IGCSE ICT 0417 Theory Notes PDF

THEORY NOTES PAPER 01  single integrated circuit board found on the computer motherboard 1. Types and Components of made up...

THEORY NOTES PAPER 01  single integrated circuit board found on the computer motherboard 1. Types and Components of made up of: Control unit: controls the input and output devices Computer Systems associated with the computer Arithmetic and logic unit: carries out calculations and 1.1. Hardware & Software makes logical decisions Immediate access store (RAM) Hardware Internal Hard Disk Drive (HDD) or Solid State Drive Tangible physical components of a computer system (SSD) You can feel it or touch it Internal Hardware Devices: computer’s main internal storage Processor this stores the application software, operating system, Motherboard and files RAM & ROM they have fast data transfer rates and data access times Video & Sound Cards large memory capacity to store data Internal Storage devices like Hard disk drives (HDD) & Solid state drives (SSD) RAM: External Hardware Devices: Random access memory (RAM) is an internal chip Monitor where data is stored temporarily Keyboard Memory can be written to and read from Mouse Stores anything that needs to be changed Printer All programs and data being used are on RAM External Storage Devices Contents are lost when the computer is turned off Referred to as volatile memory Software ROM: Programs that control computer systems Set of instructions that make the computer do something Read-only memory (ROM) is memory used to store You cannot physically touch the software permanent information Relates to ideas & instructions for using physical objects Used to contain configuration data for a computer etc. Chips cannot be altered, only read from Two types of software: Data is not lost when the computer is turned off Referred to as non-volatile memory Application software: BIOS: Programs that allow the user to do specific tasks ROM contains a boot file, referred to as BIOS (basic Design to carry out tasks input/output system) It can be general-purpose software or custom-made Tells computers what to do when it first starts software (specialist software) Does hardware check when the computer is turned on E.g. Spreadsheets, databases, word processing Then it loads the operating system into the RAM System Software: BIOS stores the date, time and system configuration Programs that allow the hardware to run properly Control the computer's hardware and application program Input & Output Devices Communicate with user E.g. Operating system, device drivers, compilers Input devices: The purpose is to provide data for processing 1.2. The Main Components of Computer Data is raw facts that alone have no meaning Examples: keyboard, mouse Systems Output devices: Displays the result of processing CPU Information is processed data that has been given meaning is now called the microprocessor Examples: monitor, printer interprets and executes the commands of the computer hardware and software WWW.ZNOTES.ORG CIE IGCSE ICT Secondary/Backing Storage Interface type Advantages Disadvantages -user is in direct Stores data/information & programs not being used at the -user has to learn communication current time many commands with the computer Backing store device = reader or recorder for simple functions \n -low resolution, Example: Hard disk drive \n -command has to cheap monitors can Backing store media = hardware containing data be in correct be used \n -less Example: Hard disk format, spelling (no expensive than GUI errors can be made Command Line \n -possible to alter or else command Interface (CLI) computer’s Basic Computer Model will not work) \n - configuration often difficult to settings \n -can change a command type commands to after it is typed in \n carry out any task -all commands on the computer need to be typed in, (not limited to icons time consuming on the screen) -expensive compared to CLI \n -user-friendly \n - -takes up more user doesn’t need computer memory 1.3. Operating Systems to learn any \n -user is limited to Enables users to communicate with computer systems commands \n -can choose from the Graphical User click on icons to icons present on Controls operation of input, output & backing storage Interface (GUI) open applications, the screen \n - Supervises loading, running & storage of application program simpler than typing requires an Deals with error in application programs In commands \n - operating system Maintains security of whole computer system easy to explore the (eg. WIndows) Maintains a computer log system which takes up Two main types of interfaces: CLI & GUI memory and is expensive CLI - Command Line Interface 1.4. Types of Computers Types commands to tell the computer what to do The user must know all the commands Desktop/Personal Computers Must not make typing errors Refers to general-purpose computers Used by technicians PC refers to IBM compatible computers, distinguishing Can access everything on the computer system them from the Macs GUI users can only access places they have icons for Made up of separate monitor, keyboard, mouse and \ processing unit Advantages GUI - Graphical User Interface Spare parts standardized results in low costs Uses graphics to stand for the complicated actions Tend to have better specifications Uses icons Less power consumption since computer is plugged Uses a mouse to select the icons into an electric socket always Screen divided into windows allows different things on A large casing allows good dissipation of heat build-up each Internet access is more stable because the computer is in one position WIMP - Windows Icons Menus Pointers Disadvantages Interface type Advantages Disadvantages Not portable since they are made up of separate components Wiring clutters up desk space Necessary to copy files as they aren't portable takes up a lot of desk space WWW.ZNOTES.ORG CAIE IGCSE ICT Laptop/Notebook Computers Advantages: Smallest lightest most portable Refers to computers where monitor, keyboard, pointing Integrated/virtual keyboard device and processor together in a single unit Often the least expensive device Extremely portable systems More practical for day-to-day use Low weight Disadvantages: Low power consumption Small screen may be difficult to use The processor doesn't generate too much heat Not as powerful as other devices Advantages Often has the lowest battery life Portable because monitor, pointing device, keyboard, Small size makes it easy to steal/lose processor & backing store units are together in one box Smartwatches No trailing wires Full advantage of Wi-Fi Have the same functions as a smartphone Can link into any multimedia system Uses OLED (organic light emitting diode) technology Disadvantages Can link to smartphones using Bluetooth Easy to steal features: Limited battery; need to carry charger Internet connectivity Keyboard and pointing device awkward to use Ability to message via text or video Heat dissipation is difficult due