GCSE ICT:

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• Microprocessors: Microprocessors (microchips) are in every computer and are basically the brain of a computer (where all the data is processed). They are responsible for running computer programs, responding to user input and lots more. They are installed on circuit boards.
• Central Processing Unit (CPU): A computers main processor is the CPU. They also contain: video card (a circuit board that generates video output), sound card (deals with input and output of sound), Wireless Card (picks up wireless signals), motherboard (the main circuit board which holds the CPU, memory chips and connections) as well as backing storage (the hard drive).
• Mainframes, Servers and Supercomputers: Computers range in size from the mainframes to tiny processors. Companies like banks and search engine firms do lots of processing so need lots of computing power. They use mainframes or servers. Mainframes are reliable, big and contain multiple copies of their parts so if one fails they just switch to another. Servers are fast PCs without parts to talk to the user (e.g. keyboards and screens). Servers can be connected together so they act like a single machine making it easy to increase and decrease the processing power and also doesn't matter if one machine fails. Embedded computers are inside everyday objects like washing machines, TVs, central heating systems, cars and phones. Supercomputers are new technology which contain the fastest and most powerful processors that computer manufacturers can make.
• Types of Computers: 1) Laptops - are small and thick, they're very portable. 2) Netbooks - are smaller, thicker and portable. 3) Tablets - are smaller, they have their own operating system and can have various applications loaded onto the. They are designed for internet use, have powerful processors and have large high resolution screens. They have touch screens and features like cameras, media players and GPS. 4) E-book readers - are more basically tablets designed for reading books. They use non-reflective display screens to mimic ink on paper. They have long battery lives and are light. 5) Smartphone - are like tablets but are smaller and lighter.

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• Hardware:
• Software:

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• Keyboards and Mice: QWERTY keybords are the most common type of keyboard, each key is connected to a switch which when pressed sends a signal to the CPU based on the keys location. Concept keyboards are typically found in shops and restaurants, they are faster but more limited. If you go to a fast food restaurant and order the worker will press an image of the burger. The CPU then tells a display panel to show the price and sends a message to the kitchen and stock control room. The mouse has two parts. They have two or three buttons, when the pointer is over an icon the mouse can be clicked or double clicked to give the computer a command. It can also be held down to drag something across the screen. The tell the computer direction and speed they are pushes to move pointer on the screen. Optical mice have an optical sensor underneath and work out their movement by watching how the surface below them move. Older mice had balls that rotates when the mouse is moved and sensors measure the movement of the ball in two directions.
• Types of Input Devices: 1) Keyboard 2) Mouse 3) Graphics Tablets 4) Joysticks 5) Scanners 6) Optical Character Recognition (OCR) 7) Optical Mark Recognition (OMR) 8) Chips or a magnetic strip on credit cards 9) Digital cameras 10) Web cams 11) Bar code readers 12) Touch screens 13) Microphones 14) Sensors 15) Midi Instruments 16) Remote Controls 17) Interactive Whiteboards
• Input devices are any hardware which is used to enter data into the computer system.

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• Printers and Monitors: Laser printers work like photocopiers and have four man parts: an electrostatic rotating drum, a lazer which etches onto the drum a negative image by removing the electrical charge, toner cartridge with ink when the drum passes over the toner cartridge ink is attracted to charged areas of the paper and transferred onto it and a fuser unit which heats the paper to fuse the ink onto it. These images have a very, high resolution, are very fast and quiet but they are expensive and contain complex equipment which is expensive to repair. Inkjet printers have a printhead and lots of nozzles with jets of ink which are sprayed onto the paper. They flow of ink is controlled by crystals inside the printhead which change shape when electricity is passed through and ink can be heated so that it expands. It produces a good resolution image, it cheap to buy and small but is slower and cartridges of ink are expensive. Computers process data faster than printers can print it so to prevent hold ups they: use a printer buffer that is memory that stores the pages that haven't been printed and spooling is when the document to be printed is saved onto the hard disk before entering the print queue, this frees up the CPU to continue to process data so other tasks can be done while waiting to print.
• Types of Output Devices: 1) Printers 2) Monitors 3) Speakers 4) Projectors 5) Actuators 6) Robotic arms
• An output device is any hardware used to communicate the result of data processing e.g. Printers are used to produce a permanent hard copy of the information on paper.

