Data representation Flashcards

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1
Q

What is a bit?

A

A single 0 or 1

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2
Q

What is a byte

A

8 bits

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3
Q

What is a nibble

A

4 bits

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4
Q

How many bytes in a kilobyte

A

1000

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5
Q

What is the most significant bit?

A

The bit with the largest value (128)

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6
Q

What is the least significant bit?

A

The bit with the smallest value.

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7
Q

How can we convert 8 bit binary to hex?

A

Split the binary into two four bit binary, and convert each one into the relevant hex value.

Vice versa for hex to binary

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8
Q

Why is hexadecimal used?

A

Simpler to remember than binary

Quicker to write or type as it uses 1 digit rather than 4 bits

People less likely to make an error

Easier to convert into binary

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9
Q

What is an overflow error when adding binary

A

When the result of an addition is too large for the number of bits the computer works with

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10
Q

What is a character set?

A

A set of letters, symbols and digits that can be represented by a computer

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11
Q

What does ASCII stand for?

A

American Standard Code for Internet Interchange

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12
Q

What does concatenate mean?

A

Two strings that are joined together.

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13
Q

How many bits does ASCII use?

A

7 bits, which means that 128 characters can be stored

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14
Q

Why is Unicode also used as a character set?

A

Unicode is used as it can store more characters from many different languages
It can also store emojis

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15
Q

What is pixel an abbreviation of?

A

Picture element

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16
Q

What is a pixel?

A

The smallest identifiable element of an image

17
Q

What is resolution?

A

Resolution is the concentration of pixels within a specific area

72 PPI - 17 pixels per inch

18
Q

How can we work out the number of different colours that are available using the colour depth?

A

2^bit depth = number of colours

A colour depth of 4 means 2^4 colours, which is 16

19
Q

How can we work out the file size of an image?

A

Resolution x bits per pixel

20
Q

What is metadata?

A

Other information about the data

Colour depth
Resolution
Date created
Author

21
Q

What is ADC

A

Analogue to Digital Converter

22
Q

What is DAC

A

Digital to Analogue Converter

23
Q

What is the sound sample?

A

A measure of amplitude of a soundwave at a given time

24
Q

What is sample resolution?

A

The bit-depth (how clear the sound is)

25
Q

What is the sample rate?

A

The number of samples taken per second

26
Q

How can we calculate the file size for a sound file?

A

File size = sample rate x resolution x duration

27
Q

What is lossy compression?

A

Removes sounds we can’t hear or that least affects the perceived playback quality

28
Q

What is lossless compression?

A

Reduces the file size without removing any information

29
Q

What is compression?

A

The name given to algorithms that reduce file sizes

30
Q

What are examples of lossy compression file types?

A

JPG
GIF
MP3

31
Q

What are examples of lossless compression file types?

A

TIFF
PNG

32
Q

What is RLE?

A

Run length encoding uses frequency / data pairs to encode each run length of the same coloured pixel

33
Q

What is Huffman coding?

A

Huffman coding counts the frequency of each character in a Huffman tree

34
Q

What are the advantages of compression?

A

Download times reduced
Data allowances go further
Possible to transmit video and music as fast as they are being played

35
Q

Why are smaller files sent faster?

A

Fewer packets which means they are transmitted faster

36
Q

What is buffering?

A

When the download speed is slower than the playback speed