Computer Motivations & Online Notes

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Network:-

To share data from one computer to another, we need some kind of network. In order to communicate in the computer, there should be networking between them, that is, they should be connected to each other in some way or the other. Connecting two or more nodes together is called a network.

To connect two computers, it is necessary to have the following components.

1. Two pc with Networking Operating System

2. Protocol (Rule of Networking)

3. Media (Wired, Wireless)

After this, all the devices can be connected and communication can be done between those computers.

Flow of Data Transmission (3 Types of Data Transmission Mode)

1. Simplex Communication:-

In this communication, only data (signal) is sent from one side. And on the other hand only Signal Receive is done. Like- TV, Radio.

2. Half Duplex Communication:-

In this communication, Signal can be sent from both sides. And can receive Signal. Can't send Signal from both sides at the same time (simultaneously). And neither can receive the signal. When a signal is sent from one side. So at that time the second one receives the signal. If a signal is sent from both the sides simultaneously, then there is a collision between them. And the signal is destroyed. Like- Walky-Talky.

3. Full Duplex Communication:-

In this communication, signals from both sides can send and receive signals at the same time. It is called full duplex communication. Like- mobile, internet, chatting etc.

Data Communication Technique:-

There are three types of this technology.

• Unicast:-

This is one to one communication. That is, communication with only one computer at a time

is done. It is called Unicast Communication.

• Multicast:-

This is One to Many (Group) Communication. i.e. communication with one group at a time

is done. It is called Multicast Communication.

• Broadcast:-

This is one to all communication. That is, communication with all computers at a time

is done. It is called Broadcast Communication.

Types of Communication Medium:-

1. Guided Medium

2. Un-guided Medium

Guided Media:-

Guided media is used in relation to the method of transmission of data over which signals go in a network. Example- Wired, Twisted-Pair cable, Coaxial cable, Fiber-optic.

Un-guided Media:-

Un-Guided Media is the medium in which signals are not directed through a solid medium, air is the medium through which electromagnetic energy can flow easily. Example- Wireless, Radio Waves, Microwave, satellite.

Network Architecture (1- Peer to Peer) (2- Client Server)

There are three types of networks on the basis of physical and geographical area.

• LAN

• MAN

• WAN

LAN Network:-

Its full name is Local Area Network. With this, two or more computers and other devices are connected together. It is confined to a single room or a building. It is confined to a single room or a building. Its data transfer speed is fast. In this the data is kept safe. It is easy to maintain it. Technologies:- Wireless Lan (PAN, CAN), Ethernet.

MAN Network:-

Its full name is Metropolitan Area Network. It is a large network in terms of area. This network is not limited to one building. Is. This is an expensive network. It consists of LAN network. By this, two different offices are connected together, in which the data is sent and received securely.

WAN Network:-

Its full name is Wide Area Network. With this network, one city to another city or one country to another country is connected. It is a high speed network. It is made up of lane and main network, in which satellite and fiber optical cable are used, in which different types of network devices are used to connect the network among themselves. Its maintenance is difficult. Which is done in collaboration with different companies.

VPN connection:-

They are interconnected through VPN connection. Its full name is Virtual Private Network.

Topology:-

The method of connecting computers and data flow in it is called topology.

1. Mesh Topology

2. Bus Topology

3. Star Topology

4. Ring Topology

5. Tree Topology

Internet :-

The Internet is the largest computer network, which shares data and information using the Internet Protocol. Such as - Email, Web Portals, Chat Blogging, Online Transactions, Web Site Etc.

History Of Internet:-

The Internet was started in the 1970s and 1980s. The Internet was started by the Defense Department in the name of ARPANET (Advance Research Projects Agency Network). In 1974, many Local Area Networks were connected to ARPANET with the help of TCP / IP. The rule used for the exchange of information is called Transmission Control Protocol or Internet Protocol. To connect any computer to the Internet, the telephone line has to be connected to the Internet Service Provider. Internet service in India was first used by Videsh Sanchar Nigam Limited on 15 August 1995, after that Internet was used mainly by other companies as well. Web Browsers :- Google Chrome, Internet Explorer, Mozilla Firefox, etc.

Domain Name System:-

Domain Name is a set of possible values ​​or identifiers that represent a website such as - google.com etc.

Domain Type:-

.com – Commercial

.edu – Education

.gov – Government

.mil – Military

.net – Networking

.org – Organizational

.co - Company

.au – Australia

.ca – Canada

.in – India

.fr – France

.nz – New Zealand

.uk – United Kingdom

.pk – Pakistan

Virus (Malware):-

The full name of VIRUS is Vital Information Resource Under Seize. Viruses are small programs in the computer. Which are executable programs that enter the computer and affect the working system of the computer. It's called a virus. The way viruses enter the human body and affect the human body. In the same way, computer viruses enter the computer and affect the working system of the computer. But this human body is completely different from the virus.

Symptoms:-

1. The speed of the computer slows down.

2. Change in working of keyboard.

3. In this the size of the file becomes more or less.

4. Useless information starts appearing on the screen.

5. Formats the disc.

6. Creates files and folders. and create its shortcuts.

7. Destroys the information in the computer.

8. Computer restarts.

9. Reduces computer memory.

10. Prevents program from running.

Due to spread of virus:-

1. By using stolen or fake software:-

Software which is obtained illegally. It is called Pirated Software. It can be a software virus.

2. From Network:-

When a virus enters a computer in a computer network, the virus spreads to all the computers in the entire network.

3. From CD and Pen Drive:-

To copy data from one computer to another, CD or pen drive is used. Due to which the fear of spreading the virus remains. The computer from which the data is being copied. And if there is a virus in it, the virus spreads to other computers as well.