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• RAM: Random Access Memory is temporary memory that can be read from or written to quickly. There are two types of RAM. Volatile RAM keep its contents only while the power is supplied to it so if the power is cut the data is lost. Non volatile RAM needs power to change its contents so data stored there even when the power is switched off. If  computer doesn't have as much RAM as the programs running need it will use the hard drive as an overflow memory which is slower to access. So adding RAM will influence its processing power, speed and how many programs can be run at the same time.
• ROM: Read only memory is permanent memory that wont be lost in a power cut, so is a type of non volatile memory. The amount of ROM in most computers compared to the RAM is small. ROM contains the instructions that enable the operating system to be loaded into RAM from the backing store when it is turned on. However for mobile devices the operating software is stored on ROM.
• Bytes: Computers consist of a number of electric circuits and each circuit must either be switched on or off. This is why binary code is used to represent data, if a circuit is switched on it is represented as 1 and if it is off it is represented by 0. Bit - Each individual 0 or 1 is a bit, short for binary digit. Byte - 8 bits is called a byte. Kilobyte - 1 kilobyte (1KB) is about a thousand bytes. Megabyte - 1 megabyte (1MB) is about a million bytes. Gigabyte - 1 gigabyte (1GB) is about  thousand million bytes. Terabyte - 1 terabyte (1TB) is about a million bytes.
• Hard Disks, Solid-State Drives and Optical Disks: Hard disks are the main data storage found inside the computer. They are stacks of magnetised circular metal plates divided into different sized circles called concentric tracks and into triangular sectors. The data is on both sides of the sectors. Read/write heads just float above the surface of the disk so a speck of dust would ruin the hard drive so they must be kept in a sealed unit. However you can get external hard drives for extra storage. Hard drives have a large capacity (thousands of gigabytes) but all of the stored data can be lost. Solid state drives preform the same function as a hard drive no have no moving parts so aren't affected by movement, therefore are great for mobile devices. They have a quick access time (can read data very quickly) but are more expensive. Optical Discs are the main external backing store, they include Compact Discs (CD) and Digital Versatile Discs (DVD). They store digital data as pits (indentations) on the surface of the reflective disc. The data is read by a moving laser beam across the surface of the disc and reading the change in position of the reflected beam. DVDs old more data than CDs but less than Blu-ray discs.
• Flash Memory, Memory Sticks, Magnetic Tape and On-line Storage: Flash memory is a type of solid-state drive and a type of non-volatile memory which can be used to store gigabytes. It is a lot slower than the computer's main RAM but faster than a hard disk. It is very stable and doesn't break easily but it does wear out eventually. Flash memory's often sold in pen-sized devices that connect using USB socket, they allow you to easily transfer data between computers but are easily lost or stolen. Memory cards are used by digital cameras and some mobile devices. Magnetic tape can back up large amounts of data, this data can be stored relatively cheaply however the access time is slow. On-line storage is good for backing up data and for easy access from any computer with internet access also you can share your files with other people. The data is stored on file servers of an ISP (Internet Service Provider) instead of your own computer's hard disk.
• Backing Up: Backing up means making copies of files that can be stored somewhere safe so if the original gets lost or damaged there data is still safe. Back-ups need to be kept secure ideally in locked fireproof safes in a different location.

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• Types of Operating Systems: Operating Systems (OS) is the software that enables applications and the rest of the computer system to work e.g. Windows, Mac and Linux. All OSs have the same function  to talk to various bits of a computer so applications and hardware can run properly. 1) Interactive OSs allows users to interact with programs - they can alter the results of the program while it's running which is different to older OSs where the user couldn't run the program to affect the final outcome. 2) Multitasking OSs can run many programs at the same time which means they can share out resources such as available memory and CPU time. If more than one program wants to communicate with a peripheral (e.g. the internet) at once then the OS has to make sure it's shared too. 3) Multi-user OSs allow many people to log into a computer and use it at the same time. A multi-user OS has to do similar sharing of resources to do multi-tasking OS it also has to keep track of multiple workspaces so that each user has the same experience as they would using an individual computer. 4) Real time OSs run programs that need to react in a specific amount of time to events occurring in the outside world e.g. the stock market or the weather. The OS manages the computer's resources so that programs aren't interrupted allowing them to meet the deadline for their responses. 5) Online OSs are stored on a computer server that doesn't belong to the user. User files are stored on the server, users log in to the OS from any internet-enabled computer so they can use the OS as if it was on their own computer.
• Drivers: Drivers let Operating Systems (OS) talk to hardware, they are files that tell OSs how to communicate with computer hardware. Most devices e.g. printers come with a disc with suitable drivers on it. You need to install the driver on the computer that the device is hooked up to so the OS knows how to speak to the new device and make it work.

