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Standard Grade Computing Communications and Networks.

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Presentation on theme: "Standard Grade Computing Communications and Networks."— Presentation transcript:

1 Standard Grade Computing Communications and Networks

2 What is a Network? A series of computers linked together so can send and receive data. A series of computers linked together so can send and receive data. They are divided into two types: They are divided into two types: Local Area Network (LAN) Local Area Network (LAN) Wide Area Network (WAN) Wide Area Network (WAN)

3 Local Area Networks Local Area Networks (LANs) operate in one area, such as an office block, a factory a school a bank or even a home Local Area Networks (LANs) operate in one area, such as an office block, a factory a school a bank or even a home The computers are joined together using cables or wireless transmitters The computers are joined together using cables or wireless transmitters

4 Advantages of LANs users can share peripherals such as hard drives, printers, and web cameras users can share peripherals such as hard drives, printers, and web cameras users can share data files such as database files, standard letters and multimedia presentations users can share data files such as database files, standard letters and multimedia presentations they make it easy to communicate by sending s they make it easy to communicate by sending s

5 Copper Cabling Coaxial cabling The central cable that transmits the data is surrounded by a shield of copper braiding. This protects it from interference and so is found in in places such as factories where there could be a lot of interference The central cable that transmits the data is surrounded by a shield of copper braiding. This protects it from interference and so is found in in places such as factories where there could be a lot of interference

6 Copper Cabling Twisted-pair cabling This is a simple type of cabling made up of two copper cables. It is relatively cheap and can support quite high transmission speeds, for example over 100 Mbits per second This is a simple type of cabling made up of two copper cables. It is relatively cheap and can support quite high transmission speeds, for example over 100 Mbits per second

7 Fibre-optic Cables Fibre-optic cable is made up of fine strands of glass that carry pulses of light Fibre-optic cable is made up of fine strands of glass that carry pulses of light These pulses of light represent data being transmitted These pulses of light represent data being transmitted More difficult to break into the cable and is more secure More difficult to break into the cable and is more secure Does not suffer from electro- magnetic interference Does not suffer from electro- magnetic interference Transmits data at high speed Transmits data at high speed Costs more to buy and install than other types of cabling Costs more to buy and install than other types of cabling

8 Wireless Networking Wireless networking transmits data through the air using radio waves and microwave frequency radiation Wireless networking transmits data through the air using radio waves and microwave frequency radiation a wireless network is relatively easy to install, all you need is a transmitter/receiver and a wireless Network Interface Card on each computer on the network a wireless network is relatively easy to install, all you need is a transmitter/receiver and a wireless Network Interface Card on each computer on the network there is no need for any wiring there is no need for any wiring transmission speeds are very fast transmission speeds are very fast security is a problem, wireless networks are easy to hack into security is a problem, wireless networks are easy to hack into

9 Wireless Protocols Infrared communication Infrared communication Like the TV controls Like the TV controls Bluetooth Bluetooth Range of about 10 metres Range of about 10 metres WIFI ( Wireless Fidelity Alliance) WIFI ( Wireless Fidelity Alliance) Range of about metres Range of about metres

10 Network Interface Card A NIC takes the data sent by your computer on to the network, stores it in its own memory locations and then adapts it to make sure that it follows the communication rules that govern the network A NIC takes the data sent by your computer on to the network, stores it in its own memory locations and then adapts it to make sure that it follows the communication rules that govern the network It takes data coming in from the network to your computer and passes it on to the processor It takes data coming in from the network to your computer and passes it on to the processor Every device that is connected to the LAN will need a NIC, e.g.. computer, printer and scanner Every device that is connected to the LAN will need a NIC, e.g.. computer, printer and scanner

11 Clients and Servers A client is a workstation on the network A client is a workstation on the network A server is a computer that has a fast processor and lots of memory and is used to A server is a computer that has a fast processor and lots of memory and is used to hold all the data files or the applications software hold all the data files or the applications software organise the clients access to the internet organise the clients access to the internet control the resources the client workstations can use. For example printing, internet access etc control the resources the client workstations can use. For example printing, internet access etc

12 Wide Area Networks Wide Area Networks (WANs) connect computers across large distances Wide Area Networks (WANs) connect computers across large distances WANs stretch across towns, link up cities and countries using telecommunications links WANs stretch across towns, link up cities and countries using telecommunications links

