Input Devices
Definition
Input devices are used to enter data and commands into a computer system. These devices translate the physical or analogue world into a digital format that computers can process.
Example
Common Input Devices:
• Keyboard - Input text and commands
• Mouse - Point and click interface
• Webcam - Captures video and photos, converting them into digital form
• Microphone - Captures audio input
• Scanner - Converts physical documents to digital images
• Magnetic Stripe Reader - Reads data from credit/debit cards
• Barcode Reader - Scans and decodes barcodes in retail environments
• Sensors - Temperature, motion, light, pressure sensors for various applications
• Keyboard - Input text and commands
• Mouse - Point and click interface
• Webcam - Captures video and photos, converting them into digital form
• Microphone - Captures audio input
• Scanner - Converts physical documents to digital images
• Magnetic Stripe Reader - Reads data from credit/debit cards
• Barcode Reader - Scans and decodes barcodes in retail environments
• Sensors - Temperature, motion, light, pressure sensors for various applications
Key Point
Considerations for Input Devices:
• Speed - How quickly data can be entered
• Accuracy - Precision of data capture
• Cost - Budget constraints
• Suitability for the specific task
• User accessibility and ease of use
• Speed - How quickly data can be entered
• Accuracy - Precision of data capture
• Cost - Budget constraints
• Suitability for the specific task
• User accessibility and ease of use
Output Devices
Definition
Output devices are responsible for conveying information from the computer to the user or another device. They translate digital data back into a format that can be understood by humans or other systems.
Example
Common Output Devices:
• Monitor/Screen - Visual display of information
• Speakers - Convert digital audio signals into audible sound waves
• Printers - Convert digital documents into physical copies
• Projector - Projects visual data onto a larger screen
• Actuators - Control physical movement in robotics
• Monitor/Screen - Visual display of information
• Speakers - Convert digital audio signals into audible sound waves
• Printers - Convert digital documents into physical copies
• Projector - Projects visual data onto a larger screen
• Actuators - Control physical movement in robotics
Dual-Function Devices
Definition
Some devices serve as both input and output devices simultaneously.
Example
Touch Screen:
• Displays visual output (output function)
• Accepts touch input (input function)
Modem:
• Sends data (output)
• Receives data (input)
• Displays visual output (output function)
• Accepts touch input (input function)
Modem:
• Sends data (output)
• Receives data (input)
Applying Devices to a Problem
Exam questions describe a scenario and ask for a device and the reason it suits that scenario. The device has to be a specific one, and the reason has to refer to the scenario.
Key Point
Sensors and actuators:
• A sensor is an input device that measures a physical quantity, such as temperature, light, movement or heart rate, and passes the reading to the computer without anyone entering it
• An actuator is an output device that turns a signal from the computer into movement, such as a motor turning or a valve opening
• A control system reads its sensors, processes the readings and responds through its actuators
Barcode reader and RFID reader:
• A barcode reader reads a printed pattern of lines using reflected light, so it needs a line of sight to the code
• An RFID reader reads data from a tag using radio waves, so it needs no contact and no line of sight
• A sensor is an input device that measures a physical quantity, such as temperature, light, movement or heart rate, and passes the reading to the computer without anyone entering it
• An actuator is an output device that turns a signal from the computer into movement, such as a motor turning or a valve opening
• A control system reads its sensors, processes the readings and responds through its actuators
Barcode reader and RFID reader:
• A barcode reader reads a printed pattern of lines using reflected light, so it needs a line of sight to the code
• An RFID reader reads data from a tag using radio waves, so it needs no contact and no line of sight
Worked Example
Worked Example: A Fitness Tracker
A fitness tracker worn in an athlete's shirt records speed, position and heart rate during a match.
A fitness tracker worn in an athlete's shirt records speed, position and heart rate during a match.
| Need | Device | Why it suits this scenario |
|---|---|---|
| Measure heart rate | Heart rate sensor (input) | Takes readings automatically while the athlete is playing |
| Track position and speed | GPS receiver or accelerometer (input) | Records movement without the athlete having to do anything |
| Show that the tracker is switched on | LED (output) | Small and uses very little power |
| Store the readings | Flash storage | Has no moving parts, so it is not damaged if the athlete falls. It is also small, light and low in power use |
Exam Tip
Name the device precisely: "accelerometer" or "heart rate sensor", not just "sensor". Then tie the reason to the scenario: flash storage is durable, so it survives a collision between players.