Memory and Storage Part 2

Question 1

What is Denary?

Answer 1

In our standard number system we have 10 digits:
0 1 2 3 4 5 6 7 8 9
This is called denary, decimal or base 10.

Question 2

What is Binary?

Answer 2

Binary only uses two different digits, 0 and 1.
Computers use this system as computers are made up of switches which can be on or off.

Question 3

What is Hexadecimal?

Answer 3

Hexadecimal (or base 16) uses 16 different digits:
0 1 2 3 4 5 6 7 8 9 A B C D E F
Large numbers can be written simply using Hex instead of binary.

Question 4

What are the rules for binary addition?

Answer 4

0 + 0 = 0
0 + 1 = 1
1 + 1 = 10 (binary for 2)
1 + 1 + 1 = 11 (binary for 3)

Question 5

What is a Binary Shift?

Answer 5

A binary shift moves every bit in a binary number left or right a certain number of places. Gaps at the beginning or end of a number are filled with 0s.
Moving left multiplies the number.
Moving right divides the number.

Question 6

What effect does moving left or right in binary shifts have on the number.

Answer 6

Moving left multiplies the number.
Moving right divides the number.

Question 7

What is an Overflow error?

Answer 7

Overflow errors occur when the result of a calculation requires more bits (place values) than expected or are in the available range.

Question 8

How are Binary Codes used to represent characters?

Answer 8

This is done by assigning each character a unique binary code, using only 0’s and 1’s.

Like the letter ‘a’ being represented by 01100001 in ASCII

Question 9

What are Alphanumeric Characters?

Answer 9

Alphanumeric characters are used to make words and strings.

They include uppercase and lowercase letters, the digits 0 – 9 and symbols like: ? £ and +.

Question 10

What are Character Sets?

Answer 10

Character sets are collections of characters that a computer recognises from their binary representation.

Question 11

What are the two common Characater sets?

Answer 11

ASCII (American Standard Code for Information Interchange)
Unicode

Question 12

What is ASCII?

Answer 12

ASCII is the most commonly used character set in the English- speaking world.
ASCII uses 7 bits whereas Extended ASCII uses 8 bits.
27 = 128
28= 256

Question 13

What is Extended ASCII?

Answer 13

Extended ASCII uses eight bits, giving a character set of 256 characters. This allows for special characters such as those with accents in languages such as French and Spanish.

Question 14

What is Unicode?

Answer 14

Unicode uses 16 bits. It aims to cover every possible character or symbol in all major languages.
With 16 bits we can have:
2**16 = 65,536 different characters.

Question 15

What is the impact of ASCII?

Answer 15

It is suitable/sufficient for the English language but it’s insufficient for many other languages or all symbols
Limited Character Set.

Question 16

What is the impact of Unicode?

Answer 16

It allows for a wider range of characters, including those from diverse alphabets and symbols across different languages, unlike the limitations of ASCII. it can be used around the world.

Question 17

How many bits does ASCII use and how many characters can be represented?

Answer 17

7 bits.
128 different characters

Question 18

How many bits does Unicode use and how many characters can be represented?

Answer 18

16 bits.
65,536 different characters.

Question 19

What is a Pixel?

Answer 19

A pixel is the smallest identifiable area of an image.
Each pixel has a specific colour, represented by a specific binary code.

Question 20

What is Colour Depth?

Answer 20

The amount of bits available for colours in an image.
e.g.
2 bits , 22 = 4 colours
3 bits , 23 = 8 colours
4 bits, 2**4 = 16 colours

Question 21

What is Resolution?

Answer 21

Resolution is the number of pixels in the image. It is often given as width x height.

Question 22

What is Metadata?

Answer 22

Metadata stores information about the image, in an image file.

e.g. file format, height, width, colour depth, resolution

Question 23

What impact does resolution and colour depth have on the image file size?

Answer 23

Increasing either increases the file size.
Higher colour depth - more bits per pixel are needed.
Higher resolution - more pixels means more data is needed to store the image

Question 24

What impact does resolution and colour depth have on the quality of the image?

