Computer Studies for B.B.A

INTRODUCTION TO COMPUTER

INTRODUCTION

Computer:
The word computer comes from the Latin word “compute” that means something calculate. At first
computer is used as a calculating device but the use and expansion of computer is increasing day by
day.


Q. What is software? Describe the classification of software.
Software:
Software is the set of computer programs, procedures and associated documents. The main word of
software is to enhance the capabilities of the computer.

Classification of software:
Software1.System software
a.System Support
b.System Development
c.Operating Sysytem

• Text Based 
• GUI Based

2.Application software
a.Special Purpose Application Software
b.General Purpose Application Software


Q.What is computer system? Describe the elements of computer system.

Computer system:
A system is composed of a set of interacting parts which operates together to achieve some objective.
Since a computer is composed of a set of parts like central processing unit, input or output devices,
storage devices integrated together to process the data under program control. The term computer
system rather than the term computer is used.

Different elements of computer system:
computer is consists of given elements
a)Hardware
b) software
c) Input/ Data
d) People
e) Procedure
f) Communication

Hardware:

Hardware is the physical part of the computer. A computer hardware is consists of interconnected
electronic devices that can use to control the computers input and output.

Software :
Software is the set of instruction or programs that makes the computer perform tasks. In other words,
software tells the computer what to do, how to do.

Input/ Data:
Input is one of the main element of a computer system, because when we want to do any kinds of work
on the computer we have to give some input or data.

Procedure:
Procedure are descriptions of how things are done or steps for accomplish a result.

People:
People are the most important component of the computer system. People operate the computer
hardware and they create the computer software or programs. Also computer is used by the people for
different purpose.

Communication:
when a computer system is set up to share data or information electrically with other computer
system,It creates communication. For example: phone liner, microwave, transmission or satellite.

Q. What are the differences of data and information.

Data Information
1) Data is a raw material on which a computer
operates
1) When some appropriate structure is applied on
data we can get information.
2) Data is used as input 2) Information is used as output
3) Data is not organized 3) Information is organized
4)Data has no accurate meaning 4) Information is meaningful
5) We can collect data from any source 5) We find information from the raw material


Q.What is BIOS? What are the functions of BIOS?

BIOS:

BIOS means Basic Input Output System. It is a set of instruction permanently encoded on a computer
chip. The BIOS instruction are burned or permanently encoded onto ROM chip. Some times the BIOS
is referred to as the ROM BIOS.

Functions of BIOS:

The first function of BIOS is to run the power on self test.
It runs diagnostic texts on the CPU on various times and controllers.
IOS offers important services to DOS and other software programs.
The BIOS allows software tho communicate with input and output devices such as the floppy
diskette drive, hard disk, printer, scanner and keyboard.
Finally BIOS starts the computer's operating system.
BIOS hands over control of the machine to the operating system.


Q. What is operating system? Write down the functions of operating system.

Operating system:
An operating system is a program that act as an intermediary between a user and the computer
hardware. The purpose of an operating system is to provide an environment in which a user can execute
a program.

According to American National Standards Institute(ANSI):
software which controls the execution of computer programs and which may provide scheduling,
debugging, input/ output, controlling, completion, storage assignment, data management and related
services.

Functions of operating system:
The main functions performed by most operating system of today are as follows--
User interface:
user interface operating system is a system which make connection, combination and helps to receive
direction between user and software. This system must be able to load a program and to run that
program.

Process management:
the process management operating system takes care of the creation and deletion of processes,
scheduling of various system resources and providing mechanisms for synchronization and
communication.

Memory Management:
This system take care of the allocation and deallocation of memory space to the various programs in
need of this resources.

File Management:
This system take care of file related activities such as organization, storing, retrieval, naming, sharing
and protecting of files.

Security:
The security module of (operating system)OS protects the resources and information of a computer
system against destruction and unauthorized access.

Command Interpretation:

This system take of interpreting user commands and directing the system resources to handle the
request.

• User Interface

• Process management

•  Memory Management

• File Management

• Security Management

• Command Interpretation

In addition to the above listed major functions on OS also performs few other functions like keeping an
account of which users use how much and what kinds of computer resources. Maintenance of log of
system usage by all users and maintenance of inter time click.



Q. “Computer is a multipurpose device” explain why?

Computer:
Computer is an automatic machine made up of electronic and electro mechanical devices that process
data under program control to generate meaningful information with speed and accuracy. Besides
computer has diligence, versatility, storage, automatic operation, no intelligence, no feelings. And
because of these characteristics we can use computer in many types of fields in different kinds of
objects-

Computer are so fundamental to modern society. Most people in business community use it
everyday. Office workers use it to write letters, keep and find information, create budget and so
on.

The use of computer in industry is very essential. that's why the use of computer in increasing
in this sector. Quality of goods, size, packing etc are done by computer.

Computer is used in scientific purpose. Scientists use computer to develop hypotheses, collect
and test data and exchange data with colleagues around the world. Computer is also used to
keep scientific calculation data in storage devices.

In the medical science, computer is used for everything from diagnosing illness and monitoring
patients to control the movement. Many major operation, treatment of serious diseases all are
done with the help of computer.

Computer has created a new dimension in engineering sector. An engineer can design a project
or product with a computer.

Computer has sparked a revolution in education. Now a days we can't think about a complete
education without computer. Reading, writing, presentation, making document all are done
with the help of computer.

The use of computer in Banking and insurance sector is most essential, because it helps to
complete work very quickly, keeping the accounts and information, money transfer, on line
banking all are done by the computer.

Computer has become a creative tool in music, theater, film and television. On these sector all
kinds of activities are related to computer.


Q. Describe the application of computer in business.

Computer:
computer is device or machine or system which take input and process it and give a output. At first it is
used as calculating device but now it is used in all part of our life .

Computer in business:
Computers are so fundamental to modern society. Without this we can't think our modern business.
Seeing the advantages of computer most people in business community use computer in different
purpose-

Office workers use computer to write letters, keep employee records, create budgets,
communicate with workers, find information,manage projects and so on.

Sales representative use computer to manage accounts and make presentations.
With a laptop a sales person can write letters, track travel expenses, update customer files and
create multimedia presentation to help sell a product.