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• Files and Directories: Data is stored in files and directories. A file is a block of data that is stored under one name, called the filename. Some OSs store extra information with the file to identify the type and program needed to open it. A directory is a file but also an index, it tells the OS where on disk the files are, how big each file is and when it was created. In some OSs the files in a directory are images called folders and sub folders. Every file as a filepath which describes its location with the root directory at the beginning, then subfolders with the filename and its extension at the end. Files can be created, deleted, saved, managed and copied.

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• User Interfaces: The user interface (UI) is the way the user communicates with the OS and other software. Some UIs use command lines which is a black screen with lots of text, it can take a long time to learn all the commands but it is very powerful. Some UIs don't need a mouse and keyboard so instead use touchscreens, voice control or direct neural interfacing using your brain as the controller.
• Graphical User Interfaces: GUIs are the most popular types of user interface, they combines a menu-driven interface with icons to represent the main commands. They are more intuitive and accessible, users can also customise them to personal taste and you don't need to learn command lines.

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• Specific Purpose: Application software has a specific purpose, each task needs a different application software e.g. spreadsheet, database, word processor etc. Most application software has the same basic features to make them easier to use e.g. undo, wizards, zoom. You can change the font, text size, line spacing, alignment, justification, headers and margins.

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• The Basics: When turning on a computer it loads the operating system, it will stop loading if you need to log in. After you've finished using the computer you can shut it down, log off or put it on stand by (reducing energy consumption).
• Hardware and Software Problems: When a software freezes (stops responding to the users input) or a piece of hardware stops working you can: 1) Restart your system. 2) Reinstall software if the program isn't working frequently as a file may be corrupted. 3) Install patches if there is a problem with the source code. 4) Check your hardware is connected properly. 5) Update the driver. 6) Read the instructions or call a help line.

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• The Basics: Spreadsheets are clever calculators. It is a program that can display and process data in a structured way. They can record data, sort data, search for items of data, perform calculators based on data and produce graphs and charts of the data. For example they are used in doctor's surgery, calculating exam results or producing graphs for questionnaires. Data is entered into cells. A spreadsheet is made up of table in rows and columns. Each cell has a column letter and row number (coordinates). Cells can contain one of these: numerical data, text or formulas. But you can't mix letters and numbers like 3g. You can enter information using a mouse, radio buttons, tick boxes and a drop down list. Data can be formatted to improve its appearance by changing the font, the alignment, shading, border etc.
• Functions: A formula is an instruction to the computer to process data held in specific cells. Click in a cell, enter an equals sign and type in the formula. The formula can be copied to other cells and if the data n cells change is recalculated. Relative cell references use the data in the same place relative to the answer cell. Absolute cell references refer to specific cells that won't change. Sum, average, round, roundup, max, min, rank, count and if which checks if data matches a condition (e.g. if it true or false). Colons are used to show ranges e.g. A1:D7. The lookup function displays specific data to find products. 
• Charts and Graphs: To make a chart put all data into a single column, highlight the data, select the type of chart, choose a title and if needed use a key (also called a legend). Bar graphs are used for discrete data, line graphs for things like time, scatter graphs show the relationship between data and pie charts show contribution of categories to a total.

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• Models: Spreadsheets use formulas to try and describe the rule that real world problem. Input values can then be processed using these formulas to produce output values. They can carry out what if analysis to see the outcome of changes which can be put into charts and graphs.
• Example 1: A school could build a model to represent the relationship between the number of pupils wanting to eat in the canteen, the number of staff and the queuing time. It could find out the number of staff needed to keep queuing times down in a specific time. However it is questionable data as the number of staff is infinite and other things could go wrong.
• Example 2: A pizza business could use a model to show its profits from selling pizzas. They could change the variables and numbers to see the impact on the profit. It could be extended to give a direct link between the price of pizza and the number sold.