to laptop structure Weather forecasts GPS Advantages: Tablet Computer Very easy to use for monitoring health and fitness Convenient as notifications are delivered straight to These are small hand-held devices that can perform users wrist many functions that PCs & laptops do Disadvantages: Use touch screens to operate Large and bulky (heavy on the wrist as they have to On-screen virtual keyboard replaces physical keyboard accommodate the battery and screen to display apps) Often used by graphic designers to digitalize their content Usually unattractive in design with a stylus pen Can be used like a PC and/or a Smartphone Mainframe computers anti glare displays front and back facing cameras Large, very powerful computer systems longer battery life than laptops Are used to run commercial applications, such as banking light or insurance, where huge amounts of data need to be cloud storage facilities and SSD processed everyday equipped with sensors Features: Advantages: Have several CPUs Small, light & portable Fast processor speeds Built-in cameras for photos & videos Multiple operating systems Touchscreen can be used with a stylus pen Huge storage capacity Long battery life Huge internal memory (RAM) Fast to switch on Often use time sharing or batch processing No generation of heat because of SSD Disadvantages: 1.5. Impact of Emerging Technologies Less storage spaces Lacks power of laptop/PC This is technology that is being newly developed Digital keyboard can be difficult to use These can have several impacts on our society Touchscreen may be difficult to use for detailed work Artificial Intelligence (AI) Smartphone Technology that focuses on creating a computer system Modern phones that can perform similar tasks to all the that can closely mimic or simulate human intelligence above AI can be used to: Main use of smartphones is social media & day-to-day Enhance video games and computer tactics planning Help decision making steps in expert systems Use varies from person to person Make robots to imitate human behaviour WWW.ZNOTES.ORG CAIE IGCSE ICT Understand different human languages Dangerous jobs such as bomb disposal Impact on everyday life: Exploring extreme environments such as volcanoes Can be used to accurately predict hazardous weather Repetitive manufacturing jobs such as welding conditions and signal warnings automatically Moving heavy objects such as large engines Take over menial tasks for humans; increasing our Examples of robotics: leisure time Drones: used by civilians in surveying the landscape Can be used for safer automated travel; cars that can with GPS, and checking weather phenomena. Drones drive and park by themselves are also used by military for reconnaissance missions Increases home safety by being able to tell the Robots in surgical procedures: allow the surgeons to difference between owner & intruder; call authorities perform the procedures with more precision, flexibility automatically and control. Improved medical care as decision making skills and Impacts on everyday life: precision can be enhanced Increased personal time since robots can take over domestic chores Increased manufacturing efficiency since robots are Biometrics much faster and less expensive than human labour Unemployment as robots replace humans in A part of a person’s body is used to identify that individual autonomous jobs Can be: Safer working environments since robots can perform Fingerprints tasks that are too dangerous for humans Retina Iris Face Quantum Cryptography Voice These are all unique to everyone thus can be used as an Technology that allows messages and data to be sent with authentication technique complete privacy; basically, an advanced encryption Must be added initially to a system to use as identification An analog of normal cryptography i.e it still follows the Impacts on everyday life: church-Turin. The only difference is the speed at which Better security at the airport since most use at least they work. one form of biometric check if not more Makes it much more complex to decrypt Increased security in certain places as only authorized Impacts on everyday life: personnel can gain entry Completely secure voting ensuring that votes cannot Reduced vehicle theft since newer car doors come be tampered with or changed with a fingerprint lock on the door handle Completely secure communication eliminating the risk More secure mobile devices as most now have some of being read/heard by the wrong eyes/ears sort of biometrics integrated into them Completely secure bank transactions so money goes exactly where it is intended Completely secure personal information preventing Vision Enhancement hackers access to intrusive details about a person LVES: low vision enhancement systems: video projected inside a headset in front of the user’s eyes. Brings the Computer Assisted Translation (CAT) objects closer for the viewer. NVE: Night vision enhancement: dim light is captured and When human translators use computer software to help passed through a light intensifier tube, which converts in the translation process light to electrons. Electrons pass through another tube Can reduce translation time where they are amplified to produce more electrons. May not be 100% accurate Amplified electrons pass through to the end of the tube Common CAT tools: where they hit a screen coated in phosphor dots that glow Spell checkers when collided with. this creates an image several times Translation memory software brighter and clearer than the original Language search-engine software Impacts on everyday life: More accurate documents since most software can Robotics automatically detect errors More multilingual society since anyone with an Programmed machinery widely used to do physically internet connection can now essentially learn multiple demanding tasks languages using translators Can be automated or manually operated Quicker translations Used to perform several tasks: WWW.ZNOTES.ORG CAIE IGCSE ICT 3D & Holographic Imaging Technology that makes images appear to be 3- dimensional by adding a layer of depth Holograms use 2 regular 2D images and manipulate them to produce a 3-dimensional image QWERTY- layout Different laser beams are used to record the 2D images Ergonomic- reduces health related problems onto a single photographic plate Uses This creates an illusion of one 3D images Keyboards are used to input data into application Impact on everyday life: software Improved security since majority of credit/ID cards & Also used to for typing commands to the computer bank notes use holograms to prevent forgery (CTRL + P) Better movie experiences since 3D viewing can Advantages provide a more immersive experience for the Enables fast entry of new text into a document audience Well-tried technology & well-known method of entry Greater data storage since holographic layers can Most people find them easy to use potentially decrease the thickness of disc storage Easy to do verification check as data is