Download System Flow Diagram - E

STUDY MATERIAL
Subject
:
Introduction To Information Technology
HARDWARE AND SOFTWARE:
Hardware:
The physical and tangible components which are seen and touched in a
computer such as electrical and electronic units are known as hardware of the
computer. That is input units, Output units, CPU and Backing storage are called
Hardware.
Input devices – Keyboard, Mouse, Joystick, Lightpen etc
Output Devices – Visual Display Unit(VDU), Printer etc
Secondary storage units – Magnetic Disk ,Magnetic Tape, Floppy Disk Drive
etc
Software :
A computer is directed to perform input, arithmetic, logical, output and
storage operations by a series of instructions called a computer program. A
computer program specifies what operations are to be performed and the
sequence in which they are to be performed. The program should be in the main
memory for its execution. Computer programs are commonly referred to as
‘computer software’.
Software activates the hardware. Software is developed by human thinking
whereas the hardware is developed by the technological improvement.
Generally software means all the computer programs associated with a computer
system like compiler, assembler etc..
Computer software can be broadly classified as:
 Application Software
 System Software
The application software refers to a collection of programs meant for a
specified application.
Eg: programs for Payroll, Inventory etc.,
System Software deals with programs concerned with the system
Eg: Assembler, Compiler, Linker etc.,
COMPUTER SYSTEMS:
Definition:
Computer is an electronic data processing (EDP) device, which accept data
from the keyboard, process the data as per instructions given and produces the
output.
Characteristics/Advantages of Computers:
(1) Speed:
A computer is a very fast device that can perform an amount of
work that human being can do in months. Since all operations of the computer
are fast , they can perform large number of operations in a second. The
processing speed of the computer is measured by nano seconds(1 nano sec is 1
billion of a second)
Small computers take a few micro seconds to execute an operation.
Whereas large computer takes only few nano seconds for the same operation.
(2) Accuracy:
The next very important characteristic of a computer is its
accuracy. It is estimated that a human being commits at least one error for
every thousand operations but computers do millions of operations in a second
committing no errors. If the output is not correct then it is not the computer’s
mistake, it is due to the input error, if the data and instructions are given
correctly to the computer it will give accurate information.
(3) Memory Capacity:
It can store large amount of data and information, which is
expressed in terms of Kilobytes. This memory capacity can be increased by
using secondary storage devices such as floppy disk, optical disk etc..
Bit
-> 0,1
1 byte ->8 bits
1 KB ->1024 byte
1 MB ->1024 KB
1 GB ->1024 MB
1 TB ->1024 GB
(4) Automation:
The computers execute the program completely without human
instruction until completion. If we want to repeat the same process for another
set of data there is no need to feed the program once again but we have to give
execution command once again.
(5) Versatile :
Computer is a versatile machine and is capable of solving any
problem and can be applied to all sorts of business and other activities.
Example:
Computers are used in banks, education, preparing electric bills, telephone
bills, reservations etc.
(6) Diligence:
Computer being a machine wont suffer from tiredness and lack
of concentration. The computers can work for hours together but a human
being becomes tired after a certain time.
Disadvantages:
(1) The intelligence of the computer is zero. Computer is an obedient servant
to its master and work according to his command.
(2) The computers will not correct logical errors.
(3) Lacks commonsense
(4) It has to depend upon programmer’s instructions.
DATA AND INFORMATION
Data:
The word data is plural form of DATUM, which means raw fact (ie.)
collection of facts is said to be data. The data is a name given to basic fact such as
names and numbers. Data may be numeric such as date, price, weight, number of
items sold, students marks etc., Data may be non-numeric such as customer
names, student names, addresses, product names etc.,
Information:
The processed data is called INFORMATION (ie.)when data is connected
into meaningful results it becomes information.
1,2
Raw data
1+2
Processed
3
Information
Difference between Data and Information

one.
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Data
Information
Raw Fact
Finished meaningful
Unprocessed
Unstructured
What exists
Processed
Structured
What required.
DATA PROCESSING:
Data Processing means conversion of data into meaningful
information ie.Data processing means calculating or manipulating data. The mere
data cannot solve problems so the data is arranged by the computer to produce
meaningful information.
Processor:
Processor is a hardware device, which is used to process the data. There
are different types of processors namely 80286, 80386,80486, Pentium series etc.
Data Processing Cycle:
Source
documents
Input
Storage
Device
Processing
Output
Preparation of source documents.
(1)
Input of data
(2)
Manipulation of data
(3)
Output of information
(4)
Storage of data
Source documents:
The first step is to obtain the relevant facts and figures and to set
these out on source documents. For example , in a population survey, the name ,
address, age, sex, occupation, etc., must be first written down onto a survey
sheet or some other document. These documents may be so designed that
information is recorded in the same structure as the data required by the
computer program.
Input:
Once the data has been extracted from the source document, it must
be supplied to the computer through input devices like keyboard etc.,
Data Manipulation:
This includes all the operation performed on the raw data. It can do
arithmetic operations like addition , subtraction, multiplication and division on
the data. It can compare the data whether it is greater than or less than or equal
to by using relational operator(<,>,=). It can also carry out logical operations by
using(and,or,not).
For example, in the population survey, we may want to classify people by
occupation or age.
Output of Information:
The objective of outputting results is to provide meaningful
information to managers, accountants, population survey analysts etc.
Careful consideration should be given to the presentation of results so that they
can be digested easily and quickly.
Data Storage:
In most cases, the results of processing one set of data are retained
for future use or reference. This means data processing installations require a
great deal of secondary storage space to store all the programs and the different
sets of data.
Types of Data Processing:
 Manual Data Processing
 Mechanical Data Processing
 Electronic Data Processing
Manual Data Processing:
In manual data processing human being converts the data into
information. Mere data is processed using manual operations.
Mechanical Data Processing:
In mechanical data processing , a person uses various machines to
get the work done. Eg: calculators, tabulators etc. This method has both
human interaction and machine operation.
Electronic Data Processing:
In electronic data processing the data is processed by the computer.
DATA STORAGE:
Retaining data for future reference is said to be data storage. The data and
instruction that are entered into the computer system through input units have to
be stored inside the computer before the actual processing starts. The results
produced by the computer after processing must also be kept inside the computer
before passing to the output units. The intermediate results are also stored inside
the
computer. Thus the functions of storage units are to hold
 All the data to be processed.
 Intermediate results.
 Final results after processing.
The data stored in a location called memory referred by its address. There are
two classes of memory called main memory and secondary memory. When the
data is stored outside the processing unit it is called as external storage or
secondary storage or auxillary storage.
Example: hard disk,magnetic tape, magnetic disk, floppy disk etc.
The secondary storage is needed because the size of the main memory is limited.
When the data is stored inside the processing unit , it is called as internal storage
or main memory or primary memory.
Example: RAM
Difference between main memory and secondary memory
Main memory





Data cannot be kept for long time.
time
Memory size is small.
Expensive
An integral part of the computer.
system
Not transportable
Secondary memory
Data can be kept for long
Memory size is large
Not expensive
Not an integral part of the
Transportable
Types of Main Memory:


RAM(Random Access Memory)
ROM(Read Only Memory)
RAM:
Random Access Memory is also called as Read/Write memory. The main
memory of the computer is made up of RAM chip. Data can be written into a
RAM chip and be read. It can also be erased and re-written. When the power is off
any information stored in the memory is lost.
ROM:
Information can be written into ROM chip only once. Once written, it
cannot be altered and no fresh information can be written into the memory. When
the power is off the data stored inside the ROM will not be lost.
ROM can be classified into:


PROM(Programmable Read Only Memory)
EPROM(Erasable Programmable Read Only Memory)
PROM:
The ROM chips are supplied by the computer manufacturer while
purchasing the computer system. It is not possible for a computer user to modify
the program stored inside the ROM chips. But it is possible for the user to store
his own program in PROM chip. Again once it is programmed, recorded
information cannot be changed.
EPROM:
Once the information is stored in ROM and PROM, it cannot be altered or
changed. To remove this problem EPROM was introduced. It is possible to erase
the program inside the chip using ultra-violet rays.
Difference between RAM and ROM:
RAM
ROM

The information is stored and retrieved
by the programmer’s choice
Constructed by the
manufacturer.
Information stored in
this memory cannot
be modified by the
programmer

Volatile memory(ie.Information will
memory.
be lost on power failure)
Non – Volatile

Used to store programs in execution.
like
Permanent functions
Sinx,cosx are stored.

Easiest to change
to
ROM’s are expensive
Change.
DATA RETRIEVAL:
Recovering or getting back stored data is called the data retrieval.
Data retrieving is a process of searching or locating a data item from the storage.
The data can be retrieved from the storage device in sequential mode, indexed
mode, and random mode.
Sequential Storage and Retrieval:
Each record is stored on the tape or disk one after another, and the
data is retrieved in the same sequence as they are stored. For example: the file
having student details, records are stored in sequence by social security
number.The data in the file is retrieved one record after another and processed in
the same sequence as it is stored in the file. In most cases, when sequential
retrieval is used, the data is stored in some defined sequence based upon a value
in record(called a key), such as social security number in this example.
Disadvantage:
Sequential retrieval has a major disadvantage – since records are
retrieved one after another in the same sequence as they are stored, the only way
to retrieve the third record is to read the two preceding records first. Because of
this, sequential retrieval is never used when fast access to a record is required.
Instead, sequential retrieval is used when records are processed one after
another, such as when creating printed reports.
Random or Direct Access Retrieval:
Data stored on magnetic disk can be randomly retrieved, which
means records can be retrieved regardless of the order in which they are
physically stored. Random retrieval can be used when fast access to a record is
required.
In most cases, records are randomly retrieved based upon a value
within the record itself. To illustrate this, sample records containing an account
number, customer name, and the account balance are stored on disk. When a
customer with account number 124 wants to know his balance, the application
requires that the program be able to immediately retrieve the data. Sequential
retrieval would not work here.
A request is made to the system for the balance in account number
124. The record associated with the account number will be directly retrieved
and brought into main memory. From there the program can display the balance
on the CRT screen. This ability to randomly access records based upon a value
in the record is very important. In this example the record is accessed based
upon the account number stored in the world.
Indexed Mode Retrieval:
The indexed mode combines both sequential and random mode of
processing. For example: A file has 2000 records, in that file 1220 to 1250
records have to be retrieved. The computer will locate the record number 1220
randomly and access the records up to 1250 sequentially. The online data
storage and retrieval is very useful for the functioning of modern business. The
online device means those devices that are directly connected to the CPU.
IMPORTANCE OF COMPUTER IN BUSINESS:
In the modern business world, it is not unusual for the computer to be used
by management personnel at all levels to aid in decision making; by office
workers in all departments for automating the tasks of preparing documents,
filling documents, retrieving data, and communicating information to others
throughout the company and by personnel in the manufacturing and production
departments for tasks varying from automated assembly by computerized robots
to controlling shipping and warehouse scheduling. Most jobs in modern
companies require some knowledge and use of computers.
The needs of the computer user fall into three broad categories:
 Information Management
 Management Support
 Function Support
Information Management refers to the task of managing and controlling the data
and information required within an organization for that organization to function.
Management support consists of those activities carried out within a company to
supply management personnel with information on which decisions can be made
and action taken. Systems that provide management support are sometimes known
as Decision Support System.
Function support refers to the use of the computer by people to perform their jobs
faster;more efficiently, and with less cost to the company.
Three ways, in which individuals can meet their information management,
management support and function support are
(1) Uses of Personal Computers
Personal computers are widely used in the business environment by
personnel at all levels. Personal computers are often used in conjunction
with specialized software packages that have gained almost universal
acceptance.
These packages include:





Word Processing S/W – used to write letters, memos and other
documents.
Electronic Spreadsheets S/W-used for calculations using formulas
Computer Graphics S/W-transforms the series of numeric values
into a graphic form
Database and File Management S/W-allows user to access data at
any required form
Electronic main S/W-lets users to communicate with each other via
their personal computer network.
(2) Use of Information Centers
A second major way for users to obtain access to computing power
is
through the use of an information center. An information center is an
area within the information systems department that contains a number
of CRT terminals, hardcopy generators(usually printers), and perhaps a
smaller computer. These devices have direct access to a centralized
computer in the information systems department.
The major reason for an information
center is to give employees a simple,effective way to meet their own
departmental and individual information processing needs. This is
accomplished by providing computing power, training and access to
sophisticated software so users can generate their own reports and
develop their own applications. Thus, the information center provides
more sophisticated hardware and software than personal computers. The
information center’s main goal is to provide extensive computer
processing for computer users.
(3) Use of a Centralized Computer
When processing large volumes of data or when large databases
must be accessed by many users, a centralized computer is used.
Information from a centralized computer is commonly delivered by
printed reports or as output on a CRT terminal.
When a centralized computer is to be used for an application, a
formal process will usually followed to develop the application system.
Management and other personnel who will be using the system will be
involved with the professional staff of the information systems
department in the design and implementations of the system. This
process of design and implementations can be lengthy and difficult.
Once the system is designed, it can be used by all personnel who
are authorized to use it. In some applications, such as airline reservation
systems a centralized computer will be used because the speed and data
access available on a large, powerful computer are required by the
application. For example in a banking application thousands of accounts
must be accessible by hundreds of tellers and other bank employees. A
large computer is the only machine with the processing power to satisfy
the requirements of their applications.
COMPUTER RELATED JOBS IN S/W AND H/W INDUSTRY:
In the computer-related industry, numerous career opportunities in a wide
variety of areas are available. In Information systems departments, opportunities
can range from such diverse jobs as data entry operators to business or scientific
programmers. Those with an entrepreneurial flare will find opportunities in S/W
development, consulting and education . Many opportunities exist in both small
and large companies for those interested in pursuing a career in the information
processing industry.
 Computer Operations Personnel: Computer operations personnel are those
who are responsible for the day-to-day operations.
 Computer Operations Manager:The Computer operations manager is incharge of the entire operations such as ,responsible for hiring and
assigning the other operations personnel, establishing operations center
policies, planning the installation and removel of equipments and generally
doing all other activities to ensure the processed data is efficient.
 Computer Operators:Computer operators are the people running the
equipment in the computer center.Their job includes loading tapes and
disks, monitoring system performance and initiating solutions to
malfunctions.
 Data-Entry operators:Data entry personnel are the people who enter data
into the computer systems.
 System Librarians:System librarians are responsible for data stored offline
such as on tapes and disks , and to back-up copies of important programs
and data for future references.
 System Analyst:Systems analyst is responsible for analyzing, designing
and implementing large computer based information systems. Since they
are the interface among users, upper management and programmers, they
must be skilled in business, computer technology , interpersonal
communications and people.
 Programmers:Computer professionals who specifically write computer
programs are called as programmers. They are classified as application
programmers, maintenance programmers and system programmers.
Application programmers write application programs i.e., S/W that serves
the direct needs of end-users.Maintenance programmers maintain and
update application programs, and keep application programs running for
years after they were written.System Programmers write system S/W that
control the operation of computer H/W and make it possible to run
application programs.
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


