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CS 2 > 2.1 Fundamentals of data representation > Flashcards

2.1 Fundamentals of data representation Flashcards

1
Q

Define natural number

A

A positive whole number including zero

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2
Q

Define integer

A

Any whole positive or negative number including zero

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3
Q

Define rational number

A

Any number that can be expressed as a fraction or ratio of integers

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4
Q

Define irrational number

A

A number that cannot be represented as a fraction or ratio as the decimal form will contain infinite repeating values

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5
Q

Define real number

A

Any positive of negative number with or without a fractional part

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6
Q

Define ordinal number

A

A number used to identify position relative to other numbers

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7
Q

Define cardinal number

A

A number that identifies the size of something

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8
Q

Define well-ordered set

A

A group of related numbers with a defined order

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9
Q

Define number base

A

The number of digits available within a particular number system

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10
Q

Define bit

A

A single binary digit from a binary number - either a zero or a one

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11
Q

Define byte

A

A group of bits, typically eight, used to represent a single character

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12
Q

Define unit

A

The grouping together of bits or bytes to form larger blocks of measurement

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13
Q

Define unsigned binary

A

Binary that represents positive numbers only

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14
Q

What is two’s complement?

A

A method of working with signed binary values

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15
Q

Define fixed point

A

Where the position of the decimal / binary point is fixed within a number

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16
Q

Define floating point

A

Where the position of the decimal / binary point can move within a number

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17
Q

Compare floating point and fixed point representation

A
  • Floating point gives a wider range of numbers possible to produce from the same number of bits
  • It can be faster to process fixed point values as processing the decimal point can be similar to integers
  • The absolute error will be constant with fixed point whereas with floating point this could vary
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18
Q

Define signed binary

A

Binary with a positive or negative sign

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19
Q

Define overflow

A

When a number is too large to be represented within the number of bits allocated

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20
Q

Define underflow

A

When a number is too small to be represented within the number of bits allocated

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21
Q

Define precision

A

How accurate a number is

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22
Q

Define normalisation

A

A process for adjusting numbers onto a common scale

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23
Q

Define mantissa

A

The significatn digits that make up a number

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24
Q

Define exponent

A

The power part of a number indicating how far a binary point should be shifted left or right

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25
Q

Define character code

A

A binary representation of a particular letter, number, or special character

26
Q

What is ASCII?

A

A standard binary coding system used for characters and numbers

27
Q

Why was Unicode needed?

A
  • 256 characters are not enough to represent all of the possible characters, number, and symbols
  • It was initially developed in English and therefore did not represent all of the other languages and scripts used in the world
  • Widespread use of the web made an international encoding system more important
28
Q

How do parity bits function?

A

Using a parity bit is a method of checking binary codes by counting the number of 0s and 1s in the code. Either even or odd parity will be agreed upon before communication begins. With each piece of data sent, the number of 1s in the data will be counted. If even parity is agreed upon, for example, and the number of 1s in the data is odd, a 1 will be added as a parity bit. Conversely, if there is already an even number of 1s, a 0 will be added as a parity bit. If the recieved parity matches the agreed parity, the recieved message is assumed to be correct

29
Q

How does majority voting work?

A

Majority voting is a method of checking for errors by producing the same data several times and seeing if the data is the same each time. When data is being sent, it will be sent multiple separate times, and the most common digit in each position will be assumed to be the correct one

30
Q

How do check digits work?

A

A check digit is a digit added to the end of binary data to ensure that it is accurate. The check digit is generated by performing some sort of function on the data sent that gives a unique digit. This value is then also calculated by the reciever once the data has been recieved. If the recieved check digit matches the calculated one, then the data is assumed to be correct

31
Q

Define pixel

A

An individual picture element

32
Q

Define resolution

A

width x height or pixels per inch

33
Q

What is a bit-mapped graphic?

A

An image made up of individual pixels

34
Q

Define colour depth

A

The number of bits or bytes allocated to represent the colour of a pixel in a bit-mapped graphic

35
Q

Define vector graphic

A

An image made up of objects and coordinates

36
Q

What is the difference between analogue and digital data?

A

Analogue data is infinitely variable and can often be represented in the form of a wave, whereas digital data is often represented as discrete values

37
Q

What data can be controlled in MIDI sound?

A
  • When to play a note
  • When to stop playing the note
  • Timing a note to play with other notes or sounds
  • Timing a note to play with other MIDI-enabled devices
  • What pitch a note is
  • How loud to play anote
  • What effect to use when playing a note
38
Q

What are the advantages of MIDI?

A
  • File sizes tend to be much smaller meaning they require less memory and can be loaded faster, which is especially useful when used over the Internet
  • MIDI files are completely editable as individual instruments can be modified
  • MIDI supports a wide range of instruments and options for customisation
  • MIDI can produce authentic and high-quality representations of an instrument
39
Q

What is Nyquist’s theorem?

A

To faithfully recreate an analogue signal, you should sample at at least twice the highest frequency of the signal

40
Q

Define sample rate

A

The number of samples that will be taken per second

41
Q

How does analogue sound sampling work?

A
  • A series of samples of the amplitude of the wave are recorded
  • The original sound can then be reproduced by connecting these amplitudes to give a reconstruction of the original wave
  • With a greater sample rate, the stored sound will be more accurate to the original sound wave
42
Q

Define compression

A

The process of reducing the number of bits required to represent data

43
Q

What are the 2 types of compression?

A
  • Lossy: there will be some degradation / loss of the data in compression
  • Lossless: the compressed file is accurate to how it was before compression
44
Q

What is run-length encoding?

A

A method of compressing data by eliminating repeated data - this is a type of lossless compression

45
Q

What is dictionary-based encoding?

A

A method of compressing text files

46
Q

Define encryption

A

The process of turning plaintext into scrambled ciphertext which can only be understood if it is decrypted

47
Q

Define decryption

A

The process of deciphering encrypted data or messages

48
Q

What is plaintext?

A

Data in human-readable form

49
Q

What is ciphertext?

A

Data tat has been encrypted

50
Q

What is a caesar cipher?

A

A substitution cipher where one character of plaintext is substituted for another, which becomes the ciphertext

51
Q

What is a vernam cipher?

A

A method of encryption that uses a one-time pad (key) to create ciphertext that is mathematically impossible to decrypt without the key

52
Q

What is a transposition cipher?

A

A method of encryption where the characters are rearranged to form an anagram

53
Q

Define key

A

In cryptography it is the data that is used to encrypt an decrypt the data

54
Q

What is a substitution cipher?

A

A method of encryption where one character is substituted for another to create ciphertext

55
Q

What is frequency analysis?

A

The study in cryptography of how often different letters or phrases are used

56
Q

What is a railfence cipher?

A

A type of transposition cipher that encodes the message by splitting it over rows

57
Q

What is a route cipher?

A

A type of transposition cipher that encodes the message by placing it into a grid

58
Q

What is a one-time pad?

A

A key that is used only once to encrypt and decrypt a message and is then discarded

59
Q

Define computational security

A

A concept of how secure data encryption is

60
Q

Define computational hardness

A

The degree of difficulty in cracking a cipher

CS 2 (7 decks)

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