entered, as it appears on the screen simultaneously Disadvantages Virtual Reality (VR) Users with limited arm/wrist use can find keyboards hard to use When computers create an artificial environment that Entering data is slow when compared to direct data users can virtually interact with entry (e.g. Optical mark recognition) Uses: They use up desk space as they are quite large Allow architects to walk around a virtual version of their design Training soldiers for combat by allowing them to fight Numeric Keypads against virtual enemies Training surgeons by allowing them to operate on virtual patients Playing games and enhance the level of immersion General VR equipment: Eye goggles that produce 3D images to develop the artificial environment A numeric keypad is used to enter numbers only Special gloves or controllers to perform precise Although some have function key to allow input of actions inside the simulation alphabetical characters Headphones to control what is heard in the virtual Uses world Used in Automatic teller machines (ATMs), where Powerful computer to run the entire VR system in real customers can key in their personal identification time number (PIN), or an amount of money Impacts on everyday life: Used to key in phone numbers into telephones Improved medical surgeons/soldiers Electronic point of sale (EPOS) terminals have numeric Stronger buildings keypads in case the barcode reader fails Treatment of phobias as certain situations can be Used in Chip and PIN devices to key in PIN, or amount treated using simulations of money More realistic education as students can learn in a Used to enable fast entry of numeric data into a more interactive environment spread sheet Advantages Numeric keypads are faster than standard keyboards 2. ## 2.1. for entry of numeric data Since many are small devices (e.g. mobile phones), they are easy to carry around Input & Output Devices Disadvantages Can be difficult to use due to the very small keys Difficult to use for entering text Input Devices & their Uses Sometimes the order of numbers isn’t very intuitive Keyboards Mouse WWW.ZNOTES.ORG CAIE IGCSE ICT An example of a pointing device They are more difficult when doing operations such as The ball underneath the mouse is used to detect ‘drag and drop’ movement The left button is for selecting by double on it and the right is to bring drop-down menus Tracker Ball There is usually a scroll button which speeds up the process of moving through a document Uses Used for opening, closing and minimising software Used for grouping, moving and deleting files Tracker ball is like a mouse except that it has a ball on the Useful when editing images (e.g. controlling the size top of the device and position of the image) Users control the pointer on the screen by rotating the Used for controlling the position of a pointer on the ball screen to allow: Uses Selection from a menu Have the same pointing/cursor control capability as a Selecting an icon mouse Scrolling up/down and right/left Used in applications where the user has a disability Advantages (RSI) Faster to select an option by a mouse than a keyboard Used in a control room environment, where it is faster Enables rapid navigation through applications and the than a mouse to navigate through process screens internet and more robust than a mouse Mice are small and don’t take much area Advantages Disadvantages Tracker balls don’t need the same fine control as a People with restricted hand/wrist movement can find it mouse hard to operate a mouse People with limited hand/wrist movement find easier Easily damaged and can easily be clogged up with dirt to use than a mouse They are hard to use if there is no flat surface The pointer can be positioned more accurately on the available screen than with a mouse They take less desk space than mice since they are stationary Touchpad Disadvantages Touchpads are used in many laptop computers as a Tracker balls are not supplied with the computer as pointing device standard, so they are more expensive The pointer is controlled by the user moving their finger User may need training since they are not standard on the touchpad equipment Uses Used for opening, closing and minimising software Remote Control Used for grouping, moving and deleting files Useful when editing images (e.g. controlling the size A remote control is used to control the operation of other and position of the image) devices remotely by using infra-red signals Used for controlling the position of a pointer on the Uses screen to allow: In home entertainment devices such as Televisions, Selection from a menu DVD player/recorder and satellite system Selecting an icon Used to control multimedia systems Advantages Used in industrial applications to remotely control Faster to select an option by a touchpad than a processes, stop and start machinery keyboard Advantages Enables rapid navigation through applications and the Enable devices to be operated from any distance, internet which is useful for people with disabilities Since the touchpad is integrated into laptop computer, Some chemical processes are hazardous, so it is safer there is no separate mouse, aiding portability to operate equipment from a distance They can be used when no flat surfaces are available Disadvantages Disadvantages People with limited hand/wrist movement can find People with limited hand/wrist movement can find them hard to use touchpads hard to use The signal between the control and the device can be It can be more difficult to control the pointer when easily blocked compared to a mouse WWW.ZNOTES.ORG CAIE IGCSE ICT Joystick Non-digital photographs can be scanned for storing on a computer Advantages Images can be stored for editing later Scanners are much faster and more accurate than typing in documents again It is possible to recover damaged documents and By gripping the stick, a pointer on the screen can be photographs by scanning them and then using controlled appropriate software to produce an acceptable copy Buttons are used to make selections Disadvantages Uses The quality can be limited depending on how good the Video/computer games are often controlled by scanner resolution is joysticks They are used in simulators to mimic actual controls Advantages Digital Cameras Easier to navigate round a screen compared to a keyboard Control is in three dimensions Disadvantages More difficult to control the on-screen pointer with a joystick than with other devices such as mice Photographs are stored in memory They can be easily transferred to a computer using a USB Touch Screen Uses Digital cameras can produce photographs for direct User can choose an option by simply touching a transfer to a computer or to print out button/icon on the screen Digital cameras allow short video clips to be produced The selection is automatically made without the need for Photographs can be uploaded directly into application any pointing device software such as word processor Use Advantages Used for