Information Center Personnel: Information center is meant to help end
Users choose the decision support resources they need in order to perform
better, training users to use specific S/W package and to set standards for
the growth of personnel computing resources within the firm are some of
the other functions performed by information center personnel.
Management Information Systems Management(MIS):They are
responsible for full range of MIS related activities such as transaction
processing , telecommunications, data administration and ebd-user
support.
In many organizations a ‘data processing director’ is responsible for all
personnel involved with the company’s major transaction processing
applications.
Database Administrator: They are usually responsible for ensuring both
the integrity and security of the data in the database.
Telecommunications Managers and Network Managers are responsible for
meeting the data communication needs of users in the organization.
Hardware Industry
Today the hardware portion of the information processing industry
includes personal computer manufacturers, small business computer
manufacturers, mini computer and mainframe manufacturers, and
manufacturers of peripheral devices including computer terminals, disk
drivers and printers. Data communication equipment ,office automation
equipment, and computer assisted manufacturing hardware are an
important part of the information processing industry .
Additional jobs may be found working for computer manufacturers
,s/w companies , service and supplies companies, and retail computer h/w
and s/w stores etc. These jobs include Sales Representatives after
comprehensive training by the company; call upon the prospective
customers with the intent of selling them the hardware.Systems engineer is
a term used by some companies to describe individuals eho are technical
specialists and serve as consultants to customers.
COMPUTER APPLICATIONS IN BUSINESS

