DSL GCSE ICT Revision

Network Topologies

2006-12-01T12:52:00.000Z

Bus.

Networks can be connected in a number of different ways. Each method has its pros and cons.
A Bus Network
This is the simplest way to connect workstations, servers and other components of a network by using a single cable. One or more of the workstations act as the File Server, whilst the other machines are used as workstations or terminals.

Advantages:

Cheap
Easy to install.

Disadvantages:

If there is a problem with the cable, the entire network stops working.
If many workstations are using the network at the same time, response can be very slow, thus frustrating users who want to work quickly. The technical term for data trying to travel simultaneously along the cable in different directions is called 'data collision'. A busy network will have many data collisions.

Star.

Each workstation has its own direct line to the server. Connections to the server are made with hubs or switches.
Hubs connect many lines together.
Switches allow the network manager to connect certain workstations to specific servers.

Advantages:

Reliable - if one connection fails, it does not affect others.
Good performance, fewer data collisions as each workstation has its own line.
Good Security - no workstation can interact with another without going through the server first.

Disadvantages :

Expensive to install - lots of cables required.
Installation is an expert job.
Extra hardware required such as hubs, switches and wiring centres.
Star networks are normally preferred because of their reliability.

Ring.

The workstations are attached to a cable arranged in a ring .

Advantages:

Very fast - all data traffic occurs in the samedirection so there should be no data collisions.

Disadvantages:

If a single machine is switched off then the network does not work. If the cable breaks, once again, the network does not work.

Copywrite Law

2006-12-01T12:41:00.000Z

You have spent three months working on your coursework. It is absolutely brilliant, even if you do say so yourself, you just know that it is worth that A* grade. How would you feel if you found out someone in your class had secretly copied your work when you went out of the room for five minutes and then handed it in as their own? I bet you would feel pretty miffed, to put it mildly.How about that song that you spent last week writing? You are sure it is great chart material and is going to get you that break into the music industry. You record a demo of it and send it to a record company, but you don't hear anything from them. How does it make you feel when you see the latest boy band performing your song on Top of the Pops, and you haven't been paid a single penny for it?Its not fair is it? That's why we need a law to protect the author of any original material from someone else taking it and claiming it as their work.There is such a law, it is called the 'Copyright, Designs and Patents Act' and it was passed in 1998.Covers
This Act was introduced to protect the investment of time, money and effort by the people who create original pieces of work.This can mean authors of books, composers of music, the makers of a film, a computer game designer or a company that creates applications such as word processing software.They all invest a great deal of time and money to produce these things and quite rightly, their work belongs to them.The Copyright, Designs and Patents Act has two main purposes:1. To ensure people are rewarded for their endeavoursand2. To give protection to the copyright holder if someone tries to copy or steal their work.Copyright and ICT
As you have seen, the Act protects a wide range of work, both written and computer based.We are more concerned here with the ICT examples. Some of these are:Copying softwareCopying or downloading musicCopying images or photographs from the webCopying text from webpagesHow many of these are you guilty of?After all, does it really matter if you copy your mate's computer game?How about downloading a few tracks from the internet - they are free aren't they?How many times have you been to a website and just copied what was written and pasted it into your own work?Come on, if we tell the truth, I bet we have all done these things. Does it really matter?Does it matter?
It is estimated that almost 40% of software is copied. This has a huge impact on the software industry. By just cutting the software piracy rate from 25% to 15% would result in an extra 40,000 jobs in the IT sector and an extra £2.5 billion in tax revenues.The extra revenue that software companies would receive would mean that they could reinvest more into new product development, perhaps a new game or a new application package.It’s estimated, in fact, that people breaking the law and downloading copyrighted music costs the industry something like £8.5 billion a year – and loses £1.5 billion for the VAT man.So, the end result, if everybody that has a PC in the UK decided to download ripped off music rather than buy it, would be an end to the music industry in the UK.That’s a pretty sobering thought.A new and growing concern is the large amount of 'instant essays' or even full pieces of coursework now readily available for purchase over the internet.Exam boards and universities are clamping down on this and have had to put in place sophisticated monitoring systems to ensure that a student is handing in theit own work.One university student recently failed his degree when the university caught him cheating after he submitted a dissertation that he had purchased from the Internet.Exam boards will instantly disqualify you if they catch students trying to submit work which is not their own.Softwear licences When you purchase a piece of software you don't actually own the software. What you have purchased is a 'single user licence' for you to be able to use it.You are able to load your software onto your machine at home and use it for as long as you like. You are not however, allowed to take it to your mates and load it onto his computer - he doesn't have a licence to use it.Your school or a business needs the same piece of software to be available for many people.They don't buy lots of copies of the software, they buy one copy and will buy either a 'multi-user licence' or a 'site licence'.A multi-user licence allows a certain number of users e.g. 15 to use the software at any one time. When they log off the machine, another 15 can use it. However, if they allow the software to be used by 16 people at the same time then they are breaking the terms of the licence.A site licence allows everyone on that site or in that office to use the software. It can be loaded onto every machine and people can use it whenever they want.myths about copyright" I didn't know so I'm not guilty"You won't get way with saying ‘I’m sorry, I didn’t know’. If you copy things and pass them off as your own, you are guilty of breaching Copyright.."If it doesn't have a copyright notice, it is not copyrighted."Nope, you won't get away with this one either. Any original work is copyright, whether it has a copyright notice on or not. If something looks copyright then you should assume that it is."If I don't charge for it, I can copy it’False. It doesn't matter if you charge someone or not, copying is copying is copying, whichever way you look at it.Breaking the copyright laws can result in very heavy penalties - you can get a hefty fine and even get sent to jail!Confusion about copyright
When you write copy you have the right to copyright the copy you write. You can write good and copyright but copyright doesn't mean copy good - it might not be right good copy, right?Now, writers of religious services write rite, and thus have the right to copyright the rite they write.Conservatives write right copy, and have the right to copyright the right copy they write. A right wing cleric might write right rite, and have the right to copyright the right rite he has the right to write. His editor has the job of making the right rite copy right before the copyright would be right. Then it might be copy good copyright.Should Thom Wright decide to write, then Wright might write right rite, which Wright has a right to copyright. Copying that rite would copy Wright's right rite, and thus violate copyright, so Wright would have the legal right to right the wrong. Right?Legals write writs which is a right or not write writs right but all writs, copied or not, are writs that are copyright. Judges make writers write writs right.Advertisers write copy which is copyright the copy writer's company, not the right of the writer to copyright. But the copy written is copyrighted as written, right?Wrongfully copying a right writ, a right rite or copy is not right.

