Input output devices

Question 1

what do barcodes do

Answer 1

Barcode readers are used to quickly and accurately scan barcodes

Question 2

when are 2d barcodes used

Answer 2

• ticketless entry to concerts
• ## boarding trains

Question 3

advantages of laser scanners

Answer 3

• available in a variety of forms
• reliable and economical for low volume applications

Question 4

examples of laser scanners

Answer 4

• CCD readers
• Camera based readers - used for age verification or event ticketing

Question 5

how do digital cameras work

Answer 5

• shutter opens to let light on CCD
• Each sensor produces an electrical signal
• The signal represents a pixel;
  An (ADC) converts measurement of light intensity into binary/digital data;
  -filter is applied to generate separate data values for red, green and blue
  colour components;
• The pixels are recorded as a group / array;

Question 6

what does a digital camera use

Answer 6

a CCD or CMOS

Question 7

advantages of CCD sensor

Answer 7

• produces higher quality images
• used in higher end cameras
• more reliable since the technology has been around longer

Question 8

disadvantages of a CCD compared to a CMOS

Answer 8

• cost of power consumption, uses up to 100 times that of CMOS sensor

Question 9

what are RGB filters used for

Answer 9

to separate out wavelengths

Question 10

how do RFIDs work

Answer 10

• RFID tag contains circuitry and antenna
• RFID reader transmits electromagnetic field
• signal activates current in RFID tag
• RFID reader converts radiowaves back into binary

Question 11

how does a laser printer work

Answer 11

• Bitmap of image built in memory from page description.
• charge applied to drum.
• Laser beam directed at drum.
• Mirror is used to direct laser beam.
• Where laser strikes drum charge is neutralised
• charge applied to toner.
• Toner sticks to drum based on charge
• Paper passed over drum and toner transfers to it.
• charge applied to paper assists with transfer.
• Heater fuses toner onto paper.
• four drums are required.

Question 12

how to prevent sticking in laser printing

Answer 12

the electric charge on the drum is removed

Question 13

how does a barcode work (light source)

Answer 13

• light source directed at barcode
• prism moves light beam across barcode
• light is reflected back
• black reflects less light, white reflects more
• light sensor measures the intensity of light reflected back
• and converts it into binary

Question 14

digital camera barcodes process

Answer 14

• CMOS sensor measures light intensity at a point
• sensor outputs voltage, dependent on light intensity
• voltage turned into binary via ADC
• image processing software analyses image
• and identifies black and white bars in barcode

Question 15

How do optical discs read

Answer 15

• laser shone on disk
• light is focused on spot on track
• light is reflected back from disk
• amount of light reflected is measured
• disc spins at constant linear velocity

Question 16

hows data represented using a optical disc

Answer 16

• data is stored on one track
• continuation of pit reflects light whereas transition between land and pit scatters light
• transition between land and pit indicates a 1 and continuation of land/pit represents 0

Question 17

advantages and disadvantages of secondary storage

Answer 17

advantages - provides non-volatile memory that retains information even when the computer is turned off. This enables long-term storage of programs

disadvantages - secondary storage is not directly accessible to the processor and has slower access speeds

Question 18

problems with primary storage

Answer 18

its volatile, if you turn the computer off, data gets lost

Question 19

characteristics of hard disk

Answer 19

• they help fit more data in the same physical space
• they are more densely packed
• ## use magnetic storage to store data.

Question 20

what is latency

Answer 20

the time taken to read/write disk data

Question 21

examples of latency

Answer 21

seek delay - the time the head takes to move across the disk
rotational delay - the time the disk takes to move to the correct sector underneath the read/write head

Question 22

examples of optical disk formats

Answer 22

• read only
• recordable
• re writeable

Question 23

recordable formats features

Answer 23

uses a transparent dye that becomes opaque when heated by a laser

Question 24

rewriteable format features

Answer 24

uses a laser to change the state of a phase change alloy and a magnet to set the new state

Question 25

what is a solid state disk

Answer 25

a disk that compromises millions of NAND memory cells

Question 26

how do optical disks write

Answer 26

- a high powered laser burns pits into the CD surface - a low powered laser detects the reflection from pits and lands - only a put end deflects the laser light end and is read as a binary 1 - the point where the pit starts or ends causes the light to scatter

Question 27

Definition of drive

Answer 27

a device that reads and writes data from secondary storage

Question 28

What is media?

Answer 28

What the data is actually stored on

Question 29

Advantages and disadvantages of optical storage

Answer 29

ADV: - low cost per gigabyte - high capacity, ease of transport, data durability, and low cost DISADV: - Lower storage capacity - slower access times - Fragile

Question 30

advantages and disadvantages of magnetic storage

Answer 30

- cheap - large capacity, so popular choice for archives - low cost per unit capacity BUT - slow access time and fragile/not robust(as it has a lot of moving parts - noisy(due to disk spinning) - heavy, making them less portable

Question 31

how fast does a disk spin

Answer 31

speeds of up to 10,000 RPM

Question 32

features of a hard disk

Answer 32

- a drive head moves across the disk to access different tracks and sectors - data is read or written to the disk as it passes under the drive head - holds the operating system, application, and user data

