data representation Flashcards

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1
Q

how do you convert from hex to denary

A

go through binary and then to denary, you cannot go straight through

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2
Q

3 reasons hex is used

A

easier for humans to read. uses less digits than binary. less input errors

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3
Q

how do you times or divide a binary number

A

using binary shift. shift to the left for times and to the right for divide

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4
Q

how would you add two binary numbers

A

using column addition

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5
Q

what is an overflow error

A

when adding two 8 bit numbers gives a nine bit number

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6
Q

what is a problem with overflow errors

A

it gives an incorrect calculation

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7
Q

how do you convert from binary to hex

A

“split the 8 bit binary to two 4 bit binary numbers. assign each one to a hex no then
merge the two”

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8
Q

what is ASCII

A

most commonly used character set in english speaking world

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9
Q

how many bits are in ASCII and how many characters can it code for

A

7, 128

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10
Q

what is extended ASCII

A

same as normal ASCII but codes for 256 characters, using 8 bits

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11
Q

what does unicode do

A

“it tries to cover every possible character from all languages for example. 16 or 32
bit.”

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12
Q

how are images stored

A

as a series of pixels, which are coded through binary

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13
Q

what is the formula to work out how many colours are stored in an image

A

2^no of bits

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14
Q

what does resolution mean

A

density of pixels in an image

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15
Q

what is analouge

A

pieces of continually changing data

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16
Q

what is the formula for bit rate

A

sampling freq x sampling size

17
Q

define lossy compression

A

compresses by permenantly removing data from the file, reducing bits

18
Q

define loseless compression

A

“makes the file smaller by temporarily removing data which is restored when the file
is reopened”

19
Q

two pros of lossy compression

A

more files can be stored, uses less bandwidth

20
Q

two cons of lossy compression

A

data is lost, worse quality

21
Q

two pros of lossless compression

A

no reduction in quality, data is not lost

22
Q

two cons of loseless compression

A

only provide a slight reduction in file size