Input Devices - Theory Notes PDF

Ch.2: Input Devices Theory Notes Chapter 2 Input Devices Eng. Omar El Safty Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes 2.1 Analogu...

Ch.2: Input Devices Theory Notes Chapter 2 Input Devices Eng. Omar El Safty Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes 2.1 Analogue and Digital data Analogue data Definition: Data that is continuous In waveform Needs to be converted to be processed by a computer All natural/physical variables are analogue data. Digital data Definition: Discrete data In form of 1s and 0s (binary) Can be processed by a computer without conversion Any electronic device reads digital data. Analogue to Digital Converter (ADC) Example of devices that use ADC: Microphone ADC is needed to convert the analogue signals from the microphone into digital data that the computer can then process. Why analogue data may need to be converted to digital data: To be read/processed by a computer. Eng. Omar El Safty 14 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Digital to Analogue Converter (DAC) Example of devices that use DAC: Headphones/Speakers DAC converts digital data from the computer into analogue signals, which the loudspeaker then converts into sound. Why digital data may need to be converted to analogue data: To control an external device To be sent to an actuator 2.2 Pointing devices Definition: Devices used to move and control on-screen pointer/cursor. Mouse Advantages: Does not need a large desk area when compared to a keyboard A faster way to choose an option compared to a keyboard Disadvantages: Difficult to use for people with restricted hand/wrist movement Difficult to use if no flat surface is readily available Excessive use can lead to RSI Uses: Controlling the position of a pointer on the screen Opening, closing, and minimising software Moving and deleting files Touchpad Advantages: A faster way to choose an option compared to a keyboard Takes less physical space than a mouse More suitable if there is no flat surface available Eng. Omar El Safty 15 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Disadvantages: More difficult to control compared to a mouse Difficult to use for people with restricted hand/wrist movement More difficult to use when doing certain operations such as drag and drop Uses: Controlling the position of a pointer on the screen Opening, closing, and minimising software Moving and deleting files Tracker ball Advantages: Easier to use than a mouse and touchpad if the user is disabled More accurate positioning of pointer on screen than a mouse They are more robust than a mouse Needs less desk space than a mouse or keyboard Disadvantages: Needs training as it’s not standard equipment More expensive than a mouse Uses: Can be a good alternative to a mouse for people with restricted hand/wrist movement Used in some luxury cars to select functions 2.3 Other input devices Keyboard Advantages: Fast entry of new text into a document Easy way to input data Allows to input variety of data including text, numbers and symbols Disadvantages: Must learn how to type to achieve high input speed Slower method compared to direct data entry devices Excessive use can lead to RSI Fairly large device which uses up desk space Eng. Omar El Safty 16 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Uses: Input of data into applications software Typing in commands to the computer Numeric keypad Advantages: Very easy to carry around Faster than keyboards to input numbers Disadvantages: Sometimes, they have small keys, which can make input more difficult Not used to enter text Uses: In ATMs, to enter details Point of sale terminals (POS) in case the barcode reader fails to read the barcode Chip and PIN devices when paying by credit/debit cards Fast entry of numeric data into a spreadsheet Remote control Advantages: Operate devices from a distance, which allows for easier control of devices Useful for people with walking difficulties Disadvantage: Objects between the device and the remote control can prevent its operation Hard to use if the user has a disbaility in hand movement Joystick Advantages: Control is more realistic than using a mouse Easier than a keyboard to navigate the screen Disadvantage: More difficult to control a pointer using a joystick than other pointing devices Uses: Used in video/computer games Used in simulators (for example, flight simulators) Eng. Omar El Safty 17 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Driving wheel It is like a joystick but used whenever steering is required. Advantage: Easier than a keyboard or joystick to control steering movements Disadvantages: More expensive input device compared to a mouse or joystick Movements in the steering can be too sensitive, giving an unrealistic ‘feel’ Uses: Used in video/computer games Used in simulators (for example, flight simulators) Touch screen Advantages: A quick method to select options Small footprint Improved hand coordination No training is necessary to use it Disadvantages: A limited number of options are available Excessive use can lead to RSI The screen can get dirty with constant touching, which reduces its responsiveness Touchscreen is considered an input device and an output device. Touchscreen is NOT a pointing device. Uses: ATMs to choose from on-screen options Public information systems at airports, railway stations, tourist offices, etc. Mobile phones, tablets and phablets They can be used as an output device as a flat-screen monitor Eng. Omar El Safty 18 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Microphone Advantages: It’s faster to read text than to type it in using a keyboard If used in cars, it has the advantage of improving safety Disadvantage: Sound files can use up a lot of computer memory Speech recognition software is prone to errors Uses: To input speech/sounds to be used in various applications (for example, in presentations) Used in a voice-recognition system to enhance safety Used to input in speech recognition software to convert voice into text Graphics tablet Advantage: More accurate in drawing than using pointing devices Disadvantages: More expensive than other pointing devices It takes longer to produce a drawing using a graphics tablet than using a pen and paper Uses: To input freehand drawings. Digital camera Advantages: Memory cards can hold several hundred photographs The image can be immediately seen on the screen Disadvantages: Images often need to be compressed to reduce the amount of memory used Resolution