GCSE notes

Página 1

Computer Science - Revision.

Title - Computer Systems (Page 1)

Specfication requirments:

> I can define a computer system.

> I can describe the importance of a computer sustems in the mordern world.

> I can explain the need for relibility in computer systems.

the definition of a computer system:

1) a computer system takes a set of inputs, process them and gives a set of outputs.

1a)This is done by a combination of the software and hardwarw.

Input -> Process -> Output

Sub title - Importance of a computer systems:

> Computer systems give constant results.

> Faster access to information allowing jobs to be carried out quickly.

> Easier to analyse records and measure the performance.

> Improved communication.

> Cheaper and more accurate manufacturing.

Sub title - Reliability of computer systems:

> In critical applications, live may be at stake if there by carrying out testing.

> Loss of data/power or any system down time can lead to problems both personal and /or for the organisation.

Sub title - Dealing with failure:

> We can improve the reliability of computer systems by carrying out testing.

> If failure occurs risks to data can be reduced by duplicating the data by having backups.

Title - Professional Standards (Page 2)

Specification Requirements:

I can explain the need for adherence to suitable professional standards in the development, use and maintenance of computer systems.

Standards are the agreed convection and rules followed in the given industry.

Without these standards there is a risk if developing systems that are not compatible with each other.

Standards are important for the following reasons:

> Enable different equipment form different manufactures to word together.

> Make learning to use new systems and software easier.

> Allow communication between systems and software to take place.

Sub - sub title - Proprietary Standards.

> Standards owned by a company E.g Windows software all have the same look and feel and will run on a windows platdorm.

Sub - sub title - Industry Standards.

> Standards agreed across the computing industry mainly to do with the hardware to allow connection between devices. Eg USB.

Sub- sub title - De Facto Standards.

> Standards that develop over time through conman usage. E.g QWERTY keyboard layout, the use of Microsoft Word for word processes documents.

Sub- sub title - De jure Standard.

> De jure Standard that have become universally accepted so that they have to be followed for cummunication E.g ASCII, PDF, Unicode, 801.11 wireless standard.

Sub- sub title- Open standards.

> Publicly available. Software under these santards can be modified by users E.g HTML, Mozilla Firefox, Python.

Note:

>When writing software, programmers working in a team have standards to ensure that their code is understandalbe to others in their team,

different parts of code can work together and each member is professional completing work to an agreed standard. Examples may include indenting code, using

comments, using common variable names.

Title - Computer systems Implication (Page 3)

Specification Requirements:

I can explain the importance of ethical and legal considerations when creating compueter systems.

Sub title - Legal Implications.

'Health and Safety Act'.

> Employers are responsible for their staff. They must provide the correct equipment for them to use such as height adjustable chairs. Design consideration need to be made so that

software is easy to user.

Sub title - Copyright Design and patents act.

> It is illegal to use software you do not have the licence for. This is also covers material such as music and films.

If you do not have the licence you are not allowed to download or stream it. Designers must observe copyright when developing software.Sub title - Data Protection Act Requires that personal information is stored securely and is only used for the purpose for which it was originally gathered. The Data held must be.

Processed fairly and lawfully.

Obtained for specific lawful purposes.

Adequate (not excessive) and relevant for the purpose for which it is collected. Held no longer than required.

Accurate and up-to-data. The 'data subject' has the right to access their data, have it correct or removed.

Kept securely against loss, damage or unlawful processing.

Shared only to countries with similar data protection.

Sub - Ethical implications

An 'ethical' act is something that is fair and morally right. Examples of ethical issues around computer systems are:

Will everyone be able to afford it?

Will there be fair charging

Are some countries being exploited as a source of cheap labour for all centres and for programming

Does the system design promote accessibility for all?

Is the computer system being misused

Sub - Environmental Implications

Computer systems can be good for the environment but can also harm it with waste and energy use.

positive:

Reduce the use of resources such as paper.

Lead to more efficient manufacturing.

Reduction in fuel used for transportation.

Negative:

Disposal of systems due to toxic components.

Use of energy.

Página 2

ICT - revision

Introduction (Page 1)

Sub - Data Information and Knowledge

Data : Facts that have no meaning until they have been given a context.

Information : Data that has been given a context and therefore a meaning.

Knowledge : The bringing together of information in order to do something useful with it.

Sub - Hardware:

This is the term given to the physical devices that make up a computer. There is always at least one 'processer' to carry out the instructions given to the computer.

'Buses' are electrical links that are essential doe data to be transferred between components ans the outside world.

Common examples of computer hardware are:

Input devices.

Output devices.

Storage devices.

Sub - Software:

Software is the generic term given to programs that instruct a computer or other device to perform particular operations. These are given asa stream of binary symbols (0s and 1s) known as 'machine code'. Common examples of computer software are :-

System Software controls the hardware. It can also used to create new software.

Operating Systems let the user interact with the computer.

Editors let the user wrtie program source code

Compilers change the program source code to machine code that the computer can run.

Loaders copy programs from hard disk into RAM.

Utility Software lets the user do maintenance jobs on the computer.

Defragmenters let the user clean up the disks, getting rid of wasted empty space.

Compression software shrinks files, making it quicker to send them to somebody else.

Anti-Virus software detects and gets rid of viruses that might damage the computer system or data.

Anti-malware software can prevent programs taking control of a computer.

Image editors allow the user to edit and manipulate image files.

PDF (Portable Document Format) readers can display documents so that they exactly match the original.

Applications software carries out the jobs that we want.

Generic Software is the name given to universally used applications.

Proprietary Software is software owned by an individual or company. It is subject to copyright. Source code is a closely guarded secret (MS Windows, MS office and Adobe Design Suite)

Open Source software is developed by a worldwide community, where anybody can look at the source code (Linux OS,Mozilla,Firefox and Apache Web Server.

Página 3

Media Studies - revision

Title - Representation:

Introduction...

Representation is how media texts deals with and present gender, age, ethnicity, national and regional identity, social issues and events to an audience. Media texts have the power to shape an audience’s knowledge and understanding about these important topics.This makes them very powerful in terms of influencing ideas and attitudes.

In order to analyse media texts to determine how they've represented ideas and issues, it's important to be familiar with some of the key terms.

National - relating to or characteristic of a nation; common to a whole nation.

Regional - relating to or characteristic of a region.

Ethnicity - the fact or state of belonging to a social group that has a common national or cultural tradition

Sub - Key terms in representation:

> Construction

This is the way a media text is put together. In film or television programme this includes the editing and choice of camera angles, in a magazine or newspaper it includes the layout and writing as well as the choice of images.

>Mediation

This is the process everything goes through before it reaches an audience.

This can be how a film script is written and re-written before it makes it to production, newspaper or magazine photographs are cropped and captioned, or how real life events - like a protest or a speech by a politician - are portrayed in a news report.

>Selection

This refers to what has been selected to include in a media text.

This can be particularly important newspaper articles, where selecting certain facts over others can change the angle of a story; what is omitted is sometimes as important as what is included.

>Anchorage

These are the words that go along with images to give those pictures a certain meaning is a specific context. This includes captions and headlines in newspapers and taglines in adverts or on film posters.

>Stereotypes

These are a simplified representation of a person, groups of people or a place, through basic or obvious characteristics - which are often exaggerated.

For example, Vicky Pollard from 'Little Britain" is a stereotypical example of a working class teenage girl.

Página 4

Chemistry - revision

Sub-Atoms

Atoms consist of electrons surrounding a nucleus that contains protons and neutrons. Neutrons are neutral, but protons and electrons are electrically charged: protons have a relative charge of +1 and electrons have a relative charge of -1.

> Atoms and elements

All substance are made of tiny particles called atoms. An element is a substance that is made of only one sort of atom. There are about 100 different elements. These are shown in the periodic table, which is a chart with all the elements arranged in a particular way. The horizontal rows in the periodic table are called periods and the vertical columns are called groups. The elements in a group have similar properties to each other.

>Chemical symbols

The atoms of each element are represented by a chemical symbol. This usually consists of one or two different letters, but sometimes three letters are used for newly discovered elements. For example, O represents an oxygen atoms, and Na represents a sodium atom.

The first letter in a chemical symbol is always an UPPER-CASE letter, and the other letters are always lower-case. So, the symbol for a magnesium atom is Mg and not mg, MG or mG.

>Atomic structure

All substances are made from tiny particles called atoms. An atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons.

Different subject

>Chemical reactions

When elements react, their atoms join with other atoms to from compounds. Chemical bonds form when this happens, which involves atoms transferring or sharing electrons.

> Reactions and compounds

New substance are formed by chemical reactions. When elements react together to form compounds their atoms join to other atoms using chemical bonds. For example, iron and sulphur reacts together to form a compound called sulfied.

Compounds usually have different properties from the elements they contain.

> Ionic bonds

Chemical bonds involve electrons from the reacting atoms. Compounds formed from metals and non-metals consist of ions. Ions are charged particles that form when atoms ( or clusters of atoms ) lose or gain electrons:

Metal atoms lose electrons to form positively charged ions

non-metal atoms gain electrons to form a negativly charged ions.