Name

Group

Contents

Information can be qualitative or quantitative :

• The purpose that the information is being used for.
• Who the information is being presented to.
• What facilities you have to help you present the information.

Information is stored by many organisations and companies such as banks, hospitals, libraries and schools.

• Input : Information going into an information system.
• Processing : Organisation and manipulation of data by an information system.
• Output : Information produced by an information system.
• Store : The ability to remember information temporarily or permanently.

Feedback usually occurs in control systems and when turnaround documents are used.

• Storage : Computerised systems can store vast amounts of data in small spaces and retrieve this data very quickly.
• Processing : Computerised systems can manipulate and analyse data very quickly and accurately.
• Networking : Data can be quickly and easily passed around the world electronically and shared between different companies.

• For small information systems many of the advantages of a computerised system are not important.
• The cost of purchasing a computerised system may outweigh its advantages.
• Users of an existing manual system may not want to change to a new computerised system.

A computer system will input, process and then output data.

• A microprocessor that can carry out arithmetic and logical operations on data.
• Some RAM that will store temporarily the programs and data that the user is currently working with.
• Some ROM to store the BIOS program that is run when the computer is first turned on.
• A hard disk drive that will store the programs that the user has installed and any files that he has created.
• A floppy disk drive and CD-RW or DVD drive that can be used to install software and to transfer files from one computer to another.
• A modem that can be used to send data over a telephone line to access the Internet.

An input device transfers data from the outside world into a computer.

• Manual Input Devices : User must enter data into the computer by hand.
• Direct Data Entry (DDE) Devices : Transfers information automatically from a source document such as a form or barcode into the computer.

An output device takes data from the computer and converts this into information in a form which is normally understandable by humans.

Comparisons of Printers and Plotters
Type	Cost	Speed	Quality	Graphics	Paper	Colour	Fonts
Dot Matrix	£100 +	300 cps	Poor	Yes	Continuous or Sheets	Poor	Lots with Software
Laser	£80-£15000 Mainly £600	8-100 ppm	Excellent	Yes	Sheets	Very Expensive	Lots
Ink Jet	£30+	8-24 ppm	Excellent	Yes	Sheets	Yes	Lots
Thermal	Built into other devices (cheap).	3 ppm	Poor	Yes	Roll of Special Paper	No	Lots
Plotter	£700-£5000+	Very Slow	Excellent	Yes	Large Sheets e.g. A4-A0	Yes	Draw as Graphics

Abbreviations : PPM = pages per minute, CPS = characters per second

A storage device stores programs and data either temporarily or permanently.

The capacity of a storage device is described in terms of bits, bytes, kilobytes, megabytes and gigabytes.

• Immediate access store holds programs and data that the user is currently working with.
• Backing store keeps data and programs when the computer is turned off.

Immediate access store is also known as main store or primary store. Backing store is also known as secondary store.

• Read Only Memory (ROM) : Contents are kept when computer is turned off (non-volatile) but can not be altered.
• Random Access Memory (RAM) : Contents are lost when computer is turned off (volatile) and can be altered by the user.

ROM is used to store the BIOS program in a microcomputer and the programs that run embedded systems. RAM is used to store programs and data the user is currently working with.

There are many different types of backing storage device. The main ones are :

Types of Backing Storage Device
Type	Examples	Common Applications
Magnetic Disk	Floppy Disk	Transporting files, small backups.
	Hard Disk	Running software, storing data files.
	Zip/Jaz	Transporting big files, medium size backups.
Optical Disk	CD-ROM	Distributing software, multimedia products.
	CD-R	Permanent backups, small volume distribution.
	CD-RW	Temporary backups.
	DVD-ROM	High quality digital films.
	DVD-RAM	Backup of moderate volumes of data.
Magnetic Tape		High volume backups, batch processing.
Flash Memory		Transferring files, storage in compact devices.

