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computer science revision > Topic 1-Data Representation > Flashcards

Topic 1-Data Representation Flashcards

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1
Q

1 Byte(B) equals to

A

8 bits(b)

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2
Q

Bit

A

one binary digit

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3
Q

Nibble

A

4 bits

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4
Q

Byte

A

8 bits

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5
Q

Word

A

16/32/64 bits

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6
Q

Kilobye(KB)

A

1024 bytes

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7
Q

Megabyte(MB)

A

1024 KB

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8
Q

GIgabyte(GB)

A

1024 MB

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9
Q

Terabyte(TB)

A

1024 GB

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10
Q

Petabyte(PB)

A

1024 TB

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11
Q

0+0=

A

0

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12
Q

1+0=

A

1

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13
Q

0+1=

A

1

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14
Q

1+1=

A

0, carry the 1 to the left

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15
Q

1+1+1=

A

1, carry the 1 to the left

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16
Q

1010+1001=

A

10011

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17
Q

101101+111101=

A

1101010

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18
Q

What number system do these facts describe: 0 or 1(2 digits) - base 2 - Used by computers - Uses more digits for the same number

A

Binary

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19
Q

Name 4 facts about the denary number system

A

0, 1, 2, 3, 4, 5, 6, 7, 8, 9(10 digits) - Base 10 - Used by humans - Uses less digits for the same number

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20
Q

a bit is either a _ or a _

A

1 or 0

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21
Q

Binary digit can be shortened to

A

bit

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22
Q

The smallest piece of computer memory is

A

a bit

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23
Q

A single 1 or 0 is called a

A

bit

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24
Q

Computers convert ____ data to ____ data

A

analogue to digital

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25
Q

How many megabytes in a gigabyte?

A

1024 MB

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26
Q

what comes after Kilobyte?

A

megabyte

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27
Q

One Byte can store a single ___

A

character

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28
Q

?

?

32​

16

8​

?

2​

?

A

1, 4, 64, 128

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29
Q

0+0+0=

A

carry 0, sum 0

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30
Q

0+0+1=

A

carry 0, sum 1

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31
Q

0+1+0=

A

carry 0, sum 1

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32
Q

0+1+1=

A

carry 1, sum 0

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33
Q

1+0+0=

A

carry 0, sum 1

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34
Q

1+0+1=

A

carry 1, sum 0

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35
Q

1+1+0=

A

carry 1, sum 0

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36
Q

What is the logical (binary) shift?

A

Moving the binary number to the left/right. Each shift left is equivalent to multiplying the binary number by 2 and each shift right is equivalent to dividing the binary number by 2.

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37
Q

10010101 in a denary number

A

149

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38
Q

how to convert from denary to binary

A
  • keep dividing by 2
  • use INTEGERS only
  • write down the REMAINDERS
  • write the remainders from BOTTOM to TOP
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39
Q

177 in a binary number

A

10110001

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40
Q

what is two’s complement for?

A

to convert negative denary numbers

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41
Q

name 4 facts about the hexadecimal system

A

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A(10), B(11), C(12), D(13), E(14), F(15) (16 digits) - Base 16 - FOUR binary digits are equivalent to each hexadecimal digit

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42
Q

1 1 1 1 =

A

F, 15

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43
Q

0 1 0 0 =

A

4, 4

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44
Q

how to convert from Binary to Hexadecimal:

A
  1. from RIGHT to LEFT, split the binary into groups of 4 BITS.
  2. write BASE 2 headings(8, 4, 2, 1) for each group of bits.
  3. work out the DECIMAL value for each group.
  4. replace any value above 9 with its HEX code.
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45
Q

1011010101 in HEX code=

A

2D5

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46
Q

how to convert from Hexadecimal to Denary:

A
  1. write the Base 16 headings(256, 16, 1).
  2. Multiply out(HEADING x HEX code).
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47
Q

define MEMORY DUMP

A

when the memory contents are output to a printer or monitor

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48
Q

why might a programmer prefer to use hexadecimal to ss the contents of locations?

A
  • easier to identify values
  • easier to spot errors
49
Q

MAC address stands for

A

Media Access Control; refers to a number that uniquely identifies a device on the internet; usually made up of 48 bits(6 groups of hexadecimal digits)

50
Q

What does the first half of a MAC address identify?

A

the manufacturer

51
Q

What does the second half of a MAC address identify?

A

the serial number of the hardware

52
Q

one type of MAC address

A

UAA(Universally Administered MAC Address); by far the most COMMON type of MAC address; set by the manufacturer

53
Q

another type of MAC address

A

LAA(Locally Administered MAC Address)

54
Q

3 facts about a MAC address

A
  • on mainframe systems all MAC addresses of devices may need to fall into a strict format
  • to bypass a MAC address filter on a router/firewall
  • to get past certain types of network restrictions it may be necessary to emulate unrestricted MAC addresses
55
Q

IP address stands for

A

Internet Protocol

56
Q

An IPv4 address is a ___-bit number written in ____ or _____ form

A

32, denary, hexadecimal - IPv4 has recently been improved upon by the adoption of IPv6.

