3.3 Fundamentals of data representation

Question 1

What base is decimal?

Answer 1

base 10

Question 2

What base is binary?

Answer 2

base 2

Question 3

What base is denary?

Answer 3

base 16

Question 4

why is hexadecimal often used in computer science

Answer 4

often used in computer science as hexadecimal can be expressed more compactly/use fewer digits than binary

Question 5

What does b represent?

Answer 5

bit

Question 6

What does B represent?

Answer 6

byte

Question 7

What is a bit?

Answer 7

a bit is the fundamental unit of information

Question 8

What is a byte?

Answer 8

a byte is a group of 8 bits

Question 9

What is the unit for a kilobyte?

Answer 9

kB

Question 10

What is the unit for a megabyte?

Answer 10

MB

Question 11

What is the unit for a gigabyte?

Answer 11

GB

Question 12

What is the unit for a terabyte?

Answer 12

TB

Question 13

How many bytes is one kilobyte?

Answer 13

1,000 bytes

Question 14

How many bytes is one megabyte?

Answer 14

1,000 kilobytes

Question 15

How many bytes is one gigabyte?

Answer 15

1,000 megabytes

Question 16

How many bytes is one terabyte?

Answer 16

1,000 gigabytes

Question 17

Why are binary shifts used?

Answer 17

Binary shifts can be used to perform multiplication/division by powers of 2.

Question 18

Define character set

Answer 18

A character set is the defined list of characters recognised by the computer

Question 19

Examples of character sets:

Answer 19

• ASCII
• Unicode

Question 20

What is “A” in ASCII?

Answer 20

65

Question 21

What is “a” in ASCII?

Answer 21

97

Question 22

What is “0” in ASCII?

Answer 22

48

Question 23

When do Unicode use the the same codes as ASCII

Answer 23

Up to 127

Question 24

What is the purpose of ASCII?

Answer 24

• Used to represent characters in the English language

Question 25

What is the purpose of Unicode?

Answer 25

- Used to represent characters across the world

Question 26

Benefits of Unicode over ASCII

Answer 26

- Can represent more characters than ASCII - Can support all common characters across the world - Can represent special characters e.g. emojis

Question 27

What is a pixel?

Answer 27

- Pixel is short for picture element - A pixel is a single point of an image

Question 28

What is colour depth?

Answer 28

The number of bits used to represent each pixel

Question 29

How do you calculate image size?

Answer 29

image size = width X height

Question 30

How can you improve the quality of a picture?

Answer 30

- Increase the resolution

Question 31

How does the number of pixel and colour depth affect the file size?

Answer 31

- A greater amount of pixels and colour depth leads to a greater file size

Question 32

How do you calculate image file sizes?

Answer 32

- size (bits) = width X height X depth - size (bytes) = (width X height X depth) / 8

Question 33

How is sound stored/ processed in a computer?

Answer 33

- Sound is in analogue form when said in a room - It is converted to digital form (by sampling) usually by a microphone

Question 34

What is a sample?

Answer 34

a sample is a measure of amplitude at a point in time

Question 35

What is sampling rate?

Answer 35

Sampling rate is the number of samples taken in a second and is usually measured in hertz (1 hertz = 1 sample per second)

Question 36

What is sample resolution?

Answer 36

Sample resolution is the number of bits per sample

Question 37

How do you calculate sound file sizes?

Answer 37

File size = sampling rate x sample resolution x seconds

Question 38

What is resolution?

Answer 38

a measurement of the number of pixels

Question 39

What is data compression?

Answer 39

When we take steps to reduce the size of a file

Question 40

What types of compression are there?

Answer 40

- Lossy compression - Lossless compression

Question 41

What does lossy compression do?

Answer 41

- Lossy compression completely removes some data - Attempts to remove data that will not be noticed - When the file is reconstructed, some data will be missing from the original file

Question 42

What does lossless compression do?

Answer 42

- Lossless compression removes no data - It works by identifying and summarising patterns in the data - When the file is reconstructed, it will be identical to the original file.

Question 43

Why use data compression?

Answer 43

- To use less storage - To transmit files faster - To send large files by email within the file size limits