ASCII, symbols: description, code table and views

As you know, the computer stores information in binary form, representing it as a sequence of ones and zeros. To translate information into a form that is convenient for human perception, each unique sequence of digits is replaced by a corresponding symbol when displayed.

One of the systems of correlating binary codes with print and control characters is the ASCII encoding.

With today's level of development of computer technology, the user does not need knowledge of the code of each specific symbol. However, a common understanding of how coding is performed is extremely useful, and for some categories of specialists it is absolutely necessary.

Creating ASCII

In its original form, the encoding was developed in 1963 and then updated for 25 years.

In the original version, the ASCII character table included 128 characters, later an extended version appeared, where the first 128 characters were stored, and the codes with the eighth bit involved corresponded to the missing symbols.

Over the years, this encoding has been the most popular in the world. In 2006, Latin 1252 took the leading place, and from the end of 2007 to the present time Unicode firmly holds the leading position.

Computer ASCII Presentation

Each ASCII character has its own code, consisting of 8 characters, representing a zero or one. The minimum number in this representation is zero (eight zeros in the binary system), which is the code of the first element in the table.

The maximum binary code in the original version of ASCII is zero + seven units, and in the extended version - eight units, since the eighth bit is connected.

Control characters

Control characters are signs that do not have a graphical representation and are used to organize text, control devices, etc. They can denote the beginning or the end of the text, tabulation, the generation of a sound signal, various operations for working on a teletype (teletype-machine for data transmission by An electrical channel), the resolution of the output of data on the device, the cancellation of the action,

In the ASCII character table, positions 0 to 31, as well as 127 are allocated to control characters. Total of such signs 33.

Other characters

The remaining 95 positions are assigned to punctuation marks and mathematical operations signs, decimal numbers, letters of the Latin alphabet, which differ in the register: "A" uppercase and "a" lowercase correspond different codes in the ASCII character table.

Numbers of symbols in the table

If a person is developing software or performing some other tasks in the field of information technology, he needs to know the numbers of a number of ASCII characters.

As mentioned above, positions 0-31 and 127 occupy control characters. Number 32 is assigned to a space, numbers 33-47 and 58-64 are assigned to punctuation marks and basic mathematical operations.

Latin uppercase letters are arranged alphabetically and have numbers from 65th to 90th. Lowercase letters are also arranged alphabetically, their positions are from 97th to 122nd. The remaining numbers (91-96 and 123-126) are assigned to the square and curly braces, oblique and straight line, and also some diacritical marks.

A complete table of symbols in a convenient graphical representation can be seen in the image presented above. The figure below shows the character numbers in the Russian ASCII character table.

Advanced ASCII

Since the original version of the encoding was developed based on the American user, it did not provide for not only different types of writing and national alphabets, but even the convenient use of diacritic marks actively used in European languages.

To form the extended encoding, the 8th bit was used. This version includes the symbols of the national European alphabets and phonetic transcription, the graphics elements used for drawing tables, a number of mathematical signs.

Some ASCII characters are rarely used today. In particular, this concerns the signs used to draw tables, since many more convenient ways of graphical representation of tables have been introduced in the years since the development of the extended encoding.

National encoding options

Before the advent of the extended version of ASCII, the revised versions of the encoding were used to display the national alphabets, where Russian, Greek, and Arabic characters were placed in place of the Latin letters.

Two codes in the table were assigned to switch between the standard US-ASCII and its national variant.

After ASCII began to include not 128, but 256 characters, the distribution received an encoding option, in which the original version of the table was stored in the first 128 codes with zero 8th bit. Signs of national writing were kept in the upper half of the table (128-255th position).

You do not need to know the ASCII character codes directly. It is usually sufficient for a software developer to know the number of an element in a table in order to calculate its code, if necessary, using a binary system.

Russian language

After the development in the early 70's of codings for the Scandinavian languages, Chinese, Korean, Greek, etc., the creation of its own version was also taken up by the Soviet Union. Soon, a version of the 8-bit encoding called KOI8 was developed, preserving the first 128 ASCII character codes and allocating as many positions under the letters of the national alphabet and additional characters.

Prior to the introduction of Unicode, KOI8 dominated the Russian segment of the Internet. There were variants of encoding for both Russian and Ukrainian alphabet.

Problems with ASCII

Since the number of elements even in the expanded table did not exceed 256, the possibility of containing several different scripts in one encoding was not available. In the 90s, the problem of "crocosyabr" appeared in Runet, when the texts typed by Russian ASCII characters were displayed incorrectly.

The problem was the inconsistency of the codes of different ASCII variants to each other. Recall that at positions 128-255, different characters could be placed, and when one Cyrillic encoding changed to another, all the letters of the text were replaced by others having an identical number in another version of the encoding.

Current state

With the advent of Unicode, the popularity of ASCII has plummeted.

The reason for this lies in the fact that the new encoding allowed to contain the signs of almost all written languages. The first 128 ASCII characters correspond to the same Unicode characters.

In 2000, ASCII was the most popular encoding on the Internet and was used on 60% of Google's indexed web pages. By 2012, the share of such pages has fallen to 17%, and the place of the most popular encoding was occupied by Unicode (UTF-8).

Thus, ASCII is an important part of the history of information technology, but its use in the future is seen as unpromising.