Computer are also vital in accounting department of business to keep accounting related
information.

Accountants use computer to judge budget, create purchase order, track expense and incomes
and pay taxes.


Q. What do you understand by coo processor?

Coo processor:
coo processor is a helping processor. When an extra processor is works as a supporting or helping
processor are called coo processor.


Q. Describe the classification of computer( according to space, size, and value/ according to
purpose/ according to organization)

Classification of computer:
Computer

According to purpose

• General Purpose 

• Special Purpose

According to size, space &Value

• Supper

• Mainfram 

• Mini 

• Micro

According to organization

• Analogue 

• Digital

Q. What are the differences between system software and application software?

Application software & System software

1) Application software is designed to solve the
users problem.
1)System software is designed to control the
computer operations
2)Application software is software that can
perform task.
2)System software Is software that can run basic
operation
3)It solves the specific problems 3)It doesn't solve specific programs
4) Application software is usually custom written
for the system.
4)The system software tends to be made by
computer specialist
5)The application software layer as what the
computer is doing
5)The system software layer as how computer
does
6)The programs included in a application software
package are called application programs
6)The programs included in system software
package are called system programs
7)Special purpose and general purpose application
program are application software.
7)System support, system management, system
development program are system software.


Q. What are the differences between analog computer and digital computer?

Analog computer and  Digital Computer

1)The analog computer is fundamentally a
measuring device
1)The digital computer is basically a counting
device
2)Analog computer works by the method of
measurement
2)Digital computer works by the presence and
absence flow of electricity
3)Analog computer can understand only
changeable condition of electric frequency
3)Digital computer can understand binary code 0
and 1
4)Output is shown by meter or written graph 4)Digital computer shows output by monitor or
other output devices
5)At a time we can solve one problem though this
computer
5)We can solve many problem at a time
6)Analog computer works very slowly 6)Digital computer works faster
7) Only one user can work at a time 7)Many users can work with this computer at a
time


Q. What are the differences between text based and graphical user interface operating system?

Text based operating system and Graphical user interface operating system
1)If operating system is run by text or command
then the system is called text based operating
system
1)If any operating system works by various kinds
of pull down menu and icon then it is called
graphical user interface operating system
2)Users need to memorize many command to run
this operating system
2)User not need to memorize any command to tun
this operating system
3)This operating system takes less memory when
it is run
3)It takes more memory than text based operating
system
4)Basically keyboard is used to give input int the
computer
4)Users need to use various pull down menu and
icon for giving command
5)This operating system is not much popular 5)This operating system is more popular than text
based operating system


Q. What is computer generation? Write the characteristics of computer generation.

Computer Generation:
The computer has come on this present position bu passing different steps , each one step
of variation or evaluation is called the computer generation.

There are five generation of computer. They are-

First generation
Second generation
Third generation
Forth generation
Fifth generation

First generation(1942-1955)
characteristics:
i. Thousands of vacuum tubes were used to make one computer.
ii. They were the fastest calculating devices of their time.
iii. Using magnetic drum as a memory
iv. Because of using vacuum tubes the power consumption of these computers was very high.
v. At a time only one user could use a computer.
vi. Use punched cards for giving input.

Second generation:(1955-1964)
Characteristics:
i. Use of semi conductor device or transistor
ii. Use of magnetic core memory for storing data
iii. High level programming language like FORTRAN, COBAL were developed in this time.
iv. Telephone lines were used to transfer data from one place to another

Third generation(1964-1975)
Characteristics:
i. Comprehensive usage of Integrated Circuit(IC)
ii. Origin and the evaluation o semi conductor memory
iii. Usage of mini computers made computer affordable
iv. Computer was used by multi-users
v. Use of satellite

Forth generation(1975-1989)
Characteristics:
i. Use of Very Large Scale Integration(VLSI)
ii. Expansion of using micro processors or micro computers
iii. Spread of high speed computer networking system like LAN and WAN
iv. Several new operating system were developed like MS Dos, Windows etc
v. Graphical User Interface (GUI) enabled how users to quickly learn how to use computer

Fifth generation(1989-Present)
Characteristics:
i. Use of Ultra Large Scale Scale Integration(ULSI)
ii. Use of Artificial Intelligence(AI)
iii. Usage and expansion of supper computer
iv. Use of multi processors
v. Use of optical fiber in computer circuit
vi. Newer and more powerful application including multimedia application make the system more
useful.


Q. Difference between Compiler and interpreter

Compiler and Interpreter

1) Translates the full program at a time 1)Translates the program line by line
2)Requires more memory to translates data 2)Requires less memory to translates data
3)Neither source nor the compiler are required for
execution
3)Source program and the interpreter are required
for execution
4)Slow for debugging and testing 4)Good for fast debugging and at testing stage
5)Execution time is less 5)Execution time is more
6)All problems are shown at a time 6)Shows the problem only for the working part


Q. Difference between Batch processing and multi-programming

Batch processing and Multiprogramming

1)This system would process the program one
after another
1)This processing system would run program or
process data at a time
2)It is a serial process 2)It is a parallel process
3)It works slowly 3)It works quickly
4)In this system CPU has to remain idle many
time
4)In this system CPU don't have to remain idle


Q. Difference between time sharing and real time operating system

Time sharing operating system and Real time operating system

1)In this sharing operating system it has time slice
to process any program
1)It is a system which supports a real time
application
2)It acts on first come first serve basis 2)It acts on priority basis
3)In time sharing operating system users can share
the resource
3)In real time operating system resources are
estimated for a fixed time for any user


Q. Difference between Multiprocessing and Multiprogramming

Multiprocessing and Multiprogramming

1)A computer that contains two or more CPU or
processor is called multiprocessor
1)A computer system that has capability to run
more than one program is called
multiprogramming
2)It depends on processor 2)It depends of device
3)It has more speed than multiprogramming 3)It has less speed than multiprocessing


Q. Difference between Multiprogramming and Time Sharing operating system

Multiprogramming Operating System and Time Sharing Operating System

1)It allows many programs to run at a time but
sequentially
1)It allows many users to share the computer
simultaneously
2)It depends on device 2)It depends on time
3)Easier than time shared operating system 3)Complex than multiprogramming OS
4)It increases CPU utilization 4)It executes multiple


