of programs, which are specifically written to provide the user a precise functionality like
solving a specific problem is termed as a software package. For example, word processing
software package provides functionality to the computer so that it can be used to create text
documents like letters and mailing lists. Similarly, an image processing software package assists
a user in drawing and manipulating graphics.

2.3.1 FEATURES OF SOFTWARE

1. Ease of use The software systems and applications are becoming more and more easy to
use. In fact, software developers and system analysts go to great lengths to ensure that the
products they develop are user-friendlier than their competitor’s products.
2. Graphical user interface (GUI)
GUI or graphical user interface has now become the default standard for most of the software
applications. Gone are the days of the crude character based interfaces of UNIX and DOS
application. Today’s software applications and products provide the users with perceptive,
graphical and easy-to-use interfaces. Now the users do not have to remember the cryptic
system commands or shortcut keys that were a must in the character based era. Now almost
any task can be accomplished by a mouse click.
3. Multi-platform capability
Today’s software applications are not developed for just one platform. Most of the software
applications supports multiple platforms-both hardware and software platforms. There are
software applications that support hardware platforms ranging from mainframes to PCs and
different software platforms like MVS, Solaris, AIX, UNIX, Windows and so on. For example
IBM’s DB2 Universal database is available for a variety or hardware and software platforms.

Another important feature of today’s software application is that they support multiple languages
and multiple currencies. Many vendors are providing their applications in many languages like
English, Arabic, Japanese, and Chinese and so on.
4. Compatibility with other software Now the competition for each market segment in the
software marketplace is rather fierce. We have many software vendors battling for the market
share in the same segment. For example, Microsoft Word 2000 supports all previous versions of
Work like Word 97, Word 6, Word and so on. The two features –compatibility with earlier
versions and compatibility with other products make it easier for the users, as they can choose
the application they want and still use the old files they have created using other applications or
using older versions of the same application.
5. Mail enabling
Mail enabled applications are designed to take advantage of on e-mail. These are the familiar
word processors, spreadsheets, and other individual desktop applications that have e mail
features built to them. There is another class of message-centered programs that are built
specifically around e-mail functions.
6. Web enabling
With the ever-increasing popularity of internet and the amount of information that is available on
the net, most software applications are now web-enabled. Web enabling helps the user in many
different ways. Its use starts while the user is installing the application. During installation, most
of the applications will automatically connect to the Internet and to the vendor’s web site and will
register their products (earlier one had to fill in a paper form and mail or fax it to the vendor).

2.4 DIFFERENCE BETWEEN HARDWARE & SOFTWARE

HARDWARE
1.It is the physical unit of the computer
2. It has permanent structure and cannot be altered
3. It is normally affected by agent like dust, heat, humidity, etc
4. Hardware understands only machine language ,lower level language or binary
5. It works with binary code, the presence or absence of Pulses as 1’s or 0’s.

SOFTWARE
1.It is a collection of programs to bring the hardware system into operation
2. It has no permanent structure but can be altered and reused
3. It is not affected by these agents to some extent
4. It is written by a well versed programmer and generally in higher level language which is
readable by human being
5. It is represented by the Higher Level Languages such as BASIC, COBOL, Etc

LESSON -3
DATA PROCESSING

3.1 INTRODUCTION Data Processing Concepts

Data
Data means any collection of raw hand figures facts. Data can be considered as the raw
material of information. The data may be numerical such as payroll, employee Number, etc. or
non-numerical like Student names, Product names, etc.
Data Processing
As data is in its raw form it cannot solve any problem. The data needs some processing to make
it useful. Data processing is the conversion of data into a more useful form. That is, transmission
of data into meaningful information is called data processing.
Information
The result obtained by data processing is called information. That is, the processed data is
known as information. However, information produced in one data processing step may be used
as data in the next data processing step.
DATA Vs INFORMATION
Data Information
Raw records Completed One
Un ordered Ordered
Unrefined Data Refined Data
What prevails What is necessary?

3.2 DATA PROCESSING CYCLE

Data Processing is viewed as a system that accepts data as input, processes it into information
as output. This can be explained with the help of the following diagram.

