American Standard Code for information Interchange, US standard Information Interchange code
From 0 to 127 of the 128 numbers represented by the English alphabet or the same result and meaning
Use only 7 bits (bit) can represent numbers from 0~127, but most computers use 8 bits to access a character set (character set)
The number between 128~255 can be used to represent another set of 128 symbols, called extended ASCII
Attention:
In the computer's storage unit, an ASCII value takes up one byte (8 bits), and its highest bit (B7) is used as a parity test bit
Parity: A method used to check for errors during code transfer, generally split/even two
Odd Check rule: the number of 1 in a byte must be an odd number, if not odd , the highest bit B7 add 1
Parity rule: The number of 1 in a byte must be even, not even, the highest bit B7 add 1
48~57:0~9 10 x Arabic numerals
65~90:26 Uppercase English letters
97~122:26 a lowercase English letter
0~32 and number 127th (34 total) are control characters or communication-specific characters, such as
Control: LF (line feed), CR (carriage return), FF (page feed), DEL (delete), BEL (ringing)
Communication-specific: SOH (head), EOT (end), ACK (confirmation)
ASCII Code Table