4. From Internet:-

Nowadays the Internet is considered the main carrier of viruses. Virus makers use the Internet to spread viruses. Which was a simple and cheap medium.

Type of virus:-

Viruses are divided into several classes on the basis of their function and principle. which is the following.

• Boot Sector Virus:-

These viruses are saved in the boot sector area of ​​the disk. And when the computer is started. So it prevents the computer from starting. And create hindrance in computer work. This is a very dangerous virus.

• Partition table Virus:-

This virus damages the partition table of the disk. This does not cause any damage to the data. It reduces the capacity of RAM. And do problems in input and output devices.

• File Virus :-

This virus affects the working system of the computer by associating with the files being executed.

• Stealth Virus (Secret Virus):-

This virus keeps trying to hide its identity according to its name. and damage the computer.

• Polymorphic Virus:-

This virus itself has the ability to change again and again. So that it keeps itself safe in the computer for a long time. and damage the computer. And it is difficult to find them. Because it is in a completely new form every time.

• Macro Virus:-

It damages specific types of files. It harms the data of MS Office Files.

Is. And it is hidden in the form of micro program. Following is an introduction of some important viruses.

• Michelangelo Virus:-

This virus damages the computer on March 5, the birthday of Michelangelo. Most of the computers in the world remain closed on this day. This virus works only for one day. And causes great damage to the computer.

• Disk washer:-

This virus deletes the data by formatting the disk. And later leaves a message. Disk washer with Love got its name on the basis of this message.

• Bomb:-

A bomb is a program hidden in a normal program. The bomb is set by an angry employee. Examples of bombs are also found in software. So that if the stolen software is used, the bomb will erase that copy from the hard disk. Like viruses and Trojans, it ignores user bombs.

• Trojans:-

This is such a program. Those who claim to do some useful and beneficial work. And object: damage the system when executed. Some of these types of viruses are infected that do not do their work but become active after a particular date. and damage the computer. Like formatting a hard disk.

• Worms(Left):-

The Left is similar to a virus in a way. Because it also has the ability to double itself like a virus. But it does not infect executable files. It tries to make the hard disk full by repeating its code rapidly.

• E-mail Hoaxes:-

This virus is a virus sent with the help of e-mail, it informs the user about the virus. And it asks to inform its friends. While nothing like this actually happens, this virus wastes the user's time. and disturbs you mentally.

• Companions:-

This virus gets attached to the executable files. and runs itself in place of files, leading to dangerous results.

Virus Prevention and Detection:-

Preventing virus is not a difficult task. For this, we should use a little knowledge and some utility software. Original anti virus should be used in the computer. This software automatically detects viruses. And remove it from the computer. Antivirus should be updated from time to time so that it can also detect new viruses. Nowadays many companies manufacture anti virus in the market. Out of which you should buy and use anti virus according to your requirement, some of the popular virus repellents are as follows.

McAfee Virus Scan, K7 Total Security, Norton Anti Virus, Etc. Different antivirus have different features.

Absolute cell address:-

A cell address or range name in a formula that always refers to the same cell or range of cells. A $ sign is used in front of the row and column to make the cell address absolute. For example $AX$2.

Access Time:-

The time interval between receiving the data from the storage device and starting the operation is called the access time.

Architecture:-

Overall designer, design, organization and inter-connectivity of various components of a computer system. It specifically refers to the processor hardware and their bytes size and ordering sequence.

Artificial Intelligence:-

A branch of computer science that describes a computer that has the ability to think, learn and reason, as well as the ability to recognize people.

Backup:-

An optional feature of programs, data files, hardware devices, etc., to be used in the event of loss, loss or damage to the original program.

BIOS :-

Bios is largely responsible for handling input/output functions. It also involves relating the program's logical records to the physical records of a peripheral device.

Boot:-

It brings the operating system to the computer's memory to start processing. Rebooting means bringing back the program that started your operating system. A boot program is a small set of instructions that are presented to load a larger program. It is a shortened form of the word boot strap. The term boot is generally used to refer to the initial loading of an operating system or some other program into a computer.

Buffer:-

It is a device or storage area in which data is temporarily stored.

Bug:-

This is an error in a computer program.

Chip:-

A thin wafer of silicon on which electronic components are mounted.

Code:-

A set of rules under which data is entered into a computer system. It also explains the rules for converting data from one representation to another.

Computer :-

It is an electronic machine which automatically accepts the input data, stores, manipulates them and also gives output based on the given program and instructions.

Computer Network:-

A distributed data processing system in which multiple computers are connected to each other. For data communication and resource sharing.

Cursor:-

A small line or rectangular pointer on the screen that shows you the location in the text. The size of the cursor varies according to the operating system.

Data :-

A collection of information/facts to be stored or processed by a computer which is organized or processed into information.

File:-

A collection of related records.

File Management System:-

A software package allows the user to define these data items, places these items in a specified location, associates records with certain files, and then manipulates and retrieves the stored data as per the user's purpose.

Graphic:-

Graphic images come in all shapes and sizes. Examples of special graphics are clip art images, drawings, photographs, scanned images, signature files, etc.

Object:-

A single component of your drawing. You can draw objects on the Drawing and AutoShape toolbars with the text and drawing tools. Objects can be of any type like rectangle, square, circle, oval, rectangle with rounded corners, diamond, trapezoid, stars, freeform, graph etc.

User:-

Any person who supplies data to a computer based system or uses information generated from it.

Virtual Memory:-

Techniques for using diskspace to make programs believe that there is more random access memory (RAM) on the system than is actually available. This can be implemented with pure segmentation, pure paging, or a combination of both.

Client:-

It is a node or software program that requests services from a server.

Download:-

Transfer files from the Internet to other networks or from the mainframe to the PC.

Web Server :-

A computer that stores web pages and responds to requests received from the browser.

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