INPUT OUTPUT
Data Processing information data

3.3 DATA TYPES

The data types may be as follows:
1. Qualitative data: It denotes the characteristics of things such as Average, Fair etc.
2. Quantitative data: It is expressed in terms of measurable quantities such as 10 KG, 40
degree Celsius etc.
3. Numeric Types: The data types may also be an integer (+, -) without any fractional part or
real number which includes integers and fractions.
4. Floating Point Representation: These data types consist of 3 components namely:
(1) Mantissa (2) Radix or Base and (3) Exponent Besides the above, the data types include
alphabetic data and alphanumeric data.

3.4 KINDS OF DATA PROCESSING

The important kinds of data processing are as follows:
1. Manual Data Processing:
Data is processed without the help of mechanical devices. Here the data is processed using
manual things such as abacus, slide rule, Napier bones etc.
2. Mechanical Data Processing:
In Mechanical Data Processing, mechanical devices like calculators, tabulators, etc, are used
for processing.
3. Electronic Data Processing:
In Electronic Data Processing, the data is processed by either analog or digital computer.

3.5 OBJECTIVES OF DATA PROCESSING

After the industrial revolution, the needs of the mankind increased. Man had to deal with large
volume of data. He had to cope up with more and more information. The information collected is
to be sorted out, stored and retrieved at short intervals. This necessitated the concept of data
processing
As the complexities of business increased, the number of functions to be performed also
increased. The data processing system must be responsible to supply the information when it is
needed, so as to make the performance of the organization optimum.
Let us have a look at the general objectives of Data Processing.
1. Handle huge volume of Data:
The basic objective of data processing is to handle huge data in order to enable the
organization to function efficiently.
2. Qualitative and quantitative information:
The next important want of data processing is to provide qualitative and quantitative
information.
3. Proper and Timely Information:
Different kinds of information are needed in almost all organizations. Data processing provides
correct and timely information.
4. Storage and retrieval of data:
Through data processing, information can be stored and retrieved as and when necessary.
5. Helps in Decision-making:
In every organization various decisions are taken at different levels. Such decisions can be
more accurate if effective data processing system is used
6. Improves Productivity:
To improve productivity, various measures are to be identified and implemented. It is possible
through the properly designed data processing system.
7. Maintaining Performance at Optimum Level:
To maintain the performance of the organization at best possible level various functions at
different levels of the organization are to be coordinated. There should be a smooth flow of
information among various functional departments. This can be easily achieved through data
processing system.
8. Efficient Office Management: In office management also data processing plays a very
important role, through which office automation can be done.

3.6 STEPS IN DATA PROCESSING

1. Identifying the data
Accuracy of information depends on accurate data input. The first step in data processing
therefore, is to locate necessary facts and figures from source documents. Accurate, relevant
and adequate data must be used as input.
2. Input of data:
After extracting the necessary data from the source documents, they must be transposed in a
suitable form acceptable to the computer. Great care should be taken to avoid wrong entries in
the forms.
3. Manipulation of data:
It involves the process of shifting, sorting and rearranging the given input. Before processing,
validation procedures may be built in to the code to so that input forms do not accept any
incorrect data.
4. Output of information:
The main purpose of data processing is to provide meaningful information to the
decision-maker. Hence, in data processing the person involved must be very careful about what
information is needed and in what form he likes to have it.
5. Storage of information:
The data processed need to be kept for future use. All the processed data will need some form
of secondary storage. When storing the data, it is always important to maintain a backup. It
should be noted that at each and every step the storage might be done.