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

Payroll and personnel records
Office Automation
Word processing
Desktop publishing
Electronic office
Stock control and sales
Banking
Insurance and stockbroking
OBJECTIVE QUESTIONS
1. Printed copy of a data is called
(a)Carbon Copy (b)Duplicate copy (c)Hard copy (d)none of the
above
2. Primary storage is
(a)A part of CPU
(b)requires very fast access data
(c)Relatively expensive
(d)None of the above
3. Pick out the most powerful computer
(a) Supercomputer (b)Micro computer (c)Mainframe computer
(d)Mini Computer
4. A collection of eight bits is called
(a) Byte (b)Word (c)record (d)file
(b)
5 ._______________ is the product of data processing
(a) Data (b) Information (c) Software (d) None of the above
6.
In computer technology, information means
(a)Raw data
(b)Data in meaningful form
© Alphanumeric data
(d) Program
7.
A factor which would strongly influence a business person to adopt a
Computer is its
(a)Accuracy (b)reliability (c) Speed (d) all of the above
SHORT ANSWER QUESTIONS:
1.
2.
3.
4.
5.
6.
7.
Define Data and Information.
What is Data Processing?
What are the differences between Data and Information.?
Define ROM,PROM, and EPROM.
What is the difference between main memory and auxillary memory?
What is data retrieval?
Differentiate RAM and ROM?
LONG ANSWER QUESTIONS:
1.
2.
3.
4.
5.
Explain Data processing and its types
Define data retrieval and explain various data retrieval techniques.
Explain data storage
Explain the importance of computers.
Describe various computer related jobs in software and hardware
industry
Components of Computer System:
Input Unit:
Data and the programs are entered into the computer through these
devices. The computer accepts the data to be processed and the instructional
details required for processing. When the data and instructions are entered into the
input unit they are passed to the memory unit of the CPU. Various input devices
are available in this regard. Some of the important input devices are given below:
1. Punched Card Reader.
2. Punched Tape Reader
3. Magnetic Tape
4. Cassette Tape
5. Magnetic Disk
6. Floppy Disk
7. Electronic Key Board
8. Magnetic Ink Character Reader
9. Optical Character Reader
10. Optical Mark Reader
11. Bar Code Reader
12. Visual Display Unit
13. Light Pen
14. Mouse
15. Joystick
16. Touch Screen
17. Microphone (voice input)
Punched Cards:
Punched cards are still in use as medium for recording data and
instructions in the form of punched holes to denote and then they are sequentially
read by the card reader. The card reader sends the data and instructions to the CPU
to process them.
The punched cards used for data processing are made generally of 80
columns and 12 rows. Today 96 columns cards are available. In these cards a hole
is punched to represent the binary 1. The absence of a hole represent binary 0. If a
card is punched wrongly it cannot be corrected, further the punched cards are not
reusable, i.e., cannot be used for any other data. Many numbers of cards are
required for the computer programs. Such a collection of card is called a deck.
Each card has the left top corner cut to identify the arrangement of the cards is
correct or not.
The cards are read by a unit called card reader. The punched cards are
placed in the Reader Hopper after verification. On receiving the command from
the control unit the devices move the cards one by one over two sub-devices. One
of which, senses the punched holes (0s and 1s) and transcribes the pulses to the
CPU. The output is given as per user specification.
Advantages:
1. It is very easy to read data on the cards.
2. The cards are less expensive than other storage media.
3. It is much simple to operate
4. After inserting a card, if an error is detected the whole system stops
functioning.
Disadvantages:
1. Punched cards are bulky when put together, so they require large space to
store
them.
2. The cards are easily damaged and perishable
3. Transfer of data is relatively very slow
4. An on correctly punched card cannot be corrected, it must be replaced.
5. Unit Record machines require manual intervention at every stage.
6. Data is not processed in ordinary language. It has to be translated into
something we can understand.
Paper Tapes:
The punched paper tape is a continuous strip of a paper about one inch
wide and up to 300 meters long. The characters are recorded on tape, which may
be 5 or 8 as per the design of the tape. These punched positions are called as
channels. It is the oldest media, of input and output media. Her also, a hole
represent 1 and its absence represents 0. Data from the tape is read through a Tape
Recorder per second. The tape comes in various forms viz. Oil paper, dry paper,
and metallised paper and laminated paper.
Advantages:
1. Compared to the punched card, it is more compact and economic on
storage.
2. It is less weight and easy for mailing etc.
Disadvantages:
1. Since the roll is so long, correcting or inserting data can be very tedious
process and time consuming.
2. The life of the paper tape is short. This makes it inconvenient for storing
over a long period. It is not durable.
3. Moreover, it is a sequential data processing medium.
Magnetic Tape:
Because of the problems faced in the paper media, magnetic substances
have come first among these was the magnetic tape. This is also a sequential
media for normally between 1.25-2 cms. Wide and up to 900 meters long. It is
made of plastic with a metallic magnetic oxide coating on one side. Generally,
data is recorded on either a 7 parallel-track-tape or on a 9 parallel-track-tape.
Writing on and reading from the tape is done with the assistance of
READ/WRITE head. The number of characters per inch length of tape stored is
called the ‘density’ of the tape. This varies from 550 to 1600 or even 16 k. the 9
Track tapes have the higher densities. Then comparing with the punched card and
punched tape, the magnetic tape has certain advantages and disadvantages.
Advantages:
1. Data are stored very compactly.
2. It is very easy to handle the Magnetic Tape than the Deck of Cards.
3. The Magnetic tape costs less than the cards.
4. It requires less storage space for data and therefore has a large capacity.
5. It is reusable i.e., the old data can be wiped out and fresh information
could be recorded on it.
6. The speed of transferring the data is very high comparing to paper devices.
Disadvantages:
1. In magnetic tapes, the data has to be accessed sequentially. This makes the
retrieval of data slow.
2. The punched cards can be read visually, whereas to read the magnetic tape
a machine is needed.
3. the tape is subject to the usual wear and tear of time.
4. Data will be erased if the tape is exposed or placed nearby any Magnetic
field or high voltage circuits.
Using these devices, the data are entered onto the computer to get
meaningful information. The most commonly used input devices are magnetic
disk, floppy disk, electronic keyboard, visual display unit and mouse.
Magnetic Disk:
It is a yet another step in the evolution of input/output devices. The magnetic disk
has an advantage over the punched cards and magnetic tapes i.e., the data stored
on a disk can be read randomly while in the magnetic tape, the data are read
sequentially. The Random access is that the particular record in a file can be
detected directly and the access time is saves. In magnetic disk the record is
accessed in a fraction of second i.e., less than 0.01 sec. The disks varying in
diameter are generally coated on both sides with magnetic oxide. Each surface of
the disk is divided into a number of sectors, called storage segments. The storage
segments is a specific portion of a specific side of the disk. A segment can store
one or more record of a file, which will vary according to the size of the record.
While searching, a particular record can randomly be selected and directly
accessed, because, each storage segment is uniquely marked by an address with
side number, track, sector number etc.
Advantages:
i) Direct access of data is possible. The data can be retrieved almost instantly.
ii) The disk is more durable than the tape. This reduces the chances of loosing
data.
iii) The storage capacity of the disk is large.
Disadvantages:
i) The disk come in packs and a disk pack is heavy. So, it is difficult to
transport disks.
ii) It requires more sophisticated hardware and operating systems than any of
the earlier mentioned input devices.
Floppy Disks:
In the early 1970’s IBM introduced a new medium for storing data. This
medium consists of a circular piece of thin plastic material, approximately 8
inches in diameter that is coated with an oxide material. The circular piece of
plastic called a disk is enclosed in a square protective jacket with a cut out so that
the magnetic surface is exposed. When inserted in the appropriate hardware
device, the disk is rotated inside the protective jacket, allowing keyed data or data
from main memory to be stored on the rotating disk. Once data is stored on the
disk, it can be read from the disk into main computer. This medium for input and
auxiliary storage called a floppy disk or disk.
Disks are available in a number of different sizes. Although the original disk
was of the size of 8 inches, most personal computers now a days use a disk 51/4
inches in diameter. Even smaller sized disk approximately 31/2 inches in diameter
are also available. Regardless of the size of the disk, the method of storing data is
essentially the same. Each disk is divided into concentric circles called tracks.
Each track is further divided into number of sectors. Data is stored on disk, in
tracks, the number of which varies from computer to computer. The most
commonly found configurations are 40 tracks, 72 tracks and 80 tracks.
To read data stored on disk or to store data on disk it is inserted in a disk drive.
The large center hole fits over a hub mechanism, which positions the disk in the
unit. The disk within the protective covering is rotated at approximately 300 to
600 revolutions per minute. To read or write data, a read/write head in the disk
drive rests on the surface of the rotating disk, sensing or generating electronic
impulses representing bits to be read or recorded. Characters are stored on a disk
as bytes in the same manner as they are stored in main computer memory. To read
data from the different tracks, the read/write head moves from track to track.
Disk drives and the related disks can provide storage capacities that vary from
approximately 1.2MB(1 MB=106) characters per disk. The number of characters
that can be stored on disk by a disk drive is dependent on the following 3 basic
factors.
1.The number of sides of the disk used:
The earlier disks and drives were designed so that data could be recorded
on only side of the disk. These drives were called single-sided drives. Now-adays disk drives are manufactured that can read and write data on both sides of
the disk. Such drives are called double-sided drives. The use of double sided
drives and disks approximately doubles the number of characters that can be
stored on the disk.
2.The recording density of the bits on a track:
The recording density refers to the number of bits that can be recorded on
a disk in 1-inch circumference of the innermost track on the disk. This
measurement is referred to as bits per inch (bpi). For the user, the disks are
identified as being either single density (SD) or double density (DD). A single
density drive can store 2768 bpi on the innermost track. Double density can
store 5876 bpi. With improved technology, it is anticipated that recording
densities in excess of 10000 bpi will be possible.
3.The numbers of tracks on the disk.
The number of tracks o
40 tracks on the surface of the disk. Other drives, however can record 80
tracks on the disk. These drives are sometimes called double track drives.
Depending on the number of sides used and the density, the floppies can
be grouped as follows:
SSSD-Single Sided Single Density
SSDD- Single Sided Double Density
DSSD- Double Sided Single Density
DSDD-Double Sided Double Density
DSHD- Double Sided High Density
Care required in using and storing a disk.
On receiving a new disk, it should be inspected for sign of obvious damage.
The surface of the disk should not be touched with hand or some sharp object.
Write-protect precaution should be observed by peeling off or sticking on (as
applicable) the aluminium square on the notch.
Direct data entry devices.
Direct data entry refers to entry of data directly into the computers through
machine-readable source documents or through use of on-line terminals. Direct
data entry does not require manual transcription of data from original paper
documents. There are two types of direct data entry devices, which is used for
direct data entry. First type of Direct Data Entry devices can scan source
documents magnetically or optically to capture data for direct data entry into the
computer. Magnetic ink character readers and optical character readers are
examples of such devices. The second type of direct data entry devices uses a
keyboard inclusive of terminals connected directly to a computer.
Scanner:
The scanner is an input device that is capable of recognizing text or
graphics on the input document. You can use a scanner to convert a photograph or
drawing into a computer file. After an image has been converted into a file, it can
be printed or used along with some other document. For instance, you can scan the
logo of a company in a graphics file. Later, you can print it at the top of letters.
Through generally not used with PCs, scanners are also used for the following
applications:
1. As barcode readers to identify a product
2. As magnetic –ink character recognizers to sort bank cheques.
3. As a optical mark readers(OMR) or optical character readers(OCR) to
automatically evaluate objectives type answer sheets.
Magnetic Ink Character Recognition (MICR)
An MICR can identify and decode characters printed with special ink that
contains particles of magnetic material. The reading process is called Magnetic
Ink Character Recognition. The major advantage of these characters is that they
are machine-readable, the process is faster and less-error prone when compared to
the previously discussed devices. Since MICR systems can recognize only certain
character styles, the characters have to be accurately formed.
MICR employs a system of printed characters, which are easily
decipherable by human beings as well as a machine reader. There is used special
printing font to represent characters. In this font, each character is basically
composed of vertical bars. The characters are printed in special ink which contains
a magnetizable material.
This method is primarily used in banking industry. And most cheques are
now processed under the MICR approach. The data printed across the bottom of a
blank cheque are recorded in MICR form: the characters represent the bank on
which the cheque is drawn, the customers account number and the amount of
cheque. The cheques themselves are prepared off-line. When they are originally
printed by a printing press, the MICR about the bank identification number, as
well as the data about the customers bank account number are printed
simultaneously. The cheques then are turned over to the proper bank customer for
use. Once the cheques have been cashed or deposited in bank, an operator uses an
off-line enclosing machine to encode, in magnetic ink, the amount on the cheque’s
bottom right side.
MICR data are used for input purposes. Unlike other media(floppy and magnetic
tape) MICR cannot be used for output purposes.
Advantages Of MICR:
i) MICR possesses a very high reading accuracy. Cheques may be smeared,
stamped, roughly handled yet they are accurately read.
ii) Cheques can be handled directly without transcribing them on floppy disk,
magnetic tape etc.
iii) Cheques can be read both by human beings and machines.
Disadvantages of MICR
i) MICR has not found much favour from business.
ii) Damaged documents, cheques not encoded with amount etc.., have still to be
clerically processed.
Optical Character Reader (OCR)
An OCR recognizes or interprets printed or handwritten data directly from
documents. The essence of OCR is pattern recognition, i.e. ability to identify a
recorded symbol as a familiar from. OCR devices are expensive and are used only
where the volume of the data to be fed into the computer is large.
OCR also employs a set of printing characters with standard font that can
be read by both human and machine readers. The machine reading is done by light
scanning techniques in which each character is illuminated by a light source and
the reflected image of the character is analyzed in term of the light-dark pattern
produced. Keyboard devices are used to give the required print quality. OCR has
the potential of reading even handwritten, typed or printed depends upon the type
of OCR being used.
Large volume billing applications (e.g.: bills of utility companies, credit
card organizations, and magazine subscription outfits) increasingly are being
adapted to OCR methods. The customer paying the bill returns the bill, which has
OCR data (e.g.: customer number and amount of the bill) recorded on it, along
with payment? Thus the billing organization’s bill (or the part returned by the
customer) becomes input for recording cash payments received from the
customer. This procedure, sometimes, referred to as the use of “turn-around
documents” has the advantage of minimizing or eliminating the keying process
when cash receipts are received from customers.
Advantages of OCR:
i) OCR eliminates the human effort of transcription.
ii) Paper work explosion can be handled because OCR is economical for a high
rate of input.
iii) Since documents have only to be typed or handwritten, not very skilled staff
(like the keypunch operators) is required.
iv) Furthermore, these input preparation devices (typewriters etc.) are much
cheaper than the keypunch or the key-to-tape devices.
Limitations Of OCR:
i) Rigid input requirements. These are usually specific requirements for type font
and size of characters to be used. In typing there is always the scope for stikeovers, uneven spacing, smudges and erases; and the form design, ink
specifications, paper quality, etc. become critical and have to be standardized.
A transaction is relatively high. However, further developments in OCR are likely
to make optical reader much cheaper.
OCR characters can be sent as input to the CPU. Also, printers can be used to
generate OCR output.
BAR CODE Reader:
Certain data like the product codes of groceries or books etc., can be
recorded or small strips optical reading is done by using printed ‘bar codes’ i.e.,
alternating lines and spaces which represent data in binary form. As the item
having the code is passed over the bar code reader, the reader automatically
decides the strips and passes the data to the computer.
A bar code is a set of parallel printed lines of varying thickness and
separation. These lines are normally alternate lines of black and white. They
represent a number which is sometimes written at the bottom or above the bar
code for the convenience of the human reader. The typical example of the barcode
can be seen on the back cover of books. Normally a barcode has on it number
code for the country of the goods origin, the manufacturer and also the item
number of that particular product.
The bar codes are useful because of the names of products do not have a
repeatedly written down. They are very much useful in places like supermarkets,
at the point of sale, libraries, hospitals, warehouses etc. however, the barcodes
having the disadvantage of being read only by a machine.
Optical Mark Reader (OMR)
Optical marks are commonly used for scoring tests. It is marked by the
person taking the test and can be read by the optical mark page reader. The optical
mark reader when on-line to the computer systems, can read upto 2,000
documents per hour seemingly this rate is slow but the fact that transcription has
been eliminated, the overall time is less than those of the conventional file media.
OMR can also be used for such applications as order writing, payroll,
inventory control, insurance, questionnaires, etc. however, it is to be noted that
designing the documents for OMR is rather a tough task. They should be simple to
understand otherwise errors may result more perhaps than would occur in using
traditional source documents and keypunching form them.
KEYBOARD:
The keyboard is the most commonly used and most versatile of all input devices,
the keyboard layout is similar to that of a typewriters’ with some additional keys.
A keyboard may have 83,84 or 104 keys. Whenever a key is pressed the electrical
contacts and circuits just below the key translate the message from the key into
equivalent binary codes.
The keyboard is divided into three parts-The main keyboard, thefunction
key and the numeric keypad. Function keys perform some special functions such
as loading programs and offering help. These are programmable (i.e., they can be
usually made to perform a different function other than the original).
The numeric keypad is used to enter numeric data or to move the cursor.
(The cursor is the blinking indicator which indicates where on screen the character
that we type will appear). We can switch between these type uses by toggling the
numlock keys. Pressing the same key to choose between two modes is called
toggling.
Keys Functions:
Ctrl:
The Ctrl (Control) key is normally located on the left-bottom corner of the
keyboard. This is also called the super-shift key. It’s function is quite similar to
that of the shift key, i.e. if you press and hold Ctrl key and press another key, your
computer may type a different keystrokes or perform a special function. This key
is used extensively with most programs, including Microsoft word and Excel. The
Ctrl key is usually represented by the ^ symbol. We will follow same convention,
i.e., ^B means-press and hold the Ctrl key, and then press B, and then release both
keys.
Alt:
The Alt key is normally located on the left side of the spacebar key or shift
key. As its name suggests, it is an alternate shift key. This key is used in
combination with other keys to perform a specific function. For instance, Alt can
be used to reset your PC, if you press it in combination with Ctrl and Del Keys.
Alt can also be used to type special symbols, such as ¥© and TM
Tab:
The Tab key found on the keyboard of the PC is similar to the Tab key
used on the ordinary typewriter, and is used for the same purpose. When you press
this key, it moves the cursor in the forward direction to the next tab stop position.
Function Keys:
There are 10 or 12 functions key located on the top or the left side of the
keyboard. These are numbered as F1 through F12. The function keys are different
from the ordinary keys (A, B, 1 etc.). These are programmable keys and each
application(e.g. Word, Excel and FoxPro) can use these keys for a specific
purpose. For instance, the F7 key in one application may spell check the
document, and it may display the contents of the memory variables in another
application.
Caps Lock:
The caps lock key is used to automatically type all the alphabets in upper
case without the pressing the shift key. However, this key has no effects on
numeric keys. Usually, the keyboard provides a visual indication through a light
emitting diode (LED) when you select the Caps lock mode. To cancel the caps
lock mode and to bring the keyboard in the normal mode, press the caps lock key
again, when the caps lock mode is selected, if you type an alphabet with shift key
you will get lower case letters.
Enter:
The Enter Key is analogous to the carriage return lever on the typewriter
keyboard, except that it takes cursor to the next line on video display unit of the
PC. This key is sometimes also called the return key. On some keyboards, this key
is also marked as
Del and Backspace:
The Del and Backspace keys are used to delete keystrokes.
Ins and Esc:
The Ins key is used to select the insert or the overtype modes in the
keyboard. The Esc key is a special key that may have different functions in
different programs.
Numeric Keypad:
The keyboard also has an extra numeric keypad located on the right hand
side. The keypad contains keys to enter numbers. The same keys can also be used
as direction keys to move the cursor. If you want to use this keypad to enter
numbers, press the num lock key to select the num lock mode. To cancel the
numlock mode and to use these keys to move the cursor press the num lock key
again.
Direction Keypad:
The direction keypad is located on the left side of the numeric keypad.
This keypad contains keys to move the cursor in a particular direction, or to the
beginning or end of the page (Screen).
Light Pen and Digitizer Pads:
Pencil sized units that can be used to print inward and menu items or
create drawings on the screens. Light pen operates like a magi wand as one moves
it. In any desired pattern across the screen, it automatically creates a
phosphorescent line, when the light pen is activated; a sensor inside detects the
scanning beam sweeping across the face of the picture tube. A tiny circuit
compares this signal with the scanning process to locate the pen’s position.
Digitizer pads are similar to light pen inputs except that a Digitizer pad is
mounted horizontally so that it provides a much more comfortable way to enter
data into a computer. Its horizontal mounting makes it convenient for tracing
engineering drawings, charts and graphs.
Mouse:
A small hand-held unit that controls the location of a cursor on the screen
when it is slide over the top of a table or other horizontal surface. Its movements
tracked by optical means or by sensing the rotation of a ball protruding form the
bottom of the mouse. The mouse communicates with the computer through its
electrically conducting “Tail”. Buttons on the top of the mouse add an extra
element of control. It enables the user to manipulate a pointer or arrow on the
screen. The movements of the mouse enables the user to
1.
2.
3.
4.
Point to icons (tiny pictures that identify the processing choices)
Click on such icons to run those programs
Choose an item from a list (menus)
Draw lines or pictures on the screen. But they cannot be used where text
has to be entered.
JOY STICKS and TRACKBALLS:
Joysticks provide an alternative method for feeding the computer visually
interesting data. When you move the joystick, a cursor on the screen moves in a
corresponding way. A trackball is a plastic sphere mounted in a socket so that it is
free to rotate in any direction.
TOUCH Screens:
Touch Screens are another favorite “User Friendly” method for feeding
data into computer. Users can command the computer to perform various useful
tasks simply by touching specific sectors of the screen with their forefingers. The
computer senses the location of the finger in various ways.
VIDEO Display Unit:
Video display units are the most common input/output devices used today
in direct –access processing applications. The keyboard is used to enter data into
the computer, and a cathode ray tube (CRT) like a T.V Screen is used to display
the input data as well as the messages and processed output from the computer.
The CRT produces a beam of electrons that makes the picture on the screen.
Within the VDU is the Raster Scan. The Raster scan helps to convert the beam
produced by the CRT unto a picture. It scans the screen back and forth, from the
top left hand corner to the bottom right within VDU is the Raster Scan. The Raster
Scan helps to convert the beam produced by the CRT into a picture. It scans the
screen back and forth from the top left hand corner to the bottom right hand corner
at a rapid speed and while doing this; it is constantly redrawing the picture.
The characters or pictures that are displayed on the screen are built up
using a combination of dots called ‘pixels’ (i.e. picture elements). The generation
of the appropriate number of pixels at the appropriate locations is achieved by
using some hardware circuitry. Such hardware is termed as video Display
Adaptor.
Output Unit:
We have seen that there are several paths by which humans can
communicate with computers. There are also several ways in which the machine
can communicate with man.
At one time all that appeared to matter was obtaining results from the
computing process and no one bothered very much about presentation of the
material. However, it is now becoming increasingly important to present
information in the best possible fashion and the industry is responding by placing
greater emphasis on improving peripheral type devices (display terminals as well
as those providing hard copy output). The provision of quality output is an area of
research and development and recently great improvements have been made.
It is a device through which the data processing results are presented to the
user. Many output devices are available to present the results. They are
1. Card Punching Machine
2. Paper Tape Punching Machine
3. Magnetic Tape
4. Magnetic Disk
5. Visual Display Unit
6. Floppy Disk
7. Electronic Tele-Type Unit
8. Dot-Matrix Printer
9. Daisy Wheel Printer
10. Graph Plotter or X-Y Plotter
11. Magnetic Ink Character Printer
12. Optical Printer
Of these various devices the printer is the most commonly used device,
now-a –days the VDU is also used substantially. The copy on the screen is
called soft copy and the printed copy is called as hard copy.
Printer:
The Printer is an output device that is used to print documents on paper.
Various kinds of printers are used with PCs. The Dot Matrix Printer(DMP) is the
most commonly used printer with PCs because of its low cost and reasonably
good speed. The print head in a DMP contains a few tiny needles. There are 7 or 9
needles in a low quality DMP and up to 24 needles in a high quality DMP. At the
time of printing, as the head moves from one end of the paper to the other, these
needles are fired selectively to print different characters or graphics. Dot matrix
printers usually have a printing speed of 100 to 500 characters per second.
Inkjet/DeskJet printers are also fast becoming a popular choice for use
with PCs. These printers offer good print quality and noiseless operation. These
are non-impact types of printers that print characters and graphics by spraying
very tiny drops of ink directly onto paper. The print quality of these printers is
much better as compared to DMPs. The Typical print quality of these printers is
from 300 dots per inch(DPI) to 720 DPI. These printers can also print in color.
Laser printers are also being commonly used with high-end PCs.
Particularly those used for Desk Top Publishing (DTP). The laser printers provide
very high quality printout, typically in the range of 300 DPI to 2400 DPI. The
typical printing speed of laser printer is between 3 to 12 pages per minute.
Line printers, drum printers and chain printers are some other types of
impact printers. These printers are high-speed printers and chain printers are some
other types of impact printers. These used with mini or main frame computers,
and are not so popular with PCs.
Each Printer has its own style of loading paper and ribbon/ink cartridge in
it. If you face any problem in loading paper or ribbon/ink cartridge, refer to the
printer manual or contact your printer supplier/vendor.
Compact Disk (CD) Drive:
The Compact Disk (CD) used in a PC is similar in shape and size to the
audio CD. The Computer CD can hold about 650 MB of data. The computer CD
is used to lead computer programs and other data in the hard disk of a PC. Most of
the new computer programs are now available only on CDs. Some times programs
are directly run from the CD. Also sometimes the PC may directly read the data
stored on the CD at the time of running a program.
Most of the CDs are read only type. That is, the CPU can read information
stored on a CD, however, it cannot store (write) any information on CDs.
However, wirtable CDs are also available. Therefore, if a PC has a CD drive that
has writing capacity, you can store information on a wirtable CD. So, normally the
CD drives works as an input device, but it can also act as an I/O device.
Zip Drive:
The Zip Drive and I/O device is modified floppy drive. Each zip floppy
disk can hold up to 100 MB of data. The size of the zip floppy disk is same as that
of an ordinary micro floppy disk, through it is slightly thicker. The data transfer
rate between CPU and the zip drive is slightly slower than that between CPU and
hard disk. The zip disk is very useful to backup large amount of hard disk data or
to transfer large amount of data from one computer to another.
Primary memory storage:
Registers:
We have noted that there is movement of information within the CPU as
each instruction is interpreted and executed. To handle this process satisfactorily it
is necessary, at various stages, to retain information on a temporary basis. To do
this, the computer uses a number of special memory units called Registers. They
are not considered part of the main memory and there are several types of
Registers, each designed to perform a specific function, what they have in
common is the ability to receive information, to hold it temporarily, and to pass it
on as directed by the control unit.
STORAGE: A Register that holds information on its way to and from
memory
INSTRUCTION: A Register that holds an instruction whilst it is being
executed
ADDRESS: A Register that holds a storage location address until it is
needed.
ACCUMULATOR: A Register that accumulates results.
Storage Media (Secondary)
It is a Storage that supplements the main memory of the computer. It is
also called as Auxiliary memory. So many secondary storage devices are available
which enhance the processing ability of the computer. Let us see some of them.
(i) Hard Disk: There are one or more platters or disks mounted with a common
spindle. Each platter has two magnetic surfaces, top and bottom which is divided
into sectors and tracks. The head is available between the platters to read/write
data.
(ii) Magnetic Tape: A reel of magnetic tape is accumulated for storage media.
The standard size is ½ inch width and 2400 feet length.
(iii) Cartridge Tape: Another smaller size of the tape is called cartridge tape.
Standard size is ½ inch width and 300 to 600 feet length.
(iv) Floppy Disk: Floppy diskettes are also random access devices like the
magnetic disks. Floppy diskettes store data similar to disk pack or hard disks in
concentric circles, which are called tracks. These tracks are also divided into
sectors. The capacity of the floppy diskette varies based on density. Generally,
floppies are of two types.
(i) Low Density ad (ii) High Density
Systems Software:
Software that controls the computer and enables it to run applications
software, systems software which includes the operating system, allows the
computer to manage its internal resources.
Systems software consists program that start up the computer; load,
execute, store, and retrieve application programs; store and retrieve files; and
perform a series of utility functions. So system software is of three basic types.
They are