Q. Difference between OMR and OCR

OMR and OCR
1)The full meaning of OMR is Optical Mark
Reader
1)The full meaning of OCR is Optical Character
Reader
2)OMR is a kind of machine which can
understand the mark of pencil or ink
2)OCR is a kind of machine which can not only
understand the mark but also identify the letter,
symbol and number
3)The mode of operation of OMR is
comparatively easy
3) The mode of operation of OCR is very complex
4)OMR is used for examining the answer sheet of
objective question,counting population and other
activities
4)OCR is used for making electric bill, insurance
premium notice and other activities


Q. Difference between BCD and Binary

BCD and Binary

1) BCD is not a number system 1)Binary is a number system
2)IT is easy to express decimal number into BCD
code
2)It is not easy to express decimal number into
Binary number
3)The base of BCD is 4 bit 3)The base of Binary is 2 bit
4)IT needs more bit to express any number into
BCD code
4)It needs less bit to express any number into
Binary


Q. Difference between Primary and Secondary memory

Primary memory and Secondary memory

1)CPU has direct access with primary memory 1)CPU has not direct access with secondary
memory
2)Storage capacity is less than secondary memory 2)Storage capacity is more than primary memory
3)It is more expensive than secondary memory 3)It is less expensive than primary memory
4)The access time of CPU with primary memory
is less than secondary memory
4)The access time of CPU with secondary
memory is more than primary memory
5)The price of primary memory is high 5)The price of secondary memory is less than
primary memory


Q. Difference between RAM and ROM

RAM and ROM

1)The abbreviation of RAM is Random Access
Memory
1)The abbreviation of ROM is Read Only
Memory
2)It is volatile memory 2)It is non volatile memory
3)Active or changeable data is stored in this
memory
3)Basically those data need not to change
regularly are stored in ROM
4)We can read and write data from RAM 4)We can only read data from ROM


Q. Difference between Static Ram and Dynamic Ram

Static RAM and Dynamic RAM

1)Static RAM is consists of Flipflop 1)Dynamic RAM is consists of capacitor
2) Static RAM is very expensive 2)It's cost is less expensive than Static RAM
3)Speed is less than dynamic RAM 3)Speed is more than Static RAM
4) Power is not waste 4)Automatically the charge of the
5)Not need to refresh 5)Need to refresh time to time



Q. Difference between EPROM and EEPROM

EPROM and EEPROM

1)The full meaning of EPROM is Erasable
Programmable Read Only Memory
1)The full meaning of EEPROM is Electrically
Erasable Programmable Read Only Memory
2)Ultra violate ray is used to erase data from
EPROM
2)Electrical system is used to erase data from
EEPROM
3)If we want to erase data from EPROM the
whole data will be erased
3)We can erase data only we want to erase from
EEPROM


Q. Difference between Impact printer and non impact printer

Impact Printer and Non impact Printer
1) 1)
2)The printing speed is less than the non impact
printer
2)Printing speed is very fast
3)Printing quality is so good 3)Printing quality is standard
4)It makes sound when printing is running 4)It does not make any sound
5)It is less expensive than non impact printer 5)It is very expensive


Q. What is CPU? Describe the functions of CPU.

CPU:
The full meaning of CPU is Central Processing Unit. It follows the instructions of the software to
manipulate data into information. It is considered as brain,accuracy and capacity of computer depend
on CPU.
The CPU consists of three parts-

Control Unit
Register set
Arithmetic and logic unit

Functions of CPU:
The part of a computer which does the job of processing data is called the central processing unit. The
job are given below-

Timing and control signal:
The CPU controls all the part of a computer and it provides timing signal also

Transferring data:
The CPU transfers instruction or data through memory and input/ output device

Execute program from memory:
The CPU executes the instruction or data in their stored sequence to run any program successfully.
Programs are execute from memory

Fetching instructions and data:
The CPU helps to recover the data and instruction as if the man who is in terminal can fetch the data
easily.

Decode:
The CPU decodes the instruction, that means it translates a letter or symbol or sign etc. from code to
ordinary language

Arithmetic and logic operation:
The CPU does different arithmetic function like adding, subtracting, multiplying, dividing and also
computes some logical operations.

Input and output interfacing:
The CPU helps to make a combination with input devices that means it interfaces the input and output
devices.


Q. What is memory? Explain the necessity of memory.

Memory:
Memory is a device which can store data. Evey computer system consists of a variate of devices to
store the instruction and data, required for its operation. The instruction and data are stored in the
memory unit of the computer.
The memory components of a computer system can be divided into following main groups-
Main memory
Secondary memory
Internal processor memory

Necessity of memory:
The computer executes the instruction one after another. Thus it is necessary to have a memory in
which all the instructions and data can be stored first and can be taken one after other later for
execution.

The memory is needed for following purpose:

To store the program during execution
To store the program for repetitive use
To store the data for future/ periodical use
To store the results of execution.


Q. What is memory cell?

Memory Cell:
A memory cell may be defined as a device which can store a symbol selected from a set of symbols and
may be characterized by the following propertied:-

The number of stable status in which it can be placed.
Whether a cell can store a symbol indefinitely even when power is turned off.
Whether a symbol, once written can only be read and not changed.
If in a memory cell information is permanently written and can only be read then it is known as a read
only cell.


Q. What is main memory? Write down its features.

Main memory:
This kind of memory has a direct access with CPU(Central Processing Unit) because of being direct
access with ALU(Arithmetic Logic Unit) main memory has to be speedy. Those kinds if data
information are essential they kept in main memory. Besides when ALU counts for that reason essential
data,information or direction are kept in main memory temporarily collecting then for secondary
memory. After completing count, again they are transferred to secondary memory.

Features:
Main memory preserve the continuous/active program, data accounting results etc.
Main memory (RAM) is volatile
It's access time is 4-100 nanosecond


Q. Write the features of RAM?

RAM:
The abbreviation of RAM is Random Access Memory. Ram is a primary storage device, where both
data and instructions are temporarily stored for immediate access and used by the computer's
microprocessor. It is a volatile memory, because data and instructions are lost when the computer is
turned off.

Features:

It can access directly with CPU
It is possible to read data from Ram
RAM is a volatile Memory
Active and repeatedly changeable data are preserved in RAM.


