NETWORKING SYSTEM (DATA COMMUNICATION SYSTEM)

 OBJECTIVE

The objective of this topic to understand networks of  Local and wide area communication.This topic will help to understand network connectivity issue of any organization.Various types of data communication and how this will work this is covered in this topic.

DATA COMMUNICATION 

Data may be sent for short distances or for long distances also .In case of short distances digital data can be sent direct over direct wire digital link it may be through simple copper conductors.In case of long distances we used digitally modulated analog carrier signals.

ELECTRONIC MAIL

In such communication we can transfer data in form of text from one place to another .Each user having a mail box in which the message are stored which are sent by sender and from mail box we can access the messages.

An email data communication system consists of 

1.Source computer and destination computer                                                                                               

2.Modems which is data communication devices\

3.Cable which works like a communication channel

4.Data communication Software

DIAL-UP LINES

In this data communication two computer systems use dial up lines connected by modems and using telephone network.It is the simple method .we can connect two remote computer easily.In case of  Dial-up lines the charges or cost depend on distance between two user and time spent or how long connection is made.It is the cheapest transfer medium.

LEASED LINE

It is dedicated data communication where dedicated link established between the source user and destination user.It is high performance data communication because leased line is permanently allocated by telephone network.In leased line cost is fixed i.e same rate is charged whether you used communication facility or not.

INTERNET CONNECTIVITY

The connection can be either wired or wireless.The wired connections use PSTN(Public switched telephone network) /PSDN(Public switched data network.The wireless connection in wide concept using satellite communication.Many internet service provider provides internet servers like GIAS(Gateway Internet Access Service) of TATA Communication,NICNET(National Informatics Centre Network) .The user get connected with internet through Internet Server

There are mainly two ways of connection methods

a) On-Line Connectivity

b)Off-Line connectivity

INTRANET

Intranet and Internet are two different things.Intranet is nothing but an application of the internet technology to a closed network where every user is not allowed to connect with Intranet.Intranet uses Internet-derived communication protocols(TCP/IP),IP network and a user interface like Web browser .Protocol is nothing but set of rules which helps electronic devices to communicate with each other.

It i used for corporate application.

LAN

In LAN(Local area network) more than one computers connected together typically a single building,office,home and communicate with each other and also share computing devices like file servers,printers,scanners etc.This are called node and this nodes are connected with LAN through Interface Hardware called adapter

The network consists of shared transmission medium having data rate 100Mbps or 10Gbps.

Many different types of media are used for LAN

1.Guided Media

  In this media the transmitting signal follow a narrow path and will behave predictably.The three most commonly used media are Twisted-Pair wiring ,coaxial cable and optical fiber cable.

2.Unguided Media

It can be used as physical paths to carry electrical signals.The atmosphere and outer space are example of unguided  media which can carry microwave infrared light waves and radio waves.

HUB

It acts as a central point for LAN cable.Repeater is the example of hub which simply connect cables together and regenerate data thereby passing  data from one device to another.There are also hub which connect network segments and routers ,which connect different types of both local and wide area networks.This types of hubs are specialized and related to the network they are used in.They are typically installed in very large and complex networks.

BRIDGE

In a network if more devices are connected  more collision will happen and therefore the avg throughput will go down so as a solution if we divide the network into separate networks or segments and within each segment device will continue to communicate with each other then throughput remain same and to do this a device  called bridge is often installed that connects to these network.

SOFTWARE

Software is required by the network to operate which is Known as NOS(Network Operating System).NOS support peer to peer architecture and also support Client/Server architecture.Device drivers program is required for adapters installed in LAN.

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DATA PROCESSING

 

              DATA PROCESSING

Today  I would like to discuss about data processing .First of all regarding this a question will arise in our mind that  data and information are same or different thing .What would be the answer lets see .

DATA is nothing but raw thing  which individual meaningless.

INFORMATION on the other hand meaningful or meaning based on the raw facts of data.

Lets take an example :COMPUTER this is a meaningful word which is nothing but an information  but I am telling  alphabet like C,O,M,P,U,T,E,R individually called data not information.When this alphabet combined and creates a meaningful words COMPUTER it is information.Now you are understand the difference between data and information.

DATA PROCESSING

It is performed by administrative organization for the business and is followed by systematic recording,arranging,filing,processing and reflecting the physical events occurring in the business.

Example like in an organization said Bank I want to disclose balance sheet to process that physical events I have to  collect so many information related to this means -recorded this data then arranging it properly after that filing it and processing it to get balance sheet.

In simple way data processing consists of

                                               1.INPUT

                                               2.PROCESSING

                                                3.OUTPUT

In any application we need to hold the data in various files that is master files and transaction files.

Master files known as permanent file and transaction file which is temporary in nature.

Lets take an example In a company named ABC Company thousand of employees are working

They are taking salary each month and for this company need to generate salary slip for every month now think about it what data is may changed and what data will be the permanent I am listing this below.

PERMANENT DATA	TEMPORARY DATA
EMPLOYEE NAME,ADDRESS,EMPLOYEE CODE,INCOME-TAX CODE E.T.C	EMPLOYEE WORKING DAYS,HOURS,OVERTIME,E.T.C

The above data is required to generate employee pay slip so from above which data need to set up in master file and which data  need to be store in transaction file it is cleared.We set all permanent data in master file and all temporary data in transaction file.

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CLASSIFICATION OF COMPUTERS

 

  CLASSIFICATION OF COMPUTERS 

Today we are going to discus about classification on computers

It can be classified as

1. Analog

2.Digital

 

 

 1. ANALOG

So first we discussed about analog computer.First you have to understand what is analog

It is nothing but continuous physical magnitudes. Lets take an example I want to measure temperature

Of my room or I want to calculate the pressure or voltage this are continuous physical magnitude which are analogous  to the numbers under consideration.

Lets take another example like petrol pump in which quantity of petrol and price of that quantity are the two measurement made by analog computer.These computers gives approximate result as because they deal with quantities which is vary continuously.       

    

 

DIGITAL

Drawback of analogue computer is it gives the approximate result means the result is not accurate but

In case of digital computer it gives accurate result because it deals with numbers or characters which is expressed as digits in the number systems like binary or decimal.Digital computer is used for business and scientific processing.

Now I am talking that if I am combined both the computer that is analog and digital then it is called hybrid computer where both the features is added.

Digital computer can be used for specific purpose as well as general purpose.

Specific purpose machine doing specific task not have versatility so it can not used for other purpose.

This kind of machine is used to solve complex navigational problems.

Now I am talking about general purpose machine which is used for scientific as well as business purpose application.Now think about storage capacity for scientific purpose the storage capacity need not to be high but for business purpose storage capacity need to be high.

In case of business purpose it may involve thousand of customers and million of transactions,but in case of scientific application input may quite small and output is also small but it involves complex calculation

The processing may involved thousand of calculation so computational speed is critical.

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