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Computer Science: Unit 4: Input Devices
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- 1Manual Inputdata being entered by had - human user
- 2Automatic InputData being read directly by the computer
- 3Input DevicesAny piece of equipment that turns data into electronic signals that can be processed by the computer.
Transfer data from the source in the outside world to the computer. - 4Give 3 examples of Automatic input devicesScanners
Barcode readers
Digital Cameras - 5Give 5 examples of manual input devicesKeyboard and keypads
Pointing devices
Microphones
Touch Screens
Interactive Whiteboards - 6What are keyboards/keypads?Small peg under key which pushes into a small hole and makes contact with a conducting membrane when pressed. - makes electrical signal to the processor. Piece of rubber under key makes it bounce up again. Each key uses a different binary number code to represent character. Info sent down wire or wireless to processor.
- 7Tracker ballHave a ball on tip of the device - moved by user. Device remains stationary
Requiring less desk space - 8What are the 2 types of mouses?Mechanical
Optical - used to input positional data - 9Mechanical mouseUses a rubber ball underneath which moves on a hard surface and sensors work out the orientation of the mouse.
- 10Optical MouseUses a red LED and a sensor to determine the movement of the mouse as it passes over patterns on a surface.
- 11Why would a tracker ball, touch pad and game counsel be used?Tracker ball - people who find a mouse uncomfortable
Touch pad - when don't want to plug in other devices into laptop
Game counsel - give control over game in 3D - 12What are 3 advantages of Mouses and Keyboards?Easy and familiar to use
Free with a typical computer
useful for a wide rage of tasks - 13What are 3 disadvantages of Mouses and Keyboards?Slower than automatic systems
Human users can make mistakes
People get tiered if type for too long - 14Digital MicrophoneTurns sound into electrical signals
Microphone detect sound waves. Diaphragm vibrates when hit by a sound wave. Causes coil to vibrate which changes the magnetic field produced by the magnet. Changes in current are detected and a signal is outputted.
microphone outputs analogue - ADC - digital - 15What are 4 common touchscreen technologies used with tablets, watches, mobile phones?Resistive
Capacitive
Infared
Surface Acoustic Wave (SAW) - 16Resistive TouchscreenHas 2 layers that conduct electricity. When touch the screen you push the 2 layers together, allowing electricity to pass through them - complete circuit.
Position touched calculated by microprocessor. - 17What are 2 advantages of Resistive Touchscreens?Least expensive type of screen
Can touch screen with any object - 18What is a disadvantage of Resistive touchscreens?Type of screen is easily damaged
- 19Capacitive TouchscreensMade of glass layers.
Uses conductive strips either side of a transparent conductive sheet at right angles so strips make a grid. An electric charge on the screen changes when you touch it. Screen checks which strip on either side has changed charge - finger where 2 strips cross - position calculated by a microprocessor. Stores electrical energy. - 20What is a advantage 2 and disadvantage 1 of Capacitive touchscreens?Adv - screen stronger than resistive, make brighter image
Dis - Must use finger (glove or pen don't work) - 21Infra-red TouchscreenUses a grid pattern of LEDs and photocells (light sensors). Has grid of invisible beams projected across a screen. Finger, pen or pointer will break the beams. Screen checks which 2 beams have been broken by pointer.
- 22What are 2 advantages and a disadvantage of Infra-red Touchscreens?Advs- strong bright image, can touch screen with any object
Dis - More expensive than others - 23Surface Acoustic Wave ScreensUse of ultrasonic sound waves. Uses 2 sound wave transducers (generate ultrasonic sound) and 2 receivers. Sound waves travel parallel to edge of glass vertically and horizontally. Position where screen touched is detected by a reduction in the sound wave amplitude
- 24Interactive WhiteboardsAllow user to use board as touchscreen or write over screen to create annotations - can be saved.
- 25Digital CamerasTurns light into electronic signals. Has aperture at front containing a lens and allowing light through. lens focus' light onto a sensitive electronic surface made of a grid of tiny sensors which turn pattern of light into electrical signals. Information stored as image in camera memory
- 261D BarcodeWay of holding a code number. Number is turned into a pattern of black and white pars. Patterns (wide and narrow) represent different digits
- 27EPOSElectronic Point of Sale
EPOS terminal is used at the checkout of many shops - 28How does a Barcode Reader work?Flashes light onto the barcode - light bounces back to the reader. Sensors in reader can detect the pattern of light and dark from the barcode - represent a code.
- 29Barcode ScannerSimilar to barcode reader but moves light across the barcode.
- 30What are 2 advantages of Barcode Readers?Quicker and more accurate than manual data entry
Barcode can be printed by any ordinary black and white printer - 31What are 2 disadvantages of Barcode Readers?Can only don 1 job - read barcodes
Not part of an ordinary computer - bought separately - 32What are the 2 common types of Barcode Systems?Universal Product Code Version 'A' (UPC-A)
Code 128 - 33What is the difference between the 2 barcode systems?Code 128 can represent letters and numbers. UPC-A can only represent numbers
- 34QR CodesQuick Response code
2D barcodes and can be ready by smartphones or tablets. Contain links to websites or information. - 35What are 3 advantages of QR codes?Has large pattern that stores more data than ordinary barcodes
Can store a web link
Can be read by special devices but also by using a smartphone app. - 36What are the types of dimensions?1D - one dimensional - a line
2D - flat surface
3D - 3 dimensional solid object - 37Document ScannerScans a flat surface ie a page to record content. Simplest scanner form will record the document as a single image. 2D
- 382D/ Document ScannerUsed to convert a hard/paper copy document or photograph into computer -readable format
- 39How does a Document Scanner Work?Bright light illuminate document. Head moves across the document scanning it to produce an image which sent to a lens. Focused image falls on a light sensitive sheet made of thousands of pixels that record the light intensity or color falling on each pixel. info stored as image.
- 40OMROptical Mark Recognition
Detects marks on paper or card
ie multiple choice on exams - 41OCROptical Character Recognition
Takes an image of a document. Software linked can detect different letters
Much quicker than typing - 423D Scannerrecords whole shape of a solid object. Use light or physical contact info sent to computer.
Uses: industrial - copy and manufacture objects
Medical - body scan. Cultural - 43SensorsAutomatic input Device. Measures and records the environment outside the computer. Measurement converted to digital value and inputted to the processor.
Hardware device - 44Types of Sensors 9Gas
Infra-red
pH
Light
Temperature
Magnetic field
Pressure
Moisture/humidity
Acoustic - 45ActuatorsMotors that are commonly used in conjunction with sensors to control a mechanism
- 46MonitoringReport the values and inform users of the status of the process being monitored.
- 47ControlOutput from computer or micro-processor can affect next input it receives
- 48Advantages of sensors rather than Humans 3Sensors more accurate and precise
can record constantly without a break
can record data in places humans can't - 49Disadvantages of sensors rather than Humans 2Can only detect one thing
Must use pre-set responses, not as flexable - 50Control SystemAutomatic system run by a computer. The computer monitors an environmental condition using sensors. The computer changes the environmental condition using devices it controls
- 51Give a diagram of a control systemInput - process - output
( )
Feedback - 52Describe a sensor feedback for any sensorMicrophones will have access to pre-set values for all sensors. Microprocessor will check/sample each sensor at a given frequency. If any sensor readings exceed the pre-set values, then microprocessor sends a signal to warn the user. Monitoring continues until user keys in pin/pass code to deactivate system - continuous
- 53Describe Temperature SensorTemperature sensors constantly take readings from ___
Data converted into digital format using an ADC and is sent to the computer. Computer has pre-set values for temp in memory. If temp below __ or higher than _ then computer sends a signal to an actuator to switch on the heating/cooling. Once temp withing acceptable boundaries computer sends signals to close value and/or switch off heater/cooler. Control continues till process complete
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- (Unit 4) Computer Science GCSE Fichas sobre Computer Science: Unit 4: Input Devices, creado por HRYN red el 21/01/2021.
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- HRYN red
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