Input/Output Devices

Objectives 

• Describe different input devices
• Explain how different input devices can be applied as a solution to different problems
• Describe different output devices 
• describe how different output devices can be applied as a solution to different problems

Manual Input Devices

All input devices transfer data from the source in the outside world to a computer 

Some require more human intervention than others such as:

• Keyboards and keypads
• Pointing devices
• Microphones
• Touch screens
• Interactive whiteboards

Manual Input Devices

What are the positives and negatives of each input device? 

• Keyboards and keypads
• Pointing devices
• Microphones
• Touch screens
• Interactive whiteboards

I/O Devices

Now complete Tasks 1 and 2 of Worksheet 4 in your notebooks, the page is called I/O Devices

Barcode Readers

There are two common types of barcode systems:

Universal Product Code  version 'A' (UPC-A)

• Typically used in retail and warehousing

Code 128

• Used in transport and shipment tracking 

• Code 128 can represent letters and numbers whilst UPC-A can only represent numeric digits

Barcode Readers

QR (Quick Response) Codes

QR codes are 2D barcodes that can be read by smartphones or tablets 

They contain: 

• Links to websites or
• Information 

Try scanning these codes as examples:

Uses of QR codes in society

Common uses include:

• Restaurant coupons
• Mobile concert tickets
• Real estate agency boards
• Business cards
• Tourist information
• Advertising posters
• Cinema tickets

2D Scanners

•These are used to convert a hard/paper copy document or photograph into a computer-readable format

•Useful for emailing hand-drawn images or text to someone else

•For what other reasons might you use a document scanner?

3-D Face Recognition

•Security cameras may use face recognition

•Specialist software measures and compares the proportions of a person’s face with those stored

3D Scanners

•3D scanners are used in both industrial and medical fields

•Many 3D scanners rely on a technology called Tomography which basically means to image something in very thin slices (less than 0.1 mm thick)

•Here a solid cone has been sliced up into several thin slices which when put back together again form the original cone   

3D MRI Scanners

Sensors

•Some data can be obtained directly
through the use of sensors

•Sensors often collect data in an analogue
form and require conversion to digital data
to be processed

•Sensors are used in both monitoring
and control applications

•A Sensor is ‘A hardware device that can take measurement of physical properties, such as temperature or pressure, from real world surroundings. These measurements are usually a representation of the actual property being measured.’

Types of Sensors

• There are many types of sensor designed to carry out specific tasks. These include:
  • Gas (e.g. oxygen, carbon dioxide)
  • Infra-red (e.g. motion or heat source)
  • Light
  • Temperature
  • Pressure
  • pH (i.e. acid or alkalinity)
  • Magnetic field
  • Moisture/humidity
  • Acoustic (i.e. sound)

I/O Devices

Now complete Task 3 of Worksheet 4 in your notebooks, the page is called I/O Devices

Monitoring and Control

•Monitoring:

•With these applications, the computer or microprocessor will make no changes to the actual process; it will simply report the values

•Control

•The output from the computer or microprocessor can alter how the process is operating;

•it can change the value of the next input received by, for example, opening a valve, switching off a heater or changing the speed of a pump

•the output from the computer or micro processor can affect the next input it receives

Detection Systems

•The pressure sensors monitor an intruder stepping on the floor next to the windows, doors or on the floor next to valuable paintings

•The acoustic sensors pick up the sound of breaking glass or footsteps on the floor

•The infra-red sensors pick up movement in the rooms but also any changes in heat (e.g. heat radiation from an intruder)

Detection Systems

•This example of monitoring involves an intruder detection and alarm system in a house:

Detection Systems

•The system is first activated by the user keying in a PIN code or by placing an alarm fob near a receiver

•Sensors constantly monitor the rooms for intruders

•Data is converted into digital form using an ADC and is sent to a microprocessor

I/O Devices

•Now complete Tasks 4, 5 and 6 on Worksheet 4 in your notebooks, the page is called I/O Devices

•This task asks you to describe how sensors and a computer can be used to monitor the pollution levels in a river, at a number of points, over a period of time

Examples of Monitoring and Control

•Explain how the system used in a supermarket can control the quantity of tins of beans in stock so that the chance of running out is minimised.

(6 marks)