1. Communications & Networks Intermediate 2 Computing (Systems Unit)

2. What is a Network? A series of computers linked together so can send and receive data. We use them for sending e-mails, downloading files, shopping, etc They are divided into two types: –Local Area Network (LAN) –Wide Area Network (WAN)

3. Local Area Network (LAN) Cover a small area such as one room or building. –The school has a LAN Each computer on a LAN is called a station One station is called the file server. –The file server is where all the data & files are kept

4. Advantages of a LAN Share data Share peripherals (resource sharing) E-mail Passwords keep data secure Different levels of access –stop unauthorised access Flexible access –Use any station connected to the LAN Many users can use same document at the same time (workgroup computing)

5. Transmission media for LAN Stations can be connected by cables or wireless technology Cables: –Unshielded Twisted Pair of copper wire (UTP) Uses electrical signals to transmit data Cheaper but can get interference –Optical fibre Uses light beams to transmit data Expensive but doesn't get interference

6. Transmission media for LAN Wireless –Infrared communication Like the TV controls –Bluetooth Range of about 10 metres –WIFI ( Wireless Fidelity Alliance) Range of about 12-50 metres Bluetooth & WIFI use radio waves

7. Wide Area Networks (WAN) Connect computers across large distances Spread across countries & cities worldwide using telecommunications links Similar advantages to LAN but on a bigger scale.

8. Transmission Media for WANs Telecommunications links –The communication of information over a distance using: Microwave transmission Satellite links

9. Network Security Security methods include: –Passwords & user IDs –Encryption –Physical methods

10. We will learn about: –Client Server Networks –Network Interface Cards –Multi-Access Computers –Social, Legal & Ethical Issues Lesson Objectives

11. Recap - LAN Area: Room, building or group of buildings Stations & File Server Transmission Medium: –Copper cable –Fibre optics –wireless Advantages of LANs –Share data –Resource sharing –Different levels of access –Flexible access –workgroup computing

12. Recap - WAN Area: town, city,world Transmission Medium: –Telecommunications Links Satellites Microwave transmission Network Security: –Passwords & user IDs –Encryption –Physical methods

13. Client & Server Networks A method of network organisation Each workstation is called a client Each workstation is connected to a central system called a server The server can be used for: –Holding all the data files and application software –Organising printing on the network –Organising the clients’ access to the internet

14. Server Client Printer Client Client / Server Network

15. Network Interface Card Allows the computer system to communicate with the network Every device that is connected to the LAN will need a NIC, for example, computer, printer and scanner. It take the data sent by your computer –stores it in its own memory locations, –then adapts it ensuring it follows the communication rules

16. Multi-Access Computers Enable many users to: –Access the system at the same time –Share the proccessing power of the system –Share the available memory –Share the data on backing storage The terminals attached to these computers useually have no processing power of their own. The terminals would be made up of just a monitor and keyboard

17. Multi user computer

18. Mainframe Computer Printer Multiuser Computer Terminal

19. Social Issues Teleworking –Process of using a WAN to work from home WANs can improve communications for people in remote areas Some people can’t afford the cost so a gap could form between the “Information Rich” and the “Information Poor” Some people believe that computers cause social isolation

20. Legal & Ethical Issues Legal: –Computer Misuse Act –Copyright, Designs & Patents Act –Data Protection Act Ethical: –Invasion of personal privacy –Censorship & freedom of speech

21. Communications & Networks Electronic Communications

22. Lesson Objectives Electronic Communication Text/Instant Messaging E-Mail Advantages & Disadvantages File Attachments Netiquette

23. Electronic Communication The process of sending and receiving electronic messages. Electronic messages include: –Electronic mail –Text messaging –File transfer (attachments)

24. Text Messaging Types: –Short text message. –Instant messaging. Language used: –Casual/Informal –Abbreviations –Acronyms

25. E-mail Advantages: –Fast compared to post –Cheap – ISP connection only –Web mail – access anywhere –Send multiple copies (CC) –Organise folders Disadvantages: –Spam –Viruses –Lack of Netiquette File Transfer –Files can be attached –Size limit –Attached viruses

27. Netiquette DON’T WRITE IN CAPS! Don’t leave the Subject Field blank Don’t over use Formatting Don’t give out personal details Don’t start Flame Wars (Trolling) Use proper English in e-mails. Don’t send dumb jokes, chain mail, etc Code of conduct used in e-communications

28. Communications & Networks The Internet

29. Internet Services Accessing the Internet The World Wide Web Search Engines Lesson Objectives

30. The Internet Enables computers and networks worldwide to connect with each other The network of networks

31. Internet Services World Wide Web (www or just web) –Used for browsing or searching E-mail –Communication & exchange of information File transfer –Sending & receiving large amounts of information

32. Accessing the Internet Internet ready computer Internet Service Provider (ISP) –A company that provides access to the internet Browser –Software used to view web pages Email client –Program for sending and receiving email

33. Accessing the Internet Dial-Up –Uses a modem and an ordinary phone line to dial up the number of your ISP that connects you to the internet. Broadband –Uses either a digital subscriber line (DSL) or a cable modem Modem –The telephone line doesn’t understand binary –A modem is needed to translate for the computer

34. World Wide Web Information is stored in web pages on web sites These pages can be viewed in a browser They are found by an address such as: –www.google.co.uk –www.msn.com Hyperlinks are used to ‘travel’ around the web

35. The Web - HTML Title of the document The body of the document H yper T ext M ark-up L anguage The language used to write web pages

36. Search Engine Special web site to help you find information A big database! Some of the main search engines:

37. Software on the internet Video conferencing Streaming media Internet services Mobile Internet Lesson Objectives

38. Software on the Internet Freeware –Free software but the author still holds the copyright –You are not allowed to change it Shareware –30-Day trial period –After that either pay for it or delete it

39. Software on the Internet Commercial –Pay full price up front –Limited to one backup copy –Licence agreements are very detailed

40. Video Conferencing Using networks to send audio and visual data. Enables people to have face-to-face meetings Saves time and money No need to travel long distances for business

41. Video\Audio Streaming The internet is used to send data one way Online radio stations do this Uses large amount of network bandwidth

42. Other Internet Services Chat & instant messaging –Text based communication –Communication is in real time (instant) Weblogging (Blogs) –A type of online diary –Used for both business & personal Bulletin boards –Electronic notice board

43. Mobile Internet Using the internet while on the move –Walk ‘N’ Surf Devices include –Mobile phones, Laptops, palmtops, pdas