is not as good as many expensive traditional cameras Eng. Omar El Safty 19 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Scanner Advantage: Allows images to be stored for further editing Disadvantages: They can be slow Quality is dependent on the resolution of the scanner Uses: Scan in documents and convert them into a digital format Scan in photographs and covert them into a digital format Light pen Advantages: Greater accuracy than touch screens Small so can be used where space is an issue Easy-to-use technology. Disadvantages: Problems with lag when drawing on screen Only works with CRT monitors Outdated technology Uses: Selecting objects on CRT screens Drawing on CRT screens Eng. Omar El Safty 20 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes 2.4 Direct Data Entry (DDE) devices Definition of direct data entry devices: Devices are used to input data into a computer with minimal human interaction. General advantages of using direct data entry devices: Faster data-entry system than manually typing data Errors are reduced as there is no manual input Optical Character Reader (OCR) Definition of OCR: A device that scans text from a hard-copy document. Specific advantage of using OCR: More accurate in reading detailed data compared to OMR Disadvantages of using OCR: Not a very accurate technique for reading handwriting Uses of OCR: Processing of passports and identity cards Converting hard-copy documents into digital form to be stored on a computer Automatic number plate recognition (ANPR) systems in car parks Optical Mark Reader (OMR) Definition of OMR: A device that can read the position of marks written on hard-copy forms. Disadvantages of using OMR: OMR is unable to recognize machine or hand-printed characters Marks need to be within a specific area for OMR to read correctly If the marks are not dark enough, they may not be read correctly Sometimes, they have to be manually checked before being read; this is both time- consuming and expensive Uses of OMR: Used in multiple-choice examination papers School registers Used to read questionnaires Eng. Omar El Safty 21 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Barcode reader What is a barcode? A barcode is a series of black and white lines of varying thickness Used to represent numeric digits or characters Uses of barcode: Used in supermarkets and other shops Used in automatic stock control Used in libraries to keep track of books on loan Barcode reader definition: A device used to scan barcodes on products. Disadvantages of using a barcode reader: More expensive to purchase than a keyboard Barcode reader needs to be close to the barcode Barcode reader might have read errors if the barcode is scratched Quick Response (QR) reader What is a QR code? Matrix black and white squares that can link to websites, videos, text, etc. Three large squares at the corners function as a form of alignment Advantages of using QR codes compared to barcodes: Can hold more data QR codes can be read from many angles Easier to scan as they can be read by any device with a camera and suitable software Faster to scan The QR code’s physical size can be small, so it takes up less space on a box, paper, etc. It is possible to encrypt QR codes, which gives them greater protection Disadvantages of using QR codes compared to barcodes: QR codes can be used to transmit malicious codes More than one QR format is available QR code uses: Advertising products Can automatically link to email, website, or contact telephone number Storing boarding passes electronically at airports and train stations Eng. Omar El Safty 22 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Advantages of using a QR code reader compared to a barcode reader: QR code reader has a faster reading rate than barcode reader QR code reader can read the code from any angle, whilst barcode reader must be aligned with the barcode to the reader QR code reader produces fewer errors during scanning Radio Frequency Identification (RFID) reader Definition: RFID readers are used to read information stored on RFID tags. What is an RFID tag? The RFID tag is composed of two components: 1 Microchip to store and process data RFID tag 2 Antenna to receive and transmit data Advantages of using RFID tags compared to barcodes: RFID tags can be rewritten so they can be reused RFID tags are more robust than barcodes RFID tags can store more data than a barcode Disadvantage of using RFID tags compared to barcodes: More expensive to use compared to barcodes Specific advantages of using an RFID reader: No line-of-sight contact is necessary for the RFID reader to read the tag Very fast read-rate RFID reader allows both read and write operations to take place An RFID reader can scan multiple items at the same time RFID reader can read scratched tags (as long as they are not severely damaged) Disadvantages of using an RFID reader: Tag collision may occur Easy to jam as RFIDs use radio waves Can hack into the signal transmitted by the tag RFID technology uses: Storing product details in supermarkets Tracking of livestock (animals on a farm) Tracking books in libraries Storing the fingerprint of the passenger in a passport Storing details of automobiles Contactless payment Eng. Omar El Safty 23 Eng. Mustafa El-Komy Ch.2: Input Devices Theory Notes Magnetic stripe reader Definition of magnetic stripe reader: A device is used to read the information on the magnetic stripe card. Specific advantage of using magnetic stripe reader: There is no typing, which removes the risk of shoulder surfing Disadvantages of using a magnetic stripe reader: No PIN is required, thus less secure if the card is lost/stolen Doesn’t work at a distance Chip and PIN reader Definition: A device used to read information stored on a Chip and PIN card. Disadvantages of using Chip & PIN reader: Requires typing PIN, which increases the risk of shoulder surfing Doesn’t work at a distance 2.5 Sensors Definition: It’s an input device used to measure the physical properties of the surrounding environment. Examples: Temperature sensor Pressure sensor Sound sensor Advantages: They take more accurate readings than humans They take more frequent readings than humans Disadvantage: Faulty sensors can give false results Why data from the sensors need to be converted for use by a computer: Sensors read analogue data Computers only understand digital data ADC must be used to convert analogue to digital so that data can be understood by the computer Eng. Omar El Safty 24 Eng. Mustafa El-Komy