4.7.4.1 Input and Output devices

4.7.4 External Hardware Devices

An external device is a piece of peripheral hardware that is not located directly within the computer's casing. In order for the computer to be able to communicate with an external device an Input/Output controller is needed. An I/O controller manages the communication between the device and the processor, allowing the processor to send and receive signals and data.

4.7.4.1 Input and Output Devices

Barcode Reader

There are two types of barcode: 1D (linear), and 2D (Quick Responce (QR))

Barcode readers consist of laser light source, a lense, photodiodes and a mirror.

• The mirror directs light from the laser onto a printed barcode. As this barcode is made up of white and back speced the light sections will relefect the light whereas the black sections will absorb it. This pattern corresponds to binary 1s and 0s.
• The light reflected by the barcode passes through the lense and is incident on the photodiodes.
• The photodiode then turns the light into an electrical charge which can be measured and processed to form a digital signal

Digital Camera

• Consist of a lense that reflects light onto a sensor. Sensors:
  • Are…