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[Overall] Computer Science Paper 2 > Topic 5 > Flashcards

Topic 5 Flashcards

1
Q

What notation is used for natural numbers?

A

N

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2
Q

Give some examples of natural numbers

A

1,2,3,4,5

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3
Q

What is the definition of natural numbers?

A

Positive integers

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4
Q

Is 8 a natural number?

A

Yes

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5
Q

Is -8 a natural number?

A

No

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6
Q

Is 0.5 a natural number

A

No

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7
Q

What notation is used for integer numbers?

A

Z

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8
Q

Give some examples of integer numbers

A

-2,-1,0,1,2

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9
Q

What is the definition of integer numbers?

A

Integer numbers are numbers that a whole but can be either positive or negative

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10
Q

Is 8 an integer number?

A

Yes

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11
Q

Is -8 an integer number?

A

Yes

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12
Q

Is 8.78 an integer number?

A

No

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13
Q

What is the notation for rational numbers?

A

Q

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14
Q

Give some examples of rational numbers

A

7/2,8/1,100/3

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15
Q

What is the definition of rational numbers?

A

Numbers that can be written as simple fractions or ratios of integers.

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16
Q

Is √4 a rational number?

A

Yes √4 = 2 or 2/1

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17
Q

Is -2 a rational number?

A

Yes

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18
Q

Are prime numbers rational numbers?

A

Yes as they are still divisible by 1

7/1

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19
Q

What is the notation for irrational numbers?

A

There isn’t one

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20
Q

Give some examples of irrational numbers

A

pi, √2, √3, √99

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21
Q

What is the definition of irrational numbers?

A

n irrational number cannot be written as a ratio of two numbers. Note that not all square roots are irrational.

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22
Q

What is the notation for real numbers?

A

R

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23
Q

Give some examples of real numbers

A

1, 12.41, √2, 0, 12/7

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24
Q

What is the definition of real numbers?

A

They include: whole numbers, integers, rational, irrational numbers; they can be positive, negative or 0.

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25
Q

What are ordinal numbers?

A

Numbers used to denote the position of an object in relation to a list

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26
Q

Give some examples of ordinal numbers

A

1st, 2nd, 3rd, 4th

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27
Q

What base is decimal?

A

Base 10

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28
Q

Give examples of numbers represented in base 10

A

5, 69, 420, 9528759274981840

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29
Q

What base is binary?

A

Base 2

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30
Q

Give examples of numbers represented in base 2

A

111, 1010, 110, 10001

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31
Q

What base is hex?

A

Base 16

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32
Q

Give examples of numbers represented in base 16

A

2E1, 6F, 7, E2

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33
Q

Click on this link to learn how to Convert Hexadecimal to Binary or Decimal

https://www.wikihow.com/Convert-Hexadecimal-to-Binary-or-Decimal

A

https://www.wikihow.com/Convert-Hexadecimal-to-Binary-or-Decimal

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34
Q

Click on this link to learn how to convert between binary and decimal

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/decimal-to-binary

A

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/decimal-to-binary

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35
Q

What is a benefit of unsigned binary?

A

They can store larger numbers than signed binary.

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36
Q

What is a negative of unsigned binary?

A

Unsigned binary do not have a positive or negative sign and so can only be used to represent positive whole numbers.

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37
Q

An un______ binary number has a minimum of _____ and a maximum of ________ , where n is the number of bits available.

A

An unsigned binary number has a minimum of 0 and a maximum of 2n-1, where n is the number of bits available.

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38
Q

Click on this link to learn how do unsigned binary arithmetic

https://www.youtube.com/watch?v=t15dhDG_WUA

A

https://www.youtube.com/watch?v=t15dhDG_WUA

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39
Q

What is signed binary?

A

Signed binary numbers are encoded to include a positive or negative sign

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40
Q

Signed numbers are represented in computers using what method?

A

Signed numbers are represented in computers using the two’s complement method

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41
Q

How does two’s complement work?

A

The most significant bit will indicate 1 for a negative number and 0 for a positive number.

42
Q

How can you do two’s complement subtraction?

A

Add a negative number.

43
Q

Covert 15 to -15 in binary

A 
0000 1111 = 15
1111 0000    (flip the bits)
1111 0001     (Add 1)
44
Q

Subtraction using two’s complement

15 - 12

A 
15 = 0000 1111
12 = 0000 1100 which is 1111 0100 in two's complement

0 0 0 0 1 1 1 1
1 1 1 1 0100
——————–
0000000011 or 3

15 - 12 = 3

45
Q

What is fixed-point binary?

A

Fixed point binary is used to represent a fractional part of a number.

