Hardware Flashcards
1
Q
Input device meaning
A
a device that converts inputs into digital data which can be processed.
2
Q
Output device
A
A device that shows the results of the processing in a way humans can understand
3
Q
Resistive screen
A
- consist of two conductive layers.
- Top layer made of polyester
- Bottom layer made of glass
- when touched, top layer makes contact with bottom layer
- Completing a circuit
- Sensor sends signal to Microprocessor which calculates coordinates of touch
4
Q
Capacitive screen
A
- Contains a conductive layer
- An electrostatic field is created around screen
- Sensors around screen monitor electrostatic field
- When touched, a charge is transferred to finger
- Microprocessor calculates coordinates of touch
5
Q
Infra red touchscreen
A
- Infrared rays are sent across screen from the edges forming a grid across the screen
- Sensors around edge capture beams
- Infrared ray is broken by a finger blocking a beam
- Microprocessor calculates coordinates of touch
6
Q
How QR (Quick Response) code works (a type of barcode)
A
- Scanned using a camera
- and is decoded by an application
- Illuminator shone on code
- Black squares reflect less light than white squares
- Corners of code are used for orientation
- Each small square is converted to a binary value
- Directs to website with information
7
Q
Optical mouse
A
- Shines an LED from bottom of mouse onto a surface
- Light reflected back from surface into a photoelectric cell
- This has a lens that magnifies the reflected light to detect of smaller movement
- When button on mouse is clicked, a microswitch is pressed. A USB connection is used to carry the data to the computer.
8
Q
2D scanner
A
- Scanner shines a light onto the surface of a document
- Reflected light is captured
- Uses mirrors and lenses
- Captured image is converted into a digital file
- Produces a 2D digital image
9
Q
3D scanner
A
- Scanners shines a laser over the surface of a 3D object
- Which records measurements of the dimensions of the object
- Measurements are converted to digital file
- Produces a 3D digital model
10
Q
Barcode Scanner
A
- Scanner shines red laser at barcode
- light is reflected back
- the black bars reflect less light than the white bars
- Guard bars used for orientation
- Sensors detect light
- Different reflections are converted to binary values
- A microprocessor interprets the data
11
Q
Keyboards
A
- Circuit board is located at base of the keys
- When a key is pressed, it completes a circuit
- Microprocessor determines which key has been pressed
- Microprocessor refers to a character set to indenfity which character the key represents
- Each character has a corresponding ASCII value
12
Q
Advantages of capacity
A
- Better image clarity espicially in strong sunlight
- Very durable screens with high scratch resistance
- Can allow multi-touch
13
Q
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Disadvantage of capacitive
A
- Does not work with gloves (only bare finger + special stylus)
- Sensitive to electromagnetic radiation
14
Q
Advantages of infra-red ts
A
- Allows multi-touch
- Good screen durability
- can operate with cracked or scratched screen
15
Q
Disadvantages of infra-red
A
- Sensitive to water or moisture
- Accidental activation
- Sometimes sensitive to light interference
