Data Representation

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  • Created by: Snowy271
  • Created on: 22-10-18 17:27
What is meant by a bit (of data)?
A binary digit, either 1 or 0
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What is the size of a nibble?
4 bits
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What is a logic gate?
An electrical component that performs a boolean operation
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List the units of data in ascending order of size
Bit, Nibble, Byte, Kilobyte, Megabyte, Gigabyte, Terabyte, Petabyte, Exabyte, Zettabyte, Yottabyte
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What is a check digit?
A digit added to a string of digits to make sure data has been entered and read correctly.
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State what is meant by the following expressions showing logic notation: a) ¬A b) A ∧ B c) A V B
a) NOT A b) A AND B c) A OR B
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What is the size of a byte?
8 bits
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What is a parity bit?
A bit added to the end of a binary string, similar to a check digit.
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Perform a 3-place left shift on the binary number 00101001
00101001000 (This will cause an overflow)
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Add the following binary numbers: 00110011 and 01111001
10101100
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How many different characters can be represented by ASCII? How many bits is each character given?
128 different characters each represented by a 7-bit binary code
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What is an overflow error?
An error that occurs when a computer tries to process a number that has too many bits
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In what direction would you shift a binary number to multiply it?
To the left
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Convert the hexadecimal number 87 to denary
135
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Convert the denary number 106 into hexadecimal
6A
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What is a character set?
Collections of characters that a computer recognises from their binary representation
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What is an analogue signal?
A signal consisting of continuously changing data which cannot be processed by a computer
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What are pixels?
Small picture elements arranged on a 2-dimensional grid
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Convert the denary number 79 to an 8-bit binary number
01001111
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How many different characters can be represented by extended ASCII? How many bits is each character given?
256 characters each with an 8-bit binary code
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What is unicode? How many bits is each character given?
A large character set which attempts to include all possible characters. Each character is most commonly given either a 32-bit or 16-bit binary code
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What is colour depth?
The number of bits used for each pixel in an image file
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What is resolution?
The density of pixels in an image
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How can the file size of an image be reduced?
By decreasing colour depth and resolution
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How is the total number of colours calculated in an image?
2^n (where n is the number of bits per pixel, or colour depth)
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What are the advantages of lossless compression?
No reduction of quality (as no data is lost), lossless files can be decompressed- the data is not removed permenantly, lossless compression can be used on text and software files
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What is the RGB colour model?
A 24-bit depth colour model which aims to cover every possible colour seen by the human eye by mixing red, green and blue in different amounts
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What is metadata?
Extra data stored with a file which gives information about the files properties
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Give some examples of metadata
File format, colour depth, resolution, height width
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What is sampling?
The process of converting analogue signals to digital data
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What is sample rate?
The number of samples taken from an analogue signal per second, measured in kilohertz
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What is the bit rate?
The number pf bits used per second of audio.
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Give three advantages of lossy compression
Great reduction in file size, lossy files take up less bandwidth: can be downloaded/streamed easier, lots of software can read lossy files
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How is bit rate calculated?
Bit rate = Sampling frequency x Sample size
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What is data compression?
The process of making the size of a file smaller
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Give some benefits of compression
Take up less storage, streaming and downloading files from a device is quicker- they take up less bandwidth, web pages can load more quickly, helps to stay within the limitations of email services: there are usually restrictions on attatchment sizes
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What is the difference between lossy and lossless compression?
Lossy compression permenantly removes data from a file while lossless compression only does so temporarily
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Give three examples of file types which use lossless compression
FLAC, TIFF, PNG
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What are the disadvantages of lossy compression?
Data is permenantly lost from the file, lossy compression can't be used on text or software files, worse quality than lossless compression
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What are the disadvantages of lossless compression?
Still take up lots of storage space on a device because there is only a slight reduction in file size
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Give three examples of file types which use lossy compression
MP3, AAC, JPEG
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Other cards in this set

Card 2

Front

What is the size of a nibble?

Back

4 bits

Card 3

Front

What is a logic gate?

Back

Preview of the front of card 3

Card 4

Front

List the units of data in ascending order of size

Back

Preview of the front of card 4

Card 5

Front

What is a check digit?

Back

Preview of the front of card 5
View more cards

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