57
Q

An IPv6 address is a ___-bit number broken down into ____-bit chunks, represented by a _____ number.

A

128, 16, hexadecimal

58
Q

An IPv6 address is a ___-bit number broken down into ____-bit chunks, represented by a _____ number.

A

128, 16, hexadecimal

59
Q

HTML Colour Codes

A
  • every pixel in a computer colour monitor may have only ONE COLOUR at any moment
  • each made up of a combination of RED, GREEN, and BLUE
  • hexadecimal RGB colour values that specify the AMOUNT of red, green, and blue light that need to appear at a pixel, in order to produce a specific colour
  • each colour value is represented as a HEXADECIMAL value of 2 digits that may take up values from 00 to FF.
60
Q

the first 2 digits of HTML Colour Codes represent the ____ colour, the next 2 the ____ colour, and the last 2 the ____ colour.

A

Red, Green, Blue

61
Q

ASCII code stands for

A

The American Standard Code for Information Interchange

62
Q

What is an ASCII code?

A

a character-encoding scheme originally based on the English alphabet; a number is assigned to each letter from 0~127 in denary or 0 to 7F in hexadecimal; 32 control codes(that use codes O to 31(denary) or 00 to 19(hexadecimal))

ASCII uses 7 bits to represent each character which means that it can achieve 27=128 different representations

63
Q

x-axis in representation of sound shows:

A

the TIME INTERVALS when the sound was sampled(1 to 21); At time interval 1, the approximate amplitude is 10. At time interval 2, the approximate amplitude is 4.

64
Q

y-axis in representation of sound shows:

A

the AMPLITUDE of the sampled sound to 10

65
Q

What is a sampling resolution(aka the bit depth)?

A

the number of bits per sample

66
Q

What is a sampling rate?

A

the number of sound samples taken per second. Measured in hertz(Hz), where 1 Hz means ‘1 sample per second’.

67
Q

How is sampling used to record a sound clip?

A
  • the amplitude of the sound wave is first determined at set time intervals (the sampling rate).
  • this gives an approximate representation of the sound wave.
  • each sample of the sound wave is then encoded as a series of binary digits.
68
Q

Using a _____ sampling rate/____ resolution will result in a more _____ representation of the original sound source. However, the _____ the sampling rate/sampling resolution, the _____ the file size.

A

higher, larger, faithful, higher, greater

69
Q

Benefits of using a LARGER SAMPLING RESOLUTION when recording sound

A

larger dynamic range; better sound quality; less sound distortion

70
Q

Drawbacks of using a LARGER SAMPLING RESOLUTION when recording sound

A

produces larger file size; takes longer to transmit/download music files; requires greater processing power

71
Q

What are bitmap images?

A

made up of PIXELS(picture elements); an image is made up of a 2-DIMENSIONAL MATRIX of pixels; pixels can take DIFFERENT shapes

72
Q

representation of (bitmap) images: Each _____ can be represented as a ____ number, and so a bitmap image is stored in a computer as a series of ______ numbers so that a ____ and ____ image only requires 1 bit per pixel 0 - this means that each pixel can be one of two colours, corresponding to either __ or __. If each pixel is represented by __ bits, then each pixel can be one of four colours(22=4), corresponding to [ ]. If each pixel is represented by __ bits then each pixel can be one of eight colours (23=8), corresponding to 000, 001, 010, 011, 100, 101, 110, 111.

A

pixel, binary, binary, black, white, 1, 0, 2, [00, 01, 10, or 11]

73
Q

define colour depth

A

The number of bits used to represent each colour; increasing colour depth also increases the size of the file when storing an image.

74
Q

define Image resolution

A

the number of pixels that make up an image; the resolution can be varied on many cameras before taking

75
Q

Photographs with a ____ resolution have ____ less detail than those with a ____ resolution.

A

lower, less, higher

76
Q

What does resolution measure?

A

the number of pixels in a digital image/display; defined as width by height

77
Q

The file size of an image is determined by:

A

the number of pixels

77
Q

The file size of an image is determined by:

A

the number of pixels

78
Q

memory size is measured in terms of powers of:

A

2

79
Q

file size(of an image) formula

A

image resolution(in pixels) x colour depth(in bits)

80
Q

size of a mono sound file formula

A

sample rate(in Hz) x sample resolution(in bits) x length of sample(in seconds)

81
Q

stereo sound file formula

A

2 x [sample rate(in Hz) x sample resolution(in bits) x length of sample(in seconds)]

82
Q

In ASCII code each character from the keyboard has a value of __ byte.