46
Q

Convert 1010000111.10010 to decimal

A

512 256 128 64 32 16 8 4 2 1 . 1/2 1/4 1/8 1/16 1/32
1 0 1 0 0 0 0 1 1 1 . 1 0 0 1 0

512 + 128 + 4 + 2 + 1 + 0.5 + 0.0625 = 775.5625

47
Q

What is a rounding error?

A

When rounding creates an error between the original number and the rounded number

48
Q

Define absolute error

A

Absolute error is the difference between the theoretical exact value calculated with no errors present and the processed computed value to be stored

49
Q

Define relative error

A

Relative error is the value of the absolute error divided by the theoretical exact value with no errors present

50
Q

What is the formula to find the absolute error?

A

exact value - computed value

51
Q

What is the formula to find the relative error

A

exact value

52
Q

Find absolute and relative errors for a computed value of 0.02 and an exact value of 0.017

A

Absolute error = exact value - computed value
Absolute error = 0.017-0.02 = 0.003

Relative error = Absolute error over the exact value
Relative error = 0.003/0.017 = 0.17647

53
Q

Define precision

A

Precision is associated with word length and the maximum number of significant digits that can be represent

54
Q

Define range

A

range is the set of all numbers that can be represented using a specific number system

55
Q

Define floating point

A

Floating point is a real data type where the binary point can move within the number

56
Q

Define fixed point

A

Fixed point is a real data type where a number has a fixed number of digits either before or after the decimal point

57
Q

Define normalised floating point

A

Normalised floating point number is where the binary point position is fixed in standard form position and the exponent can float to reflect different values of that number

58
Q

Define mantissa

A

Mantissa is the part of the floating point number that includes the significant digits within a number

59
Q

Define exponent

A

Exponent is the power that the number within the mantissa is raised

60
Q

Define underflow

A

If the result of a calculation is smaller than the smallest number that can be represented by the system, then an underflow will occur and the result will be stored as zero; dividing very small numbers can cause underflow.

61
Q

Define overflow

A

If the result of a calculation is too large a value to be represented by the system, then an overflow will occur; this can cause serious problems and is most likely to occur when multiplying two large numbers. Double precision registers can be used to minimise the occurrence of overflow.

62
Q

When does underflow occur?

A

Underflow occurs where the required value is too small to be stored using the number of bits available

63
Q

When does overflow occur?

A

Overflow occurs where the required value is too large to be stored using the number of bits available

64
Q

What is character encoding?

A

When a character is pressed on a keyboard, a binary code for that character is input into the computer.

65
Q

How can characters be encoded?

A

Characters can be encoded into either ASCII or Unicode

66
Q

What is the main limitation of ASCII?

A

It cannot represent large character sets

67
Q

What bit is ASCII?

A

7 bit

68
Q

What bit is Unicode?

A

16 bit

69
Q

What is a disadvantage of Unicode?

A

It uses 2 bytes per character compared to ASCII which only uses 1. Therefore Unicode uses more storage space

70
Q

Name 2 problems with parity checking

A

It can only detect an odd number of errors

It cannot correct the errors found

71
Q

What is the method for parity checking?

A

1) The sending and receiving computers agree the protocol to be used (even or odd)
2) The sending computer adds the correct parity bit to the binary data (either an extra 1 or 0)
3) The sending computer sends the binary data, including the parity bit
4) The receiving computer checks to make sure the overall parity of the data received is as agreed (an even or odd number of 1 bits)
5) If the parity of the data is incorrect, the receiving computer will request that the data is transmitted again

72
Q

What is the main difference between parity checking and majority voting?

A

The parity bit approach can only detect errors while majority voting can correct errors

73
Q

How does majority voting work?

A

Bits can change from 0 to 1 or from 1 to 0 during transmission because of interference.

So each bit is transmitted three times, so that if 1 bit accidentally changes then the device that receives the transmission can fix the error.

In your example, 000 has changed to 010. Since there are 2 zeros and 1 one then the program can use the rule of majority vote to assume that it should have been transmitted as 000.

Since the receiving device knows that 000 represents 0, it can reproduce the original signal

74
Q

What is checksum

A

A checksum is an error detection method where the number of bits transmitted in a message is counted; this checksum is compared with a count of the data received to check the integrity of the data transmission

75
Q

What are check digits?

A

A check digit is added to binary data to check that the data is accurate; this is an approach used by stores to check that the bar code printed on an item of shopping has been correctly inputted into the computer.

76
Q

What is a bit pattern?

A

A bit pattern is an arrangement of binary digits arranged in a sequence; they can be used to represent text as well as images, video and sound.

77
Q

What is the difference between analogue and digital?

A

Analogue is continuous and digital is discrete.

78
Q

How does a ADC work?

