3.2 input and output devices Flashcards
1
Q
what is an input device
A
a device that allows you to pass information from outside world into computer system
2
Q
what are examples of input devices
A
- barcode scanner
- digital camera
- keyboard
- microphone
- optical mouse
- qr code scanner
- touch screen (resistive, capacitive, infra-red)
- 2d/3d scanner
3
Q
what does a barcode scanner do
A
- shine red laser at barcode to illuminate
- white lines reflect light back, black lines absorb some and reflect less
- strength of reflection interpreted by microprocessor, converted to binary value
4
Q
what are barcodes typically used for
A
- scanning goods at supermarket checkout
- checking library books in/out
- tracking packages out for delivery
5
Q
what does a digital camera do
A
- as light enters camera, falls onto sensor made up of millions of pixels
- each pixel measure light intensity
- microprocessor converts into digital data representing colour values
6
Q
what is digital camera typically used for
A
- integrated into almost all smartphones
- professional photography
- security/surveillance systems
7
Q
why is digital camera required
A
- replaced traditional film based cams
- instant photos, no development required
- digital photos can be easily transmitted via wifi, bluetooth, etc
8
Q
why is barcode scanner required
A
- faster checkout q
- less error caused by manual input
- automatic stock control
9
Q
what does keyboard do
A
input text and numerical data
10
Q
what does optical mouse do
A
input movement to control cursor
11
Q
what is optical mouse used for
A
navigation and interaction with almost all elements of graphical user interface (GUI)
12
Q
what does microphone do
A
allows input of sound data
13
Q
why is microphone required
A
capture sound and store as digital approximation
14
Q
explain resistive touch screen
A
- 2 conductive layers
- layers separated by insulating layer
- when screen pressed, metal sheets touch, complete electrical circuit
15
Q
explain infrared touch screen
A
- grid of IR light over screen
- when screen touch, beams broken