• What the maximum storage capacity of the device is.
• How much the device costs per megabyte (Mb) of storage space.
• How quickly the data stored on the device can be accessed.
• Whether the device can store data whilst the computer is turned off.
• Whether the data stored on the device can be changed or not.
• Whether the storage device can be used to transfer data from one computer to another or not (is it portable?).
• The method used to store the data e.g. electronically, magnetically, optically.

The table below compares the main types of storage device.

Device	Capacity	Cost per Mb	Transfer Speed (capacity per second)	Direct or Serial Access	Stores Data when Computer Switched Off	Can Have Data Written to It	Portable
Immediate Access Store
RAM	32Mb to 1024Mb	35p	500Mb to 1500Mb	Direct	No	Yes	No
ROM	1Kb to 64Mb	35p	500Mb to 1500Mb	Direct	Yes	No	No
Backing Store
Floppy Disk	1.44Mb	17p	0.2Mb	Direct	Yes	Yes	Yes
Hard Disk	40Gb to 300Gb	0.05p	40Mb to 100Mb	Direct	Yes	Yes	No
Zip / Jaz	100Mb to 2Gb	1p	0.5Mb to 8Mb	Direct	Yes	Yes	Yes
Optical Disk	650Mb to 17Gb	0.02p	3Mb to 22Mb	Direct	Yes	Depends on Type	Yes
Magnetic Tape	20Gb to 400Gb	0.03p	5Mb to 60Mb	Serial	Yes	Yes	Yes
Flash Memory	16Mb to 1024Mb	20p	0.4Mb to 10Mb	Direct	Yes	Yes	Yes

Caching is a technique used to speed up access to data stored on a backing storage device. A cache is a part of a computer's RAM that is set aside to store copies of frequently used sectors on a backing storage device such as a hard disk drive so that they can be accessed more quickly.

• Direct Access : The drive head can move directly to any record/file on the device so locating data is very fast. All types of disk are direct access. Used for transaction processing.
• Serial Access : The drive head must read through all of the data that comes before the record/file to be loaded so locating data is slow. Only magnetic tapes are serial access. Used for batch processing.
• Sequential Access : Identical to serial access, but records/files are stored in a particular order.

• Sorting is arranging the records in a file into a particular order.
• Merging is combining the contents of two files into one file. The simplest method of merging two files together is to take the contents of one file and add them to the end of the other. This is known as appending.

Processing is the act of doing something (e.g. organising and manipulating) with data to produce output.

Software programs are originally produced in a programming language.

Application software is software that is written to solve a particular problem or carry out a particular job. Application software can be either generic or application specific :

Generic	A generic package is a package that can be put to a wide variety of uses. The most common generic software packages are : word processors, desktop publishers, graphics packages, spreadsheets and databases.
Application Specific	An application specific package is produced to perform one specific task. For example a program written to produce invoices and manage stock levels for a garage.

• Off-the-shelf : If a package already exists that performs exactly the task that you need then you can buy it "off-the-shelf" from a shop.
• Customise a Generic Software Package : Modify a generic package such as a database to carry out the task.
• Custom Written Software : Pay a computer programmer to write a new piece of software to perform the task.

It is likely that you will encounter two different types of database package :

Flat File	A flat file database package will only let you store one file/table in each database you create.
Relational	A relational database will let you create many files/tables to represent different types of objects within each database you create. Links or relationships can be established between the different files in a database.

• The names of the fields in the record.
• The data types of the fields in the record.
• The lengths of the fields in the record.

• Control Over Redundant Data : Wherever possible data is only stored once, so storage space is not wasted
• Data Consistency : Because each data item is stored only once it is not possible for the same item to store two different values, hence the data will always be consistent.

• A sound card.
• A fast microprocessor.
• Quite a lot of RAM.

• Reference CD-ROMs such as encyclopaedias.
• The Internet, in particular the World Wide Web.
• Presentations such as training materials.
• Computer games.

• Managing communications between computer and connected peripherals.
• Providing a user interface.
• Allocation of computer memory.
• Organising data on backing storage devices.

