1. ©Contrinex 2013 - JDC PPT_XF_BinHexDecASCII Encoding information J.-D. Chatelain

2. To represent numbers, men have first used the hand, which has led to the decimal base 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

3. Imagine that instead of ten symbols, we do has only two, 0 and 1, called bits. Counting A binary numbering system is used in electronics because it is easy to determine whether a switch is open or closed. 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

4. 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 Counting

5. ASCII (American Standard Code for Information Interchange) used for encoding alphanumeric characters in computer Example: encoding M: HexBinary 4D01001101

6. ©Contrinex 2013 - JDC PPT_XF_BinHexDecASCII Encoding information J.-D. Chatelain End of this chapter