Q. Write the features of ROM?

ROM:
ROM(Read Only Memory) is a non volatile memory that means if the electricity is stopped, the stored
data will not be removed. We can only read data from ROM.. Data are stored here permanently, so it
can't be changed.

Features:
Generally new data are not written in ROM but when it is necessary data can be read from

ROM
Rom is not volatile
Basically data are stored permanently in ROM.

MOS:
MOS for Metal Oxide Semi conductor technology is used to make a computer's main memory chip.
MOS memory can be produced mechanically. It is cheaper than core memory. MOS memory is
available on a miniaturized chip and is therefor much smaller in size than core memory. It is volatile
memory. It has non destructive read operation.

MROM:
Mask Read Only Memory. It's features are given below-
Data is stored by using photographic mask
MROM is expensive
It is not possible to reprogram it.

PROM:
The abbreviation of PROM is Programmable Read Only Memory.
Features:
User can store data in PROM by him self through programmable
The user can write his information in a PROM only once and it can't be altered.

EPROM:
Erasable Programmable Read Only Memory.
Features:
EPROM is not volatile
User can store data bu himself through program in EPROM
FET- Field Effect Transistor is used to make EPROM
Storing data of EPROM can be removed by using ultra violate ray

EEPROM:
Electrically Erasable Programmable Read Only Memory.
Features:
user can store data through program in EEPROM
Storing data of EEPROM can be removed by using electrical process
To store data or removed data, EEPROM takes less time than EPROM

Semiconductor memory:
This kind of memory consists of semiconductor things. Semi conductor memory is much smaller and
cheaper compared to magnetic core memory. It is also called straight access memory. The base of this
memory is a small logical circuit having two stage known as flipflop.

Static RAM:
Static RAM consists of flip-flop which contains binary bit 0 and 1. the ability of a memory cell to store
data, as long as power supply continuous. If power supply keep stop, the stored data will be removed.

Dynamic RAM:
In dynamic RAM, binary bit(0 and 1) remain store in capacitor as electric charge. Here the power
wastage is less.
Dynamic RAM is classified in two types. They are
1. Synchronous Dynamic RAM
2. Asynchronous Dynamic RAM

Bipolar:
Bipolar is used to provide high speed buffer storage sections in central processing unit. Bipolar
memories have two dual emitter bipolar transistor coupled to from a distable circuit or flip-flop. There
chips are faster than even Mos chips but more expensive. These are used as cache memory.

Secondary Memory:
This kind of memory has no direct access with central processing unit. Mainly secondary memory is
used to store the permanent file. Generally the storing capability of secondary memory is more than the
primary memory, but its speed is less than the primary memory. Its access time is a few milliseconds
upon microseconds.

Some secondary memory-
Hard disk
Floppy disk
Magnetic tape
Magnetic drum. Etc

Optical disk:
A storage media consists of a rotating disk, which is coated with a thin metal or some other material tat
is highly reflective. Laser beam technology is used as laser disks.

Memory cell:
The smallest unit of the memory where one bit data like binary (0 or1) can be stored is called memory
cell. Computer memory consists of millions of memory cells.

Memory address:
Every memory cell has a fixed address by which that memory cell can be found out. Similarly every
register has special number by which the location of that register can be recognized and that is called
memory address.

Memory word:
Memory word consists of a number of memory cell.


Q. What is plotter? Describe different types of plotter.

Plotter:
A plotter is a specialized output device to produce high quality graphics in a variety of colours. Plotters
are especially for creating maps and architecture drawings, although they may also produce less
complicated charts and graphs.

Different kinds of plotter:
There are three kinds of plotter. Such as

Pen plotter
Electrostatic plotter
Thermal plotter

Pen plotter:
A pen plotter is designed so that paper lies flat on a table like surface(flatbed plotter) or is mounted on a
drum(drum plotter) between one and four pens move across the paper or the paper moves beneath the
pens. This is most popular type of plotter can produce up to four color.

Electrostatic:
Instead of using pens, an electrostatic plotter uses electrostatic charges to create tiny dots on specially
treated paper. The paper is then run through a developer to produce the image which may be four color.

Thermal:
A thermal plotter uses electrically heated pins and heat sensitive paper to create images. Thermal
printers are capable to producing only two colors rather than four.

Intranet and Extra net:
Intranet is mainly an another version of Internet. Intranet is network within an organization and extra
net is also a network within more organization.

Internet:
Internet consists hundreds of thousands of network. It is a giant network of computer network. In the
era or modern information technologies, Internet is a real appearance of information super highway.
Internet is an inter connection of different networks in different computers.

IP Address:
Every computer has an address which are connected with IP network as well as Internet. That addresses
are called IP address. For example it can be like address 120,256,175,56. It requires 8 bit for every
number and 32 bit for full addresses of IP address.

Domain:
Internet is divided into different hundreds of area, these are called domain. Each of domain have many
host or computer. For example- com, net, edu,gov, org etc

HTML:
HTML means Hyper Text Markup Language. HTML is used for creating web page. It is one kind of
language which is used WW W's file as well as web page making. Typically HTML is platform
dependent with the combination of platform dependent, different types of elements of WW'S document
can be prepared. It is a versatile language. It is the advanced edition of SGML- Standard Generalized
Markup Language. In 1990 Tim Bernus Lee invented it at cerm in Geneva while he was testing about
it.

Use of Internet:

On line communication
Software sharing
Exchange of views on topics of common interest
Posting of information of general interest
Product promotion
Feed back about products
Computer support service
On line journal and magazine
On line shopping
Word wide video conferencing
On line chatting
Voice chatting
Downloading of information


Q. Describe different types of transmission?
There are three ways or modes of transmission of data from one point o another. They are given below-

Simplex
Half duplex
Full duplex

Simplex:
If transmission is one way then it will be called simplex transmission. In this process sender/
transmission media send information and receiver can receive. But the receiver can't send data or
information. . Devices connected to such a circuit are either a send only or receive. Example- Radio
Station.
Medium
Fig: Simplex

Half duplex:
A half duplex system can transmit data in both devices, but only in one direction of a time. That means
a half duplex line can alternately send or receive data. It requires two devices. For example wireless or
walkie talkie.