A

1

83
Q

Benefits of data compression

A
  • save storage space on devices such as hard disk drive/solid state drive
  • reduce the TIME taken to STREAM a music/video file
  • reduce the time taken to UPLOAD, DOWNLOAD, or TRANSFER a file across a network
  • reduced file size also reduces COSTS
84
Q

2 types of file compression

A

Losy or Lossless

85
Q

File compression is enabled through a ___ or ____ compression software that creates a _____ version of each processed file

A

file, data, compressed

86
Q

Lossless file compression

A

all data bits from the original file are RECONSTRUCTED when the file is again uncompressed

87
Q

In what cases are Lossless file compression crucial?

A

Files where loss of any data would be disastrous. E.g. a spreadsheet file.
OR
where code must be exactly the same as the original. E.g. computer program

88
Q

Features of Lossless compression

A
  • If the code different from the original, the file won’t work
  • an algorithm used
  • no data removed in the process
  • in a text file repeated words are identified/replaced by an index
  • the number of times the word appears is stored
89
Q

Lossy file compression

A

the compression algorithm eliminates unnecessary bits of data as seen in MP3 and jpeg formats; IMPOSSIBLE to get the original file back

90
Q

When is Lossy file compression mostly used?

A

In compression of files where removing certain bits doesn’t detract from the quality. E.g. Video file

91
Q

Features of Lossy compression

A
  • makes the file SMALLER than lossless
  • quality REDUCED but the file still RUNS
  • REDUNDANT amount can be removed
92
Q

MIDI stands for

A

Musical Instrument Digital Interface

93
Q

MIDI files are not ____ and don’t contain any ____

A

music, sounds

94
Q

What is a MIDI file?

A

a communications protocol that allows electronic musical instruments to interact with each other.

95
Q

The MIDI protocol uses __-bit serial transmission with one start bit and one ___ bit; asynchronous

A

8, stop

96
Q

A MIDI file consists of a list of _____ that instruct a device how to produce a particular ____ or _______.

A

commands, sound, musical note

97
Q

MIDI file size

A

bc MIDI files don’t contain any audio tracks, their size is considerably smaller compared with an MP3 file; makes them ideal for devices where memory is an issue E.g. storing ring tones on a mobile phone

98
Q

Mp3(MPEG-3) uses:

A

audio compression to convert music/other sounds into an Mp3 file format.

99
Q

Audio compression reduce the size of a normal music file by about ____ per cent.

A

90

100
Q

Bit rate

A

the number of bits per second

101
Q

Mp3 files use ___ format bc part of the original file is lost following the _______.

A

lossy, compression algorithm.

102
Q

What technique is used in Mp3 files?

A

PERCEPTUAL MUSIC SHAPING - removes sounds the human ear CANNOT detect; where two sounds are played SIMULTANEOUSLY the softer sound is REMOVED

103
Q

Mp3 is a digital recording of sound whilst MIDI is a

A

non-audio recording

104
Q

MIDI is produced by synthesizer whilst Mp3 is produced by

A

recording software

105
Q

difference between Mp3 and MIDI

A

MIDI is an instruction of how to make sound

106
Q

Mp3 is a compressed file format whilst MIDI file is created using

A

digital musical instruments

107
Q

Mp4(MPEG-4) allows the storage of

A

multimedia files(music, videos, photos) rather than just sound.

108
Q

define Image Compression

A

When a photographic file undergoes file compression, the size of the file is reduced.

109
Q

image compression - TIFF and BMP are the highest image quality because

A

unlike jpeg, they’re not in a compressed format.

110
Q

JPEG

A

another example of LOSSY file compression; reduce the RAW BITMP image by a factor of between 5 and 15 depending on the original quality.

111
Q

JPEG relies on certain properties of the ____ and, up to a point, a certain amount of file compression can take place without any real ____ of quality.

A

human eye, loss

112
Q

RLE stands for

A

Run-length Encoding

113
Q

What type of compression is used in RLE?

A

lossless(reversible)

114
Q

Features of RLE

A
  • Reduces the size of a string of adjacent, identical data
  • RLE is only effective where there is a long run of REPEATED units/bits.
115
Q

What does the first value represent in a repeating string encoded into two values in a RLE?

A

The number of identical data items in the run.

116
Q

What does the second value represent in a repeating string encoded into two values in a RLE?

A

The code of the data item(such as ASCII code if it is a keyboard character).

117
Q

What is a FLAG in RLE?

A

a flag preceding data indicates that what follows are the number of repeating units

118
Q

What happens when a flag is not used in RLE?

A

the next bytes are taken with their face value and a run of 1.

computer science revision (12 decks)

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