1 Data Representation

Question 1

Character sets

Answer 1

character sets are all characters & symbols that can be recognized by a computer, where each character is assigned a unique binary value

Question 2

Difference between ASCII and Unicode?

Answer 2

• ASCII has limited characters, Unicode has more
• Unicode includes more languages/emojis
• ASCII uses up to 7/8 bits per character whereas Unicode uses up to 16/32 bits per character
• ASCII has 128/256 characters

Question 3

Pixel

Answer 3

A tiny dot of color on a computer display

Question 4

Bitmap

Answer 4

A photo image consisting of pixels

Question 5

Resolution

Answer 5

Number of pixels in an image (width x height)

Question 6

Colour depth

Answer 6

Number of bits used in each pixel to represent a colour

Question 7

Image size

Answer 7

Dimensions of the image on the screen (w x h x color depth)

Question 8

Metadata

Answer 8

Information that is stored along with the image (e.g. filename, format, time, etc.)

Question 9

Lossy compression

Answer 9

• Data is permanently removed
• irreversible
• greatly reduce the size of file and loses quality

Question 10

Lossless compression

Answer 10

• Uses RLE (Run-length encoding) to reduce the size of the file where patterns are identified
• reversible and restorable
• image quality is not reduced

Question 11

Why is compression used?

Answer 11

• faster to download
• less storage space required
• shorter transmission time
• doesn’t exceed email limit

Question 12

Sound (5 steps)

Answer 12

• Analogue sound is recorded using a microphone
• Analogue sound is converted to digital using ADC
• sound wave is sampled and each sample taken is converted into binary
• each amplitude sampled (at regular time intervals) has a unique binary value
• Sample rate is set which is the number of samples taken per second.
• Sample resolution is set which is the number of bits per sample.

Question 13

Image (3 steps)

Answer 13

• An image is a series of pixels that are converted into binary, processed by a computer
• Camera captures image, turning into pixels
• Each pixel is given a binary value as they form a grid to create an image

File size and quality of the image increases as the image resolution and colour depth increase.

Question 14

Nibble

Answer 14

4 bits

Question 15

Uses for hexadecimal

Answer 15

• IPv6 address
• colour
• MAC addresses
• error codes

Question 16

Why is hexadecimal used

Answer 16

• easier debug
• easier to understand
• takes up less space

Question 17

calculating file size of sound

Answer 17

sample rate x sample resolution x length of sound clip