• Games can be played on desktops, laptops, PDAs, games consoles and even cellular telephones.
• Modern games are supplied on CD-ROM or DVD and need a fast processor and a lot of RAM to run.
• Games can be played across the Internet with other people.
• Some people are worried about the social effects of games such as lack of exercise, reduced socialising and exposure to violence.

• Computer Aided Learning (CAL) systems teach a user by presenting him or her with material to learn then assessing how well the material has been understood.
• Home/Distance Learning systems allow people to study at home using the world wide web and email.
• Using computers to assist learning allows learners to progress at their own pace and to work where and when it suits them.

• The knowledge is stored in a knowledge base in the form of rules.
• An inference engine will apply the stored knoweldge to problems posed by the user.
• Most expert systems work by asking the user questions and analysing the responses to these questions.
• Example applications of expert systems are medical diagnosis and technical customer support.

1. Almost anyone, anywhere in the world can send and receive a package.
2. Parcels can be sent in the post.

1. You can communicate instantly with another person, anywhere in the world.
2. A telephone conversation is interactive.

1. Packages can not be sent by telephone.
2. There is no permanent record of what you have said or heard.

1. Can be used anywhere there is a transmitter.
2. Easy to get hold of someone if he carries phone with him.

1. Poor quality sound transmission.
2. Slow data transmission.

1. Documents sent quickly between locations.
2. Permanent record of communication.

1. Quality of printed copy not very good.
2. Fewer people have access to a fax machine.

1. Any sort of information (e.g. text, video) can be sent.
2. Information sent by email arrives very quickly.

1. Not many people have access to email.
2. Parcels can not be sent by email.

1. Allows people to communicate in a conference without having to travel.
2. Some information can be better represented visually.

1. Quality of images often not very good.
2. Specialised equipment required for high quality transmission.

1. Allows people to communicate in a conference without having to travel.

1. Sometimes it is better to meet people as information can not always be conveyed easily by talking. e.g. images, demonstrations

1. Can be viewed on most modern televisions.
2. Teletext is free to use.

1. Limited number of pages to look at.
2. Information can only be sent one way.

1. More channels than analogue TV.
2. Less interference than analogue TV.
3. Extra services such as television Internet, pay-per-view.

Computers can be connected to a WAN using a modem and telephone line, a terminal adaptor and ISDN channel or broadband :

Access to shared resources such as printers and file storage space can be controlled using either a central server based system or a decentralised peer-to-peer system.

• Sharing of expensive resources such as printers reduces cost.
• Files stored on a file server can be accessed and used from any station.
• Access to a centralised database of information is possible.
• Email can be used to communicate between users of computers.

• The initial outlay on network interface cards, cables etc. can be expensive.
• The failure of a network cable or server might cause the whole network to stop functioning.
• Viruses could be transmitted over the network.
• Unless appropriate security measures are taken it could be easier to steal or destroy data stored on a networked computer.

• A multimedia computer or suitable Digital TV control box.
• A telephone line or cable TV connection.
• Communications hardware such as a modem or an ADSL modem.
• Software to access services such as a web browser and electronic mail software.
• A subscription to an Internet Service Provider.

• Advantages : Can prevent access to unsuitable material.
• Disadvantages : Can sometimes let unsuitable material through, may block useful sites.

• An incredible range of information can be obtained through the world wide web and USENET.
• Information can be instantly updated on the Internet.
• Information can be accessed and sent quickly and conveniently using the Internet.
• The Internet brings people across the world closer together.

• You can not know who has put information onto the Internet, why they have put it there or whether it is true or false.
• The slow speed at which the Internet can be accessed by a modem places limitations on the types of information that can be sent via the Internet.
• There are some concerns over how securely information can be sent over the Internet.
• Many people don't have access to the Internet.

Online Banking	Customers manage their accounts on the Internet. Cash can be taken out at ATMs.
Ticket Booking	Tickets can be booked online. Availability and prices can be easily checked.
Auctions	Items can be auctioned online. Internet auctions can attract more bidders than ordinary auctions.
Car Importing	Cars can be purchased from other European countries for importing into the UK. Cars bought abroad can be cheaper than cars bought here.
Books and CDs	Online book and music shops can offer a wider range of products than actual shops.

• It is important to check that a website you are buying from is run by a reputable company.
• Credit card details should be encrypted before they are transmitted so that they can not be stolen by hackers.
• As e-commerce web sites are often linked to a company's other computer systems, it is vital that these systems are also secure.

• A customer can shop from home. There is no need to go out so time spent shopping can be reduced.
• It is easy to compare product descriptions and prices from different companies.
• E-commerce creates more competition between companies which means lower prices.
• Specialist products which are not usually available on the high street can be found.

• A company can sell its goods in a larger market place if it trades on the Internet so it has more potential customers.
• The cost of selling goods is lower because the sales process is highly automated.
• An e-commerce website can be open all day every day with miminal human involvement.

• Some people do not have the skills or equipment to access the Internet.
• Some people enjoy shopping and treat a visit to the shops as a leisure activity.
• Some people are concerned about the security of e-commerce transactions and so are unwilling to buy on the Internet.
• Some purchases such as clothing are highly personal and people like to try out items before they buy them.
• To engage in some activities such as having a haircut you have to visit a real building.

• Digital sensors are either on or off.
• Analogue sensors produce a varying voltage which depends on the quantity measured.

• It protects the computer from potentially dangerous voltages produced by sensors.
• Using an analogue-to-digital converter (ADC) it converts the analogue voltages produced by sensors into digital signals that a computer can process.

• Transmission : Data is transmitted by a medium such as a telephone line or radio transmission from the sensors to the computer.
• Storage & Collection : Data is stored by the sensors in RAM in a small device called a data logger which can be collected at a later date and taken to the computer to transfer the data.

• Measurements always taken at the right time.
• No errors in the measurements.
• Data logging systems can be placed where humans can't go.
• Graphs and analysis can automatically be performed on the data.

• An Analogue to Digital Converter (ADC) which changes the analogue voltages produced by the sensors into digital signals that the computer can process.
• A Digital to Analogue Converter (DAC) which changes the digital signals that the computer produces into analogue voltages which can control the devices.

• Faster response time.
• Low operating costs (fewer wages to pay).
• Very reliable. A control system will not get tired or make mistakes.

• High initial costs of design and purchase of system and training.
• Jobs lost when new system introduced.
• System will fail if the program that controls it has not been designed properly. If no-one notices this then it could be dangerous.

• The sequence of traffic lights at a road junction can be controlled by a computerised system.
• The sequence of traffic lights at different road junctions can be co-ordinated to improve traffic flow.
• Congestion charging systems can charge drivers for the journeys they make.
• Entry to car parks and charging can be managed by a computerised system.
• Satellite Navigation (SatNav) systems can give a driver instructions to tell him how to get to his destination.

• PENDOWN
• PENUP
• FORWARD
• BACK
• LEFT
• RIGHT

Organisations can store and process data more easily and quickly using computerised information systems.

1. be processed fairly and lawfully
2. be processed only for limited purposes
3. be adequate, relevant and not excessive in relation to the purpose for which they are held
4. be accurate and up to date
5. be held no longer than is necessary
6. be processed in line with a data subject's rights
7. be kept securely
8. not be transferred to countries that don't have similar data protection laws to the UK.

1. A subject is entitled to view any data that a data controller stores about him.
2. A data controller must correct or delete any data about a data subject which is inaccurate.
3. A data subject may prevent processing which could cause damage or distress.
4. A data subject may prevent processing for direct marketing purposes.
5. A data subject may demand that any decision which will significantly affect him is not taken solely on the basis of automatic processing.
6. If a data subject is not happy with the way he has been treated by a data controller then he can complain to the Information Commissioner.
7. If a data subject suffers actual loss as a result of the use of inaccurate data then he can claim compensation from the responsible data controller.

1. The Act does not provide individuals with a method to find out who stores data about them.
2. There are many exceptions of data which are not covered by the act.
3. Organisations are free to pass on information about you to other organisations so long as they tell you.