Full duplex:
A full duplex system can transmit data in both devices at a time. By this process both sender and
receiver can send or receive data. For example Telephone, mobile etc
Sender Receiver
Sender Receiver
Sender/ Receiver Sender/ Receiver


Q. What is data communication? What are the elements of data communication?

Data communication:
communication is the process of transferring message or data from one point to another. Hence the
electronic systems which transfer data from one point to another are called data communication system.

Elements of data communication:

Source
Transmitter
Medium
Receiver
Destination


Q. What is computer network? Describe different types of network.

Computer network:
When different computers are connected with a communication system then it is called computer
network.

Types of network:

Local Area Network
Metropolitan Area Network
Wide Area Network

Local Area Network(LAN):
A LAN is restricted to a limited geographic coverage of a few kilometers. LAN typically provide
communication facilities within a building or a campus.
Features:
LA N's have own CPU for every computer.
LAN's are used for data processing, data entry and transferring email.
Network topologies used in LAN are star, ring or broad cast channel method.
The most common communication links used in LAN are twisted pair, coaxial and fiber optics
cable etc.
Data transmission rated are high in LAN(10 mbps to 1 gbps)

Metropolitan Area Network(MAN):
The MAN usually cover a wide geographic area( up to about 50 km) than LAN. The main objective of
MAN is to interconnect LAN located in entire city or metropolitan area. Example: Cable TV network.
Features:
Telephone line, modem or sometimes microwave is used as a transmission media
Co axial cables are also used
Ti covers a wide geographic area
It is mainly of metropolitan basis

Wide Area Network(WAN):
A WAN may extend over several thousand kilometers. Typically WAN may operate nation wide or
even world wide. WAN consists of the connection of LAN/MAN located I different cities or personal
computer. Example: Internet
Features:
Telephone lines, microwave links and satellite channels are used as transmission media
Data transmission rates in WAN is 1200 bps to 2 mbps.
The cost may be very high.


Q. Describe inter networking?

Inter networking:
Inter networking is the method of connection different network. Through tele-communication or packet
switched network, LAN to LAN, LAN to WAN, LAN to WAN to LAN etc. creating such types of
connection it is possible to communicate from one computer to another. That's why it is called Inter
networking.
As it is combination of hardware and software there are some media to crate the acceptability on
transferring data. They are-

Repeater:
Repeater is used to send a data in different addresses.

Bridge:
It is known as data link relays. It connects segments of local area network (LAN). It is used in same
types of network connection. For example LAN to LAN connection.

HUB:
It is one kind of switching processor. It is in small size. It is used in similar types of network.

Gateway:
It is used to connect different types of network such LAN to WAN or WAN too WAN network. Mainly
it has own security system. It is most expensive and complex.

Router:
Router are used in different types of network. Basically mobile company use it to generate call. It
controls different messages through network.


Q. What is on line and off line Internet?

On line Internet:
on line Internet is a system where Internet connection remain all times in a computer that's why that
computer requires a fixed IP address. Generally large companies and Internet Service Provider(ISP)
create connection in on line Internet. It is a expensive process.

Off line Internet:
It is a process of establishing a Internet connection through any near ISP (Internet Service Provider)
service. General user use Internet by connection off line Internet. In the circumstance users are
connected within ISP server and take the benefit of Internet.


Q. What are the roles of communication protocol? Describe the protocol.

In any computer network a communication protocol normally performs the following function for the
efficient and error free transmission of data.

Data sequencing:
It refers to breaking a long message into smaller packets of fixed size. Data sequencing rules define the
method of numbering or sequencing packets to detect loss or duplication of packets.

Data routing:
Touting algorithms are designed to find the most efficient paths between the source and destination
nodes of message. They can handle varying degree of traffic on the present network configuration with
optional time utilization.

Data formating:
Data formating rules define which group of bits or characters within a packet constitutes data, control,
addressing or other information.

Flow control:
It ensures resource sharing and protection against traffic congestion by regulating the flow of data on
the communication lines.

Error control:
These rules are designed to detect errors in messages and to ensure transmission of correct messages.

Precedence or order of transmission:
These rules ensure that all nodes get a chance to use the communication lines and other resources of the
network base on the priorities assigned to them.

Connection establishment and termination:
These rules define how connections are established maintained and terminated when two nodes of a
network want to communicate with each other.

Data security:
Providing data security and privacy is also built into most communication software packages. It
prevents access of data by unauthorized users.

Log information:
Several communication software are designed to develop log information which consists of all jobs and
data communication tasks that have taken place. Such information may be used for charging the users
of the network based on their usage of the network resources.


Q. What is communication software?

Communication software:
Communication software massages the transmission of data between computers and terminates.
Popular micro computer commmunicatio9n s software packages include Smartcom, Crosstalk,
ProComm, Pc -dial, Blast and PC talk. For example- opera, Internet explorer communication software
may perform following operation:

Error correction
Data compression
Remote control
Terminal emulation


Q. What is firewall?

Firewall:
The metal between an automobile's passenger area and engine compartment is called a firewall because
it is designed to prevent an engine fire from spreading into the passenger compartment. A firewall is to
prevent unauthorized users, data, mail etc. Firewalls are necessary is to prevent attacks that can be
launched against a network connected to the Internet.

SHORT NOTES

Access time:

The tine interval between the instant at which data is called for from a storage device and the instant
delivery begins.

Address:

An identification represented in the form of a name, level, or number for designation a particular
location in storage area.

ANSI: 

ANSI means American National Standards Institute. AUS based national organization which
establishes uniform standards in several fields.

ASCII:

American Standard Code for Information Interchange(ASCII)

Analog computer:

A computer which operates on data which is in the form of continuously variable physical quantities
such as electrical current.

Application software:
A set of one or more programs designed to solve a specific problem or do a specific task. Such as
calculating, processing of examination results, stores accounting and inventory control etc.

ALU:

ALU means Arithmetic and Logic Unit. The unit of a computer system which performs all
mathematical and logical operations. It is one of the components of the central processing unit (CPU)
of the computer.

Assembler:

A computer program which translates an assembler language program to its machine language
equivalent.

Assembly language:

A programming language which allows instructions and storage location to be represented by letters
and symbols instead of numbers. It is also known as assembly language.

