GCSE ICT Transferring data. Most commercial computer users need to allow their employees to share...
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![Page 1: GCSE ICT Transferring data. Most commercial computer users need to allow their employees to share data. It also needs more than one employee to access.](https://reader036.fdocuments.in/reader036/viewer/2022082816/56649f535503460f94c78167/html5/thumbnails/1.jpg)
GCSE ICT
Transferring data
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Transferring data
• Most commercial computer users need to allow their employees to share data.
• It also needs more than one employee to access the data at the same time.
• The solution to this is for the commercial computer users to have computer networks.
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Computer networks
• A computer network is a series of computer systems that are connected together so that they can share computing power and/or storage facilities.
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Computer networks
• There are two main types of network.• These are:
– Local Area Networks (LAN) – are usually confined to a single building or site.
– Wide Area Networks (WAN) – cover a wider geographical area (e.g. anywhere in the World).
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Computer networks
• Advantages of networks– Devices (e.g. laser
printers) can be shared.
– Software can be shared.
– All users can access and update files from anywhere on the network.
– Data and software can be stored centrally.
– Network security can ensure that only authorised users can access data.
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Computer networks
• Disadvantages of networks– Networks can be
expensive to install and operate.
– Networks can be temperamental.
– Server breakdowns cause the whole network to stop working.
– Any network breakdowns can cause chaos.
– Security must be of the highest level possible to ensure that unauthorised access and infection by computer viruses are prevented.
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Network topologies
Ring network
Server
Workstation
Workstation Workstation
Workstation Laser printer
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Network topologies
Line network
Server
WorkstationWorkstation Workstation
Workstation Laser printer
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Network topologiesStar network
Server
Workstation
Workstation Workstation
Workstation
Laser printer
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Hierarchical networks
• In some networks one or more computers are more powerful than the others.
• These networks are called hierarchical networks.
• These more powerful computers usually look after specific functions on the network and are called servers (e.g. file servers, printer servers).
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Hierarchical networks
• File servers manage all the files stored on the network, including program and data files.
• File servers are also used to store program and data files.
• Printer servers manage all the printing requests on the network.
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Modems
• On WAN networks such as the Internet, computers can be connected to the network using normal telephone lines.
• To do this the computer must be equipped with a modem (Modulator – Demodulator).
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Modems
• The modem converts digital signals into analogue signals that can be sent along telephone lines.
• It can also convert analogue signals it receives back into digital signals the computer can use.
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Modems
• The speed of a modem (e.g. 56,000 bits per second) determines how quickly signals can be sent and received.
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Network software and hardware
• Networks require specific software and hardware in order to work including:– A network operating system.– Network cabling (e.g. metal or fibre
optic cables) and connectors or wireless media (e.g. radio, microwave, or infra-red).
– Network cards.
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Network software and hardware
• The quality of the software and hardware used will determine the speed at which data is transferred (i.e. the data transfer speed).
• The data transfer speed is the speed at which data is transferred from the server to a workstation/terminal.
• Download time is the time this data transfer takes.
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Network security
• Keeping networks secure is very important.
• This is usually done by giving all users a:– User ID – a unique name or number that
identifies each individual network user and allocates each user’s file access.
– Password – a string of letters and/or numbers that is only known by each individual user.