1. Copy Protection methods such as entering a unique code to use a software package and dongles make it harder to copy software.
   
   
2. Licence Agreements restrict the use that a person may make of a software package. A licence agreement is a legal contract between the person who buys a software package and the company that developed and sells it. It states what the person who has purchased the software may do with it. A network or multi-user licence agreement grants permission for one copy of a software package to be installed on many computers.

1. Security measures such as passwords and logs can be used to monitor access to a computer system.
2. Regular backups are taken so that damaged or changed data can be recovered.

• Computer programmers use programming languages to develop new software.
• Call center workers retrieve and store information in databases.
• Office workers use a variety of software packages.

• Eyes can be strained by prolonged viewing of a computer monitor.
• Repetitive strain injuries can occur in the wrist if a keyboard is used without regular breaks.
• The back and neck can be affected if a computer system is badly positioned or a chair is badly adjusted.
• Badly designed jobs and software can create stress in employees.
• Badly maintained electrical equipment can cause electric shocks or fire.

• The monitor should be correctly adjusted and room lighting should be checked.
• Regular breaks should be taken away from the computer.
• The computer, chair and desk should be adjusted to suit the user.
• An upright seating position should be maintained.
• Jobs should be designed to be achieveable and incorporate a variety of tasks.
• Electrical equipment should be regularly tested.
• Early symptoms of illness should be regularly checked for.
• Vision should be tested regularly.

The safe use of computer workstations in the workplace is governed in the UK by :

• The 1974 Health and Safety at Work Act, and
• The Health and Safety (Display Screen Equipment) Regulations 1992.

Many of the measures listed above are required by these regulations.

There are four main threats to the safety of data. These are :

Threats to Data Safety
Accidental Damage	Media storing data can be easily damaged by poor storage conditions, flood, fire etc. Users can accidentally change or delete the wrong data.
Data Theft	Confidential data can be stolen and sold.
Hacking	Hackers can gain unauthorised access to a computer system.
Computer Viruses	Computer viruses can deliberately delete or damage data.

Organisations which store important data take appropriate security measures to reduce the risk of data loss or theft. Possible measures include :

Computer Security Measures
Safe Storage of Data	Using high quality media and storing data in appropriate conditions reduces the risk of accidental damage.
Limiting Physical Access	It is possible to limit access to some computer systems physically using locks, swipe cards etc. This can reduce the risk of unauthorised personnel accessing or damaging data.
User Names and Passwords	The use of a user name and password system can restrict who can access what data on a computer system.
Biometric Measures	Biometric systems can identify people by recognising one of their unique physical characteristics.
File Access Rights	File access rights specify what actions a user can take on a file or directory. Example access rights are read only, change and append.
Logs	When a user name and password system is in use a log can be kept of who has done what on a computer system. This may deter unwanted activity and will help track down anyone who has made unauthorised used of a computer.
Encryption	Encryption is converting data into an apparently meaningless form so that it can not be read by unauthorised users.
Backups	A backup is an extra copy of data. If the original data is damaged then the backup can be used to recover the correct data.
Virus Checks	Using a virus checker to identify viruses before they infect a computer can reduce the risks of a virus destroying data.
Firewalls	A firewall is device or program that monitors and restricts the data that flows between a home computer or private network and a public network such as the Internet.
Digital Signature	A digital signature is a binary code that uniquely identifies a person. Digital signatures are used to identify who sent an email and check the email has not been altered.

• How important the data is.
• How confidential the data is.
• How likely it is that someone will want to steal, change or destroy the data.

Organisations should have a backup strategy which details how data will be backed up. The strategy should include :

• How often should data be backup up ?
• When should data be backed up ?
• What storage medium should the backups be stored on ?
• Where should backups be stored ?
• Should backed up data be compressed ?
• Who will carry out the backup procedure ?
• What will happen if data is lost ?
• How many copies to keep ?

