How many ISCII codes are there?

ASCII code.

The full name in English is america standard code for information interchange, Chinese meaning: American information exchange standard code. It has been established as an international standard by the International Organization for Standardization (ISO) and is known as the ISO 646 standard.

Suitable for all Latin alphabets, ASCII codes are available in both 7-digit and 8-digit formats. The ASCII code was introduced in 1968 to standardize data transmission in different computer hardware and software systems, and is used in most minicomputers and all personal computers. The ASCII code is divided into two sets:

The 128-character standard ASCII code and the additional 128-character augmentation and ASCII code.

Because 1 binary number can represent (21=) 2 states; A 2-digit binary number can represent (22) = 4 states; By analogy, a 7-bit binary number can represent (27=) 128 states, each of which is uniquely coded as a 7-bit binary code corresponding to a character (or control code), which can be arranged into a decimal serial number 0 127. So, a 7-bit ASCII code is encoded with a seven-bit binary number and can represent 128 characters.

No. 0 32 and No. 127 (34 in total) are control characters or communication characters, such as control characters: lf (line break), cr (carriage enter), ff (page change), del (delete), bel (ring), etc.;

Communication-specific characters: SOH (header), EOT (ending), ACK (acknowledge), etc.

No. 33 126 (of 94) is character, of which No. 48 57 is 0 9 ten Arabic numerals; 65 90 is 26 uppercase letters, 97 122 is 26 lowercase letters, and the rest are some punctuation marks, operation marks, etc.

Note: In a computer's memory unit, an ASCII code value occupies one byte (8 binary bits), and its highest bit (B7) is used as a parity bit. The so-called parity check refers to a method used to check whether there is an error in the transmission process, which is generally divided into two types: odd check and even check.

Odd check stipulates that the number of 1 in a byte must be odd, if it is not an odd number, add 1 to the highest b7; Even check stipulates that the number of 1s in a byte must be even, if it is not even, add 1 to the highest b7.

The length of the ASCII code is one byte, a total of 8 bits, which can theoretically represent 256 characters, but many times only 128 characters.

ASCII code is a 7-bit code, i.e. a byte consists of a 7-bit binary precedent, where the highest bit is the parity bit, and the other 7-bit binary number represents a character.

ASCII code can represent 127 different characters, of which 33 kinds of characters have special meanings, such as divination, line breaks, tabs, carriage returns, etc., and the other 94 kinds of characters are printable characters, these printable characters have English letters, Arabic numerals, spaces, etc., which can represent commonly used English characters.

ASCII code is particularly important for computers, and many computer languages and programming languages are represented by ASCII code, so it has become the core code for computer communication and text processing.

Subsequently, the character encoding of many advanced text and communication processing systems was extended based on ASCII code, such as GB2312 character set, that is, ASCII code is a core encoding.

For the English alphabet, a more efficient and efficient Unicode code can be used instead of the ASCII code, because Unicode can represent more characters and is more able to meet the needs of different languages.

E is the last 4 digits of A, which is 01000001 + 401000001 + 100010000101.

ASCII is a standard developed by the United States to represent characters in binary numbers, which is equivalent to ISO or a set of character encoding based on the Latin alphabet, which contains a total of 128 characters and can be stored in one byte, which is equivalent to the international standard ISO IEC 646.

First published in 1967 and last updated in 1986, the ASCII specification contains 33 control characters (characters that have some special features but cannot be displayed) and 95 displayable characters.

The ASCII standard ASCII code, also known as the basic ASCII code, uses 7-digit binary numbers (the remaining 1-digit binary is 0) to represent all the big and lowercase letters, the numbers 0 to 9, punctuation marks, and special control characters used in American English. ”

A type of cipher that corresponds to letters with numbers is called an ASCII code.

ASCII is a computer coding system based on the Latin alphabet that is primarily used to display modern English and other Western European languages. It is the most common standard for the exchange of information and is equivalent to the international standard ISO IEC was first published in 1967 and last updated in 1986, with a total of 128 characters defined so far.

ASCII code usage.

Specify a combination of 7-bit or 8-bit binary numbers to represent 128 or 256 possible characters. The standard ASCII code, also known as the basic ASCII code, uses 7 binary digits (the remaining 1 binary is 0) to represent all uppercase and lowercase letters, numbers 0 through 9, punctuation marks only, and special control characters used in American English. Where:

0 Tanchan 31 and 127 (33 in total) are control characters or communication-specific characters (the rest are displayable characters), such as control characters: lf (line break), cr (carriage enter), ff (page change), del (delete), bs (backspace), bel (ring), etc.; Communication-specific characters: SOH (header), EOT (ending), ACK (acknowledge), etc. ASCII values of and 13 are converted to backspace, tabulation, line break, and carriage return, respectively.