Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA Computer Science: Paper 2 > Internal / External Devices !! > Flashcards

Internal / External Devices !! Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Explain the operations of an SSD

A
  • Consists of NAND flash memory cells and a controller that manages the structure of data on the drive
  • NAND flash memory is non-volatile.
  • Memory cells are formed of floating gate transistors that store information by trapping electrical charge.
  • The presence of trapped charge or absence indicates 0 or 1
  • Data is stored in pages, which are combined to form blocks.
  • SSDs are not capable of overwriting data, instead the controller must completely erase the entire page before writing new info.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is NAND flash memory?

A

Non-volatile memory, meaning that the SSD’s contents are retained even when there is no power being supplied.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the advantages of an SSD?

A
  • No moving parts: suitable for devices that would experience a lot of movement (phones, tablets, laptops)
  • No moving parts: capable of higher read/write speeds than HDDS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain the operations of a Digital Camera.

A
  • Light enters through a lens. Light intensity is recorded by sensors (CCD)
  • Each sensor produces an electrical signal
  • The signal represents a pixel
  • An ADC converts measurements of light intensity into binary
  • A colour filter is applied to generate separate data values for red, green and blue colour components.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some advantages of digital cameras?

A
  • Film is not required
  • Image can be easily edited using editing software
  • Can immediately check and retake an image, the image doesn’t need time to develop.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are some disadvantages of digital cameras?

A
  • Initial cost of a digital camera is usually higher than a film camera
  • Digital storage can be lost -> doesn’t produce a physical copy
  • Digital cameras become out-of-date much faster than film cameras.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain the operations of a Laser Printer.

A
  • Bitmap of image is built in memory from page description
  • Negative charge is applied to photosensitive drum
  • A laser beam is directed at the drum
  • A mirror is used to direct the laser beam, where the laser strikes the drum the charge is neutralised.
  • Negative charge is applied to the the toner
  • Paper is passed over drum and toner is transferred to it.
  • Positively charged transfer roller assists transfer of toner from the drum to the paper.
  • A heater fuses toner onto paper.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some advantages of laser printers?

A
  • Low cost per printed page
  • It prints many pages per minute
  • No wet pages
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some disadvantages of laser printers?

A
  • Higher initial costs
  • Expensive to repair
  • Higher power consumption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain the operations of a barcode reader.

A
  • An oscillating mirrors directs light from a laser onto a printed barcode.
  • The light reflected by the barcode passes through the lens and is incident on the photodiode.
  • The photodiode turns light into electrical charge.
  • This electrical charge is measured and processed into a digital signal representing the content of a barcode.
  • Light portions of a barcode reflects the most light, dark sections absorb incident light. This corresponds to binary 1s and 0s.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do barcodes detect errors?

A

Barcodes have parity bits and check digits built in, allowing computers to tell if a barcode has been read correctly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens if a barcode reader fails to scan a barcode?

A

The reader will continue to scan until the barcode is read successfully.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why are 2D barcodes (QR codes) better than 1D barcodes?

A

2D barcodes can contain more information in the same amount of space as a 1D barcode.

It requires more processing in order for the info to be extracted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some advantages of barcodes?

A
  • Increases accuracy of receiving product info
  • Reduces training time for businesses
  • Low cost -> companies can create a limited number of barcodes for a low price.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are some disadvantages of barcodes?

A
  • Needs direct light in order for the barcode to be seen
  • Needs to be close to the barcode to be scanned
  • Must be scanned individually
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the operations of RFID.

A
  • An RFID tag contains a chip with a small amount of memory,
  • The chip is attached to a coil of wire that acts as an antenna
  • RFID tags can be passive or active:
  • When the RFID tag is scanned, the tag emits radio waves that are picked up by the tag’s antenna.
  • Power induced in the tag’s antenna from the waves is enough to power the chip.
  • The chip then uses its antenna to emit its own radio wave with information on the chip.
  • The wave from the tag is picked up by the reader.
  • The wave is decoded into information and returns the info to a computer system.
17
Q

What can Passive tags do?

A

Passive tags can induce enough power wirelessly from the reader to operate the chip.

Must be within a few centimetres of the reader.

18
Q

What can Active tags do?

A

Active tags contain a small power supply, like a battery.

Can be used much further away from readers.

19
Q

What are some advantages of RFID ?

A
  • Data on RFID systems are usually secure as it takes specialised equipment to read the data.
  • RFID tags can read multiple tags simultaneously -> increasing efficiency.
  • Automates data collections, which vastly reduces human effort and errors.
20
Q

What are some disadvantages of RFID ?

A
  • RFID tags are usually larger than barcode labels
  • The coverage of RFID is limited to ~3 metres.
  • More expensive than barcode systems.
21
Q

Explain the operations of an optical disk.

A
  • An optical disk is made up of pits and lands.
  • Pits are burnt into the disk by a high power laser, which permanently deforms the surface.
  • When a low power laser beam is passed over the flat surface of a disk, it reflects back onto a photodiode.
  • When the laser is incident on a pit, the light from the beam is scattered in different directions - NOT back in the photodiode.
  • Resulting pattern of reflections and scatters are converted into a digital signal of binary 1s and 0s.
22
Q

What are recordable and rewritable optical disks made of?

A
  • A pattern of reflections and scatters is created by an opaque dye on the disk’s surface.
  • When there is no dye, the disk reader’s laser beam is reflected off the disk’s surface.
  • Where there is dye, the laser beam is absorbed by the dye and not reflected.
23
Q

What kind of dye does recordable optical disks use?

A
  • Uses a special photosensitive dye.
  • This changes from opaque to transparent under a high power laser.
  • This is used to write information to the disk.
  • The dye remains unaffected by the low-power laser used to read the disk.

AQA Computer Science: Paper 2 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions