1.2.4 Data Storage

Question 1

How to convert binary to decimal?
Convert 1001101 to decimal

Answer 1

64 32 16 8 4 2 1
1 0 0 1 1 0 1

64+8+4+1=75

Question 2

How to convert decimal to binary?
Convert 37 binary

Answer 2

32 16 8 4 2 1
1 0 0 1 0 1
100101

Question 3

How to convert Binary to Hexadecimal?
Convert 10101110 to hexadecimal

Answer 3

8421 8421
1010 1110
10 14
A E
AE

Question 4

How to convert Hexadecimal to Binary?
Convert 7F to binary

Answer 4

8421 8421
0111 1111
01111111

Question 5

How to convert Decimal to Hexadecimal?
Convert 237 to hexadecimal?

Answer 5

128 64 32 16 8 4 2 1
1 1 1 0 1 1 0 1
8421 8421
1110 1101
E D

ED

Question 6

How to convert Decimal to Hexadecimal?
Convert 1024 to hexadecimal

Answer 6

1024 512 256 128 64 32 16 8 4 2 1
0 1 0 0 0 0 0 0 0 0 0 0
8421 8421 8421
0100 0000 0000

400

Question 7

How to convert Hexadecimal to Decimal?
Convert DE to decimal

Answer 7

8421 8421
1101 1110

128 64 32 16 8 4 2 1
1 1 0 1 1 1 1 0
222

Question 8

Convert 4B to binary then to decimal

Answer 8

8421 8421
0100 1011
128 64 32 16 8 4 2 1
0 1 0 0 1 0 1 1
75

Question 9

What are Binary Addition rules?

Answer 9

0+0=0
1+0=1
1+1=0 carry 1
1+1+1=1 carry 1

1110
+0111
———-
(1) 0101
/overflow

Question 10

What is Binary Shift?

Answer 10

Shows multiplication and division of binary numbers

Question 11

0001
Shift 1 to the left x2

Answer 11

0001 = 5
0010 = 10

Question 12

00011
Shift left twice x4

Answer 12

00011 = 3
01100 = 12

Question 13

000011
Shift left 3 times x8

Answer 13

000011 = 3
011000 = 24

Question 14

00110101
Shift left 4 times x16

Answer 14

00110101
1/1 01010000

Question 15

00010100
Shift right once /2

Answer 15

00010100 = 20
000001010 no 0 = 10

Question 16

00010100
Shift right twice /4

Answer 16

00010100 = 20
00000101 = 5

Question 17

00000101
Shift to the right once

Answer 17

00000101
00000010.1
If you lose one you do a right shift.
5-2=2 lost accuracy with the number
lose 1 = lost accuracy of the number

Question 18

What is a character set?

Answer 18

• A character set is a table that matches together a character to a binary value
• Character sets are necessary as they allow computers to exchange data and allow humans to input characters using a keyboard

Question 19

What is an example of a character set?

Answer 19

A = 01000001 = 65
B = 01000010 = 66
C = 01000011 = 67

Question 20

What is ASCII?

Answer 20

• American Standard Code for Information Interchange is a common character set which doesn’t take up too much memory
• It is important to understand that the number of characters available are limited by the number of bits available
• ASCII uses 8 bits (1 byte) per character meaning there are only 256 possible characters to use
• Only inclusive for english language - became outdated in the 1970s

Question 21

What is unicode?

Answer 21

• Unicode is a more popular character set as it uses 16/32/64 bits per character
• Unicode-16 means that 16 bits are used per character meaning there are 65536 possible characters

Question 22

What does this mean we can include in unicode with 65536 possible characters?

Answer 22

• Different languages
• Symbols
• Emojis

Question 23

How do you calculate the size of a text file?

Answer 23

The file size of a text file is calculated as shown:
bits per character x number of characters

Question 24

A small text file uses the ASCII character set (8 bits per character). There are 300 characters in the file. Calculate the size of the file (answer normally in kilobyts)

Answer 24

8 x 300 = 2400 bits
/8 = 300 bytes
/1000 = 0.3KB

Question 25

What are the 2 types of images?

Answer 25

Bitmap and Vector

Question 26

What are Bitmap Images?

Answer 26

- Bitmap images are made up of pixels - a single square assigned a colour - laid out in a grid of a certain height and width - Each pixel is assigned a binary value which represents the colour of that pixel - Because it is made up of pixels scaling a bitmap up will result in a loss of quality

Question 27

How do you improve the quality of an image?

Answer 27

- Increasing the total amount of pixels in an image - this is known as image resolution - Increasing the amount of bits per colour to allow for more colours to be available - this is known as the colour depth

Question 28

What is the image resolution?

Answer 28

- The resolution of an image is the width in pixels multiplies by the height in pixels

Question 29

How do you calculate the size of a bitmap file?

Answer 29

file size = resolution x colour depth

Question 30

An image has a height of 6 and a width of 8, colour depth = 1 bit (only two colours). What is the file size? (answer in kilobytes)

Answer 30

Resolution = height x width = 6x8 = 48 bits File size = resolution x colour depth = 48x1 = 48 bits file size in bytes = 48/8 = 6 bytes file size in kilobytes = 6/1000 = 0.006 kilobytes

Question 31

What are vector images?

Answer 31

- Drawn by the computer using precise mathematical instructions to create lines and objects - Usually smaller in file size compared to bitmaps - Vector images can be scaled up without any loss of quality and typically used for logos and animations

Question 32

What is Metadata?

Answer 32

Additional data that a computer has on an image is called metadata and can include the following: - resolution - colour depth - geolocation - date created - last edited - file type - author details

Question 33

What is sound?

Answer 33

Singing, tapping, an alarm going off, these are all sounds that we maybe able to hear. When we visualise this sound it is usually an analogue sound

Question 34

How do you convert analogue to binary?

Answer 34

- The analogue sound wave needs to be converted to store the sound in binary. This is called analogue to digital conversion (ADC) - The amplitude (height) of the wave is measured and recorded in binary at specific intervals (sample rate).

Question 35

What is the sample rate?

Answer 35

- Sample rate / sampling frequency is the number of times per second the amplitude of the sound wave is measured in kilohertz (KHz)

Question 36

What is the sample rate impact?

Answer 36

- The higher the sample rate, the better the audio quality as the digital data more closely resembles an analogue wave - However, the higher sample rates mean a larger file size because more data is stored for each individual sample

Question 37

What is Bit Depth?

Answer 37

- Bit depth is the number of bits available to represent each sample - For example, a sample with a depth of 4 could mean 0011 or 0100. A sample with a bit depth of 8 could be 01001001. A common bit depth is 16 - Having a lower bit depth reduces the amount of sounds that can be captured

Question 38

What is the impact of bit depth?

Answer 38

- The higher the bit depth, the more bits are available to be used for each sample. Therefore the quality of the audio is often higher as the wave closely resembles the analogue wave. - However this will also increase the file size as each sample stores more bits

Question 39

How do you calculate the size of a sound file?

Answer 39

sound file size = sample rate x bit depth x duration

Question 40

A sound file has a bit depth of 4, a sample rate of 10 samples per second and the clip is 15 seconds long. What is the size of the sound file?

Answer 40

sample rate x bit depth = 4 bits x 10 = 40 bits length of the clip = 40x15 = 600 bits bytes = 75 KB = 0.075 MB = 0.000075

Question 41

What is an overflow error?

Answer 41

Occurs when a binary value is too large to be stored in the bits available