Answer 24

Increasing either leads to better image quality.
Higher resolution - allows for more detail and a more realistic-looking image,lower resolution can lead to a pixelated or blocky appearance.
Higher colour depth - results in a wider range of colours and smoother gradients, leading to a more realistic and visually appealing image.

Question 25

What is Sound Sampling?

Answer 25

The process of converting an analogue signal into a digital signal is called Sound Sampling. The amplitude of the wave is sampled at regular intervals (sample), then converted into a digital signal.

Question 26

What is Analogue Sound?

Answer 26

Analogue sound must be stored as binary. Sound is recorded by a microphone as an analogue signal. Analogue signals are pieces of continually changing data.

Question 27

What must Analogue sound be stored in?

Answer 27

Binary

Question 28

What does an analogue-to-digital converter (ADC) do?

Answer 28

An analogue-to-digital converter will capture a sound wave at regular time intervals. This recording is known as a sample. The sound recorded at each sample point is converted to its nearest numeric equivalent. This data is then stored in a file for later use.

Question 29

What is Digital Sound?

Answer 29

Analogue signals need to be converted into digital data so that computers can read and store sound files. Analogue sound is a continuous representation of the audio signal, while digital sound is a sampled and digitised version, converted into binary code.

Question 30

What is Sample Rate?

Answer 30

How many samples you take in a second. It is measure in Hertz.

Question 31

What is Hertz?

Answer 31

Frequency is measured in Hertz. A frequency of 1 Hertz means that something happens once every second.

Question 32

What is Bit Depth?

Answer 32

Bit Depth is the number of bits available to store each sample. e.g. CD quality sound uses 16 bits per sample 2**16 = 65,536 values A DVD uses 24 bits 2**24 ≈ 16 million

Question 33

What is Duration?

Answer 33

How many seconds of audio the sound file contains.

Question 34

What is the equation for Sound File Size?

Answer 34

File Size (in bits) = Sample Rate (in Hz) x Bit Depth x Duration (in seconds)

Question 35

What is the effect of sample rate, duration and bit depth on the size of a sound file?

Answer 35

Higher values result in larger file sizes. Higher sample rates - more data is stored per unit time Higher bit depth - more data is stored per sample Longer Duration - more data needs to be stored

Question 36

What is the effect of sample rate, duration and bit depth on the playback quality?

Answer 36

Higher values generally lead to better quality. Higher sample rates - more accurate representation of the original analog sound Higher bit depth - more precise representation of the sound amplitude, resulting in a wider dynamic range and better audio quality. Longer Duration - directly affects the length of the audio playback, but not the quality itself.

Question 37

What is Compression?

Answer 37

Compression software reduces the file size of files so that they take less disk space and are quicker to download.

Question 38

Why is Compression needed?

Answer 38

It reduces file sizes, saves storage space and makes files easier to transmit.

Question 39

What are the two types of Compression?

Answer 39

Lossy Lossless

Question 40

What is Lossy Compression?

Answer 40

A form of compression that reduces digital file sizes by removing data. This reduces the number of bits in the file so the file size is lower. The file cannot be returned to the original.

Question 41

What is Lossless Compression?

Answer 41

A form of compression that encodes digital files without losing detail by using an algorithm to find groups of repeating data. Files can also be restored to their uncompressed/original quality.

Question 42

What are benefits of Lossy Compression?

Answer 42

- Significantly reduces file sizes - Faster data transfer - Efficient storage

Question 43

What are disadvantages of Lossy Compression?

Answer 43

- Permanent data loss - Potential quality reduction - Not suitable for all data (text)

Question 44

What are benefits of Lossless Compression?

Answer 44

- No data removed - No quality loss - Reversible

Question 45

What are disadvantages of Lossless Compression?

Answer 45

- Smaller file size reduction - Doesn't significantly reduce storage needs - Slower Processing?