A

It receives signal input via an analogue sensor in the form of voltage waveform which are converted into a digital format so they can be read into a computer.

79
Q

Digital images are composed of a series of ______, so a pixel is the ______ element in a digital image.

Images are represented in ______ or binary form to be stored or used on a computer.

Colour can be shown in digital images by using more ______ per ______.

A

Digital images are composed of a series of pixels, so a pixel is the smallest element in a digital image.

Images are represented in digital or binary form to be stored or used on a computer.

Colour can be shown in digital images by using more bits per pixel.

80
Q

Digital images are composed of a series of ______, so a pixel is the ______ element in a digital image.

Images are represented in ______ or binary form to be stored or used on a computer.

Colour can be shown in digital images by using more ______ per ______.

A

Digital images are composed of a series of pixels, so a pixel is the smallest element in a digital image.

Images are represented in digital or binary form to be stored or used on a computer.

Colour can be shown in digital images by using more bits per pixel.

81
Q

Define colour depth

A

Colour depth is the number of bits used for each pixel, where 1 bit i black and white and 8 bits will give 256 colours.

82
Q

How is image resolution found?

A

Image resolution is calculated using the pixel dimensions

83
Q

Define display resolution

A

Display resolution is the number of dots per inch (DPI). More dots per inch gives a better image resolution.

84
Q

Define metadata

A

Metadata is data about data

85
Q

Vector graphics

The size of the objects can be made ______, but the image quality of each object will be ______ and requires the same ______. A vector graphic can consist of many individual objects that can be edited ______.

A

Vector graphics

The size of the objects can be made larger, but the image quality of each object will be identical and requires the same storage. A vector graphic can consist of many individual objects that can be edited independently.

86
Q

Objects are made up of a series of ______ shapes and a set of ______ for the object. Complex geometric shapes can be constructed using mathematical formulae to create objects based on ______ and ______.

A

Objects are made up of a series of geometric shapes and a set of coordinates for the object. Complex geometric shapes can be constructed using mathematical formulae to create objects based on lines and curves.

87
Q

Name 2 differences between bitmapped graphics and vector graphics

A

Bitmapped images are used in digital photography where they provide realistic images whereas vector graphics are used in engineering to create accurate and precise technical drawings. They are also used to create clip art and logos.

Where bitmapped images are resized, the image quality is degraded and can appear fuzzy while vector graphics can be resized with no loss of quality.

88
Q

Out of bitmapped graphics and vector graphics, which one takes up more storage space?

A

Bitmap images store individual pixels and therefore take up more space than vector images

89
Q

Out of bitmapped graphics and vector graphics, which one takes up more processor power?

A

Vector graphics

90
Q

What is sampling rate?

A

It is the number of samples taken per second from the analogue input to create a digital signal.

91
Q

What is Nyquist’s theorem?

A

Nyquist’s theorem indicates that the sound must be sampled at twice the highest analogue input frequency to create an accurate representation of the original input waveform.

92
Q

How can you find the minimum file size for an audio file?

A

sample frequency (Hz) x sample resolution (bytes) x length of sound (sec)

93
Q

What is MIDI?

A

MIDI is a protocol that is used to synthesise musical instruments

94
Q

MIDI makes use of ______ ______ that are used to control musical parameters such as ______ and pitch and ______ , and to synchronise the ______ between a range of other devices

A

MIDI makes use of event messages that are used to control musical parameters such as notation and pitch and volume, and to synchronise the rhythm between a range of other devices

95
Q

Name 3 advantages of using a MIDI system

A

Music data that has been loaded onto the computer can be arranged and manipulated in many different ways

A musician or music producer can make use of overlays to create a whole band sound

It is straightforward to create a musical score from edited music

96
Q

Why is data compression important?

A

Data compression is important as compressed data takes up less storage space and the smaller files can be transmitted across the internet quicker than uncompressed files.

97
Q

When could lossless compression be used?

A

A text document might need to be compressed into a zip file for attachment and transmission using email. The document will need to be expanded to an exact copy of the original file so it can be read.

98
Q

When could lossy compression be used?

A

In sound files unnecessary data can be removed without ruining the output quality for the user

99
Q

What does RLE stand for?

A

Run Length Encoding

100
Q

What is RLE?

A

It is a form of lossless compression where a sequence that contains repeated values is replaced by a single value and a number signifying the amount of repeats.

101
Q

What is the difference between lossy and lossless compression?

A

Lossless compression allows the image or data to be reformed to its original state with no errors or changes.

102
Q

How does dictionary-based compression work?

A

An algorithm creates a dictionary (a pattern of characters) as data is scanned looking for repeated information).

Some information is replaced by a much shorter but uniquely identifiable string.

[Overall] Computer Science Paper 2 (4 decks)

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