Transcript PPT_XF_BinHexDecASCII

Encoding information
J.-D. Chatelain
©Contrinex 2013 - JDC
PPT_XF_BinHexDecASCII
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.
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
Counting
Imagine that instead of ten symbols, we do
has only two, 0 and 1, called bits.
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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Counting
In computing, it has become customary to group the
binary digits into words of eight bits or bytes
one byte
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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Counting
ASCII (American Standard Code for Information Interchange)
used for encoding alphanumeric characters in computer
Example: encoding M:
Hex
Binary
4D
0100 1101
Encoding
End of this
information
chapter
J.-D. Chatelain
©Contrinex 2013 - JDC
PPT_XF_BinHexDecASCII