13 Wide Area Networks people can communicate instantly worldwide people can communicate instantly worldwide they can be used to they can be used to send send send data files send data files carry out financial transactions carry out financial transactions work from home and still be in contact with the central office work from home and still be in contact with the central office access information access information carry out research carry out research WANs are central to the success of large businesses WANs are central to the success of large businesses

14 Wide Area Networks Telecommunications links Telecommunications links The communication of information over a distance using: The communication of information over a distance using: Microwave transmission Microwave transmission Satellite links Satellite links Optical Fibre Optical Fibre

15 Multi-access Computers These are powerful computer systems that enable many users to access the system at the same time access the system at the same time share the processing power of the system share the processing power of the system share the available memory share the available memory share the data on the backing storage share the data on the backing storage

16 Multi-access Computers Multi-access computers have many terminals attached to them Multi-access computers have many terminals attached to them These terminals are made up of keyboards and monitors that people use to These terminals are made up of keyboards and monitors that people use to interact with the main processor interact with the main processor load data to and from backing storage load data to and from backing storage display data held on the system display data held on the system The key point about these terminals is that they have little or no local processing or memory The key point about these terminals is that they have little or no local processing or memory

17 How does multi-access work? It gives each terminal a slice of the processors time. It goes round the users very quickly, so quickly that they are not aware that they are sharing the system with lots of other people It gives each terminal a slice of the processors time. It goes round the users very quickly, so quickly that they are not aware that they are sharing the system with lots of other people Large organisations such as banks, insurance companies and mail-order companies as well as colleges and universities use them to store and process their data Large organisations such as banks, insurance companies and mail-order companies as well as colleges and universities use them to store and process their data

18 Security on Networks All networks need to have security measures in place All networks need to have security measures in place If they do not then the network can be hacked into, data deleted, copied or changed If they do not then the network can be hacked into, data deleted, copied or changed

19 Physical Security Measures Physical security measures can prevent unauthorised people accessing the network Network computers with a physical lock Network computers with a physical lock Security locks on the computer rooms Security locks on the computer rooms Computers without floppy or CD drives Computers without floppy or CD drives

20 Software Security Measures Authorised users are issued with IDs and passwords to gain entry to the network Authorised users are issued with IDs and passwords to gain entry to the network When users log on, the computer system checks their IDs and passwords with those that it keeps on file When users log on, the computer system checks their IDs and passwords with those that it keeps on file Some systems use biometric systems to ID authorised users. They store data about fingerprints, voices or eyes Some systems use biometric systems to ID authorised users. They store data about fingerprints, voices or eyes Encryption encodes the data held on the system. This means that if the network is hacked into then the data is meaningless to the hacker Encryption encodes the data held on the system. This means that if the network is hacked into then the data is meaningless to the hacker

21 Text Messaging Instant messaging allows you to send text messages to people on their PCs Instant messaging allows you to send text messages to people on their PCs Short text messages can be sent to and from pagers, mobile phones, and palmtop computers Short text messages can be sent to and from pagers, mobile phones, and palmtop computers

22 Electronic-mail ( ) s can be sent anywhere in the world s can be sent anywhere in the world Mail delivery is very fast Mail delivery is very fast It costs a lot less than surface mail It costs a lot less than surface mail Web-based allows you to check your inbox anywhere there is an internet connection Web-based allows you to check your inbox anywhere there is an internet connection Multiple copies of a message can be sent easily Multiple copies of a message can be sent easily is secure as an ID and password is needed to access it is secure as an ID and password is needed to access it

23 Electronic-mail ( )

24 problems Viruses can be hidden in attachments Viruses can be hidden in attachments Lots of spam arrives by . Spam is unwanted adverts, special offers and general junk mail Lots of spam arrives by . Spam is unwanted adverts, special offers and general junk mail

25 Netiquette Netiquette is a set of rules that govern the way people behave when using , or a network Netiquette is a set of rules that govern the way people behave when using , or a network

26 Netiquette DONT TYPE IN CAPS! DONT TYPE IN CAPS! Dont leave the Subject Field blank Dont leave the Subject Field blank Do not start flame wars Do not start flame wars Do not use bad language, always be polite Do not use bad language, always be polite Use proper English in s. Use proper English in s. Do not post unwanted mail or use to spam Do not post unwanted mail or use to spam