service tills e.g. petrol stations Easier to produce better quality photographs than with Used where selections are made on a screen e.g. a tradition camera ATMs, public information systems, airports and Easier and faster to upload photographs to a railway stations computer Used in PDA’s There is no need to develop film and print out Used in Interactive white boards photographs (saves paper and no longer needs the Used in computer-based training (CBT) chemicals to produce photographs from films) Advantages Easy to delete an image from the memory if it’s not Enable faster entry of options than a keyboard/mouse satisfactory Very easy to choose options The memory card can store several hundred User friendly method for inputting data photographs They are tamperproof, preventing people from Disadvantages keying in information (which could corrupt the The camera user needs to be computer literate to use system) the camera properly Disadvantages There is some artistry lost since clever software There is a limited number of options available corrects errors in the photographs Using touchscreens often can lead to health problems The resolution is not yet as good as traditional e.g. (straining of arm muscles and RSI) cameras The screen can get very dirty with constant touching Images often need to be compressed to reduce the amount of memory used It is possible to fill up computer memory very quickly Scanners with several photos of the same subject (to find the perfect snap shot) Used to input information on hardcopy e.g. text document Uses Used to scan in documents and convert them into a Video Camera format for use in various software packages Old and valuable documents and books can be DV (digital video) camera store compressed photo frames scanned, protecting the original copies from damage at 25 MB/s – motion jpeg. WWW.ZNOTES.ORG CAIE IGCSE ICT Light turned into electronic signal through light sensitive Type of sensor Applications sensors and automatically converted to a digital file Automatic greenhouse, chemical format. pH processes, environmental monitoring Advantages Easy to edit footage in a video editing. Advantages High quality video captured, therefore Readings by sensors are more accurate than taken by Disadvantages humans Storage medium (Memory cards) more expensive to Readings are continuous, there is no break in buy than films. monitoring Because it is a continuous process any necessary Microphone action or warning will be initiated immediately The system can be automatic, removing the need for human intervention, this is particularly important if the process is hazardous Disadvantages Faulty sensors can give spurious results Graphic Tablet Can be connected directly to a computer Sounds can be inputted and manipulated Uses Microphones are used to input speech/sounds to be used in various applications They are used in voice recognition software- for A graphic tablet is used with a stylus to produce freehand conversion of speech into text, and recognition of drawings commands Uses Advantages Graphics tablets are used to produce drawings, Faster to read in text than to type it using a keyboard computer graphics Possible to manipulate sound in real time using In countries where characters are complex e.g. japan, special software they are used as a form of input If used in a voice activation system, this has the They are used in computer aided design (CAD) work advantage of improving safety Advantages Disadvantages It is possible to modify drawings before they are input Sound files can use up a lot of computer memory They offer an accurate method of drawing Voice recognition software isn’t as accurate as typing Disadvantages in manually They are more expensive than other pointing devices Sensors Web Cam Type of sensor Applications Automatic washing machines, central Temperature heating systems, automatic green houses, ovens Burglar alarm systems, robotics, Connected directly to a computer via a USB port Pressure environmental monitoring, Automatic Uses washing machines While chatting online webcams can be used to have Automatic doors, street lighting conversations Light control, Burglar alarm systems, Used to enable video conferencing to take place automatic greenhouses Advantages Burglar alarm systems, monitoring Can be left on constantly and activated when required Sound liquid and powder flow in pipes Allow people to keep in contact with each other Automatic greenhouses, without the need to travel, particularly useful for Humidity/moisture environmental monitoring, factories disabled or elderly people where moisture levels are crucial Disadvantages WWW.ZNOTES.ORG CAIE IGCSE ICT Webcams have limited features and the picture is Provide a more secure payment system than requiring often of poor quality a signature or using magnetic stripe, since the PIN They need to be connected to a computer typed in must match up with the PIN stored on the chip Provide a more robust system than magnetic stripe 2.2. Direct Data Entry & Associated since the chip does not need to be in contact with the reader Devices Disadvantages Customer needs to be careful when typing in the PIN, Magnetic Stripe readers so nobody reads it giving an opportunity for Fraud Radio Frequency Identification (RFID) Readers RFID readers work in similar ways to a bar code reader Used to read information on the magnetic stripe An RFID tag is attached to/inside a surface The stripe contains useful information such as start and The reader reads the data held on the tag which is then expiry date input into the computer system for processing Uses Radio waves are used to transmit data thus can be used Credit and debit cards have magnetic stripes that are through most materials used by ATMS or EFTPOS (electronic funds transfer Uses point of sale) terminal Used in retail or supermarkets as barcode Security cards for entering building e.g. hotel rooms alternatives Travel systems e.g. train and underground tickets Used to identify pets Advantages Used in passports Data entry is fast compared with keying in using a Advantages keyboard or keypad Can hold a lot of data System is error free, no typing involved Can be read from long distances Information is secure since there is no typing and the Does not require direct line of sight information can’t be read directly by a person Information can be read faster than barcodes Can prevent access to restricted/secure areas Can alter information Magnetic stripes are unaffected by oil water and Disadvantages moisture Thieves can steal information easily No moving parts therefore physically robust RFID tags are expensive Disadvantages Radio waves can experience interference If the magnetic stripe is damaged the data is lost \ Card needs to be in close contact with the reader Since the information is not human readable, they Magnetic Ink Character Reader (MICR) need to find a way to show the information to the customer (e.g. hotel room number not printed on cards) Chip & PIN readers Magnetic