1.3 Data Storage

Question 1

How is data stored on a computer?

Answer 1

All data stored on a computer is stored in Binary (1’s and 0’s)

Question 2

Why don’t we type in Binary

Answer 2

Because it would take too long, so the computer translates the binary into ‘human languages’

Question 3

What is ASCII?

Answer 3

A table of commonly agreed translations for all computers to exchange/record characters with. ASCII is an 8-bit language, meaning that there are only 256 possible characters, which for multiple languages is not enough for multiple languages and is therefore no longer used commonly.

Question 4

What is Unicode?

Answer 4

A table of commonly agreed translations for all computers to exchange / record characters with. Unicode is 16-bit and therefore has 65,536 characters.

Question 5

How could you represent a basic black and white image?

Answer 5

With 1 being white and 0 being black. A 6 X 3 image could be stored like this 000011 100001 110000
⬛⬛⬛⬛⬜⬜
⬜⬛⬛⬛⬛⬜
⬜⬜⬛⬛⬛⬛

Question 6

What is metadata?

Answer 6

Dimensions of an image for example, what font a text is in, or bits per character.

Question 7

What does a file extension do?

Answer 7

such as .jpg .png .docx

it tells the computer the rules of this price of data, such as font, text size, format, what software to open it with.

Question 8

What is RGB ?

Answer 8

Varying amounts of red, green and blue make any colour.

Question 9

What are colour values?

Answer 9

Each colour usually has 255 values (8-bits). If we have red green and blue, we have 16 milion different colour combinations (24-bits).

Question 10

What is the ‘sample rate’?

Answer 10

How many times per second the analogue sound signal is measured.

Question 11

What is the ‘sample resolution’?

Answer 11

How many bits per time frame are used to record the analogue audio. For example, 8-bit, 128-bit. The measure of accuracy is how many unique values of amplitude we can store, what delines this is the number of bits used.

Question 12

How can data be compressed?

Answer 12

• Bit structure manipulated
• Analogue signals measured less often
• Pictures with areas of the same or similar colours are counted as the same (depending on algorithm used)
• Words that are repeated in a document are deleted and their positions recorded

Question 13

What is ‘Lossy’ data compression?

Answer 13

Redundant or unnecessary data is removed eg. in patterns where things are repeated.

Question 14

What is ‘Lossless’ data compression?

Answer 14

No data is lost, a shortened version of the data is recorded and then reconstructed when needed.

Question 15

What is ‘sample rate’? (sound)

Answer 15

How many times per second an analogue signal is measured

Question 16

What is ‘sample resolution’? (sound)

Answer 16

How many bits per second are used to record audio. This will determine the accuracy of the sound ie how many unique values of amplitude there can be.

Question 17

What is a ‘file format’ used for?

Answer 17

• Method used to store different types of data depending on what they are
• They are need so a computer knows what method a piece of data has been stored so it can open it so the user understands it
• There are many different types of file formats, some are generic and some are software specific
• Most files formats are . then 3 or 4 characters abbreviating its name