27 Task Set your groupwise password Set your groupwise password Send an to someone in the class saying hello and giving some information about what you did at the weekend. Send an to someone in the class saying hello and giving some information about what you did at the weekend. Read any s you receive. Read any s you receive. Forward one of your messages to someone else in the class. Forward one of your messages to someone else in the class. Customise the party invitation and save. Customise the party invitation and save. Send your invitation as an attachment to five people in the class using BCC Send your invitation as an attachment to five people in the class using BCC

28 Internet A Wide Area Network across the world A Wide Area Network across the world The network of networks The network of networks Lots of smaller networks joined together Lots of smaller networks joined together

29 Accessing the Internet To access the internet an internet-ready computer system is required as follows To access the internet an internet-ready computer system is required as follows Desktop, laptop and palmtop computers are suitable Desktop, laptop and palmtop computers are suitable A modem A modem Telecommunications connection either dialup or broadband Telecommunications connection either dialup or broadband A browser A browser An internet service provider An internet service provider

30 Modem It is a device that changes your computers signals into a form that can be sent down the phone system It is a device that changes your computers signals into a form that can be sent down the phone system

31 Dialup Connection It uses a modem and an ordinary phone line to dial up the number of your ISP that connects you to the internet It uses a modem and an ordinary phone line to dial up the number of your ISP that connects you to the internet Data is transmitted at a speed of 56 Kilobits per second Data is transmitted at a speed of 56 Kilobits per second

32 Broadband Connection A broadband connection is a high-speed telecommunications link A broadband connection is a high-speed telecommunications link BT digital subscriber line (ADSL) gives speeds of maximum 512 Kbps download and 128 Kbps upload BT digital subscriber line (ADSL) gives speeds of maximum 512 Kbps download and 128 Kbps upload Cable modems can reach speeds up to 10 Megabits per second Cable modems can reach speeds up to 10 Megabits per second Actual speeds are slower because the cable bandwidth often has to be shared with other users Actual speeds are slower because the cable bandwidth often has to be shared with other users

33 Browser A browser is the software that fetches and displays web pages e.g. Microsoft Explorer A browser is the software that fetches and displays web pages e.g. Microsoft Explorer Type in the page address in the address bar Type in the page address in the address bar Click on a hyperlink Click on a hyperlink Favourites remembers where web pages are Favourites remembers where web pages are You jump back and forward between viewed pages You jump back and forward between viewed pages History shows which pages that have been visited History shows which pages that have been visited

34 Online / Offline Once your computer is connected up and ready to send and receive information it is said to be online Once your computer is connected up and ready to send and receive information it is said to be online When your computer is not ready to send and receive information it is offline When your computer is not ready to send and receive information it is offline

35 Internet Service Providers (ISPs) To access the internet you need to have an agreement with an internet service provider To access the internet you need to have an agreement with an internet service provider You have to log on to your ISPs computer to access the internet You have to log on to your ISPs computer to access the internet Your ISP Your ISP helps your browser find web pages helps your browser find web pages gives access to web-based gives access to web-based provides access to newsgroups and chat rooms. provides access to newsgroups and chat rooms. provide space on their servers to store your own web pages provide space on their servers to store your own web pages

36 How to choose a ISP? Points to consider how much they charge per month how much they charge per month how reliable the service is how reliable the service is how long you can stay online how long you can stay online how efficient the service is how efficient the service is

37 Mobile Internet Technology This technology uses devices that let you access the internet while on the move All of the devices have mobile phone technology mobile phone technology a mini-browser a mini-browser internal memory internal memory a processor a processor

38 Mobile Internet Technology Devices Some are phones with a browser – smartphones Some are phones with a browser – smartphones Some are palmtops with phone technology built in Some are palmtops with phone technology built in They often have features such as They often have features such as touch screens touch screens WIMP HCI WIMP HCI mini browser mini browser calendar calendar a database a database a calculator a calculator mobile phone connection to access the internet as well as make phone calls and send text messages mobile phone connection to access the internet as well as make phone calls and send text messages

39 Services on the Internet World Wide Web (WWW) is made up of web pages that are stored on servers worldwide World Wide Web (WWW) is made up of web pages that are stored on servers worldwide Newsgroups and take part in discussions on a whole range of topics Newsgroups and take part in discussions on a whole range of topics Chat rooms are electronic groups that are less structured than newsgroups Chat rooms are electronic groups that are less structured than newsgroups Search engines look for web pages Search engines look for web pages

40 Software on the Internet There is a wide range of software that you can download from the internet There is a wide range of software that you can download from the internet They all have different agreements attached to them They all have different agreements attached to them