ink character recognition is a system which can read characters printed in a special ink Uses Used to process cheques in banking operations – cheque is read using a batch processing method Advantages The device has a slot where the card is placed, and the MICR offers great security than OCR since the oriented chip is read characters cannot be altered A small screen is part of the reader which gives There is no manual input, thus errors are reduced instructions to the operator If somebody writes over the magnetic ink characters, Uses it can still be read Chip and PIN readers are used where payments are Disadvantages made using cards e.g. travel agents Only certain characters can be read, and the number Advantages of different characters is very limited WWW.ZNOTES.ORG CAIE IGCSE ICT It is a more expensive method than other methods used for direct data entry Optical Mark Reader Used to read information in the form of a barcode Handheld scanners or wands are very common for reading barcodes Uses Optical mark recognition is a system which can read Used in supermarkets and other shops where the marks written in pen or pencil goods are marked with a barcode Uses Used in libraries to scan user’s library card and OMR devices are used to read questionnaires, barcodes on books (to keep track of books on loan) multiple choice examinations papers and other types Used as a safety function in many companies to of forms in the form of lines or shaded areas ensure that electrical equipment is checked on a Advantages regular basis A very fast way of inputting results of a survey Advantages Since there is no typing, it is more accurate than Faster than keying in information, and fewer mistakes keying in data are made OMR is more accurate than OCR Used as a way of recording data, can improve safety Disadvantages Barcodes enable automatic stock control Forms need to be carefully designed to make sure that Barcode scanning is a tried and trusted technology the marks/shadings are correctly positioned to gather When an item price is changed, only the central accurate information database needs to be updated, there is no need to There can be problems if forms aren’t filled correctly, change the prices individually on each item sometimes they must be checked manually before Disadvantages being read by an OMR, this is both time consuming Barcode scanning is an expensive system to and expensive administer since every item in the shops needs a barcode and every barcode needs to be entered on the system Optical Character Reader Also, there is a need to invest in the computer technology together with staff training, which can all be expensive The system is not fool proof- barcode can be swapped around on items Optical Character recognition is a software that takes scanned text and converts it into a computer readable 2.3. Output Devices & their Uses form Uses CRT Monitor Processing of passports and Identity cards Cathode Ray Tube monitors OCR is used when scanning documents to modify them using a suitable software Least expensive type of monitor, becoming rarer as TFT Advantages monitors take over Much faster data entry system than manually keying Come in various sizes Picture created is made up of tiny dots (red green or in data blue), the intensity of the colour of the dot determines the Since there is no manual data entry, the number of errors is reduced colour perceived by the eye Disadvantages Uses The system has difficulty reading handwriting Primary output device for computers, user can immediately see what they are typing in It is still not a very accurate technique Used with light pens to allow designs to be created on screen Advantages Produce higher quality images than TFT monitors Barcode readers Angle of viewing is better than a TFT monitor They work with light pens in CAD and CAM applications (Computer Aided Design/Manufacturing) Disadvantages WWW.ZNOTES.ORG  Tend to be heavy, weight hazard if not supported High power consumption properly Slow response time Run very hot, can cause fires if left unattended – Note: Old LCD monitors used CCFL (cold cathode especially if they are old fluorescent lamp) technology to light up the screen. Consume more power than TFT monitors They can flicker, this leads to headaches and eyesight problems with prolonged use LED Monitor: Front layer made from liquid crystal diodes; grouped TFT Monitor together to form pixels (RGB or RGBY-more vivid colours) For the image to show up on-screen a light source of LED backlight is used. Advantages (over LCD monitors): Lighter and thinner Longer life Lower power consumption Greater contrast and more vivid colour Relatively more robust Thin Film Transistor monitors Disadvantages Taking over from CRT monitors as the main output device Glare gives viewers headaches The progress in TFT technology is one of the reasons for Images too sharp, so can cause eye strain the rapid development of laptop computers The screen is made up of thousands of tiny pixels which are made up of transistors controlled by a Touch Screen microprocessor Each pixel has three transistors-red, green or blue; the Automatic selection without a pointing device intensity of each determines the colour of the pixel seen. Uses Uses Automatic teller machines Primary output device for computers, user can EFTPOS (electronic fund transfer point of sales) immediately see what they are typing in PDA Integral part of laptop computers Smartphones Advantages Public information points Lightweight, so no weight hazards like CRT monitors Advantages Less glare produced than in CRT monitors; also emit Faster data entry less radiation Easy to choose options Consume much less power and generate less heat User-friendly and intuitive than CRT monitors Disadvantages Disadvantages Limited options Angle of viewing is critical; image appears unclear if Frequent usage can lead to RSI, etc. viewed slightly from the side Constant usage results in the screen getting dirty; This is an issue if several people are looking at the visibility and sensitivity decreases screen at the same time They cannot yet be used with light pens, Multimedia Projector IPS/LCD Monitor Front layer made from liquid crystal diodes; grouped together to form pixels (RGB or RGBY-more vivid colours) Receive analogue and digital signals, although most Receive analogue and digital signals, although most modern projectors only work with digital inputs modern projectors only work with digital inputs IPS (In-plane switching) is the technology used in LCD The signal source is usually from a computer, television, monitors. or DVD player Advantages The image from the source is magnified and projected Colour can be seen accurately from different viewing onto a large screen angles The devices usually work with a remote control, but can No lightening on touching also use virtual mouse technology – cordless PC mouse Disadvantages (has a laser pointer) Expensive WWW.ZNOTES.ORG CAIE IGCSE ICT It is then possible to direct the presentation without These have been linked to health hazards in the office being tied to the computer Most multimedia projectors take input from various types of video format e.g. PAL, NTSC or SECAM Inkjet Printer Uses Used for training presentations (allows the whole audience to see the images from a computer) Also used for advertising presentations (shown at exhibitions, shopping malls etc.) Home cinema systems (projecting the images from a DVD or television) use multimedia projectors Used to produce good quality hard copies – the quality is Advantages not as good as in laser printers but much better than that Enables many people to see a presentation rather of dot matrix printers than all of them crowded around a small computer Do not have large buffers like laser printers, so printing is screen done a bit at a time Avoids the need for several networked computers Therefore, printing is sometimes paused – the whole page e.g. when looking at a video clip on the internet, can’t be stored in the buffer, it must wait for the computer everybody can see the video on the large screen to send more data rather than logging on to several computers Uses Disadvantages Used where low volume outputs are needed Images can sometimes be fuzzy Ideal for high quality printing for small print jobs or Expensive to buy single pages e.g. for photo quality printouts Setting up projectors can be a little difficult Advantages High quality output Laser Printer Cheaper to buy than laser printers Very lightweight and take up little space (small footprint) Do not produce ozone and volatile organic compounds, unlike laser printers Disadvantages Output is slow if several copies needed – there is little buffer capacity to store the pages Produce very high-quality hard copy output The ink cartridges run out too quickly to be used for Print rate per page is fast if many pages are being printed large print jobs Rely on large buffer memories – the data for the whole Printing can smudge if the user is not careful document is stored before pages can be printed out Can be expensive to run if they are used a lot – Uses original ink cartridges are expensive Used where noise levels need to be kept low e.g. in an office The best option for fast, high quality, high volume Dot Matrix Printer printing Advantages Printing is fast for high volumes, slightly faster than inkjet if only a few pages are to be printed Can handle very large print jobs Quality is consistently high Toner cartridges last for a long time; laser printers A type of impact printer A print head made up of a matrix of pins presses against can be a cost-effective option if colour outputs are not an inked ribbon required Disadvantages Uses Can be used in noisy environments e.g. garage Expensive to buy Only fast if several copies are being made workshops Can be used in applications were the print quality is Colour laser printers tend to be expensive to run since not very important four cartridges are needed as well as diffuser kits, etc. Advantages Produce ozone and volatile organic compounds because of their printing method and type of toner/ink Can be used in environments which would be a problem for laser and inkjet printers – dusty, dirty or used moist atmospheres WWW.ZNOTES.ORG CAIE IGCSE ICT Carbon copies or multi-part outputs can be produced Used to produce prototypes which work from CAD Very cheap to run and maintain packages, photograph images, stored drawings etc. Easy to use if continuous stationary is required e.g. Scale models are produced in colour before the real long print jobs such as wage slips thing is manufactured Disadvantages The ultimate objective is to produce organic objects Very noisy – not good in an office environment using this layering technology (such as replacement Cost more than an inkjet printer to buy human organs) Very slow Advantages Printing is of poor quality Save a lot of money, other methods of making prototypes are very time consuming and expensive The powders used can often be ground up and reused Wide Format Printer Physical scale models are produced with working parts, which gives a better idea of how the product will look Disadvantages Expensive to buy Slow at producing their output Product is sometimes a little rough, often further work Devices that produce hard copies but operate in a needs to be done different way to printers Not limited to normal printer paper size and can produce Speakers highly accurate, very large drawings and posters The most common types are pen plotters, electrostatic (similar method to laser printers) and inkjet plotters With pen plotters, coloured pens are controlled by a computer and the paper can move backwards and forwards to allow accurate shapes to be drawn Uses Used to produce large drawings e.g. blueprints of buildings; are often used with CAD applications Can be connected directly to a computer or are built into Used to produce large pictures for use on billboards the monitor or casing (as in laptop computers) or giant posters Uses a digital to analogue converter (DAC) to convert They can also print on plastic coated paper digital data from the computer to analogue from so the If the pens are replaced by cutting tools, it is possible to speakers can process it; the signal is then amplified make large signs through the speakers. Advantages Uses Can produce huge printouts Used to output sound from multimedia presentations Print quality is extremely high Used in home entertainment centres Disadvantages They can help blind people through audio output of Slow in operation text on the screen (together with speech generation Expensive to buy and maintain software) Used to play downloaded sound files Advantages 3D Printer Usually long lasting and durable (if operated within their intended power levels) Often provided with the computer/laptop although these may not be the best quality Disadvantages Can take up a lot of desk space, compared to headphones A new type of printer that produces solid 3D models using Can distract people around you, everyone can hear modified inkjet technology called tomography what you are playing Very thin layers of fine powder (plaster, resin, starch) are May not be able to hear the full sound spectrum, this bonded together as a 3D model is slowly built up requires multiple speakers Items produced are known as prototypes Uses Actuators WWW.ZNOTES.ORG CAIE IGCSE ICT A type of controlling device Transducers that are used to take signals from a 3. Storage Devices and Media computer and convert them into some form of motion e.g. operating motors, pumps, switches and valves 3.1. What is backing up of data? Digital signals are sent from the computer to an actuator to operate a device Backing up refers to the copying of files or data into a Conversion of the digital signal to analogue is required different medium first (using a DAC) Examples of different mediums files can be copied to are: disk tape Motors flash drive Why do we back up data? To safeguard against loss of data when the original Turned on or off by the actuator secondary storage device fails. The secondary storage Uses device can fail due to hardware failure, problems caused Used in many domestic appliances by files being overwritten or by corruption of files. Automatic washing machines (to make the drum To safeguard against damage caused by hackers. Even if rotate) the hacker’s primary intention wasn’t to hack the data in a Cookers (to switch on fans) computer, the very act of hacking into files could lead to Water pumps in central heating systems the possible corruption of data or data loss. Automatic greenhouses to open windows and switch When files need to be used elsewhere, the data can be on fans copied into a medium and transferred to another Used to control robot arms in the industry medium. Operate fans, disk drives and DVD drives in computers 3.2. Two Methods of Accessing Data: Buzzers Serial Access: Switched on or off by the actuator This involves starting from the beginning of the file and Uses accessing each record to get to the file required Used in cookers and microwave ovens to tell the It is a very slow form of data access operator when the cooking process is complete It is used in systems where the speed of accessing data is Used in burglar alarm systems to warn if intruders are not important present It is used in magnetic tape systems examples where serial access is used: utility billing Heaters clearing of bank cheques Actuators are connected to switches which turn the producing pay slips heater on or off Uses Direct Access: Used in automatic washing machines, cookers and This is used to access data stored in any record by typing central heating systems in the required key field Used in automatic greenhouses to control the Typing in a key field will allow the user to access a temperature particular record directly from the calculated position It is used in optical storage media, magnetic disks and Lights solid state media Accessing data is much faster The actuator is connected to the switch that turns the lights on or off 3.3. Magnetic Backing Storage Media Uses Security lights Depend on the magnetic properties of certain materials. Used in greenhouses to control the lighting conditions Magnetic material is coated on the surface of a disk which can be magnetised to represent a 1 or 0 and data is read accordingly. WWW.ZNOTES.ORG CAIE IGCSE ICT Fixed Hard Disks/Drives Data transfer rate is fast Disadvantages Available on all computers and is the main method used Access time is very slow (need to go through all for data storage previous files to reach the one required) Uses a read/write head to write and read data from it When updating another tape is needed Disk surface coated in magnetic film, storage is done by Affected by magnetic fields altering binary codes to 1s or 0s These hard disks are used to store the Disk Operating 3.4. Optical Backing Storage Media System (DOS), application software and files Uses CD-ROM/DVD-ROM Used to store operating systems and working data Used for storing application software Laser light is used to read data stored on CDs or DVDs Real time systems and online systems used fixed hard Use a thin layer of metal alloy or light-sensitive organic drives dye to read the data Used in file servers for computer networks Spiral track included Advantages Read only memory – cannot be overwritten Very fast data transfer rate Data is stored as a series of pits and lands formed by a Fast access times to data laser beam etching the surface at manufacturing stage Have very large memory capacities Uses Disadvantages CD-ROM stores music files and computer games Can be easily damaged DVD-ROM used to store films, computer data and They lack portability more sophisticated gaming software Many moving parts compared to Solid State Drives Advantages (SSD) Holds more data than floppy disks Large memory capacity Less expensive than hard disk drives Portable & Removable Hard Disks/Drives Disadvantages Data transfer rate and data access time are slower Like fixed hard disks but are usually connected via universal serial bus port CD-R/DVD-R Can be removed and connected to other computers Uses The letter ‘R’ means the disc is recordable only once and Can be used as backup systems to prevent loss of then it becomes ROM data Use a thin layer of an organic dye as the recording media Can be used to transfer data, files and software DVDs also use an additional silver alloy or gold reflector between computers Laser beam produces heated spots and unheated spots Advantages and the laser beam can distinguish between the two and Data access time and transfer rate is very fast interpreting the data as 1s or 0s Large memory capacities Uses Can be used to transfer files or data between They are used for home recording of music (CD-Rs) computers and films (DVD-Rs) Disadvantages They are used to store data for later use Can be easily damaged Used in applications where it is necessary to prevent the deletion or over-writing of important data Advantages Magnetic Tapes & Drives Cheaper than RW disks Thin strip of plastic which is coated in a magnetic layer Once burned (and finalized) they are like ROM Read and written by read/write head Disadvantages Uses Can only be reordered once Application where batch processing is used Not all CD/DVD players and can read CD-R Used as a backup media Long term archiving of data due to the large memory capacity of Magnetic tapes CD-RW/DVD-RW Advantages ‘RW’ means that these disks are re-writable media can be Less expensive compared to hard disk of equivalent written over several times memory capacity Unlike CD-R/DVD-R they don’t become ROMs Very robust technology WWW.ZNOTES.ORG CAIE IGCSE ICT The recording layer uses a special phase-changing metal Blu-Ray Discs alloy The alloy can switch between crystalline and amorphous Uses (non-crystalline) phases, thus changing its reflectivity to Blu-ray disks are used in home video consoles light, depending on the laser beam power Used for storing and playing back films Spots are produced which can be read by a laser PCs can use this technology for data storage or System allows data to be written, erased and re-written backing up hard drives many times Camcorders can use this media to store film footage Uses Advantage CD-RWs and DVD-RWs are used to record radio and Very large storage capacity television programs Data transfer rate is very fast They are used in closed circuit television (CCTV) Data access speed is faster than with other optical systems media Advantages Disadvantage Can be re used many times Disks are relatively expensive Different file formats can be used each time Blu-ray disks still have encryption problems Less wasteful than R format since files or data can be added at a later stage 3.5. Solid State Backing Storage Disadvantages Relatively expensive media Solid state systems control the movement of electrons Possible to accidentally overwrite within a microchip: if the transistor conducts a current, this is equivalent to a 1, otherwise it is a 0 Have no moving parts, consume much less power and are DVD-RAM extremely robust Used primarily as removable storage devices and are Recent addition to optical media group Unlike other CD and DVD formats, DVD-RAMs have collectively known as flash memory Flash memory makes use of NAND chips whereas several discrete concentric tracks rather than a single EEPROM (Electronically Erasable Programmable Read- spiral track Only Memory) uses NOR chips Gives them advantage that writing, and reading can occur at the same time Devices using EEPROM are more expensive compared to flash memory Makes it possible to watch an already recorded television program at the same time as a different program is being recorded Solid State Drives Recording layer is made from similar phase-changing material to that used in RW technology Supports reading/writing data & maintains stored data in Shiny and dull marks represent data to a computer where a permanent state even without power they are interpreted Functions much like a hard drive but different tech Uses Built with an array of semiconductors that form its DVD-RAMs are used in recording devices such as memory and operated using an integrated circuit satellite receivers to allow simultaneous recording Uses and playback Used to store operating systems and working data They are used in camcorders to store films Used for storing application software Advantages Used in file servers for computer networks Have a long life (30 years) Advantages Can be re written on more than the DVD-RWs (100,000 Faster than hard disks because they do not need to times) ‘spin up’ the disk Very reliable as they have built in verification software Robust because no mechanical parts to ensure accuracy of data Read performance is fast even when data fragmented Access is very fast Less susceptible to data loss No need to finalize the disk No moving parts so it is more reliable Very large capacities Lighter, quieter and require less power than hard Ability to read and write data at the same time disks Disadvantage Data access times is faster than HDD DVD-RAMS are not as compatible as R or RW, many Disadvantages systems will not recognize this format More expensive than hard disks More expensive than DVD-RW Have a smaller capacity than modern hard disks WWW.ZNOTES.ORG CAIE IGCSE ICT Lower number of write cycles causing performance to Commonly used to connect computers and other network diminish over time capable devices to the internet They can be connected to through cables or wirelessly Flash Drives/Memory Sticks Function Otherwise called pen drive/memory stick/USB stick Can store several GBs of data and use solid state Makes decisions on messages being passed between the technology networks Connected to a computer through USB port and power to Reads information about the message and decides where operate drawn from host computer the message should go and the best route for it to get Some expensive software increasingly uses these storage there methods as a form of security Formats the messages making it suitable for the new Uses network Used to transport files between computers Used as a security device – a dongle – to prevent software piracy How it Works Advantages Very compact and portable media To send data to a specific device, a router needs a something like an address Very robust Not affected by magnetic fields Internet Protocol Address: a unique number assigned to Disadvantages all computers and devices connected to the internet which Not possible to write protect the data and files can determine its exact physical location Small physical size and are easy to lose. A router can use this IP to send data from the internet to the exact device that requested it Lower storage capacity than hard disk Storing IP Addresses: Routers store IP addresses in a routing table Flash Memory Cards Routing tables list all the different routes to other networks A form of electrically erasable programmable read only Routing table determines best route for data memory (EEPROM) Uses Used to store photos on digital cameras Sending Data between Devices Mobile phones use them as memory cards Used in MP3 players to store music Routers can also send ‘packets’ of data between devices on different networks Used as a backup in hand held devices Advantages Each packet contains the data itself and the IP address of the device being sent to Very compact Very robust Occurs globally using multiple routers & re-routing until Disadvantages the data reaches its intended IP address Very expensive per GB of memory when compared to hard drive disks 4.2. Common Network Devices Has a finite life in terms of the number of times they can be read from/written to. Network Interface Cards Lower storage capacity than hard disks Used to connect individual computers/devices to a network 4. ## 4.1. NICs come in two distinct types: Wired: cards that have ports which allow network cables to be plugged in directly Networks & the Effects of Wireless: cards that connect to networks using Wi-Fi signals Using them Hubs Routers They are devices that can have multiple devices A device that enables data to be sent between different connected to them types of networks WWW.ZNOTES.ORG CAIE IGCSE ICT Main task is to receive data from different ports and send Laptop computers it to each device Peripheral devices such as printers The information will be received to the device whether its Wi-Fi Hotspots relevant, or not Wi-Fi systems rely on AP (radio frequency technology) to enable the device to receive and send signals Wi-Fi hotspots are places where you can access Wi-Fi Bridges (free or paid) Hotspots are found in public places like Airports, It connects 2 different types of networks together e.g. a hotels, and cafés bus and star network War driving: The act of driving and searching for It can only connect networks that use the same way for unsecured Wi-Fi hotspots handling messages This gives a risk to the Wi-Fi system They do this by changing the form of message to suite the different type of network Bluetooth Switches Bluetooth is an example of wireless personal area networking (WPAN) technology More efficient than hubs in distributing data Spread spectrum transmission (radio waves) is used to Each device has an access control media address MAC provide wireless links between to devices such as mobile which identifies it uniquely phones and allow connection to the internet MAC Address: a number unique to each device connected A small home network can be created with this system to the network (like fingerprints) Uses Data sent will have a mac address which tells the source Transfer photos from camera to mobile phone and receiving device Wirelessly connect different external devices Modems 4.4. Accessing the Internet It stands for modulator demodulator. User can access by web browser Converts computer’s digital signals (modulates it) into analogue for transmission through telepho