2b) Data Representation And Memory

Question 1

How much is a nibble?

Answer 1

4 bits

Question 2

How much is a byte?

Answer 2

8 bits

Question 3

How much is a kilobyte?

Answer 3

1000 bytes or 1Kilobyte

Question 4

How much is a megabyte?

Answer 4

1000 KB

Question 5

How much is gigabyte?

Answer 5

1000 mb

Question 6

How much is a terabyte?

Answer 6

1000 Giga byte

Question 7

How much is a petabyte?

Answer 7

1000 TB

Question 8

What does data need to be converted in?

Answer 8

Data needs to be converted in binary so a computer can understand it.

Question 9

What is binary used to store?

Answer 9

Numbers,text,images, sound and program instructions

Question 10

Why should data be stored in binary format?

Answer 10

Computers can only understand on and off switch circuits which are represented as 1s and 0s in binary. Circuits only need to check for two states.

Question 11

How do you find the size of sound?

Answer 11

Sound file size = sample rate x duration (s) x bit depth

Question 12

How do you find image file size?

Answer 12

Image file size = colour depth x image height (px) x image width (px)

Question 13

How do you find text file size?

Answer 13

Text file size = bits per character x number of characters

Question 14

How to convert denary to binary?

Answer 14

128,64,32,16,8,4,2,1

Question 15

What is a binary overflow error?

Answer 15

When adding two binary numbers we can end up with an extra digit that doesn’t fit.

Question 16

What are the Hexadecimal digits?

Answer 16

1 2 3 4 5 6 7 8 9 A B C D E F

Question 17

How to convert denary to Hex?

Answer 17

First draw the hexadecimal digits. Then Divide the number by 16 and write the digit then use the chart and put the remainder ad well.

Question 18

How to convert binary to hexadecimal?

Answer 18

First split it up in 4s. Then 8421 above both 4 numbers. Find the numbers out and convert to hexadecimal.

Question 19

What is most significant bit?

Answer 19

Th number furthest to left ( can be 0 or 1)

Question 20

What is least significant bit?

Answer 20

Number furthest to the right ( can be 1 or 0)

Question 21

What is binary shift?

Answer 21

moving the binary digits in the accumulator to the left or right a given number of spaces.

Question 22

How are characters are represented in binary?

Answer 22

By ASCII they charcters on a keyboard are assigned to a binary number

Question 23

How are characters represented?

Answer 23

Using binary codes

Question 24

What are character sets and what are the major ones we use today?

Answer 24

Character sets are a set of letters,symbols and digits that can be represented by a computer

• ASCII
• UNICODE

Question 25

The relationship between the number of bits per character in a character set, and the number of characters which can be represented?

Answer 25

• The more bits per character in a character set the more characters which can be represented
For example:
• ASCII = 7-bits - 128 characters
• Extended ASCII = 8-bits - 256 characters
• UNICODE = 16-bit and 32-bits - every possible character which might be written

Question 26

How is an image represented?

Answer 26

As a series of pixels, represented in binary

Question 27

What is a pixel?

Answer 27

The smallest part of an image

Question 28

What does each pixel specifically have?

Answer 28

A specific colour and represented by a specific code

Question 29

What is meta data?

Answer 29

Meta data is data about data for example :
- Author
- Date created
- Resolution
- Colour depth in bits per pixel
- height, width

Question 30

What does a higher bit depth give?

Answer 30

A bigger range of colours

If 8 bits per pixel
2^8 = 256 colours
2^16 = 65,536

Question 31

The effect on image size and quality when changing colour depth and resolution

Answer 31

The more colours larger the file size will be

Question 32

How sound can be sampled and stored in digital form?

Answer 32

An Analogue to Digital Convertor (ADC) is used to
convert inputs to digital signals

Question 33

How are analogue sounds stored?

Answer 33

In binary

Question 34

What are sample rates measured in?

Answer 34

Hertz

Question 35

What is bit depth in sound?

Answer 35

Number of bits to store each sample

Question 36

What is sample rate?

Answer 36

The sample rate is the number of samples taken
per second

Question 37

What does more bits in sound do?

Answer 37

Enables the height of the wave to be accurately measured but increases file size

Question 38

What is the need for compression?

Answer 38

Reduces the storage size
Reduces download times
Music and video is streamed faster

Question 39

Where is compression needed ?

Answer 39

Communication bandwith
reduces size of am image
Send photos and videos faster

Question 40

What are disadvantages of lossy?

Answer 40

• Loses some data
• Blocks can often result from lossy compression
• Noise can be often seem where there are contrasting colours

Question 41

Lossless advantages?

Answer 41

• will not lose any data
• The algorithm finds groups of repeating data and records the
  data once along with the number of repetitions
• When data is uncompressed it is restored exactly as
  it was in the original

Question 42

Disadvantage of lossless

Answer 42

• larger than lossy files
• May impact speed

Question 43

Advantages of lossy?

Answer 43

Small file sizes. Ideal for web use. Lots of tools, plugins and software support it.