Operating systems
Language translators
Utility programs
User
Operating
Utility
Language
System
Programs
Translators
Word
Excel
DBMS s/w
Processor
Documents
Operating System:
Worksheets
Database Applications
An OS is the principle piece of systems software in any computing system.
The OS acts as an interface between the user and application programs.
Language Translator:
A language translator is software that translates a program written by a
programmer in a language such as BASIC into machine language, which the
computer can understand.
Utility Programs:
Utility programs are generally used to support enhance or expand existing
programs in a computer system.
Operating Systems Done
Operational systems are available for both personal computers and larger
computers such as mini computers and mainframes. The functions include
Booting: it refers to the process of loading an operating system into a computer’s
main memory from floppy disk or hard disk. This loading is accomplished by a
program called the ‘Bootstrap loader or Boot routine’ that is stored permanently in
the computer’s electronic circuitry, other programs are called ‘diagnostic routine’
also start up and test the main memory, the CPU and other parts of the system to
make sure they are running properly (‘Testing RAM’). Finally, other programs
(indicated on your screen as ‘BIOS’) will be stored in main memory to help the
computer interpret keyboard characters or transmit characters to the display screen
or to a floppy disk.
Housekeeping Tasks
One example of housekeeping task is formatting blank floppy disks.
Formatting or initializing electronically prepares a floppy disk so it can store data
or programs. Other housekeeping tasks are




Copy – or duplicate files and programs from one disk to another
Backup – or make a duplicate copy of, the contents of a disk
Erase-you can erase or remove, from a disk files or programs that are
no longer useful
Rename-you can rename, or give new file names, to the files on a disk
User Interface:
User Interface or shell is the part of the operating system that allows you to
communicate, or interact, with it. There are 3 types of user interfaces, for both
operating systems and applications software

Menu Driven: A menu driven interface allows you to choose a
command from a menu. A software menu offers you options to choose
from – in this case, commands available for manipulating data, such as


Print or Edit. Two types of menus are available: ‘Menu bars’ and ‘Pull
down menu’.
Command Driven: Here we are using commands through our CUI
(character User Interface)
Graphical User Interface: The easiest interface to use, the graphicaluser-interface (GUI), uses images to represent options. Some of these
images take the form of icons. ‘Icons’ are small pictorial figures that
represent tasks, functions, or programs.
External Utility Programs
Utility programs provide services not provided by other systems software.
They include screen savers, data recovery, backup, virus protection, file
fragmentation, data compression, and memory management.
Screen Saver:
It is a utility that supposedly prevents a monitor’s display screen from
being etched by unchanging images.
Virus:
A virus consists of hidden programming instructions that are buried within
other programs, causing adhoc.
Fragmentation:
It is the uneven distribution of data on a hard disk.
Data Compression:
It removes redundant elements, gaps, and unnecessary data from a
computer’s storage space so less space is required to store or transmit data.
Memory Management:
Utilities are programs that determine how to efficiently control and
allocate memory resources.
Application Software
It refers to software which perform application oriented or related function
on a computer. Application software can either be purchased or can be developed
using application development tool.
Two categories of application software can be purchased-

Specialized prewritten application software packages:
Perform
application – specific tasks, which fulfill the needs of the user. For
example, a specialized prewritten application software package could
be purchased to prepare the payroll for a firm. The package would
perform all the tasks required by the user, including writing checks and
preparing government reports.

Generalized prewritten application software packages: Perform
specific tasks, but can be used for many different applications. For
example, a word processing application package can only be used to
perform word processing functions. Thus, using the same word
processing package, letters can be written by the accounting
department to people who are late in their payments, by the marketing
department to prospective customers, and by the president of the
company to the stock holders
Application s/w development tools allow the user or the professional
information processing analyst or programmer to develop the application
software. These application s/w development tools must be purchased. They fall
into one of two categories:
1. Fourth – generation software development tools.
2. Programming languages
Under the first category ‘Electronic spreadsheet s/w’ is a s/w development tool
which allows the user to develop a spreadsheet that contains both data and
formulas.
Second s/w tool that is quite useful is file management s/w. The purpose of
file management systems (sometimes called Database Management Systems) is to
allow users to define files, records, data elements and to provide convenient
method of access, update and create reports form the data.
Programming languages are C, FORTRAN for scientific purposes and
C++, COBOL etc are used for commercial purpose application s/w tools.
Machine Language
It is important to understand the basic features of a computer program. A
‘Computer Program’ contains a series of instructions, which directs the computer
to perform those tasks necessary to process data and produce a desired output.
The language made out of binary digits (bits) 0’s, 1’s is known as machine
language i.e. this is the language which is understood by the computer directly
without using translator. A combination of 8 bits represents a specific alphabet, a
number, a character. The zero’s and one’s are the symbolic representation of
absence and presence of electric pulses. ‘1’ represents the presence of electric
pulse and ‘0’ represents the absence of electric pulse.
Two systems of coding have been used in the machine language.


ASCII code (American Standard Coder for Information
Interchange)
EBCDIC code (Extended Binary Coded Decimal Interchange
Code)
Example : ASCII
For A = 10000001
B = 100000010
C = 10000011
EBCDIC
For A = 11000001
B = 11000010
C = 11000011
An instruction prepared in any machine language has two parts
1. Operation Code
2. Operand (or) address
The first part is operation code. It tells the computer to perform certain
function. The second part is the operand, which tells the computer to process the
data. The programming for the first stored program computers was performed in
machine language. Since machine language programming was a difficult,
burdensome, and error – prone task, programming languages were developed to
facilitate the coding process.
Advantages of Machine Level Language

Efficiency at run time:
The computers can execute programs written in the machine
language very fast because CPU directly understands machine
instructions and no translation is required
Disadvantages:





Machine Dependant: Machine language differs from computer to
computer. The design and construction of ALU, Control Unit and size
of the memory determine it.
Difficult to write the programs: Machine level language programs are
difficult to write because programmer have to memorize all the code
number of the alphabets, numerals, special character and commands.
Error: To write a program in machine language the programmes have
to remember the operation coders and operands. It becomes very
difficult for the programme to concentrate fully on the logic of the
problem. The result is programme errors.
Difficult to modify: It is very difficult to modify or correct the
machine language programs.
Time Consuming: Writing a program in a machine language is a time
consuming one and very tedious.
Assembly Language
The first programming languages were symbolic programming languages,
commonly called ‘assembler languages’. Since writing instructions in a machine
language is difficult, these developed another language during second generation
called as assembly language. The assembly language use’ mnemonic codes’. The
mnemonic codes are the short form of English words.
Example:
ADDITION – the mnemonic code is ADD
SUBTRACTION – SUB
LOAD – LD
MOVE – MVC
EDIT – ED etc.,
An assembler language program consists of a series of individual
statements or instructions, which directs the computer to carry out the processing
that is to occur. An assembler language statement consists of three parts.
1. A Label
2. An operation code
3. One or more operands
As the computer cannot understand any language other than machine
language (0,1) the assembly language have to be translated into machine
language. This is done with the translator program called assembler.
Assembly Level Language
Language
Assembler
Machine Level
Advantages:
 Simple to understand and to use
 Easy to write and modify the programs
 Time consuming
 Easy debugging
Disadvantages:





Machine dependent
Knowledge of hardware is required to write and assembly language
program
More number of statements is required to write a simple program
Programming are difficult and time consuming one when compared to
high level language
Assembly language program cannot be executed directly by the
computer
High Level Language
A programming language in which the program statements are not closely
related to the internal characteristics of the computer is called a high-level
programming language
The high level language is written using an English like words and
mathematical symbols such as COBOL, which is used for business applications. A
high level language allows users to write in a familiar notation, rather than
numbers or abbreviations. Most high-level language is not machine dependent –
they can be used on more than one kind of computer. Examples of familiar
languages of this sort are FORTRAN, COBOL, BASIC, Pascal, C and Ada.
Assembly language requires an assembler as a language translator. The
translator for high-level languages is, depending on the language, either a
‘compiler’ or an ‘interpreter’.
Compiler:
A compiler is a language translator that converts the entire program of a
high-level language into machine language. The high level language is called the
source code. The compiler translates it into machine language, which in this case
is called the ‘object code’. The significance of this distinction is that the object
code can be saved.
Interpreter:
An interpreter is a language translator that converts each high-level
language statement into machine language and executes it immediately, statement
by a system. No object code is saved, as with the compiler.
The third generation, high-level languages are also known as procedural
languages.
Advantages:




To write the program in high level language is very easy
Errors can be easily removed
Software can be developed easily
Commands one similar to natural languages
Disadvantages



The program written in high-level languages takes more time to
execute
More storage space is required
Translators are required to translate high-level languages into machine
level language
Note: Difference between High-level languages, Assembly language, Machine
level languages refer the class notes.
Steps in developing a computer program
Because of the complexity of writing large business or scientific programs,
it is important that the programmer approach writing a program in a systematic
disciplined manner. Toward this end, a “program development cycle” has been
established. The program development cycle consists of five basic steps:
1.
2.
3.
4.
5.
Review of program specification
Program design
Program coding
Program testing
Program documentation
Review of program specifications
The first step in the program development cycle. These specifications
normally contain record and screen formats, printer spacing charts, database
schemes and access requirements, system flowcharts and data flow diagrams, and
a written narrative, which provides a detailed description of the processing that is
to occur.
It is extremely important that the programmer thoroughly understand all of
the various aspects of the problem to be solved. These aspects include the output
to be produced, the input that is available to produce the output, the data in the
database which is to be used in the production of the output, and the processing
that must occur to produce the output.
At the end of the review of the system and program specifications, the
programmer should completely understand the processing is to be performed what
data is to be processed, and how the output is to be derived from the data available
to the program.
Program Design
The design phase of the program development cycle is one of the most
important, for if a program is properly designed, it will be easily implemented in
code in the selected programming language. At the end of the design phase, the
structure and logic of the program should be detailed in such a fashion that the
resulting program code from the design will be efficient, and will always produce
correct output (reliable), will work under all conditions (robust), and will be easily
modified (maintainable).
Program coding
After the program has been designed, it must be coded, tested, and
documented. The programming language used to code a program will normally be
determined by the system analyst or project manager based upon the software
available, the knowledge of the programming staff, and the standards established
with in the information systems department.
Coding begins after the program has been designed. Coding the program
involves the actual writing of the detailed programming statements. Each
programming language has its own ‘syntax’, or coding rules, which must be
followed. The programmer must follow these rules explicitly, or the program will
not compile and execute as intended.
After the program has been coded (or in large programs, as the program is
coded), a walkthrough provides the opportunity for other programmers to review,
on a line for line basis, the coding developed by the original programmer.
Particular attention should be paid to ensuring that the code implements
the design logic as expressed by the flowchart or psuedocode that the program is
well documented, that the coding is free of errors, and that the coding is easy to
read, leading to a program that is easy to modify and maintain.
Once it is agreed that the program code is well written and correctly
implements the design of the program, the source program must be prepared for
processing on the computer.
Program Testing
After the program has been coded, it must be tested to ensure that it
processes data properly and produces the correct output. The basic procedures of
testing a program are:





Test data is created with which to test program. Creating test data with
which to test a program is an important responsibility of a programmer.
The development of adequate test data, together with good program
design and coding, are the most important tasks accomplished by a
computer programmer.
The program is compiled and all diagnostic errors are removed
The program is tested. If an interpreter is used, steps 2 and 3 occur
together.
Any errors, which are found in the program, are corrected, and the
testing continues until the program is certified as error-free.
The program can be used in a system test to ensure that all programs
within a system work properly together
Testing Sequence:
The programmer should develop a test plan which, among other things,
specifies the number of test runs to be executed, the portions of the program that
are to be tested on each run, and the objectives of each test run
Stub Testing:
Testing only a portion of a program to ensure that it works properly is
normally good testing strategy. This strategy, called ‘stub testing’, allows a
program to be partially coded and tested before testing could be started. With stub
testing, testing can begin shortly after coding is begun; with the result that
program testing is spread more evenly across the project time, and management
can review the progress of completed portions of the program.
Program efficiency:
Consists of two elements:
1. The amount of main computer memory required to store the program
when it is processing data
2.
The amount of time required by the program to process data. Program
efficiency is directly affected by a program design and program
coding. A well designed and coded program is not only understandable
and easy to modify and maintain, it is also efficient with respect to the
amount of main computer memory required and the speed with which
it process data.
Program Documentation
The documentation of each program developed in an information systems
department should include the following:
1. An abstract and general description of the purpose of the program
2. Records layouts for report output, terminal output, files on auxiliary
storage, user views of data bases used, and any other data which is
necessary in the execution of the program
3. A system flowchart, illustrating where the particular programs filts within
the system
4. A detailed description of the processing, which occurs within the program.
5. The structure or hierarchy chart of the modules within the program
6. The logic utilized within each module of the program. This logic should be
illustrated either through the use of flowcharts or through the use of
Pseudocode.
7. A listing of the source program
8. A listing of the test data used to test the program and the results of the
testing
9. A console run form which includes the job control statements and any
other information necessary to specify how the program is to be run on the
computer
10. Users guide on how to use the program. This guide may include what data
is used in the system; the way to prepare source documents; and, in
interactive programs, the manner in which to establish contact with the
computer and interact with the program.
Program Maintenance:
Program maintenance can be required to correct errors in a program. It can
also be required to make enhancements to a program, such as adding new features
to a word processing program. These are the steps involved in developing a
program.
Objectives:
1. The term _____ denotes those programs usually supplied by the computer
manufacturer or s/w house that are designed to maximize the overall
efficiency of the computer
2. The entire control system is referred to as a(n) _____
3. The ability of a computer to run more than one program concurrently is
referred to as _____.
4. _____ refers to hardware that has been pre-programmed or wired to
perform specific functions
5. Two popular operating systems for microcomputers are _____ and _____
Short Answer:
1. What is machine language?
2. What is a high level language?
3. What is a assembly level language?
4. What is a flowchart?
5. What are basic input units?
6. What are the basic output units?
7. Write short notes on storage devices?
8. What is system software?
9. What is application software?
10. Write short notes on flowchart symbols
Long Answers:
1.
2.
3.
4.
5.
Explain the system s/w and application s/w.
Explain flow chart designing with examples.
Explain the programming languages in detail.
What are the various steps involved in developing a program
Write short notes on: a. Assembly language b. Machine level
language
6. Write short notes on: a. Operating system b. Utility programs
7. Explain the input/output and storage devices
8. Write short notes on Keyboard keys.
9. Explain one Primary storage device.
10. Explain Register and types of Registers.
Operating System:
Operating System is a collection of programs, which interfaces between
the user or application programs and the computer itself to control and
manage the operation of the computer.
Operational systems are available for both personal computers and larger
computers such as mini computers and mainframes.
FUNCTIONS OF OS:
(1) The functions include Booting: it refers to the process of loading an
operating system into a computer’s main memory from floppy disk or hard
disk. This loading is accomplished by a program called the ‘Bootstrap
loader or Boot routine’ that is stored permanently in the computer’s
electronic circuitry.
(2) Other programs are called ‘diagnostic routine’ which starts up and test
the main memory, the CPU and other parts of the system to make sure they
are running properly (‘Testing RAM’). Finally, other programs (indicated
on your screen as ‘BIOS’) will be stored in main memory to help the
computer interpret keyboard characters or transmit characters to the
display screen or to a floppy disk.
(3) Housekeeping Tasks
One example of housekeeping task is formatting blank floppy disks.
Formatting or initializing electronically prepares a floppy disk so it can store data
or programs. Other housekeeping tasks are




Copy – or duplicate files and programs from one disk to another
Backup – or make a duplicate copy of, the contents of a disk
Erase-you can erase or remove, from a disk files or programs that are
no longer useful
Rename-you can rename, or give new file names, to the files on a disk
(4) User Interface:
User Interface or shell is the part of the operating system that allows you to
communicate, or interact, with it. There are 3 types of user interfaces, for both
operating systems and applications software



Menu Driven: A menu driven interface allows you to choose a
command from a menu. A software menu offers you options to choose
from – in this case, commands available for manipulating data, such as
Print or Edit. Two types of menus are available: ‘Menu bars’ and ‘Pull
down menu’.
Command Driven: Here we are using commands through our CUI
(character User Interface)
Graphical User Interface: The easiest interface to use, the graphicaluser-interface (GUI), uses images to represent options. Some of these
images take the form of icons. ‘Icons’ are small pictorial figures that
represent tasks, functions, or programs.
(5)Resource Management:
The OS also manages computer resources such as memory, printer
etc .and allows the user to share the resources.
(6)Memory Management:
The OS manages the allocation of memory to programs using
several methods like Contiguous Memory allocation, page memory etc.It also
swaps programs from main memory to Secondary storage and vice versa.
(7)Process Management
The OS performs process scheduling i.e allocation of the processor
for the execution of the programs. It uses algorithms like FIFO .
There are two types of operating system
1. Single User OS:
In a single operating system only one person can use the computer at a
time. Example: DOS
2. Multi User OS:
A multi user OS manages the allocation of computer resources among
many users and are allowed to use the computer at the same time. CPU is
shared by many users in multi-user operating system.
Example: Unix, Windows NT, Windows 98 etc.,
UNIX:
UNIX is a multi-user, time-sharing operating system. Ritchie and
Thompson originally wrote it at the Bell Telephone labs in 1973 for a small PDP
11 Computer. They used a high-level language C to write UNIX. It is very popular
as it was written in C and thus portable.
Shell
Kernel
H/W
Architecture of UNIX:
The UNIX OS can be bought of as a layered system. Unix Kernel controls
the resources of the computer and allocate it among users. It controls peripheral
devices such as disks, printers etc., connected to the computer. It provides user
with file systems to store data and programs. It lets users run their programs by
proper memory allocation and management.
In the next level of UNIX provides a command interpreter called ‘Shell’.
There are large no. of very useful commands provided by shell. Users can create a
series of shell commands and store it in a file. This file can be made as executable
file and when invoked will act like a new shell command.
Unix also provides a very interesting idea called a pipe. A pipe is a way to
send the output of one program as the input of another program without storing
the output of the first program in a temporary file. A pipeline is a connection of
two or more programs through pipes. There are large families of UNIX shell
programs that read an input, perform a single transformation, and write an O/P.
For example:
Grep Command - which searches a file for lines that match a given pattern and
O/P’s
them.
Sort Command - Sorts the file as per some specifications.
Such commands are called filters.
A part from filters provided by the system, user could create his own filter by
combining shell commands.
The outermost layer of UNIX has language compliers for C, FORTRAN 77 etc.
Advantages:
1. A unique feature of the language compilers in UNIX is that it provides a
common
Object code format, which allows easy mixing of high-level languages.
2. UNIX has some good text processing programs. Many additional utilities
such as calendar, games, graphics etc are available.
3. Multi-User built in networking capabilities, the ability to run multiple tasks
at one time, and versions that can run on all kinds of computers.
Other Unix based OS are Next step from Next Inc. Solaris by Sun Microsystems
etc.
DOS-Disk Operating System:
DOS runs primarily on IBM and IBM compatible microcomputers, such as
Compaq, zenith computers, Dell Computers and Gateway.
In earlier stage there are three kinds of DOS
1. MS-DOS: it is from Microsoft Corp. The latest version of this is 6.22.
2. PC-DOS: it is from IBM. The latest version of this 6.1.
3. DR-DOS (or) Novell’s DOS-for network software from Novell Inc
acquired with DR(Digital Research) upgraded it and renamed it Novell
DOS 7.
The Most recent versions are all backward compatible. Backward
compatible means that users can run the same applications on the later
versions of the OS that could run on earlier versions.
Recent versions of DOS have explained the range of the operating system.
For example, version 4.0 changed MS-DOS from a command driven interface
to a menu driven interface, version 5.0 added graphics-based interfaces.
Version 6.0 added features that tools advantage of a computer’s main memory.
It also used data compression to double the amount of information that could
be stored on a hard disk drive.
The DOS built a limitation up to one-MB memory. To exceed this limit we
need special memory system called EMS(Extended Memory System).
Disadvantages:
1. Command driven OS.
2. Single user programmable OS.
In Dos we have 2 types of commands.
External Commands:
External commands require certain special DOS files or being executed.
Example: Auto.exe, COMMAND.com, FORMAT, PRINT, TREE, SYS,
etc.,
Internal Command:
Internal Commands are already present in Dos and brought into the memory as
soon as the computer is switched on.
Example: COPY, DEL, DIR, TYPE, MKDIR, CD, RD, DATE, TIME
etc.,
Windows 98:
Microsoft’s desktop operating system dominance is mainly due to one
operating system-windows. Windows was a 16-bit operating system (windows
3.x) till the introduction of Windows 95. Now the latest version of windowswindows 98- has been released with lot of more features and integration with the
Internet.
Windows 98 makes your computer easier to use, with new and enhanced
features:
1. WEB INTEGRATION:
Windows 98 is easier to use with true web integration and
workflow enhancement such as icon highlights, forward and backward
buttons and an easy-to-customize START menu.
2. MULTIPLE DISK SUPPORT:
Multiple disk support makes it possible for you to use several
monitors simultaneously to increase the size of your desktop, run different
programs on separate monitors, work with various resolutions and run
programs or play games with multiple views.
3. POWER MANAGEMENT:
“On Now” makes your computer more responsive by improving
startup time. Using power management techniques, on now can start your
computer in just a few seconds and restore all your programs where you
left them. In addition, it allows your computer to continue working even
though it appears to be turned off. You can leave all of your programs
running, download your favorite web pages, send and receive e-mails,
backup your hard disk, or tune-up your operating system without being at
your computer.
4. UNIVERSAL SERIAL BUS:
The Universal, serial bus (USB) makes your computer easier to use
with advanced plug-and-play capabilities. Using a new, universally
standard connector, you can add device to your computer easily without
having to restart.
5. ACCESSIBILITY WIZARDS:
The accessibility wizard makes it easier for people with disabilities
to operate a computer without installing special software. Accessibility
option-such as sticky keys, show sound, and MouseKeys-are designed to
help user with specific disabilities make full use of computer.
6. HELP:
Windows 98 includes a new help system that makes your computer
easier to use. With help, you can find answer to your questions quickly and
easily. You can also get up-to-date technical support from World Wide
Web.
Widows 98 import your computer reliability by introducing new wizards,
utilities, and resources that help keep your computer system running smoothly.
1. WINDOWS UPDATE:
Windows update, Microsoft’s new web-based resource site,
automates driver and system file updates, and provides up-to-date
technical support.
2. SCAN DISK:
Scandisk runs automatically in the event the operating system is
shutdown improperly. Scandisk detects corruption when they are
most likely to occur and then corrects them.
Windows 98 includes a suite of programs like Maintenance
wizard, Drive, Converter, Disk Defragmenter, etc. Designed to
optimize your computer’s efficiency, especially when used together.
Windows 98 includes a mail icon that launches your default e-mail
programs. Outlook express provides you with secure and personalized features for
e-mail and newsgroups communication. With net meeting you can hold the digital
conversation with family, friends and business associates around the world
without spending a fortune. Net meeting also makes it possible for you to work
with a group of people from within any windows-based program by drawing on a
shared white board, sending text messages, and transferring files. Windows 98
includes front-page express, a web-page editor that give you full access to the
power of in a familiar, easy-to-use desktop interface.
Windows NT:
The Windows NT (New Technology) is one of the most powerful
operating system for business computing. The Windows NT combines the ease of
use of Windows 95 with the power and reliability of Windows NT.
Features of Windows NT:
1. Easy of use, Productivity and Compatibility:
Windows NT workstation has the Windows 98 easy to use interface, which
helps you, work easier and faster. Windows NT ensure high performance
for 32 bit programs and have the preemptive multitasking capabilities of
Windows NT and can run in separate address space for better
responsiveness and reliability.
2. System Reliability and Data Protection:
Window NT Workstation meets the reliability, a standard required by MIS
Professionals and other users to run critical line-of-business programs.
Windows NT workstation protects application programs from one another.
3. Workgroup and Networking support:
Built-in file sharing and print-sharing capabilities make it easy to use for
workgroup computing. Windows NT has an open networking system
interface that is compatible with banyan VINES, Netware Novell, UNIX
etc.
4. Object Linking and Embedding:
In Windows NT you can combine information from several application
into one compound document using the special object linking and
embedding (OLE) capabilities.
Internet:
The Internet is a computer network made up of thousands of networks
worldwide no one knows exactly how many computers are connected to the
Internet. It is certain, however, that these number in the millions and are
increasing at a rapid rate.
No one is in charge of the Internet. There are organizations, which develop
technical aspects of this network and set standards for creating applications on it,
but no governing body is in control. The Internet backbone, through which
Internet traffic flows, is owned by private companies.
All computers on the Internet communicate with one another using the
transmission control protocol/Internet protocol suite, abbreviated to
TCP/IP.Computers on the Internet use a client/server architecture. This means
that the remote server machine provides files and services to the user’s local client
machine. Software can be installed on a client computer to take advantage of the
latest access technology.
An Internet user has access to a wide variety of services: Electronic mail,
File Transfer, Vast information resources, Interest group membership, Interactive
collaboration, multimedia displays, Real – Time broadcasting, Shopping
opportunities, breaking news and much more.
The Internet consists primarily of a variety of access protocols. Many of
these protocols feature programs that allow users to search for and retrieve
material made available by the protocol.
Levels of Internet Connectivity:
Three Levels of Connectivity:
Gateway Connectivity: Imagine a small network or BBS (Bulletin
Board Service) that has nothing to do with Internet as such. But one of
the computers on the network is hooked up to it. Thus this interaction
point computer provides a gateway to Internet access for the rest of the
network.
Advantages:
 Low cost of access as the cost is shared by the whole network.
 Even the existing non-IP (Internet Packet) based networks can be
easily connected.
Disadvantages:
 The network depends on the facility provided by the gateway.
AOL (American Online), Prodigy, VSNL-GIAS are the examples of
gateway connectivity. Currently in India, VSNL gateway in providing E-Mail,
FTP, Telnet, Chat & UNIX Prompt facilities to its subscribers.
Remote Access Connectivity:
This type of connectivity is achieved through a dial-up terminal
connection. The mainframe on the Internet acts as a host using a dial-up
connection. The host carries out commands typed at terminal. This is most widely
used type of Internet connectivity.
Disadvantage:
 The problem associated with this level is that only the programs
present at the host can be executed.
 Loading a new program or client does not provide the ability to
execute it.
 Downloading a file from any site becomes a two-step process:
1. Downloading a file from any site.
2. To transfer host to local terminal.
Direct Connectivity:
This is most expensive type of connectivity is achieved by high-speed
lines to go line on the Internet. Internet is available round the clock. It is usually
opted with heavy load and number of users using mainframe computers. This type
of connection provided on demand by the service providers based on Point-toPoint protocol (PPP) or SLIP (Serial Line Internet Protocol).
Components of the Internet:
1.World Wide Web:
The World Wide Web (abbreviated as the Web or WWW) is a system of
internet servers that supports hypertext to access several internet protocols on a
single interface Almost every protocol type available on the internet is accessible
on the web. This includes e-mail, FTP, Telnet and Usenet News. In addition to
these, the World Wide Web has its own protocol: Hyper Text Transfer Protocol,
or HTTP.
The World Wide Web provides a single interface for accessing all these
protocols. This creates a convenient and user-friendly environment. It is
no longer necessary to be conversant in these protocols within separate,
command-level environments. The web gathers together these protocols
into a single system. Because of this feature, and because of the web’s
ability to work with multimedia and advanced programming languages,
the World Wide Web is the fastest-growing component internet.
The operation of the web relies primarily on hypertext as its means of
information retrieval. Hypertext is a document containing words that
connect to other documents. These words are called links and are
selectable by the user. A single hypertext document can contain links to
many documents. In the context of the web, words or graphics may
retrieve as links to other documents, image, video and sound. Links
may or may not follow a logical path, as each connection is
programmed by the creator of the source document. Overall, the WWW
contains a complex virtual web connections among a vast number of
documents, graphics, videos, and sounds.
Producing hypertext for the web is accomplished by creating
documents with a language called Hypertext Markup language, or
HTML with HTML, tags are placed within the text to accomplish
document formatting, visual features such as font size, italics and bold,
and the creation of hypertext links. Graphics may also be incorporated
in to an HTML document. HTML is an evolving language, with new
tags being added as each upgrade of the language is developed and
released. The World Wide Web consortium, led by web founder Tim
Burners-Lee, coordinates the efforts of standardizing HTML.
The World Wide Web consists of files, called pages or home pages,
containing links to documents and resources throughout the Internet.
The Web provides a vast array of experiences including multimedia
presentations, real-time collaboration, interactive pages, radio and
television broadcasts, and the automatic “push” of information to a
client computer. Programming languages such as java, java script and
visual basic are extending the capabilities of the web. An increasing
amount of information on the Web is served dynamically from content
stored in databases. The web is therefore not fixed entity, but one that is
in a constant state of flux.
2.E-Mail:
Electronic mail, or e-mail allows computer users locally and worldwide to
exchange messages. Each user of email has a mailbox address to which messages
are sent. Messages sent through e-mail can arrive within a matter of seconds.
A powerful aspect of e-mail is the option to send electronic files to a
person’s e-mail address. Non –ASCII files, known as binary files, may be attached
to e-mail messages. These files are referred to as MIME attachments. MIME
stands for multimedia Internet mail extension, and was developed to help e-mail
software handle a variety of file types. For example, a document created in
Microsoft word can be attached to an email message and retrieved by the recipient
with the appropriate e-mail program. Many email programs, including Eudora,
Netscape Messenger, and Microsoft Outlook Express, offer the ability to read files
written in HTML, which is it a MIME type.
3.TELNET:
Telnet is a program that allows you to log into computers on the Internet
and use online databases, library catalogs, chatservices, and more. To telnet to a
computer, you must know its address. This can consist of word (locis.loc.gov) or
numbers (140.147.254.3). Some services require you to connect to a specific port
on the remote computer. In this case type the port number after the Internet
address.
Example: Telnet nri.reston.va.us 185.
Telnet is available on the World Wide Web. Probably the most
common web based telnet is available through telnet are library
catalogs. A link to a telnet resource may look like any other link, but it
will launch a Telnet session to make the connection. A telnet program
must be installed on your local computer and configured to your web
browser in order to work.
4.FTP:
FTP stands for File Transfer Protocol. This is both a program and the
method used to transfer files between computers. Anonymous FTP is an option
that allows users to transfer files from thousands of host computers on the Internet
to their personal computer account. FTP sites contain books, software, games,
sounds, multimedia, Course work, articles, images, datasets, and more.
If your computer is directly connected to the Internet via an Ethernet cable,
you can use one of several PC software programs, such as WS_FTP for windows,
to conduct a file transfer.
FTP transfer can be performed on the World Wide Web without the need
for special software. In this case, the web browser will suffice. Whenever you
download software from a web site to your local machine, you are using FTP.
5.E-MAIL DISCUSSION GROUPS:
One of the benefits of the Internet is the opportunity it offers to people
worldwide to communicate via e-mail. The Internet is the home to a
large community of individuals who carry active discussions organized
around topic-oriented forums distributed by e-mail. These are
administered by software programs. Probably the most common
program is the Listserv.
List servers cover a great variety of topics , many of them are academic
in nature. When you subscribe to listserv, message from one subscriber
is automatically sent to your electronic mailbox. You subscribe to a
listserv by sending an email message to a computer program called a
list server. List servers are located on computer networks throughout
the world. This program handles subscription information and
distributes messages to and from subscribers. You must have a e-mail
account to participate in a listserv discussion group.
6.USENET NEWS:
Usenet News is a global electronic bulletin board system in which millions
of computer users exchange information on a vast range of topics. The major
difference between Usenet News and e-mail discussion groups is the fact that
Usenet messages are stored on central computers, and users must connect to these
computers to read or download the messages posted to these groups. This is
distinct from e-mail distribution; in which message arrive in the electronic
mailboxes of each list member.
Usenet itself is set of machines that exchanges messages, or articles from
Usenet discussion forums, called newsgroups. Usenet administrators control their
own sites, and decide which (if any) newsgroups to sponsor and which remote
newsgroups to allow into the system.
There are thousands of Usenet newsgroups in existence. While many are
academic in nature, numerous newsgroups are organized around recreational
topics. Much serious computer-related work takes place in Usenet discussions. A
smaller number of e-mail discussion groups also exist as Usenet newsgroups.
The Usenet news feed can be read by a variety of newsreader software
programs. For example, the Netscape communicator site comes with a newsreader
program called messenger. Newsreaders are also available as standalone products
7.CHAT and INSTANT MESSENGING:
Chat programs allow users on the Internet to communicate with each other
by typing in real time. They are sometimes included as a feature of a web site,
where users can log into the “chat rooms” to exchange comments and information
about the topics addressed on the site. Chat may take other, more wide ranging
forms. For example, America online is well known for sponsoring a number of
topics chat rooms.
Internet Relay Chat (IRC) is a service through which participants can
communicate to each other on hundreds of channels. These channels are usually
based on specific topics. While many topics are frivolous, substantive
conversations are also taking place. To access IRC, you must use an IRC software
program.
A variation of chat is the phenomenon of instant messaging. With
instant messaging, a user on the web can contact another user currently
logged in and type a conversation. Most famous is America Online’s
instant massagers. ICQ is another commonly used chat program.
Intranet:
System administrator will be there within the organization. All the
people will be given an Identity No. If any mail comes top the person
that will be given to him. Control is with the system administer,
personal department can access only personal department and not
production department control, system administer will control the
system.
Advantages:
1.Putting company related information on Net.
2.Can be accessed by all employees of the organization in the office or via dial up
access.
3.Applications used are company procedure or manuals, corporate databases.
4.It is the usage Internet Technologies within the organization to achieve better
results that the conventional means of access and transfer.
5.It should be noted that Intranet technologies could be used only if the network is
within a single campus.
Extranet is connected with outside suppliers, customers. All suppliers will
know when to supply and customers will know when they are produce goods.
It is the use of Internet technologies outside the organization boundaries to
achieve better results than the conventional means of access and transfer.
Extranet technologies are common where companies experimented their
boundaries to include their suppliers into their network.
E-mail Procedure
Step 1:The user types the document into the computer or selects the files that are
to be mailed.
Step 2:The computer files are converted into a form that is suitable or
transmission over the telephone lines using a modem.
Step 3:The files are transferred using the telephone connection to the local node
of the E-mail service Provider.(ESP).
Step 4:The reverse process of step2 occurs and the analogy signals are converted
back to digital form suitable for computer at the other end.
Step 5:As the files reach the local node of E-mail service provider, the computer
sorts the files to be transmitted to different location.
Step 6: The ESP transmits the files using the microwave link(VSAT-very small
Aperture Terminal) or some other means to the nearest node to destination.
Step 7: The ESP node nearest to the destination receives the files.
Step 8: The ESP node then resolves the address and prepares the file to be
dispatched.
Step 9: the node computer of the ESP user the same device (modem) to connect
the received signals back to analogs signals as a preparation to transmit them to
the destination. Computer over telephone lines. Thus as can be seen, modem is a
very important device not only in the case of E-Mail but the whole cycle of
Electronic information exchange.
Step 10: The files are transferred over the telephone line to the destination
computer.
Step 11: the modem then finally converts these into digital signals for the
destination computer.
Step 12: the files reach destination and the user can read them. And reply forward
or store them.
E-Commerce:
Electronic Commerce is one of the most important aspects of the
Internet to emerge. It allows people to exchange goods and services
immediately and with no barriers of time or distance. Any time of the
day or night you can go online and buy almost anything you want. This
is how e-commerce works.
The consumer moves through the Internet to the merchant’s web site.
From there. He decides that he wants to purchase something, so he is
moved to the online transaction server, where all of the information he
gives is encrypted. Once he has placed his order, the information moves
through a private gateway to a processing network, where the issuing
and acquiring banks complete or deny the transaction. This generally
takes place in no more than 5-7 seconds.
There are many different payment systems available to accommodate
the varied processing needs of merchants, from those who have a few
orders a day to those who process thousands of transactions daily. With
the addition of secure socket layer technology, e-commerce is also a
very safe way to complete transactions.
//Give Application how to do online purchasing
Mobile Computers:






Fixed point-to-point telephony is given way to global cellular mobile
communication system. Such a system provides anytime, anywhere
connectivity.
GSM-global system for mobile communication is a widely used mobile
communication system.
GSM standard is optimized for short message service (SMS) that allows
GSM mobile users to send and receive, short concise and abbreviated text
message to other mgs.
SMS length of a single message is restricted.
SMS message can be sending and received simultaneously with voice data
and fax calls.
SMS message low bit rate signaling channel for message transmission.
SMS Features:




GSM is most popular mobile cellular network.
It supports two way paging communication.
It supports store-forward capability.
Point to point short text message and cell broadcasting.
Radio Paging:
‘Paging service network’ provides for one way(receive only) message
service. This means the mobile user cannot send a message. Such a service is also
know as mobile terminated messaging.
Limitations:
1. One-way service.
2. Paging is restricted to particular city only, and does not provide to
global messaging features provided by SMS.
MOBITEX:
Is the popular and widely deployed cellular wireless data network in US.
1.It specifies both packet and circuit switched transmission facilities.
2.MOBITEX system offers store and forward capabilities. Each registered user
has a mailbox in MOBITEX system. If a packet is undelivered, then at the
sender’s discretion it can store in recipient mailbox.
M-Commerce:
E-commerce over mobile phones. It is a WAP application. WAP is a
protocol by which the mobile phone accesses specific sites on the Internet, and
handsets need specific micro-browser s/w installed to search for WAP-enabled
sites.
There are two forms of HTML programming.
HTML for normal browsing and WML (Wireless MarkUp Language) for WAP
application.
Limitations.
Reduced or to disappear with increasing data rates delivered to the hand
set (first from GPRS-General Packet Radio System and then UMTSUniversal Mobile Telephone System) and considerably improved
displays.
Japan’s I-mode handset to handle a compressed version of normal HTML
pages rather than special WML pages.
Flow Charts:
One of the most widely used devices for designing programs is the
flowchart, which graphically represents the logic needed to solve programming
problem.
A program flowchart represents the detailed sequence of steps, needed to
solve the problem. Program flowcharts are frequently used to visualize the logic
and steps in processing.
There are only few standard flowchart symbols necessary to solve almost
any programming problem.
Symbol
or
The Input /output symbol is used to represent any input
Output operation. It may represent the point in a
program
where the data (input) is required or where the
information
(Output) is to be displayed.
The process symbol represents some type of data
manipulation or arithmetic operation.
The decision symbol represents a logical comparison
operation. Based on the comparison operation. Based on
the
Comparison, one of the two paths will be taken.
The connector symbol is used when several symbols
displayed at one point might cause confusion and
reduce
understanding. The Symbol directs the reader’s attention
to
another area of the Flowchart where the programs flow
continues.
The predefined process symbol is often used to represent
a
process that is used several times in the same program.
This
process is defined only once and reference by this block
thereafter.
The annotation flag symbol is used to identify clarifying
comments to other symbols. They do not represent a
logical
step or calculations in the program. They are used only
for
documentation purpose.
The terminal symbol represents the start or end of a
program.
It is also used to indicate a program interruption point
where
information can enter or leave.
The direction of flow symbols indicates the next step in the
program.
The flow charts shown in figure shows how the employee’s salary is calculated
and paychecks are printed. The explanation of the flowchart is given below.
1. This opens the employees’ personnel file.
2. This reads the employee’s last name, first name, week ending data, hourly
pay rate etc.
3. This is the “Last record” decision point. If the answer is “yes” the program
proceeds to calculations.
4. This multiplies hours worked with pay rate to get gross pay.
5. This asks if the employee worked overtime.
6. If the answer is “yes” overtime pay is calculated and added to gross pay.
7. This asks if the gross pay for the week is above Rs 300.
8. If the answer is “Yes” a tax rate of 15 % is calculated.
9. If the answer is “No” a tax rate of 10% is calculated.
10. This calculates the subtracts deductions, such as union dues and other
taxes and computes net pay.
11. This prints out the employee’s paycheck.
12. This reads the employee file for the next employee-name, week ending
data, hourly pay rate, etc.
13. When all the employee files have been read and the answer to the “Last
record” decision is “NO”, the program begins to terminate.
14. This closes all the employees personnel file.
15. This stops the program.
Flowchart to print Paychecks(Payroll Application)
A
8
7
Tax rate is
15%
Is Gross
Pay
>300
Start
Yes
s
No
Open data file
for input
Tax rate is
10%
1
Read data
for an
Employee
2
9
Calculate
deductions & Net
Pay
10
B
Print
Paycheck
3
Close data
file
Is
there
data?
11
Stop
Read Data for
an employee
No
Ye
s
Calculate Gross
Pay
4
B
6
5
Is there
overtim
e
Calculate
overtime pay
12
2
System Flowcharts:
In this text, most of our designs have dealt with isolated program, but in
reality most programs are designed and used as part of a broad interrelated system
of programs in which the output from one program may be the input to another
program. As designers we must consider not just the specifications for the
particular program segment on which we are working but also the specifications
for the entire system in order to be sure that our segment fits in to the system as
needed. A system flow chart shows how the programs fit together.
The system flowcharts looks at first very much like a program flowchart
but there are two major differences first the program flowchart shows the detailed
steps in a program and the system flow chart shows the same program as one
process box without showing any details. Second the program flowchart uses the
same symbol for all types of input and output with a system flowchart, we need to
show more information the particular input/output hardware device must be
shown to issue compatibility within the system. So the system flow chart utilizes
a wide variety of input/output symbols to identify the medium (Disk, Tape,
Keyboard) used.
The main symbols used in a system flow chart are shown below.
Input Edit
Program
Program Box
Communication Link Flow line to Remote Device
Flow Line
Manual Operation
Corrects
Errors
Employee
File
Employee
File
Magnetic Tape (I/O)
Magnetic Disk (I/O)
Error
Report
Menu
Display
Document (Output)
Video Display (Output)
Used Input
Keyboard (Input)
Most of us are accustomed to the grocery checkout scan system that reads
the UPC from product packaging and display the price on the cash register. That
system is checking some form of on-line storage for the price and as the same
time modifying the inventory count to indicate that one item has been sold. The
inventory file can also be sued as input for a product ordering program that will
produce printed recorder forms. A typical system flow chart might look something
like the one on the next page.
Notice that we have shown the particular hardware used for input and
output. This system is a simplification of a true point of sale inventory system. But
you can see how the system flow chart clarifies the relation between programs.
You can see in the above chart for e.g. that both the cash register program and the
recorder program use the inventory disk file the system flow chart does not
replace a program design. It is a supplements that shows another new which is not
available from a program flowchart or pseudocode to see that details happening
within one of the programs we would record to have a program design.
System Flow Diagram
Code Input
Price
File
Cash Register
Program
Short Answer:
1. List out the types of operating systems.
2. What is single user operating system?
3. What is multi user operating system?
4. List out the different kinds of DOS.
5. What are the types of Command in DOS?
6. What is OLE?
7. What are the levels of Internet Connectivity?
8. Abbreviate WWW.
9. FTP stands for what?
10. HTTP stands for what?
11. E-Mail stands for what?
12. What is TELNET?
13. Define USENET NEWS.
14. What is Internet?
15. What is Intranet?
16. What is Extranet?
17. What is E-Commerce?
18. What is Mobile Computer?
19. What is Radio Paging?
20. What is M-Commerce?
21. What is HTML stands for?
Long Answer
1.
2.
3.
4.
5.
6.
What are the types of Operating System?
Explain the components of Internet.
Explain the levels of Internet Connectivity.
Explain FTP and its features.
Explain Telnet and its features.
Explain M-Commerce in detail.
Register
Receipt
7. Explain E-Commerce in detail.
8. Explain a) UNIX b) WINDOWS 98 c) DOS in detail.
9. Explain Unix OS in detail.
10. Explain Mobile Computers in detail
11. Write Short notes on FTP, HTTP.
12. Write Short notes on Internal Commands and External Commands of
DOS.
13. Explain Kernel and Pipeline technique of UNIX Operating System.
14. Explain Single User Operating System in detail.
15. Explain Multi User Operating System in detail.
16. Write Short Notes. a) Internet b) Extranet c) Intranet.
17. Write Short Notes. a) Radio Paging b) MOBITEX
18. Explain steps involved in E-MAIL.
19. Write Short Notes on Email Discussion Groups.
20. Write Short Notes on Char and Instant Messaging.
21. Write Short Notes on Usenet News.
22. Write Short Notes on Windows NT.
23. Write Short Notes on E-Mail.
24. List out the difference between Single User OS and Multi User OS.
25. List out the difference between Windows 98 and Windows NT.
26. Write short notes on different types of DOS.
27.Explain Mobile Computers in detail.
System: A System is a network of related procedure designed to perform some
activity.
Procedures: Procedures are logical steps by repetitive action are initiated, carried
forward, controlled, and finalized.
Systems, which are implemented using a computer, fall into 3 broad
classifications.



Operational System.
Management Information System.
Decision Support System.
Operational System:
Operational System is designed to process the data that is generated by the
day-to-day business transaction of companies. This SAD follows a well-defined
scientific problem solving approach. The approach can be broken down into a
series of phases:
Phases 1- Initiation of the system project & preliminary Investigation.
Phases 2- detailed system investigation & analysis.
Phases 3- System design.
Phases 4- System development.
Phases 5- System implementation and evaluation.
Phases 6- System maintenance.
Initiation of the System Project & Preliminary Investigation:
A system project can originate in several ways, but a common way is that
the manager of a user department contacts the systems analysis and design group
in the information systems department with a request for assistance.
The purpose of the ‘preliminary investigation’ is to determine if the
request for assistance, which has been communicated, to the system department
warrants further detailed investigation and analysis. The most important aspect of
the preliminary investigation is to identify if there is a problem and, if so, to
uncover the true nature of the problem. The primary method of conducing the
preliminary investigation is through the ‘personal interview’. The interviews are
conduced with managerial and supervisory personnel who may have knowledge of
the problem and system under study.
At the conclusion of the investigation, the analyst will present the findings
to management and recommend the next course of action. If it is recommended to
continue the project through a detailed investigation, the analyst will provide
management with an estimate of the cost for the next phase in terms of man-hours,
and elapsed time.
Detailed System investigation and analysis
If approval to proceed is obtained from management the analyst will begin
the ‘detailed investigation and analysis’. This phase of the system study is divided
into two parts: 1) A detailed investigation in which the emphasis is on WHAT is
taking place in the current system: 2) An analysis of what is taking place with an
emphasis on WHY the procedures found are occurring, and what the user sees as
the requiem ends for a new system.
The basic fact-gathering techniques used during the detailed system
investigation are: 1) The interview: 2) Questionnaires; 3) Gathering the current
system documentation and operating forms; 4) Personal observation of current
procedures.
Specific steps undertaken at this time to gather the facts include: 1) review
the organizational chart of the structure of the company to determine who are the
workers, supervisors, and management personnel associated with he system under
study; 2) Conduct interviews with selected personnel to determine what is actually
taking place in the current system, rather than what is supposed to take place
according to the written rules of the company; 3) Obtain actual copies of operating
documents; 4) Document and record all of the data flow within the currently
existing system and the actual procedures, which are followed.
Once of the more effective is the data flow diagram. This DFD illustrates
graphically the flow of data and the procedures used for an auto parts order entry
system. Since the present system is being reviewed in detail, there obviously were
some problems in the system. After the current system has been documented and
analyzed, the analyst must assist the user to identify the requirements of the new
system. This analyst will include understanding the problems in the current
system, planning for growth and change in the user department, understanding the
personnel requirements and capabilities in the department and a number of other
factors as well.
At the conclusion of this activity the analyst should prepare a written and
oral presentation of the findings, which can be presented to both the user and to
other management.
System Design:
Upon approval to proceed, the analyst must determine the best method for
implementing a new system. The choice usually are: 1) Personnel in the
information systems department design and implement the application: 2) The
user, through the use of fourth generation applicatio9n development tools or
through the facilities offered by the information centre, designs and implements
the application: 3) A prewritten applications software package is purchased which,
with little or no modification, will perform the tasks required of the new system:
4) The systems department designs the system and then contracts with an outside
organization to have the system programmed and implemented: 5) the entire
project is contracted out to an outside organization that designs and implements
the system.
As the design phase begins, develop a prototype of the new system. A
‘prototype’ is a series of small programs that allows a few of the transactions, with
will be processed on the real system to be processed. Because of the prototype
system, the user will have an exact idea or how the system will behave when it is
implemented, and the analysts are ensured that when the system is developed and
implemented, the user will be satisfied
When designing the ‘system output’ specific steps must be undertaken,
including o/p requirements of new system types of output etc., The analyst must
also, during the project maintain some data which will be stored by the system.
This is called ‘Data dictionary,. An important aspect of the establishment only
valid data is accepted and processed.
System Development:
After the design phase of the project, the project enters the “system
development” phase. The major tasks common to all system projects during the
system development phase are: 1) Establish a project development and
implementation plan; 2) Develop detailed programming specifications; 3)
Program and test the system; 4) Prepare final documentation of the system.
One of the first steps in the system in the system development phase is to
develop a detailed schedule of each of the activities that is to be performed. The
time schedule of the project is produced by a method often used to document the
schedule is the bar or “Gantt chart”. (flg. Refer your notebook).
Programmer’s jobs are 1) review the program 2) design the program 3)
coding the program 4) testing the program.
Program design entails the development of the structure of the program
and than the development of the logic to solve the problem presented by the
program.
After the programs in the system have been tested individually (commonly
called ‘unit tests’) the entire system of programs must be tested as a whole. This
process is called “System Testing”.
Implementation And Evaluation:
After testing has been complete and the documentation prepared, the
system is ready to be implemented on the computer and run in a production
environment. “Conversion” refers to the process of making the change from the
old system to the new system. Two methods are direct conversion and parallel
conversion.
With direct conversion, at a given date the old system ceases to be
operational and the new system is placed into use. Direct conversion, howere, can
be risky, in spite of the great care, which may have been taken in designing the
system.
Parallel Conversion consists of processing data on both the old and new
systems simultaneously and comparing the results. Regardless of the method of
implementation used. It is important to conduct a formal post implementation
evaluation of the system. The evaluation consists the designing, operating costs.
System Maintenance:
An ongoing process after the system has been implemented is ‘system
maintenance’. Maintenance consists of two major activities: 1) Changes to correct
errors in the system: 2) Changes to give the system additional capabilities or to
conform to government or company regulations.
Maintenance activities require a great deal of time for many programmers
and analysts. Systems, which are well documented and contain well-designed
programs, are much easier to maintain than those, which do not follow good
documentation and coding standards.
Computer Based Information Systems:
Transaction Processing:
In most organizations, particularly business organizations, most of what
goes on takes the form of transactions. A ‘transaction” is a recorded event having
to do with routine business activities. This includes everything concerning the
product or service in which the organization is engaged: Production, distribution,
sales, orders. It also includes materials purchased, employers hired, taxes paid,
and so on. Today in most organization the bulk of such transactions are recorded
in a computer-based information system.
A transaction processing system (TPS) is a computer based information
system that keeps track of the transactions needed to conduct business. The
transaction processing system is also sometimes called an electronic data
processing (EDP) system.
Some features of a TPS are as follows:

Input and Output: The inputs to the system are transaction data: bills,
orders, inventory levels, and the like, the output consists of processed
transactions: bills, paychecks, and so on.

For lower managers: Because the TPS deals with day-to-day matters, it is
principally of use to supervisory managers. That is, the TPS helps in making
tactical decisions. Such systems are not usually helpful to middle or top
managers.