Software

2006-12-01T12:33:00.000Z

Software refers to the programs that we run on computer systems. They allow the hardware to do their job; without software, the hardware wouldn't know what it was supposed to do.
Software is made up of a series of instructions or computer code. It is these instructions which tell the hardware it needs to print a document or save a file or even change the word 'form' to 'from'.

Imagine that you have created a fantastic new computer game... you learned how to program, saw a gap in the market, developed your skills, then spent weeks and months creating it.
You find a company to sell it for you. You are all set to make a fortune... then your 'friend' posts a copy on the internet and everyone downloads it.
All that work and effort will not be rewarded, why should anyone buy it, when it is freely available on the internet?

Or perhaps you are a talented music group just starting out... you write your songs, you make your first CD. Then someone buys a single CD and converts them to MP3 and posts them on the internet... no more sales!
This is the problem that software and music companies, large or small have to face. And so laws have been created to protect their efforts.
Making illegal copies of software is called 'Software Piracy'.

ICT and Society

2006-12-01T12:27:00.000Z

ICT is constantly changing and advancing as scientists and engineers create new technologies for us to use and enjoy.

For example in the last 50 years technologies which have become common in loads of places are:

Personal Computers
Mobile Phones
The Internet
Medical scanners
Satellites
Lasers
CD and DVD
Television
Car electronics
Credit cards

And so on.