How backups are produced often depends upon the type of processing that is in use :

Backups by Type of Processing
Batch Processing		Backups are kept using the Ancestral or Grandfather-Father-Son system.
Transaction Processing		Periodically a copy of the master file called a file dump is made. Recent transactions are stored in a transaction log file.
Real-time Processing		A lot of backup hardware is employed to reduce the risk of failure.

• Can make copies of itself without the user knowing it is doing this.
• Only spreads when the user carries out an action such as running a program or opening an email.
• Does something annoying or destructive.
• Tries to hide itself so the user can not delete it.

• Use only floppy disks and CD-ROMs from respectable sources.
• Be careful about downloading programs from the Internet.
• Use a virus checker program to detect and delete viruses.
• Use a firewall to stop your computer being accessed by other computers or people over the Internet.

Common validation checks are :

Validation Checks
Presence Check	Checks that data has been entered into a field and that it has not been left blank. e.g. check that a surname is always entered into each record in a database of addresses.
Type Check	Checks that an entered value is of a particular type. e.g. check that age is numeric.
Length Check	Checks than an entered value e.g. surname is no longer than a set number of characters.
Range Check	Checks that an entered value falls within a particular range. For example the age of a person should be in the range 0 to 130 years.
Format Check	Checks that an entered value has a particular format or pattern. e.g. a new-style car registration number should consist of a letter followed by 1 to 3 numbers followed by 3 letters.
Table Lookup Check	Checks that an entered value is one of a pre-defined list of valid entries which should be allowed.
Check Digit	A check digit is a digit attached to the end of a string of digits. It is calculated from the other digits and used to help ensure that the whole string is inputted correctly.
Parity Check	Used in data communications to ensure that data is not corrupted when it is sent down a transmission medium such as a telephone line.

• Batch Total : A count of the number of documents that data is to be entered from.
• Hash Total : A value calculated by adding together all of the entries in a chosen field on each document.

The totals are calculated by the user before data is entered and by the computer after it is entered. If the user and computer calculated totals differ then an error is identified.

Common verification checks are :

Verification Checks
On Screen	Entered data is displayed and the user is prompted to confirm that it matches the data on the input form.
Dual Input	Data is entered twice and the two data sets compared. If there are any differences then the data is checked by the user and corrected.

Data collection forms should be designed so that :

• They can be easily and correctly completed by the person filling them in, and,
• So that the information on them can be quickly and accurately transferred into the information system by a computer operator.

Following these guidelines will help to ensure that data collection forms are well designed :

1. Titles and clipart should be used to make it obvious what the purpose of the form is.
2. Language should be kept simple to avoid the possibility of confusion.
3. Clear instructions about what data is required and how it should be written down should be provided.
4. Instructions should tell the person completing the form what to do with the form when it is completed.
5. Input boxes should be drawn on the form. The person completing the form will be forced to write one letter in each box. This should make the form easier to read and ensure that the person completing the form does not write down more data than can be stored on the computer.
6. All questions should be relevant.
7. Tick boxes should be used where possible. These speed up input and ensure that the person completing the form can only choose a valid option.
8. A section should be added to the form so that the organisation that is collecting the form can keep track of what has been done with the information on it.

A turnaround document is a document which :

• Has some information printed onto it by a computer.
• Has more information added to it by a human.
• Is fed back into a computer to transfer the added information into the computer.

Simulations are used for three reasons :

• Cost : It can be much cheaper to simulate something than to actually do it.
• Safety : Some things are very dangerous. Simulating them is safer than actually doing them.
• Feasibility : Some things are just not possible but we can simulate what they would be like.

Simulations function using variables and rules :

• Variables : Variables are things in a simulation that can change.
• Rules : Rules determine how the variables in the model are changed and how they affect each other.

Spreadsheet software can be used to simulate situations which involve calculations :

• The numbers typed into the spreadsheet are the variables in the simulation.
• The formulae which perform the calculations are the rules of the simulation.

Flight Simulators are used to train pilots. Specialised input and output devices are required to operate the simulator. Rules and variables will be used to mimic the operation of a real aircraft.