Question 33

what happens to the drive head when it’s not being used

Answer 33

it’s parked to one side of the disk in order to prevent damage

Question 34

hard disk uses and why

Answer 34

huge capacity makes them suitable for desktop surfaces

Question 35

how much data can a CD ROM hold

Answer 35

650MB

Question 36

how much data can a blue ray hold

Answer 36

50GB

Question 37

uses of optical storage

Answer 37

- small backups and storing music

Question 38

how do SSDs work

Answer 38

- data is stored electronically, data is stored in floating gate transistors - electrons are trapped between oxide layers - NAND memory is used - data is organised into blocks - a whole block of data must be written - a block must be erased before it is overwritten - controller manages the organisation of the data

Question 39

why is an SSD is a better choice than a magnetic hard disk

Answer 39

- * SSDs have lower power drain; which is important if device will run on battery; * SSDs are less likely to be damaged if dropped; which is important as the devices will be worn and carried around; * SSDs have faster access time; which could allow more data to be stored per second (which may allow finer detail); * SSDs are silent; which means they will not disturb the users; * SSDs are lighter/less obtrusive/smaller; which is important for a device worn around the neck; * SSDs produce less heat; which makes them more comfortable to wear;

Question 40

adv and disadv of laser printers

Answer 40

- fast printing speeds, making them ideal for environments where large volumes of documents need to be printed quickly. - Laser printers produce crisp, sharp text and images with high resolution. - Laser printers consume more energy during operation compared to inkjet printers - there is a risk of toner smudging or streaking - higher upfront cost

Question 41

advantages and disadvantages of rfids

Answer 41

advantages: - Can be encrypted, reducing the chance of data theft. - durable and can be used loads of times - Can read RFID tags from a greater distance than barcodes. - RFID minimizes human intervention, reducing errors and saving time. disadvantages - Tags and readers can be expensive - Has shorter read ranges compared to some other tracking technologies

Question 42

advantages and disadvantages of digital cameras

Answer 42

advantages - Can store thousands of photos digitally. - Photos are easily edited and shared digitally without quality loss. - Photos can be viewed immediately after taking them. disadvantages - expensive - Large photo files require storage space and organization. - Smaller sensors may lead to lower image quality, especially in low light.

Question 43

advantages and disadvantages of barcode

Answer 43

advantages - reduces the risk of human error associated with manual data entry - Fast scanning with a high degree of accuracy. - Easy to use and understand - cheap to implement disadvantages: - Barcodes can become unreadable if scratched or dirty. - Can be easily copied or forged, offering no data encryption. - Holds less information than RFID or QR codes - Must be directly scanned, making it less efficient for bulk scanning. - Typically used for one-time applications, without durability for long-term use. -

Question 44

what are rfids

Answer 44

RFIDs provide a wireless means of identifying and tracking objects,

Question 45

disadvantages of SSDs

Answer 45

more expensive * higher cost (per megabyte) * higher error rate over time

Question 46

types of magnetic storage

Answer 46

- hard disk drives - floppy disks - magnetic tape

Question 47

what does a read/write head do

Answer 47

moves to the correct location, then reads or writes data

Question 48

difference between optical and magnetic storage

Answer 48

- magnetic uses a read/ write head - optical use pits and lands

Question 49

what does select , update, insert do in retail database

Answer 49

- SELECT query used to check if there is already a record for the product - UPDATE statement used to increase stock level if the product is already in database - INSERT used to create new record for product if it is not already in the database

Question 50

Explain why a laser printer with a built-in wireless network adapter is likely to be a suitable choice of printer for a small office.

Answer 50

** why a laser printer may be suitable** - Low cost per printed page/toner is cheaper than ink - Prints many pages per minute at high speed; - Options to install a variety of paper trays handling options; - Toner will not dry out - toner does not expire as quickly as ink; - High resolution output **Why having a wireless adapter is suitable**: - Easy to share printer between many devices; - Can print directly from computers with WiFi no need to install a network - Printer can be managed remotely - WiFi should be fast enough for likely number of users - WiFi should have sufficient range for devices to connect (as small office);

Question 51

Describe what is meant by "lower latency" in SSDs

Answer 51

Lower latency means quicker response times; the delay between requesting and accessing data is reduced in SSDs compared to HDDs.

Question 52

. Two reasons SSDs are faster.

Answer 52

No moving parts, so no seek time needed. Can access any memory cell directly (random access) instead of sequentially.

Question 53

how do magnetic discs read and write

Answer 53

- Disk is coated in a magnetisable material - Magnetising a spot in one direction could represent 0 and the other direction could represent 1 - Disk divided into rings called tracks - Tracks divided into sectors - Read/write head moves in / out - Wait until correct sector passes under read/write head - Disk spins at high speed - Read/write head senses magnetic field and converts to 0s and 1s

Question 54

why are SSDs durable

Answer 54

because they have no moving parts (found in traditional hard drives), making them more resistant to shocks, vibrations, and physical damage

Question 55

why ssds are better than optical discs

Answer 55

- can have a higher (storage) capacity; - have faster access/read/write times; - No drive is required to use a flash drive - Flash drives can be reused; - Flash drives are more compact; - Flash drives not damaged by scratches;