Asynchronous communication:

Data transmission mode in which the sender can send data at any convenient time and the receiver will
accept or receive it.

ATM:

ATM means Automated Teller Machine. An unattended machine used in banks which allows a
customer to deposit or withdraw cash by the use of an electronic card without the need to interact with
a bank employee.

Auxiliary memory or secondary memory:

A storage device which supports the main memory of a computer. This memory has no direct access
with the computer CPU. The memory capacity of this memory is more than the primary memory. It
works much slower than the primary memory. It is also known non-volatile memory.

Backup file:

A copy of a file created as a safety precaution against loss of data caused due to corruption or
inadvertent deletion of the original file.

Bandwidth:

The range of frequencies available for data transmission. The wider the bandwidth of a
communications system, the more data it can transmit in a given period of time.

Bar codes:

Representation of alphanumeric data by a combination of adjacent vertical lines (called bars) by
varying their width and the spacing between them. A bar code reader is a scanner which I s use for
reading bar coded data.

Batch processing:

The running of several computer programs one after another without the need of a human operator to
run each program individually.

Binary:

A number system with a base of two. It consists of two digits 0 and 1. computer works with this
codding system.

BCD:

BCD means Binary Coded Decimal. One of the early coding systems which is based on the idea of
converting each digit of a decimal number into its binary equi9valent rather than converting the entire
decimal value into a pure binary form. For example the decimal number 10 is represented by 1010 in
8-4-2-1 BCD notation.

Booting:

The process of automatic loading of the operating system to primary storage and readying a computer
system for use.

Browser:

A software tool which provides several navigation facilities to help users do internet surfing easily and
effectively.

Buffer:

A small storage area used to store information on a temporary basis for compensating the difference in
rates of flow of data between various computer devices. For example when data flows from an input
output device to the CPU is passes through a buffer.

Cache memory:

A small high speed memory which is used to increase the speed of processing by making current
programs and data available to the CPY at a rapid rate.

CPU:

CPU means Central Processing Unit. The control unit and the arithmetic logic unit of a computer
system are jointly known as the CPU. It is the brain of any computer system in which all calculations
and comparisons performed by a computer are carried out. The CPU is also responsible for activating
and controlling operations of other units of a computer system.

Chip:

A thin wafer of silicon on which integrated electronic components are deposited.

Clip art library:

A collection of graphic images stored on disk which can be readily used in work processing or desktop
publishing documents or in presentation graphics or for other purposes.

Coaxial cable:

A cable made up of a single wire in the center of and insulator wrapped in mesh. It is often used as a
medium to transmit data between computers and between computers and peripheral devices.

Code:

A set of rules outlining the way in which data may be represented like- BCD, EBCDIC, ASCII etc.

Code generator:

A very high level programming language in which programmers specify through and interactive dialog
with the system the design specifications of a system (which tasks are to be performed) and
automatically generates the program source code for the system.

Coding:

The process of writing computer instructions in programming language is called codding.

Communication protocol:

A set of rules and procedures established to interconnect and communicate between computers. It
provides a method for orderly and efficient exchange of data by establishing rules for the proper
interpretation of controls and data transmitted as raw bits and bytes.

Communications processor:

A processing unit which coordinates networks and data communications. Within a computer network it
ensures that data flows to and from different compute systems correctly and efficiently.

Communication software:

Software that enables transfer of data and programs from one computer system to another in a network
of computers.

Communication satellite:

A microwave relay station precisely positioned 36000 kras above the equator with an orbit speed that
exactly matches the earth's rotation speed. It is sued for data transmission between any two randomly
chosen points in a very-very large area.

CD-ROM:

A shiny silver color metal disk having a storage capacity about 650 Megabytes. It is so called, because
of its enormous storage capacity on a compact size disk and because it is a read only storage medium

Compiler:

A translator program (software package) which translates a high level language program into its
equivalent machine language program.

Completely connected network:

A network in which there is a separate physical link for connecting each node to any other node in the
network.

Computer:

An electronic device which can automatically accept and store input data process them and produce
output results by interpreting and execution program instructions.

CAD:

CAD means Computer Aided Design. CAD is used to automate design and drafting operations of
computer.

Computer audio:

The area of computer science which deals with synthesizing , recording and playback of audio or sound
with the aid of a computer.

Computer graphics:

The area of computer science which deals with the generation, representation, manipulation and
display of pictures (line drawings and images) with the aid of a computer.

Computer network:

A distributed data processing system in which multiple computers are linked together for the purpose of
data communication and resource sharing.

Computer system:

The various components (input and output devices, storage, CPU) of a computer integrated together to
perform the steps called for in the program being executed.

Computer video:

The area of computer science which deals with the recording and display of a sequence of images at a
reasonable speed to create an impression of movement.

Control program:

An operating system program which controls the operations and management of resources of a
computer system. The control program's major functions are job scheduling, input/output scheduling
and program monitoring.

Control unit:

The unit of a computer system with manages and coordinated the operations of all the other
components of the computer system. It is one of the components of the central processing unit (CPU)
of the computer.

Counter:

A device register or a storage location for storing integers which suitably incremented or decremented
to represent the number of occurrence of a an event.

Crash:

A hardware of software failure that causes a computer system to stop functioning.

Data:

A collection of facts in raw form which become information after proper organization or processing.

Data element:

A meaningful collection of related characters. It is also called a field or data item.

Data entry:

The conversion of human readable data into a corm which a computer system ca interpret. This is also
called data preparation.

Data processing system:

A system that accomplishes data processing. It includes the necessary resource which are people,
procedures and devices need to process the data.

Data storage hierarchy:

In data processing organization of data into growing hierarchy for easy manageability. A typical data
storage hierarchy consists of bits, characters, fields, records, files and database.

Data transfer rate:

The speed at which data is transferred from main memory to another medium on which data are
recorded.

Database:

A collection of data files integrated and organized into a single comprehensive file system which is
arranged to minimized duplication of data and to provide convenient access to information within that
system to satisfy a wide variety of user needs.

Database model:

The manner in which the various files of a database are linked together. The four commonly used
database models are hierarchical, network, relational and object oriented.

Database software:

A set of programs which enables users to create a database maintain it (add, delete and update its
records) organized its data in desired fashion and to selectively retrieve useful information from it.

Debugging:

The process of funding and correcting program errors is called debugging.

Decoder:

The part of central processing unit which has the necessary circuit to decode and interpret the meaning

of every instruction supported by the CPU.

Desktop publishing:

An application software package which allows a user to perform design, typesetting and paste up
functions and to produce high quality camera ready printed pages of the documents so prepared on a
high quality printer.

Digital computer:

A computer system which works with discrete quantities. It uses numbers to simulate real time
processes.

Directory:

A mapping table which is used by operation systems to map file names to their corresponding file
attributes and file data and also to provide greater flexibility to users in file naming.

Diskette:

A low cost this flexible magnetic disk storage device used on small computer systems. It is also called a
floppy disk

Distributed computing system:

A computer system consisting of interconnected multiple computers.

Documentation:

Documentation of a software system involves collecting,organizing, storing and maintaining a
complete historical record of programs and other documents used or prepared during the different
phases of the system.

Dot matrix printer:
Character printers which form characters and all kinds of images as a pattern of dots.

Dumb terminal:
A terminal which has no local processing capability.

Dynamic RAM:
A type of RAM which uses an external circuitry to periodically regenerate or refresh the store change
to retain the stored data.

Education software:
Software which allows computer systems to be used as a teaching and learning tool.

EEPROM:
EEPROM means Electrically Erasable Programmable Read Only Memory. An EEPROM chip in which
the stored information tis erased by using high voltage electric pulses. It is also known as flash
memory.

Electric mail:
A service on the Internet which allows an Internet user to send a mail to another Internet user in any
part of the world in a bear real time manner.

Electrostatic printer:
A high speed printer which uses heated elements to create characters as matrices of small dots on heat
sensitive paper.

EPROM:
EPROM means Erasable Programmable Read Only Memory. A memory chip in case of which it is
possible to erase information stored in it and the chip can be reprogrammed to store new information.

Extended Binary Coded Decimal Interchange Code (EBCDIC):
Extended Binary Coded Decimal Interchange Code is an 8 bit coding system developed by IBM which
is used to represent characters in many computers.

Firewall:
A software which usually runs on the proxy server of an organization and controls the flow of incoming
and outgoing messages from within an organization for providing better security to the organization.

Firmware:
A sequence of instruction which is substituted for hardware and stored in read only memory (ROM).

Flip flop:
An electronic circuit which can be placed in one out of two stable states. Each state may be used to
represent a binary digit.

Full duplex:
A data transmission mode in which data signals can be transmitted between a source and a destination
in both directions simultaneously.

GUI:
GUI means Graphical User Interface. AN interface of computer users which provides icons and menus
which users can select with a mouse for telling the computer what they want it to do for them.

Graphics software:
Software which enables users to use a computer system for creation, editing, viewing, storing,
retrieving and printing designs, drawings, pictures, graphs and any thing else which can be drawn in a
traditional manner
.
Half duplex:
A communication system in which data can be transmitted between a source and destination in both
directions but only in one direction at a time.

Hard disk:
A magnetic disk storage device which uses disks made of rigid metal (frequently aluminum). The hard
disk platters come in many sizes ranging from 1 to 14 inch diameter.

Hardware:
Hardware is the physical components of a computer system. Hardware is run with the help of the
software.

Hexadecimal number system:
A number system with a base of 16. Its digits range from 0 to F. It is commonly used as a shortcut
notation for groups of four binary digits.

Hierarchical network:
A communications network in which computers or processors are connected in a tree like structure.

High level language:
A programming language whose structure is application oriented and is independent of the structure of
the computer. Each statement of such a language is translated into many machine language statements.

Hybrid network:
A network which is a combination of two or more different network topologies.

HTML:
HTML means Hyper Text Markup Language. HTML is a powerful language used for creating
hypertext documents.

Hyper Text Transport Protocol:
Hyper Text Transport Protocol is an Internet protocol for interaction between the computers on the
Internet.

Impact printer:
A printer which prints characters by causing hammers to strike against the paper on which information
is to be printed.

Input device:
A device used to enter data and instructions into a computer. Examples are keyboard, mouse, trackball,
joystick, scanner, digitizer, voice recognition system and vision input system.

Integrated circuit:
Circuits consisting of several electronic components like transistors, resistors and capacitors grown on
a single chip o silicon, eliminating wired interconnection between components.

ISP:
ISP means Internet Service Provider. An organization which maintains one or more gateway computers
and provides Internet access facility to other users by allowing them to connect their computers to its
own gateway computer by using a modem.

Inter networking:
Interconnecting of two or more networks to form a single network. The resulting network is called an
internetwork.

Keyboard:
AN input device which enables data entry into a computer by pressing a set of keys (labeled buttons)
which are neatly mounted on a keyboard connected to the computer system.

LAM:
LAM means Local Area Network. A computer network which interconnects computers and other
peripheral devices within a limit geographical area of a few kilometers.

Light pen:
A pen shaped device which is used as ans input device to input data into computers by writing or
sketching on the screen of a cathode ray tube.

Machine language:
A low level language which is directly understandable by the computer system. Each model of a
computer has a unique machine language.

Magnetic storage:
Storage devices such as disks, drums, tapes, cores etc which utilize the magnetic properties of materials
to store data.

MICR:
MICR means Magnetic Ink Character Reader is a technology used by the banking industry for faster
processing of the large volume of cheques. This technology also ensures accuracy of data entry because
most of the information is pre-printed on the cheque and is directly fed to the computer.

Magnetic tape:
A secondary storage device which uses a long plastic strip coated with a magnetic material as a
recording medium.

Modulation:
The technique by which a digital signal is converted to its analog from for transmission over an analog
facility.

Monitor:
A popular output device used for producing soft copy output. It displays the output on a television like
screen.

Motherboard:
The main circuit board of a computer system. It has the CPU chip, RAM chips, ROM chips, I/O
handling chips etc. mounted on it. It is also known as system board.

Mouse:
A small hand held input device which serves as an effective point and draw device in today's
computers.

Multiprocessing:
A term used to describe interconnected computer configurations or computers with two or more
independent CPU which have the ability to simultaneously execute several programs.

Multiprocessor:
A computer system consisting of two or more Central Processing Unit under a common control.

