1 Data Representation

Question 1

How and why do computers use binary?

Answer 1

Components that process data in a computer are made up of very small logic gates which cannot process analogue data.

Any denary values have to be converted into binary for the computer to process them.

Question 2

Why is hexadecimal used as a beneficial method of data representation?

Answer 2

• Shorter way of representing binary
• easier to read, write and understand
• easier to debug and locate errors in data

Question 3

How is text converted to binary?

Answer 3

2 main types of character sets can be used by a computer: ASCII and Unicode

ASCII can represent upto 256 characters.

Unicode can represent approximately 65,000. This means many more characerts can be developed in different alphabets and also symbols and emojis can be used.

Question 4

How is sound converted to binary?

Answer 4

A sound wave is sampled for sound to be converted to binary, which is processed by a computer.

Question 5

What is the sample rate?

Answer 5

the number of samples taken in a second

Question 6

What is the sample resolution?

Answer 6

number of bits per sample

Question 7

What is the impact of increasing sampling rate and sampling resolution?

Answer 7

Increase in accuracy of recording and file size increase.

Question 8

How are images converted to binary?

Answer 8

An image is a series of pixels that are converted to binary, which is processed by the computer.

Question 9

What is the image resolution?

Answer 9

the number of pixels in the image

Question 10

What is the colour depth?

Answer 10

the number of bits used to represent each colour

Question 11

What impact will increase the image resolution and colour depth have on file size and quality?

Answer 11

Quality will increase and so will file size.

Question 12

Convert into bits:
bit
nibble
byte
KiB
MiB
GiB
TiB
PiB
EiB

Answer 12

bit- 1 bit
nibble- 4 bits
byte- 8 bits
KiB- 1024 bytes
MiB- 1024 KiB
GiB- 1024 MiB
TiB- 1024 GiB
PiB- 1024 TiB
EiB- 1024 PiB

Question 13

How do you measure the file size of an image?

Answer 13

Resolution(height and width) X Colour Depth X Number of Images in file

Question 14

How do you measure the file size of a sound file?

Answer 14

Length X Sample Rate X Sample Resolution

Question 15

What are the benefits of file compression?

Answer 15

Compression exists to reduce the size of a file.

The benefits of this are:
* less bandwith required
* less storage space required
* shorter transmission time.

Question 16

What is lossy compression and how are files compressed using lossy?

Answer 16

Lossy compression is a method that reduces the size of a file by permenantly removing data.

Unneccassary data in an image or file such as undistinguishable colours by the human eye or sounds that cannot be heard by the human ear are removed.

Question 17

What is lossless compression and how are files compressed using lossless?

Answer 17

It reduces the file size without permanent loss of data.
It finds repeating data in a file and groups it together.
Another method of this is Run-Length Encoding