Data representation

Question 1

What is a bit?

Answer 1

A single 0 or 1

Question 2

What is a byte

Answer 2

8 bits

Question 3

What is a nibble

Answer 3

4 bits

Question 4

How many bytes in a kilobyte

Answer 4

1000

Question 5

What is the most significant bit?

Answer 5

The bit with the largest value (128)

Question 6

What is the least significant bit?

Answer 6

The bit with the smallest value.

Question 7

How can we convert 8 bit binary to hex?

Answer 7

Split the binary into two four bit binary, and convert each one into the relevant hex value.

Vice versa for hex to binary

Question 8

Why is hexadecimal used?

Answer 8

Simpler to remember than binary

Quicker to write or type as it uses 1 digit rather than 4 bits

People less likely to make an error

Easier to convert into binary

Question 9

What is an overflow error when adding binary

Answer 9

When the result of an addition is too large for the number of bits the computer works with

Question 10

What is a character set?

Answer 10

A set of letters, symbols and digits that can be represented by a computer

Question 11

What does ASCII stand for?

Answer 11

American Standard Code for Internet Interchange

Question 12

What does concatenate mean?

Answer 12

Two strings that are joined together.

Question 13

How many bits does ASCII use?

Answer 13

7 bits, which means that 128 characters can be stored

Question 14

Why is Unicode also used as a character set?

Answer 14

Unicode is used as it can store more characters from many different languages
It can also store emojis

Question 15

What is pixel an abbreviation of?

Answer 15

Picture element

Question 16

What is a pixel?

Answer 16

The smallest identifiable element of an image

Question 17

What is resolution?

Answer 17

Resolution is the concentration of pixels within a specific area

72 PPI - 17 pixels per inch

Question 18

How can we work out the number of different colours that are available using the colour depth?

Answer 18

2^bit depth = number of colours

A colour depth of 4 means 2^4 colours, which is 16

Question 19

How can we work out the file size of an image?

Answer 19

Resolution x bits per pixel

Question 20

What is metadata?

Answer 20

Other information about the data

Colour depth
Resolution
Date created
Author

Question 21

What is ADC

Answer 21

Analogue to Digital Converter

Question 22

What is DAC

Answer 22

Digital to Analogue Converter

Question 23

What is the sound sample?

Answer 23

A measure of amplitude of a soundwave at a given time

Question 24

What is sample resolution?

Answer 24

The bit-depth (how clear the sound is)

Question 25

What is the sample rate?

Answer 25

The number of samples taken per second

Question 26

How can we calculate the file size for a sound file?

Answer 26

File size = sample rate x resolution x duration

Question 27

What is lossy compression?

Answer 27

Removes sounds we can’t hear or that least affects the perceived playback quality

Question 28

What is lossless compression?

Answer 28

Reduces the file size without removing any information

Question 29

What is compression?

Answer 29

The name given to algorithms that reduce file sizes

Question 30

What are examples of lossy compression file types?

Answer 30

JPG
GIF
MP3

Question 31

What are examples of lossless compression file types?

Answer 31

TIFF
PNG

Question 32

What is RLE?

Answer 32

Run length encoding uses frequency / data pairs to encode each run length of the same coloured pixel

Question 33

What is Huffman coding?

Answer 33

Huffman coding counts the frequency of each character in a Huffman tree

Question 34

What are the advantages of compression?

Answer 34

Download times reduced
Data allowances go further
Possible to transmit video and music as fast as they are being played

Question 35

Why are smaller files sent faster?

Answer 35

Fewer packets which means they are transmitted faster

Question 36

What is buffering?

Answer 36

When the download speed is slower than the playback speed