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• Types of Databases: A database is a store of data in an organised way in one or more tables. Each table is organised into fields (down) and records (across) with column headings called field names. Each table has a primary key which can uniquely identify and record. Databases can quickly find specific data and can generate reports. They can be Flat file or relational. Flat file databases have the data organised in one table, they can be created using all database programs and most spreadsheets. Relational databases store data in separate tables all linked together by key fields so things like customer addresses only need to be stored once in the database (reducing data redundancy). It is easy to update as you only need to change one table. The fields need to be well-structured  with the correct data type like audio and video.
• Entering Data: In the design view you can create fields, name them, give them a data type and a primary key. You can set up data validation rules like data must be from a list or a range. In the datasheet view you can change or add data. Forms are easy ways to edit and create data. They have selection boxes and move through records.
• Accessing Data: Database records can be sorted and filtered. To sort you can choose a field and the records are then sorted into order using the entries in that fields. They can sort into alphabetical, ascending and descending order. Filters show records that match a certain criteria. Using a query you can search a database. The query results are displayed as a separate datasheet. Simple queries tell the database to look for results meeting one conditions. Wildcard searches are searches when only part of the criteria. Complex searches search for data meeting more than one condition.
• Reports: A report is the result of a database query that is intended to be seen by someone else, they can be scree based or printed. In record format the display each record separately and in column format reports display the data in a big table. You can use calculations, charts and graphs and is flexible in terms of data.

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• Types of Text Formatting:

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• Word Processor Uses: A word processor allows users to write, edit and format text documents. It can be used to make letters, essays, memos and reports.
• Desktop Publishing Uses:
• Uses for Both:

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• Structure:
• Grouping and Watermarks:

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• Headings and Subheadings:
• Spell Checkers and Word Count:

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• Documents and Data:
• Merge Data:

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• Slides, Animations and Transitions:
• Other Features:

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• Web-design Software:
• Web Features:

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• Media Players:
• Creating and Editing:
• Downloading and Streaming:

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• Bitmap and Vectors:
• Tools for creating Images:
• Animation Frames and Uses:
• Animation Techniques:

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• Source Code:
• Interpreters and Debuggers:
• Compilers and Linkers:

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• Automatic Data Logging:
• Hardware and Software:
• Logging Period and Interval:
• Advantages and Disadvantages of Data Logging:

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• Computer Control Systems:
• Hardware and Software:
• Example 1 Greenhouses:
• Example 2 Burglar Alarms:

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• Models:
• Flight Simulators:

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• Computer Controlled Robots:
• Control Language (LOGO):

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• LAN:
• WAN:
• Advantages and Disadvantages:

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• Star Networks:
• Line Networks:
• Ring Networks:

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• The Internet:
• Connecting to the Network:
• Web Browsing:
• URLs and Search Engines:
• Features of Web Browses:

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• Encryption Software:
• Passwords and email attachments:
• Hackers and Viruses:

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• Email:
• Creating and Sending Emails:
• Managing Messages and Contacts:
• Text Messages:
• Instant Messaging, Forums and VoIP:

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• Interactive Features and Profiles:
• Advantages and Disadvantages:

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• Digital TV:
• Video Recorders:
• Home Entertainment Systems:
• Media Centres Input and Outputs:

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• System Life Cycles:
• Identifying Problems:
• Suggesting Solutions:
• Feasibility Study Checks:

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• Input:
• Process:
• Output:
• Top Down Diagrams:
• Data-Flow Diagrams:
• System Flowcharts Symbols:
• System Flowcharts Uses:

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• Ways to Implement the System:
• Types of Tests:

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• User Documentation:
• Evaluation:
• Technical Documentation:

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• Data:
• Input, Process, Output Cycle:
• The Information Age:

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• Data Capture:
• Manual Methods:
• Automatic Methods:

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• Data Validation:
• Data Verification:

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• Expert Systems:
• Solve Technical Problems:

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• Data Protection Act:
• Personal Data Guardianship Code:
• Computer Misuse Act:

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• Physical Security:
• Access Security:
• Unsafe Internet:

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• Health Issues:
• Solutions:
• Employers Follow the Law:

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• Replaced and Created Jobs:
• New Ways of Working:
• Globalisation:
• Emerging Technologies and the Future:

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• Flexible Working:
• Increase Job Satisfaction But Requires Training:
• Collaborative Working:
• Project Management:
• Collaboration Software:
• Teleconferencing:
• Sharing Information:

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• Problems of the Internet:
• Staying Safe Online:

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• Access to ICT:
• Cultures and Communities:
• Hardware and Software for Disabilities:

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• Protecting the Environment:
• Political and Ethical Issues:
• Monitoring Everyday Activities: