M

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Encoding information
J.-D. Chatelain
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Almost whole Humanity today uses the same ten
symbols called "Arabic numerals" and scored 0, 1,
2, 3, 4, 5, 6, 7, 8 and 9.
Counting
The ten symbols combined allow to represent any
number that is said then expressed in base 10, or
as decimal. What does mean a number like
8604? 8604 8 times 10 3 6 times 10 2 0
times 10 1 4 times 10 0
To represent numbers, men have first used the
hand, which has led to the decimal base
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Imagine that instead of ten symbols, we do has
only two, 0 and 1, called bits.
Counting
These two symbols, combined, can represent any
number that is said then expressed in base 2, or
in binary mode. What does mean a number like
1101? 1101 1 times 2 3 1 times 2 2 0 times
2 1 1 times 2 0 13
A binary numbering system is used in electronics
because it is easy to determine whether a switch
is open or closed.
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In computing, it has become customary to group
the binary digits into words of eight bits or
bytes
Counting
A byte allows to encode 2 8 256 different
values. It is unthinkable to use a different
symbol for each of 256 combinations
allowed. However, splitting the byte into two
4-bit words, each word can encode 2 4 16
combinations.
It is conceivable to assign a symbol to each of
the 16 different values
These symbols, combined, can represent any
number that is said then expressed in base 16, or
in hex mode What does mean a number like
D3A? D3A D(13) times 16 2 3 times 16 1
A(10) times 16 0 3386
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ASCII (American Standard Code for Information
Interchange) used for encoding alphanumeric
characters in computer
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D
0100
1101
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Encoding information
End of this chapter
J.-D. Chatelain