Simulations do not copy every aspect of a real life simulation, and so the results produced by a simulation can not always be relied on to accurately predict the behaviour of the real life system :

• Incorporating all the factors that affect a simulation would make it very difficult and expensive to produce the simulation. The number of variables and rules involved would be massive.
• Some situations that could occur in real life are so unlikely to happen that the designer of a simulation would probably not think of including the situations in the simulation.

Because of the limitations of a simulation, the results produced by a simulation are often tested in the real world. This is especially important when the simulation relates to safety matters.

1. What type (Command, Menu, GUI) of interface is it ?
2. How easy is it to use for novice users ?
3. How easy is it to use for experienced users ?
4. Can actions be carried out quickly ?
5. How easy to understand are error messages ?
6. What help facilities are provided ?
7. Is there a tutorial ?
8. Do many other programs use a similar user interface ?
9. What are the minimum and recommended hardware requirements to use the interface ?

• Window : An area of the screen which is used to display a particular program or piece of work.
• Icon : An informative picture / symbol displayed on the screen which the user chooses to select an action.
• Menu : A list of options which the user can pick from.
• Pointer : A symbol such as an arrow which is moved by a pointing device and can be used to select objects.

When you design a user interface you need to follow appropriate guidelines such as :

These symbols are used to produce flowcharts :

These symbols are used to produce system flowcharts :

There are two low level languages. They are machine code and assembly language.

A computer can only execute (carry out) a program which is written in machine code.

An assembly language is a set of simpler instructions (or mnemonics) which correspond to the machine code instructions that a computer understands.

High level language programs must be translated into machine code before they can be used. This is done automatically by a piece of software known as a compiler or by an interpreter.

This table lists some of the advantages of using low level languages and high level languages to produce programs :

• MPEG : Stores video in a highly compressed form.
• MP3 : Stores music in a highly compressed form (around 1/12th the size of a standard music file).
• MIDI : Stores the musical notes that make up a piece of music.

Music and videos are often exchanged over the Internet as MP3 and MPEG files. It is illegal to exchange copyright material in this way.

This table summarises some of the most significant changes that have occurred as a result of the use of information technology.

Lifestyles	+	Increased automation at work and home allows more leisure time. Internet makes rich variety of information available to everyone at home. Internet enhances freedom of information in authoritarian countries. Cheap and easy to keep in touch with people throughout world (Global Village). Biometric national identity cards could help trace criminals and terrorists. Internet, e-commerce and teleworking can help support small communities. Computer systems can assist people with special needs. Home learning and computer aided learning systems can help people learn at their own pace.
	-	More time spent on computer, less time spent socialising. Violent computer games may affect behaviour. Lack of control over the content of material on the Internet. Easy for organisations to store lots of info about you (big brother) including biometric data. Many of our daily activities depend on computers. What would happen if these systems stopped working?
Employment	+	New interesting, well paid jobs created in IT industry. Teleworkers can work from home. Many lost jobs would have been lost to lower wage economies anyway. E-commerce encourages trade between different countries (globalisation).
	-	Jobs lost in manufacturing as control systems introduced. Retraining required for many workers. Many teleworkers now work longer hours.
Environment	+	Data logging systems can monitor the state of the environment. Electronic storage and transmission of data can reduce the demand for paper and trees. Teleworking means less people travel to work, so less petrol used. Computerised processes often produce less pollution than equivalent mechanical ones.
	-	Increased demand for electricity produces pollution from generation.

Most people keep money in a bank account because it is safer and more convenient to keep money at a bank than as cash. You can also earn interest on money in a bank.

• Withdraw and deposit money.
• Pay for purchases and services.
• Make regular payments of bills etc.
• Accept regular payments of items such as wages.

• A large bank may have several million accounts to manage.
• Computerised systems can store vast amounts of data in a small space.
• Using a WAN account information can be made available worldwide.
• Account information can be retrieved very quickly using transaction processing.
• A large number of automatic transfers and regular payments could not be completed manually.
• Many measures can be used to keep computerised data secure.