41 Freeware Free software but the author holds the copyright Free software but the author holds the copyright You can use the software and even make copies of it and give them away to people You can use the software and even make copies of it and give them away to people You must not change the software or to sell it You must not change the software or to sell it Device drivers for printers and CD-writers are examples of freeware as are some games Device drivers for printers and CD-writers are examples of freeware as are some games

42 Shareware Shareware software comes with a free 30- day trial period Shareware software comes with a free 30- day trial period After the 30 days you should register and pay a fee or delete it from your computer After the 30 days you should register and pay a fee or delete it from your computer You can make copies of the software and distribute them to other people You can make copies of the software and distribute them to other people The disadvantage of this system is that it relies on peoples honesty The disadvantage of this system is that it relies on peoples honesty

43 Commercial software Commercial software is bought across the counter in shops such as PC World or through the internet Commercial software is bought across the counter in shops such as PC World or through the internet You are often limited to making one backup copy or simply are allowed to copy the software once on to your hard disk and keep the CD as a backup You are often limited to making one backup copy or simply are allowed to copy the software once on to your hard disk and keep the CD as a backup

44 Videoconferencing Videoconferencing is using a computer network to send audio and visual data to enable people in distant locations to have face-to-face meetings Videoconferencing is using a computer network to send audio and visual data to enable people in distant locations to have face-to-face meetings A point-to-point conference connects two people at two different locations using simple webcams, microphones and speakers attached to their computers A point-to-point conference connects two people at two different locations using simple webcams, microphones and speakers attached to their computers Multipoint conferencing links several people in distant locations Multipoint conferencing links several people in distant locations Sounds and images are captured by the microphone and camera. They are then transmitted across the network, which can either be a LAN, a WAN or even the internet Sounds and images are captured by the microphone and camera. They are then transmitted across the network, which can either be a LAN, a WAN or even the internet

45 Advantages of Videoconferencing? People who are located in different countries can have face-to-face meetings where they can discuss and make decisions People who are located in different countries can have face-to-face meetings where they can discuss and make decisions This avoids travelling and staying in hotels, saving time and money This avoids travelling and staying in hotels, saving time and money Teams of workers can be brought together quickly no matter where they are located Teams of workers can be brought together quickly no matter where they are located

46 Social Issues Social Issues The internet is a rich source of information on almost any subject The internet is a rich source of information on almost any subject This information can help you find work, be successful in school, business and leisure This information can help you find work, be successful in school, business and leisure Not everyone has access to this information Not everyone has access to this information Some people are at a disadvantage Some people are at a disadvantage

47 Isolation People could isolate themselves from others and spend most of their time communicating using computers People could isolate themselves from others and spend most of their time communicating using computers Over use could lead to people becoming detached from the world around them. Over use could lead to people becoming detached from the world around them. We should keep a balance between using networks and keeping in touch with people face to face We should keep a balance between using networks and keeping in touch with people face to face

48 Legal Issues People sadly use networks to commit crime hack into networks and steal or corrupt data hack into networks and steal or corrupt data hack into networks and cause damage by leaving viruses hack into networks and cause damage by leaving viruses commit fraud such as stealing money from bank accounts commit fraud such as stealing money from bank accounts break copyright law by illegally transferring software, data or other files break copyright law by illegally transferring software, data or other files

49 Privacy Some people disregard others right to privacy and use networks to send unwanted s, chain-mail, adverts, junk or spam Some people disregard others right to privacy and use networks to send unwanted s, chain-mail, adverts, junk or spam

50 Ethical issues When we are looking at ethical issues we are basically looking at right ways and wrong ways to use networks When we are looking at ethical issues we are basically looking at right ways and wrong ways to use networks Networks are very powerful communication tools and, used properly, they can bring great benefits to people and society in general Networks are very powerful communication tools and, used properly, they can bring great benefits to people and society in general Used irresponsibly, and for the wrong purposes, they can spread bad feelings and disinformation, stir up hatred, be a source of crime and corruption and generally undermine the bonds that hold society together Used irresponsibly, and for the wrong purposes, they can spread bad feelings and disinformation, stir up hatred, be a source of crime and corruption and generally undermine the bonds that hold society together

51 Codes of conduct Businesses and organisations have set out codes of conduct for network users Businesses and organisations have set out codes of conduct for network users These codes are called Acceptable Use Policies These codes are called Acceptable Use Policies They are based on the need to They are based on the need to respect other people, their rights and property respect other people, their rights and property adhere to the law adhere to the law


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