Multiprogramming:
Interleaved execution of two or more different and independent programs by the same computer.

Multitasking:
Concurrent execution of multiple jobs (often referred to as tasks of same user) in a single user system.

Network topology:
The structure of interconnection of nodes of a computer network. On the other words we can say
network topology is the way of connecting computer each other.

Non-impact printer:
A printer which performs some type of operation to the paper instead of physically striking it. To print
characters with non impact printers the paper can be sprayed with ink, magnetized, electrically charged,
heated, placed under pressure or struck by laser beams.

Non volatile storage:
A storage medium which retains its contents when the power is turned off or interrupted. Example:
ROM.

Octal number system:
A number system with a base of 8. the octal digits range from 0 to 7. it is commonly used as a shortcut
notation for groups of three binary digits.

Operating system:
An integrated set of programs which controls the resources of a computer system and provides its users
with an interface or virtual machine which is more convenient to use than the bare machine.

OCR:
OCR means Optical Character Reader. OCR is an input device equipped with a character recognition
software. It is used for inputting text documents and store them in a form suitable for doing word
processing of the documents.

Optical disk:
A storage medium which consists of a rotating disk, which is coated with a thin metal or some other
material that is highly reflective. Laser beam technology is used for recording or reading of data on the
disk. It is also known as laser disks.

Optical fiber:
Hair thin threads of glass or plastic used as a data transmission medium. They use light signals for data
transmission.

OMR:
OMR means Optical Mark Reader. It is an input device which is capable of recognizing a pre-specified
type of mark made by pencil or pen. Any input data which is of a choice or selection nature can be
recorded for OMR input.

OSI protocol:
A communication protocol to interconnect geographically dispersed heterogeneous computers. This
protocol has been standardized by the International Standards Organization (ISO).

Output device:
A device used in a computer system to supply information and results of computation to the outside
world. Examples are monitor, printer, plotter etc.

Page printer:
A high speed printer with a mechanism which appears to print an entire page at one time.

Palmtop computer:
A battery operated computer with personal assistance tools. It is small enough to fit in ones pocket and
operated by keeping it ion ones palm.

Parallel processing:
A technology in which a multi processor system is used to solve complex problems faster by breaking
the problem into sun problems ans allowing different sub problems to be processed simultaneously by
different processors of the multi processor system.

Parity bit:
An extra bit added to a string of bits which enables the computer to detect internal errors in th
transmission of binary data.

Plotter:
Plotter is an ideal output device which is often used by architects, engineers, city planner and other who
need to routinely generate high precision, hard copy, graphic output of widely varying sizes.

Primary storage:
A temporary storage area which is built into the computer hardware and in which instructions and data
of a program reside mainly when the program is being executed by the central processing unit.'

Printer:
Printer is an output device used to produce hard copy output.

Procedure:
A subprogram which performs an action but returns no value.

PROM:
PROM means Programmable Read Only Memory. Similar to read only memory with the exception that
these chips can be reprogrammed by using special external equipment.

RAM:
RAM means Random Access Memory. It is a memory which the time to retrieve stored information is
independent of the address where it is stored.

ROM:
ROM means Read Only Memory. A non volatile memory chip in which data are stored permanently
and can not be altered by the programmer.

Ring network:
A computer network in which there is no host computer for controlling other computers and each
computer in the network has communication subordinates.

Router:
An inter networking tool which is used to interconnect those networks, which use the same high level
protocols above the network layer.

Routing:
The selection of actual path to be used to transmit a message in a wide area network environment.

Scanner:
Scanner is an input device used for direct data entry into the computer system from source documents.

Smart card:
An electronic card having a built in microprocessor chip. Data to be encoded on the card is
permanently stored in the memory of the chip.

Software:
A set of computer programs, procedures and associated documents related to the effective operation of
a computer system.

Star network:
A network in which multiple computers are connected to a central host computer. These computers are
not linked directly to each other and can communicate only via the host computer.

Swapping:
Storing program on disk and then transferring these programs into main storage as and when they are
needed. The technique is used to process large programs or several programs with limited memory.

System software:
A set of one or more programs designed to control the operation and extend the processing capability of
a computer system.

Telecommunication:
Transmission of data between computer system and terminals at different locations through telephone
facilities.

Thermal printer:
A printing device which utilizes paper that is sensitive to heat.

Time slice:
The short period of time during which a user process gets the attention of the Central Processing Unit
in a time sharing system. It is also known as time slot or quantum.

Touch screen:
A simple intuitive and easy to learn input device which enables the users to choose from available
options by simply touching with their finger the desired icon or menu item displayed on the computer's
screen.

ULSI:
ULSI means Ultra Large Scale Integration. It is the integration of about ten million electronic
components on to a single chip.

Value Added Network:
Enhanced data transmission service provided by doing value addition to the standard services of the
common carriers. Added value may include features such as electronic mail, data encryption, access to
commercial databases and code conversion for communication between incompatible computers.

VLSI:
VLSI means Very Lager Scale Integration, is an electronic circuit with about 10000 transistors
fabricated in a single silicon chip.

Video conferencing:
A system in which persons sitting at CRT screen see and talk to each other via a computer
communications network. It saves traveling cost and the valuable time of executives.

Virtual machine:
The concept of adding the operating system layer on top of the bare hardware to manage all parts of the
system and present the users with an interface which is easier to program and use.

Virtual memory:
A memory management scheme which allows the execution of processes, which might not be
completely loaded in the main memory. The three basis concepts used for the realization of virtual
memory are on line secondary storage, swapping and demand paging.

Virus:
A computer virus is a piece of code attached to a legitimate program. When executed infects other
programs in the system by replicating and attaching itself to them.

WAN:
WAN means Wide Area Network. A computer network which interconnects computers spread over a
large geographical area. It may also enable LAN to communicate with each other.

Word processing:
The use of computer to create, view, edit, format, store, retrieve and print text materials.

                                                                                         

                                                                    Prepared and Supported by....

                                                                    NAJMUL [sec.A,Batch-X(24)]

                                                                 SHAIKET [sec.A,Batch-X(57)]

                                                                      Department of B.B.A

                                                                     DHAKA CITY COLLEGE

                                                           THANKS TO ALL