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a-level computing > Fundamentals of data representation > Flashcards

Fundamentals of data representation Flashcards

1
Q

What is a natural number

A

A whole number used in counting. In computing 0 is a natural number

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2
Q

What symbol represents a natural number

A

N

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3
Q

What is a rational number

A

Any value that can be expressed as a ratio or a fraction (Includes integer values)

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4
Q

What symbol represents a rational number

A

Q

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5
Q

What is an irrational number

A

A value that cannot be expressed as a fraction and has an endless series of non-repeating digits e.g Pi

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6
Q

What is an integer number

A

A whole number that could be positive or negative

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7
Q

What symbol represents integer numbers

A

Z

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8
Q

What is a real number

A

Any number that is natural, rational or irrational. Cannot be an imaginary number

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9
Q

What are ordinal numbers

A

Numbers used to count places in a list e.g 1st, 2nd

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10
Q

How does a parity bit work

A

If data is looking for odd parity they will look for an odd number of 1s and vice-versa for even parity

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11
Q

What are the drawbacks of using a parity bit

A
  1. It can only check for errors and not correct them

2. It may fail if there are an even amount of errors

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12
Q

What is majority voting

A

When the bits within a binary string are sent three times.
It will select the majority bit within the string once it has arrived
e.g 111000111 -> 111001110 - This will be corrected to the original

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13
Q

What is the advantage of majority voting over a parity bit

A

Not only checks for errors but corrects them as well due to the 2 additional bits being unlikely to change

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14
Q

What is a bitmap image

A

An image composed of pixels where each pixel is given a set binary value to represent a colour

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15
Q

What is a pixel

A

The smallest identifiable area of an image

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16
Q

How do you calculate image resolution

A

Number of pixels high * Number of pixels wide

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17
Q

What is image resolution

A

The number of pixels in an image

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18
Q

What is colour depth

A

The amount of bits assigned to each pixel

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19
Q

What happens when you have a high colour depth

A

More colours can be represented, increasing image quality

20
Q

How do you work out the colour depth

A

2 to the power of the amount of bits

e.g 3 bits mean 2^3 so 8 colours can be represented

21
Q

What is metadata

A

Data about data

22
Q

Give examples of metadata

A

Filename
Date created
File type

23
Q

How do you calculate minimum file size

A

Width in pixels * Height in pixels* Colour depth

24
Q

What is digital data

A 
All the processes carried out by a computer are digital
Discrete data (Limited in detail)
25
Q

What is analogue data

A

Inputs and outputs are analogue

Analogue data is continuous (infinite detail)

26
Q

What is the amplitude in relation to sound waves

A

How loud the sound is

27
Q

What is the frequency in relation to sound waves

A

The pitch of the sound

28
Q

How do you convert analogue data to digital data

A

Analogue to digital converter - ADC

29
Q

How do you convert digital data to analogue data

A

Digital to analogue converter - DAC

30
Q

What is sampling

A

Taking points of an analogue sound wave and then converting this to digital

31
Q

How can we improve the accuracy of the digital recording

A

Increase the amount of samples taken per second (Increase the sample rate)

32
Q

What are CD’s usually sampled at

A

44,100 Hz

33
Q

What are the results of a higher sample rate

A

More accurate at reflecting a true sound wave but file size increases

34
Q

How many channels is mono, stereo and cinema channels

A

Mono - 1
Stereo - 2
Cinemas 5.1 - 6

35
Q

What is sample resolution

A

The number of bits assigned to each sample

36
Q

What happens as a result of low or high sample resolution

A

Low sample resolution - Results in a lower volume range

High sample resolution - Will result in a high file size

37
Q

What is the sample resolution of a CD

A

16 bits

38
Q

How do you calculate a recordings file size

A

File Size = Sample rate * Sample resolution * Length of recording

39
Q

What is Nyquists Theorem

A

Sample rate must be twice the highest frequency

40
Q

What is compression

A

Making a file smaller

41
Q

What are the two types of compression

A

Lossless and Lossy

42
Q

Give an example of a compression technique

A

RLE - Run Length Encoding

Dictionary based compression

43
Q

How does dictionary based compression work

A

It identifies common patterns and creates a dictionary value based on this

44
Q

What is a computationally secure cypher

A

A cypher that theoretically can be broken but in too long a time that it wouldn’t be useful

45
Q

What is a digital certificate

A

A method of ensuring that an encrypted message is from a trusted source

46
Q

What is SSL

A

Secure Socket Layer. Introduced to encourage business on the internet and was designed to tackle fraud

47
Q

What are digital signatures used for

A

Used to identify the authenticity of the senders of emails

a-level computing (4 decks)

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