Important features of a bank account are :

Debit Card	A card which can be used to pay for goods and services. Information about the account that the card relates to is stored on the card using a magnetic stripe. Newer cards are smart cards and also store data in RAM.
Credit Card	Similar to a debit card, but you do not have to pay for items that you purchase with a credit card immediately.
ATM	Automatic Teller Machines (ATMs) can be used to widthdraw money from an account and to access other services. To use an ATM a debit or credit card must be inserted into the machine and a password known as a PIN muct be typed on a keyboard. An ATM uses a modem and telephone line to communicate with a bank's central computer.
EFTPOS	Electronic Funds Transfer at Point Of Sale (EFTPOS) is the method used to pay for items that are purchased with a debit or credit card. At a shop an EFTOS terminal is used to make a sale. The card is swiped through a reader which reads account information from the magenetic stripe. This information together with the amount to pay is sent using a modem to a bank's central computer so that the money can be immediately transferred from the purchaser's bank account to that of the seller. A voucher is printed showing details of the sale.
Cheques	Cheques can be used to pay for goods and services. A customer must write payment details onto a cheque to use it. Information about the account that the cheque should be paid from is printed on the cheque using MICR. The process of transferring money from one bank account to another when payment has been made by cheque is known as clearing, and can take up to seven days.
Statements	Each account holder receives a statement periodically which lists the transactions on his account. Database queries are used to select the information to print on a statement. Because many statements have to be produced they are printed on very fast laser printers.
BACS	The Bankers Automatic Clearing System (BACS) is used by companies to automatically transfer money from one bank account to another. A computer equipped with a modem is used to send details of payments to the bank's computer. Most people have their wages paid to them by BACS.
Standing Orders and Direct Debits	Standing orders and direct debits can be used to make automatic regular payments of bills. Every day a query extracts the list of payments to be made on that day from an accounts database and the payments are made automatically.

Supermarkets sell products to customers. The customers select their goods themselves and then take them to a till to pay for them.

A supermarket needs an information system which can :

• Accurately calculate the cost of a customer's purchases.
• Try to ensure that the store does not run out of products that customers want to buy.
• Take the payment for goods from customers.

Information about the products that a supermarket sells will be stored as a file in a database. The products file in the stock database will probably contain at least these fields :

• The tills are connected to the computer storing the stock database by a LAN.
• When an item is sold its barcode is scanned at the till and the product details including price are looked up in the products file. If the barcode on the product can not be scanned the checkout operator will enter the product code using a keyboard.
• The barcode number is validated using a check digit to reduce the likelihood of a number being entered incorrectly.
• After an item is sold the stock level of the item is automatically decreased.
• After all of a customers purchases have been entered into the till the customer receives an itemised receipt and can choose to pay by cash, cheque or EFTPOS.

There are five stages in the systems lifecycle :

Five Stages of the Systems Lifecycle
Analysis	Analysis is the process of deciding what (if anything) an information system should do.
Design	Design is the process of deciding how you will set up your information system using the software packages you choose.
Implementation	Implementation is using appropriate software packages to create the system you have designed.
Testing	Testing is trying out your system to see if it works properly or not.
Evaluation	Evaluation is reviewing your work to see if you have achieved the goals that you set out in the analysis.

An analysis should include these three steps :

Feasibility Study
Breaking Down The System Into Tasks
Requirements Specification

The requirements specification should set out what the new system will do. It is used to inform the design process and to evaluate the work that has been done once the information system has been created. A separate requirements specification should be created for each task you have identified. Each requirements specification should include these five sections :

Introduction
Outputs
Inputs
Desired Outcomes
Alternative Methods

The design of an information system can be broken down into four smaller steps :

Selecting Software
Selecting Hardware
Planning
Test Plans

• Typical Data : Typical, everyday data which your information system should work with.
• Extreme Data : Data which is acceptable but is on the edge of the boundaries for which an information system should work.
• Erroneous Data : Data which should not work with you information system. A good information system will display an error message when erroneous data is entered and will not crash.