3.7 PRACTICAL DATA PROCESSING APPLICATIONS IN BUSINESS

The following are some data processing information undertaken by commercial organizations.
1. Process Control:
In the production process, a computer is directly connected to some plant to control and monitor
it. Here, the computer receives the data directly from the plant. It analyses the input data and
initiates action to control the on-going process.
2. Accounting:
The Data Processing System can be used to maintain the accounting records and in
preparation of final accounts. The general ledger, Accounts Payable, Accounts Receivable, etc.,
are the examples for the computerized accounting systems followed in most business
organizations.
3. Payroll preparation:
In personnel department the data processing system is used to record the operations of the
number of employees of different departments in each shifts, leave taken, deductions such as
ESI, PF and finally in the preparation of Pay Slips.
4. Sales Analysis:
The Data Processing system is highly useful in sales analysis. The sales manager can prepare
the sales forecast on the basis of per month’s sales reports and subsequent future actions can
be taken.
5. Inventory Management:
Actually the Data Processing System is a boon to every organization, in respect of inventory
management. Data Processing is used to maintain up-to-date information about stock, their
costs and to initiate orders when the times are about to be exhausted.
6. Office Automation:
The modem offices and business organizations are dependent upon computer based office
automation for their competitiveness and better management.
7. Banking and Insurance:
Data Processing Systems are highly needed in the Banking sector where the customer
satisfaction is the main criteria. To provide quick and perfect service, data processing system is
used. Automatic Teller machines are places in big cities and linked to central computers. Hence,
the delay in processing is completely avoided.
8. Insurance and stock broking:
Insurance companies and stock broking firms also use the computerized data processing
systems. Large volume of data have to be processed for the preparation of policy statements,
interest calculations, renewal notices and in dealing with the securities.
9. Managerial aid:
The Data Processing System is used as a managerial aid in decision-making for solving
business problems. It is also very useful in the areas of linear programming, PERT, CPM etc.
Today it appears that the computer is everywhere. Not only the business organization, the other
institutions are also using data processing system for their regular use. We cannot think about a
situation without a computer. Robotics and Artificial Intelligence are the two promising areas of
applications.

3.8 DATA PROCESSING OPERATIONS

The data after some processing is transformed into information, which is organized and
meaningful. It includes the following operations.
1. Data Generation
It involves the operation of collecting the original data. It implies that the raw data are collected
and set out in the form of original document called a source document.
2. Recording
 Here raw data is converted into an acceptable form. That is, the data is transcribed from the
source documents on the cards or on some other specified forms and are made readable for the
machines. This operation is performed throughout the IPO cycle. The punched cards and paper
tapes, magnetic tapes, a magnetic disks, tape cassettes, floppy disks, magnetic drums, tape
cassettes, floppy disks, RAM cartridge, charged coupled devices, etc., are used as data
recording media.
3. Verification
After the data have been recorded, their accuracy has to be checked. This can be done with the
help of another machine called verifier or by re-reading.
4. Classification
Classification of information is the next important operation in which the data is separated into
various categories.
5. Sorting
Sorting involves sequencing the data in a pre-determined order to facilitate processing. The
order may be either alphabetic or numeric.
6. Merging
It is the operation of combining two or more ordered (sorted) sets of data to form another single
ordered set.
7. Calculating
Here calculation of greater magnitude can be processed. Calculation involves solving equations
and manipulation of the source data such as addition, subtraction, etc.
8. Data Storage
The results of processing one set of data are retained in storage for future use of reference.
The basic requirement for utilizing the computer in all business applications is the ability to store
and access data. The data is stored in a location called memory referred by its address. In large
organizations, huge volume of data is to be stored and accessed. Hence, some auxiliary
storage devices are also needed for the effective data processing.

The memory is measured by the following units:

(a) BIT (Binary digit)
It is the smallest possible unit of information. It can be either 0 or 1.
(b) NIBBLE
Four bits form one nibble
c) BYTE
It is a unit of information consisting of fixed number of bits. It is a combination of 8 bits
(d) CHARACTER
It is represented by one byte. It can be a letter, digit, punctuation mark or special characters.
(e) WORD
The combination of 2 bytes or 4 bytes or 8 bytes is a word.
The data measurement is as follows:
8 bits - 1 byte
1024 bytes - 1 kilobyte (KB)
1024 KB - Mega Byte (MB)
1024 MB - 1 Giga Byte (GB)
1024 GB - 1 Tetra Byte (TB)
(f) SECONDARY STORAGE (Backing/Auxiliary Storage):
(a) Magnetic disk - it includes the following:
Hard disk – Rigid, Floppy disk - Flexible
(b) Magnetic tape
(c) Magnetic drum
(d) Mass storage Device - cartridge
(e) Optical Disks - CD ROM (Compact Disk - ROM)
9. Data Retrieving:
Data retrieving is the process of searching or locating a data item from the storage. In EDP
system, the data is retrieved from the storage device in sequential, indexed sequential or
random access mode. The on-line data storage and retrieval is very useful for the proper
functioning of a modern business establishment.
10. Reporting:
Generally in business data processing, the processing operation comes to an end with the
reporting of data. In this operation the results of the data processing are made available to
others. The processed information may be reported in a number of ways depending on the use
of results. The results may be printed out in the form of pay slips, bills, etc. or in the form of
reports as ESI Reports, PF Reports or Sales Reports, etc.,