Produces detail reports: A lower-level manager typically will receive
information in the form of detail reports. A detail report contains specific
information about routine activities. An example might be the information
needed to decide whether to restock inventory.

One TPS for each department: Each department or functional area of an
organization-Research & Development, Production, Marketing, and
Accountings Accounting & Finance – usually has its own TPS. For example,
the Accounting & Finance accounts payable, and payroll.

Basis for MIS and DSS: The database of transactions stored in a TPS is used
to support a management information system and a decision support system.
Management Information System (MIS)
A ‘management information system (MIS)’ is a computer-based
information system that derives data from all on organization’s departments and
produces routine reports of the organization’s performance. To perform it’s major
functions of planning organizing, staffing, directing, and controlling.
Concept of MIS
Planning
Planning means to set the goals and objectives for the company:
management should know and understand the nature of the company. Its
competition, its market place etc., before planning. Establishing policies,
procedures, programs of a company are one of the important steps of planning.
Fig. Concept of MIS
Organizing
To organize means to develop and maintain the resources and structure of
a company. Managers must be assigned their duties; workers must be given their
work to meet the desired goal.
Staffing
Staffing is a continuous process of recruiting and training the employees.
Directing
To co-ordinate the activities of the company and to delegates the authority
for causing out the activities and to attain the Objectives directing is necessary.
Directing includes Co-ordination, Communicating, motivating the employees to
do their jobs to attain the goals.
Controlling
To control means to evaluate by comparing actual with the goal: Any
deviation actions are taken to correct the deficiencies. Sometimes the necessary
action requires written to the planning functions to revise the goals..
MIS can be divided into various level of management.
Operational Level
Operational manager is responsible for day-to-day operations: The
functions are employing the people, training to the employees, maintaining the
stick level, maintaining the customer relationship-supervising the employees, and
verifying the cash register.
Tactical Level:
Responsibility is given to the manager not for a single unit but for several
units. MIS functions are to rectify the consumer complaints, to achieve the
individual unit goals, to analyze and find the reason for decrease in sales and
production.
Top Level or Strategic Level:
Responsibilities given to the manager for the whole organization for long
range planning. It includes fixing the organization for long range planning. It
includes fixing the objectives, scheduling the program to prepare the budgeting.
Decision Support Systems (DSS)
A decision support system (DSS) is a computer-based information system
that provides a flexible tool for analysis and helps managers with non-routine
decision-making tasks.
Some features of a DSS are as follows:
Input and Output: Inputs consist of some summarized reports, some processed
transaction data, and other internal data. They also include data that is external to
that produced by the organization. This external data may be processed by trade
associations, marketing research firms and other government agencies. The
outputs are flexible, on-demand reports with which a top manager can make
decisions, about unstructured problems.
Mainly for Top Managers: A DSS is intended principally to assist top managers,
although it is now being used by middle managers, too. Its purpose is to help hem
make strategic decisions – decisions about unstructured problems, often
unexpected and nonrecurring. These problems may involve the effect of events
and trends outside the organization. Examples are raising interest rates or a
possible strike in an important materials-supplying industry.
Produces Analytical Models: The key attribute of a DSS is that it uses models.
A ‘model’ is a mathematical representation of a real system. The models use a
DSS database, which draws on the TPS (Transaction Processing System) and MIS
(Management Information System) files, as well as outside data. The system is
accessed through DSS software.
The model allows the manager can simulation-play a “what if”
game-to Reach decisions. Thus, the manager can simulate an aspect of the
organization’s environment in order to know how to react to a change in
conditions affecting it. By changing the hypothetical inputs to the modelnumber of workers available, distance to markets, ir whatever-the manager can
see how the model’s outputs are affected.
Group Decision Support Systems
As communications becomes a more important of an information
system, so does a kind of an information system, so does a kind of DSS called
group decision support systems. A ‘group decision support system’ (GDSS)
enables teams of coworkers to use networks of microcomputers to share
information and cooperate on projects. A group decision support system is also
called workgroup computing. By sharing ideas, workers can build consensus
and arrive are decision collaboratively. GDSSs are being found in fields
‘ranging from banking and insurance to architectural design and newspaper
publishing.
Executive Information Systems
An Executive information system (EIS) is a DSS made especially for top
managers and specifically supports strategic decision-making. An ESI is also
called an Executive Support System (ESS). It draws on data not only from
systems internal to the organization but also from those outside, such as news
services or market-research databases. An EIS might allow senior executives to
call up predefined reports from their personal computers, whether desktops or
laptops. They might, for instance call up sales figures in many forms – by region,
by week, by fiscal year, by projected increases. The EIS includes capabilities for
analyzing data and doing “what-if” scenarios.
Expert Systems
Artificial Intelligence (AI):AI is a group of related technologies that attempt to
develop machines to emulate human-like qualities, such as learning, reasoning,
communicating, seeing and hearing.
Artificial Intelligence is a research and applications discipline that includes five
areas:
o Robotics – is concerned with developing machines that can
perform work like
o Humans.
o Perception systems – are sensing devices that emulate the human
senses.
o Expert systems – are interactive programs that help people solve
problems
o Otherwise requiring a human expert.
o Natural language processing (including fuzz logic) – studies
ways computers can understand human language, and fuzzy logic
deals with problems of uncertainty.
o Neural networks – mimic human brain nerve cells. We also
consider an area known as artificial life, which involves computer
instructions that act like living organisms.
Expert Systems
An expert system is an interactive computer program that can apply rules
to input in such a way as a generate conclusions. The program helps users solve
problems that would otherwise require the assistance of a human expert.
Note: Draw the diagram.
An expert system consists of three components.
Knowledge base:
A “Knowledge bas’ is an expert system’s database of knowledge about a
particular subject. This includes relevant facts, information beliefs, assumptions,
and procedures for solving problems. The basic unit of knowledge is expressed as
an IF-THEN-ELSE rule. Programs can have as many as 10,000 rules. A system
called ExperTAX, for example, which helps accountants figure out a client’s tax
options, consists of over 2000 rules.
Inference engine:
The ‘inference engine, is the software that controls the search of the
export system’s knowledge base and produces conclusions. It takes the problem
posed by the user of the system and fits it into the rules in the knowledge base. It
then derives a conclusion from the fact and rules contained in the knowledge base.
Reasoning may be by a forward chain or backward chain. In the forward
chain of reasoning, the inference engine begins with a statement of the problem
form the user. If then proceeds to apply any rule that the problem. In the
backward chain of reasoning, the system works backward from a question to
produce an answer.
User Interface:
The user interface is the display screen that the user interacts with. If
gives the user the ability to ask questions and get answers. It also explains the
reasoning behind the answer.
Applications:
Expert systems exist in many areas.
 MYCIN helps diagnose infections diseases.
 PROSPECTOR assesses geological data to locate mineral deposits.
 DENDRAL identifies chemical compounds.
 Home-Safe-Home evaluates the residential environment of an elderly
 Person.
 Business Insight helps businesses find the best strategies for marketing a
 Product
 REBES (Residential Burglary Expert System) helps dectives investigate
 Crime scenes.
 CARES (Computer Assisted Risk Evaluation System) help social workers
 Assess families for risks of child abuse.
 Muckraker assists journalists with investigate reporting.
Flow Charts:
One of the most widely used devices for designing programs is the
flowchart, which graphically represents the logic needed to solve programming
problem.
A program flowchart represents the detailed sequence of steps, needed to
solve the problem. Program flowcharts are frequently used to visualize the logic
and steps in processing.
There are only few standard flowchart symbols necessary to solve almost
any programming problem.
Symbol
or
The Input /output symbol is used to represent any input
Output operation. It may represent the point in a
program
where the data (input) is required or where the
information
(Output) is to be displayed.
The process symbol represents some type of data
manipulation or arithmetic operation.
The decision symbol represents a logical comparison
operation. Based on the comparison operation. Based on
the
Comparison, one of the two paths will be taken.
The connector symbol is used when several symbols
displayed at one point might cause confusion and
reduce
understanding. The Symbol directs the reader’s attention
to
another area of the Flowchart where the programs flow
continues.
The predefined process symbol is often used to represent
a
process that is used several times in the same program.
This
process is defined only once and reference by this block
thereafter.
The annotation flag symbol is used to identify clarifying
comments to other symbols. They do not represent a
logical
step or calculations in the program. They are used only
for
documentation purpose.
The terminal symbol represents the start or end of a
program.
It is also used to indicate a program interruption point
where
information can enter or leave.
The direction of flow symbols indicates the next step in the
program.
The flow charts shown in figure shows how the employee’s salary is calculated
and paychecks are printed. The explanation of the flowchart is given below.
16. This opens the employees’ personnel file.
17. This reads the employee’s last name, first name, week ending data, hourly
pay rate etc.
18. This is the “Last record” decision point. If the answer is “yes” the program
proceeds to calculations.
19. This multiplies hours worked with pay rate to get gross pay.
20. This asks if the employee worked overtime.
21. If the answer is “yes” overtime pay is calculated and added to gross pay.
22. This asks if the gross pay for the week is above Rs 300.
23. If the answer is “Yes” a tax rate of 15 % is calculated.
24. If the answer is “No” a tax rate of 10% is calculated.
25. This calculates the subtracts deductions, such as union dues and other
taxes and computes net pay.
26. This prints out the employee’s paycheck.
27. This reads the employee file for the next employee-name, week ending
data, hourly pay rate, etc.
28. When all the employee files have been read and the answer to the “Last
record” decision is “NO”, the program begins to terminate.
29. This closes all the employees personnel file.
30. This stops the program.
System Flowcharts:
In this text, most of our designs have dealt with isolated program, but in
reality most programs are designed and used as part of a broad interrelated system
of programs in which the output from one program may be the input to another
program. As designers we must consider not just the specifications for the
particular program segment on which we are working but also the specifications
for the entire system in order to be sure that our segment fits in to the system as
needed. A system flow chart shows how the programs fit together.
The system flowcharts looks at first very much like a program flowchart
but there are two major differences first the program flowchart shows the detailed
steps in a program and the system flow chart shows the same program as one
process box without showing any details. Second the program flowchart uses the
same symbol for all types of input and output with a system flowchart, we need to
show more information the particular input/output hardware device must be
shown to issue compatibility within the system. So the system flow chart utilizes
a wide variety of input/output symbols to identify the medium (Disk, Tape,
Keyboard) used.
The main symbols used in a system flow chart are shown below.
Input Edit
Program
Program Box
Communication Link Flow line to Remote Device
Flow Line
Manual Operation
Corrects
Errors
Employee
File
Employee
File
Magnetic Tape (I/O)
Magnetic Disk (I/O)
Error
Report
Menu
Display
Document (Output)
Video Display (Output)
Used Input
Keyboard (Input)
Most of us are accustomed to the grocery checkout scan system that reads
the UPC from product packaging and display the price on the cash register. That
system is checking some form of on-line storage for the price and as the same
time modifying the inventory count to indicate that one item has been sold. The
inventory file can also be sued as input for a product ordering program that will
produce printed recorder forms. A typical system flow chart might look something
like the one on the next page.
Notice that we have shown the particular hardware used for input and
output. This system is a simplification of a true point of sale inventory system. But
you can see how the system flow chart clarifies the relation between programs.
You can see in the above chart for e.g. that both the cash register program and the
recorder program use the inventory disk file the system flow chart does not
replace a program design. It is a supplements that shows another new which is not
available from a program flowchart or pseudocode to see that details happening
within one of the programs we would record to have a program design.
System Flow Diagram
Code Input
Price
File
Cash Register
Program
Price
Display
Inventory
File
Register
Receipt
Recorder
Program
Recorder
Forms
Objectives:
1. The _______ must work closely with user when creating a new systems
design.
2. Middle management makes _______ decisions.
3. ______ Tools are software packages that provide computer-automated
means of designing and changing systems.
4. A (n) _______ enables teams of co-workers to use networks of
microcomputers to share information and cooperate on projects.
5. A (n) ________ is a schematic diawing that shows the hierarchy of formal
relationships among an organization’s employees.
6. A __________ provides descriptive information about the data items stored
in the database.
7. The computer professional responsible for maintaining the database is
called a ________.
Short Answers:
1. Define MIS
2. Define Decision Support System.
3. What is mean by transaction processing?
4. What is the three-management support level in MIS?
5. Define Expert System. Give any two-application tools.
6. What are the basic computers based information systems?
7. Define SAD.
8. What are the various phases in System Analysis Design?
9. What is inference engine?
10. Define EIS.
11. Define GDSS.
12. Write short notes on Office Automation.
13. Write short notes on program implementation.
14. What is meant by program maintenance?
15. What is a Prototype?
16. What is a DED?
17. What is a flowchart?
18. What is Program Design?
19. What are the processes involved in Detailed Investigation?
20. Mention any two program designed tool.
21. What is mean by a structured programming?
22. What is a testing?
23. Write short Notes on: a) System Analyst b) Programmer.
24. What is an operating system?
25. What are the basic operating systems we are using?
26. Write short notes on operating systems and its types.
27. Give examples of single user OS.
28. Define kernel.
29. Define shell.
30. What is a pipe?
31. Write short Notes. A) External Commands B) Internal Commands.
32. What is Internet?
33. What is Internet?
34. What is WWW?
35. What is Extranet?
36. Write short notes on FTP.HTTP.
37. What is E-commerce?
38. What is M-commerce?
Long Answers:
1. Explain the various phases in System Analysis and Design.
2. Discuss the Management Information System in detail.
3. Explain: 1) Decision Support System. 2) Expert Systems.
4. What are the various features of DSS?
5. What are the various features of Expert Systems?
6. Discuss the Computer based Information Systems.
7. Explain the Transaction Processing System (TPS) in detail.
8. Explain the various operating systems in detail.
9. Explain: a) UNIX b) WINDIWS 98 c) DOS
10. Explain the terms; a) Intranet b) TELNET
11. Explain WWW in detail.
12. Explain UNIX OS in detail.
13. Explain Mobile Computers in detail.