3.1.10 Data representation

Question 1

a bit has a value of…

Answer 1

1 or 0

Question 2

A nibble is …

Answer 2

four bits

Question 3

A byte is …

Answer 3

eight bits

Question 4

A kilobyte (KB) is …

Answer 4

1024 bytes

Question 5

What are the stages of converting sound to digital form/binary

Answer 5

• Computer cannot work with analogue data so it must be converted to digital data.
• Microphone picks up sound waves.
• Converted to an electrical analogue signal.
• Value read at specific point and rounded to a level.
• The points which sound is read and stored defines the sample rate.
• The higher the sample rate the better the quality but the larger the sound file.
• Binary representation of level stored.

Question 6

what happens if you reduce the sample rate?

Answer 6

reduces the data needed to store but also reduces the sound quality

Question 7

what other way can you reduce the amount of data needed for sound?

Answer 7

use less bits to represent each sample (also lowers quality)

Question 8

what are the stages of using binary to represent bitmap images?

Answer 8

• The image is represented as a grid or sequence of pixels.
• Each pixel is represented by one bit.
• White is represented by a 0
• Black is represented by a 1
• White and black are represented using different bit patterns.
• Same bit pattern used for black and white.
• Metadata about the image is also stored.

Question 9

what are the limitations of ASCII?

Answer 9

only 128 characters

Question 10

Explain the possible limitations of using ASCII character set for global communication: {3}

Answer 10

• ASCII is a 7-bit character set so can include at most 128 different characters
• characters represent mainly just the Latin alphabet
• characters of other alphabets cannot be represented.

Question 11

Advantages of using hexadecimal over binary {6}

Answer 11

• Hexadecimal is easier (for humans) to read than binary
• Hexadecimal is easier to convert to binary than denary.
• Numbers are displayed in a more compact way in hexadecimal than in binary.
• quicker to type in hexadecimal than binary
• Less memory is also used to store hexadecimal than binary.
• Easier to remember as they are shorter.

Question 12

what is a bitmap?

Answer 12

a digital image composed of individual pixels

Question 13

what do computers use to represent all data and instructions?

Answer 13

binary

Question 14

what types of data can binary code represent? {6}

Answer 14

text, images, sound, integer, data, real