Data

Question 1

What are

bits?

Answer 1

binary digits

Question 2

Why is

binary used for computers?

Answer 2

because it represents the state of the transistors that make up a computer

Question 3

What is the equation for the

number of binary patterns that can be produced by a group of n bits?

Answer 3

2^n

Question 4

What does the

ASCII character encoding system do?

Answer 4

assigns numerical values to textual data

Question 5

Defne

pixel.

Answer 5

picture element

Question 6

What is the equation for the

place value of the MSB of a binary number?

Answer 6

2^(n-1)

Question 7

What is an

overflow error?

Answer 7

when the result of an addition is too large to fit into the allocated amount of storage

Question 8

What can

overflow errors do?

Answer 8

cause programs to crash or produce unreliable/incorrect results

Question 9

What is the difference between

arithmetic shifts and logical shifts?

(right)

Answer 9

arithmetic shifts preserve the value in the MSB

Question 10

Why was

hexadecimal created?

Answer 10

because it is difficult for humans to remember and manipulate long binary patterns, and it’s easy to make mistakes when writing long strings of binary, and making sense of them is challenging

hexadecimal makes this easier

Question 11

Define

character set.

Answer 11

the defined list of characters recognised by a computer’s hardware and software

Question 12

How many

bits does ASCII use?

and what does it stand for?

Answer 12

7 bits

American Standard Code for Information Interchange

Question 13

What is the negative of

ASCII?

Answer 13

as it only uses seven bits, it cannot generate enough binary patterns to represent all the letters and symbols in common use across the world

Question 14

What are the

alternatives to ASCII?

(2)

Answer 14

extended ASCII
Unicode

Question 15

What is a

bitmap?

Answer 15

a digital image composed of a matrix of tiny blocks of colour called pixels

Question 16

What is

resolution measured in?

Answer 16

pixels per inch (ppi)

Question 17

What is

pixelation?

Answer 17

when the resolution is too low, and the individual pixels are visible

Question 18

Define

colour depth.

Answer 18

the number of bits used to encode the colour of each pixel

Question 19

What is the equation for

file size of a bitmap image?

Answer 19

width x height x colour depth

Question 20

How does

amplitude affect sound?

Answer 20

larger amplitude -> louder sound

Question 21

How does

frequency affect sound?

Answer 21

larger frequency -> higher pitch

Question 22

Define

sampling rate.

and what is this measured in?

Answer 22

the number of sound samples taken per second

Hz (1 cycle per second)

Question 23

How does

sampling rate affect sound?

Answer 23

larger sampling rate -> more accurate digital representation

Question 24

Define

bit depth.

(in terms of sound)

Answer 24

the number of bits used to encode each sound sample

Question 25

# What equation for the file size of a digital sound file?

Answer 25

sample rate x bit depth x duration

Question 26

# Define data capacity.

Answer 26

the amount of data that can be stored in a computer's memory or on a storage device

Question 27

# What do compression algorithms do?

Answer 27

reduce file sizes by repackaging or removing some of their data

Question 28

# What do lossless compression algorithms do?

Answer 28

reduce the size of a file while retaining the exact meaning of the original data ## Footnote this enable the file to be fully reconstructed to its original state when decompressed

Question 29

# What are some examples of lossless compression algorithms? | (3)

Answer 29

PNG - images FLAC - audio ZIP - archiving

Question 30

# What does a lossy compression algorithm do?

Answer 30

reduce the size of a file by permanently deleting some of its data ## Footnote this means that it can never be fully reconstructed to its original state

Question 31

# What are some examples of lossy compression? | (2)

Answer 31

JPEG - images MP3 - audio