The Data Protection Act

2006-12-01T12:20:00.000Z

the data protection act was braught out in 1998 The Data Protection Act was passed by Parliament to control the way information is handled and to give legal rights to people who have information stored about them During the second half of the 20th century computers were getting more powerful and easy to use. Companies, government and other organisations began to use them to store large amounts of information about people, such as their customers, clients and staff. Databases with this information can be quickly set up, searched, edited and accessed and take up less space than paper recordsPersonal data on computerInstead of paper records, computers were also being used routinely to keep personal data about people. This information included:-namesaddressesfinancial informationmedical recordscriminal recordsemployment historyFor example, being a member of a sports club would mean that your name, age, medical details and payment record would be stored on a computer file.Ease of access to the informationThe information stored could be far more easily and flexibly used than if it was stored on paper. For example, a database could be searched to find all customers living in a particular area, to target them for "special offer" advertising. Searches of databases like this are much faster with computers and, in particular, information can be matched from one database to another far more than if it is stored on paper. The Database section has more on searching.Communications networksStoring information about people on computers which are linked to communications networks like the Internet or private company networks has also become important. This allows databases to be used across an organisation and be shared between organisations very quickly.Misuse of informationWith more and more organisations using computers to store and process personal information, there was a danger the information could be misused or could get into the wrong hands.ConcernsA number of concerns arose about how this information could be used:-Could it be easily copied?Could it be changed with little evidence being left?Who could see this information?How accurate was the information?Was it be possible to build up detailed files on people without their knowledge or permission?Other European Union countries have passed similar laws as often information is held in more than one country. any onw who wants to store peoples personal information has to register with the information comisioner register of data controllers is kept detailing the data that will be stored so they have to say in advance what information will be stored and how they will use it.Each Register entry contains the following information:The data controller's name and addressA description of the information to be stored.What they are going to use the information for.Whether the data controllers plans to pass on the information to other people or organisations.Whether the data controller will transfer the information outside the UK.Details of how the data controller will keep the information safe and secure.Some data and information stored on computer disks is personal and needs to be kept confidential. People want to keep their pay, bank details, and medical records private and away from the view of just anybody. If someone who is not entitled to see these details can obtain access without permission it is unauthorised access. The Data Protection Act sets up rules to prevent this kind of unauthorised access to personal data and information.The Act sets up two types of personal data:-Personal data is about living people and could be:-- their name- address- medical details or banking details'Sensitive' personal data is also about living people, but it includes one or more details of a data subject's:- racial or ethnic origin- political opinions - religion- membership of a trade union- health sexual life- criminal activity.There are more safeguards about sensitive data than ordinary personal data. Usually, a person must be asked specifically if sensitive data can be kept. the 8 principals of the data protection act are:It must be collected and used fairly and inside the law.It must only be held and used for the reasons given to the Information Commisioner.It can only be used for those registered purposes and only be disclosed to those people mentioned in the register entry. You cannot give it away or sell it unless you said you would to begin with.The information held must be adequate (enough), relevant and not excessive (too much) when compared with the purpose stated in the register. So you must have enough detail but not too much for the job that you are doing with the data.It must be accurate and be kept up to date. There is a duty to keep it up to date, for example to change an address when people move.It must not be kept longer than is necessary for the registered purpose. It is alright to keep information for certain lengths of time but not indefinitely. This rule means that it would be wrong to keep information about past customers longer than a few years at most.The information must be kept safe and secure. This includes keeping the information backed up and away from any unauthorised access. It would be wrong to leave personal data open to be viewed by just anyone.The files may not be transferred outside of the European Economic Area (that's the EU plus some small European countries) unless the country that the data is being sent to has a suitable data protection law. This part of the Act has led to some countries passing similar laws to allow computer centres to be located in their area.People whose personal data is stored are called data subjects. The Act sets up rights for people who have data kept about them.the data protection act does not work on peolpe who have died.

Network

2006-11-30T15:05:00.000Z

A group of computers connected together form a network. Like at school have. Their advantages and disadvantages are:-
Advantages:

The whole network can be backed up centrallyperipherals, like printers and scanners, can be sharedmessages can be sent between usersusers can share files which prevents duplications of informationsoftware for a network is cheaper than individual licensedisadvantages:a trained person is needed to manage the networkwiring can be expensive to buy and installsecurity is an issueone way of connecting computers is in a network is by cable another way is using radio transmitters to provide wireless (LAN) local area network. A third way is by using (WAN) wide area network.WANS are connected using global communications such as telephone, satalite or cable.levels of access.

headteacher:
view view student records financial recordsview student recordsview staff recordschange own passwordict teacher:view student recordschange shared fileschange own passwordnetwork tecnician:change passwordchange shered filesadd new userschange own passwordview financial recordsview staff recordsview student recordsstudent:use of software for home workchange own passwordit is important to have different levels of access so that people dont get in to things that hey are not alloud to see.a network prevents people from seeing personal information by using passwords and user names to control what people can access.

levels of access

headteacher:
view view student records financial recordsview student recordsview staff recordschange own password.
ICT teacher:view student records,change shared files,change own password
networktecnician:
change passwordchange shered filesadd new userschange own passwordview financial recordsview staff recordsview student records.
student:
use of software for home workchange own password

Hardware

2006-11-30T14:52:00.000Z

Input devicesThere are many input formats which enable us to gather up and collect information, and enter data and instructions into the computer.Input devices can be manual or automatic.Manual input devices include:Keyboard - including concept keyboard. This is a flat board that contains a grid of buttons. Each button can be programmed to follow instructions. An overlay sheet is placed on the grid with an explanation for each button. They are used in primary schools with young children. Many modern fast food restaurants have overlays with either a description or picture of the meals that are available to make ordering easier.MouseTracker ballJoystickLight penDigital camera - this allows you to take pictures and to store a digital photographic image that can be read by a computer. You can then transfer the images directly from your camera on to your computer.Microphone - A microphone is a device to input sound information and can be used with a voice recognition system which processes the information. This can be used with a word processing program to enter text. It can also be used as part of security systems - only certain digitally stored voices will gain access.Touch screen - this is a special type of VDU, which has a grid of light beams or fine wires criss-crossing the screen. When the screen is touched (usually to choose an on-screen option), the computer senses where you have pressed. The information is stored on the computer and the touch screen is simply an interface. Touch screens have the benefit of being very robust and easy to operate and reprogram, hence why they are used in public places.Video digitiser - this takes an image from a video camera or television and converts it so that it can be used by, and stored on, a computer. Video sequences captured using a video digitiser are often used in multimedia presentations.Graphics tabletThis consists of a flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a designer can produce very accurate on-screen drawings.Scanner - these are a cheap and common way of getting images into a computer. They can also be used with OCR (Optical Character Recognition) software to scan in text.Automatic input devices include:Sensors Barcode reader Barcodes are different groups of vertical bars that can be read by a barcode reader. Barcodes are printed on nearly every product that you can buy. Shops use barcodes because they enable the shops to maintain their stock control system. The barcode contains the product details such as product name, size, manufacturer, country of origin. The price is looked up from the shop's database. When the bar code is scanned, the shop's stock is automatically reduced by one.MICR (Magnetic Ink Character Reader) - magnetic ink characters are the strange looking numbers that appear at the bottom of cheques. Banks use MICR to read the numbers from the bottom of cheques to obtain data such as account numbers and bank sort codes. This particular font is used because it is easy for a machine to discriminate between characters. The ink is magnetised because it makes it immune to creases or dirty marks.Magnetic strip (or stripe) readerMagnetic stripes are built into many plastic cards such as cheque guarantee cards, cash-point cards and personal identity cards. The magnetic strip on the back of the card can hold the personal details of the card owner and, with the necessary PIN, will allow access to secure information e.g. bank account details. Data stored on the strip is scanned and input into a computer system by a magnetic stripe reader.OMR (Optical Mark Reader) - this reads marks made by pencil on a printed form into the computer. OMR systems are suited to reading pre-printed forms and check-boxes such as National Lottery number selection sheets and multiple-choice exam papers.

Viruses

2006-11-17T12:28:00.000Z

Computer Virus - this is a phrase coined from biology to describe a piece of software that behaves very much like a real virus (only it spreads from computer to computer rather than people!).

A Computer Virus is a computer program that is designed to copy itself repeatedly and attach itself to other computer programs.
In the early days of personal computing (1980's) some of the people who created them had a certain misplaced sense of humour. For example, there was a virus that caused all the characters on screen to drop into a heap at the bottom of the display. Very annoying, but relatively harmless.
However, quite soon some really nasty versions came out that were deliberately designed to corrupt and delete your files as well as trying to copy itself everywhere.
Viruses can cause an immense amount of time wasting and financial loss for people and businesses.

Viruses can be prevented by taking sensible precautions, including:
Using anti-virus software to scan your system daily or weekly
Update the scanning software regularly
Not allowing people to load applications \ executable files on your system
Using special filtering software to prevent downloads of computer programs
Scanning all incoming e-mails
Not opening suspicious emails or attachments.
Avoiding software from unreliable sources
Backing up data regularly so you can recover your data with clean copies.

The most common way of getting a virus these days is to open an email attachment. Many viruses have been especially designed to take advantage of the way people send emails to each other. Some ways of getting viruses onto your computer are from:
storage device
floppy disk
memory stick
CD
ROM
DVD

Note:

The CD and DVD products from reputable companies are extremely unlikely to contain a virus. It is the personal 'burned' ones that are a potential problem.It is also possible to pick up a computer virus through what is known as 'peer to peer' file sharing networks. These are internet networks that are used by people to share files amongst each other.There is often no immediate evidence that a virus has been transmitted to a computer, and the user may remain unaware of it until it causes something to go wrong.Basically a virus is spread by allowing it to run (technical term: "execute") on your computer, so any executable file or computer program can contain a virus.

Health and Saftey

2006-11-14T12:47:00.000Z

There are various health problems associated with the regular use of computers, such as stress, eyestrain and injuries to the wrists, neck and back.
Employers must take steps to protect employees whose work involves the regular use of computers.
This website will introduce you to some of the most common problems and look at what can be done to reduce the risks.
Work your way through the site by accessing each menu item on the left hand side.
Once you have read all of the materials, have a go at the interactive quizzes at the end.
Your teacher will probably set you a task to complete, use the information on this site to help you.

Stress.

Stress brought on through the use of computers is one of the major causes of work related illness.
There are many different reasons why people become stressed at work. However, here is a list of some of the major causes brought about by the use of computers:
Many people are afraid of computers, they don't understand them and feel they will look stupid if they admit that they don't know how to operate one.
People worry that a computer will be able to replace them and they might lose their jobs.
Things change so fast in the world of computing that it can be very stressful just trying to keep up to date with new ideas, techniques and equipment, especially for older people.
It is getting increasingly hard to separate work and home life. People can be contacted easily by their bosses or clients. E-mail, the Internet and mobile phones mean that people continue to work even after they have left the office.
The amount of information that ICT systems can produce is often far too much for anyone to take in. This results in 'information overload' and people end up feeling they can't cope and become stressed.
Workers can be monitored using ICT systems. Call centre staff are monitored to make sure that they don't spend too long on any one call. The number of products that a check-out person scans during a minute are counted. This feeling of being constantly 'watched' can be very stressful.

Back Pains.

Many computer users suffer serious back problems. This is probably due to a poor posture or an awkward position while sitting at a computer.
Maintaining good posture can help defeat another common VDT problem,Solutions:
A fully adjustable chair should avoid poor posture
Sit with your back straight and head up
Footrests can reduce these problems
Position the monitor so that your neck doesn't have to bend
Adjust your "view angle" by tilting your monitor up or down.

RSI (Repetative Strain Injury).

Repetitive Strain Injury (RSI) is damage to the fingers, wrists and other parts of the body due to repeated movements over a long period of time.

Causes:
Repetitive finger, hand or arm movements e.g. typing
Poor posture and awkward movements
Amount of force used
Badly designed workstations

Symptoms:
In the arms and hands:
aching
pain, even after rest
weakness
swelling
tenderness
numbness
pins and needles
In the shoulders and neck:
stiffness
aching

Solution:
To prevent RSI, make sure your posture is correct
Raise your chair or use a cushion so that your wrists can be straight when you type
Keep your elbows close to your sides
Use wrist rests and avoid bending your wrists
Have a five minute break from typing every hour.

Eye Strain.

Eyes can become strained after staring at a computer screen for a long time, particularly if working in bad light, in glare or with a flickering screen.
Fortunately, eyestrain is usually a temporary problem.
The symptoms include:
Burning or itching eyes.
Blurring or double vision.
Headache.
Nausea.
Fatigue.

Solutions:
Screen filters can remove a high percentage of the harmfulrays emitted from a computer screen.
Use screens that do not flicker
Take regular breaks - do not work for more than one hour without a short break
Keep your eyes at least 18 inches from the screen
Regularly look away from the screen and focus on something in the distance e.g. across the office or out of the window (not an excuse to day dream though!).
Lighting must be suitable and blinds fitted to windows to reduce glare.
Have regular eye tests
All new monitors must comply with EU standards which ensure that radiation emissions are as low as possible.

Employer.

Laws have been passed to ensure that employers provide a safe working
environment for anyone who works with computers.
The law states that an employer must:

Provide tiltable screens
Provide anti-glare screen filters
Provide adjustable chairs
Provide foot supports
Make sure lighting is suitable
Make sure workstations are not cramped
Inspect workstations to make sure that they meet the required standards for health and safety.
Train employees how to use workstations correctly
Plan work at a computer so that there are frequent breaks
Pay for regular eyesight tests for anyone who needs prescription glasses in order to use the computer.
Note: These regulations apply only to offices - not to students or pupils in schools
There is also a requirement that employees:
Use workstations and equipment correctly and follow the training provided by their employers
Inform their employer of any problems relating to Health and Safety as soon as they arise.

LAN's and WAN's

2006-11-03T12:38:00.000Z

These are the two network areas you will need to know about. LAN is a short term for Local Area Network. Computers which are in a LAN are fairly close together. Most of the time in side a building. These computers can be connected together using cabling. They can also be connected using a wireless LAN. This is provided using radio transmitters.

WAN is a short term for Wide Area Network. Computers which are in a WAN can be spread over a much larger area and connects computers in different buildings, on different sites. Even different Countries!!! WAN can connect computers using Global Communications such as telephones, satellite or cable. A Global WAN you and millions of other people use quite often in their daily if they have access is The Internet.

Welcome to DSL GCSE ICT Revision!!!

2006-11-02T15:02:00.000Z

Hello and welcome to DSL's revision page. Hopefully you will find all the information you need for the GCSE exams or just stuff you didn't know before. Please feel free to leave your views and what you would like to see improved. I look forward to hear your thoughts. Hope you enjoy the site. Have fun!!!