What does the sign mean in ascii. ASCII encoding (American standard code for information interchange) - basic text encoding for the Latin alphabet

A computer understands the process of converting it into a form that allows for more convenient transmission, storage or automatic processing of this data. Various tables are used for this purpose. ASCII was the first system developed in the United States for working with English-language text, which subsequently became widespread throughout the world. Its description, features, properties and further use The article below is devoted to this.

Display and storage of information in a computer

Symbols on a computer monitor or a mobile phone digital gadget are formed on the basis of sets of vector forms of various characters and a code that allows you to find among them the character that needs to be inserted into right place. It represents a sequence of bits. Thus, each character must uniquely correspond to a set of zeros and ones, which appear in a certain, unique order.

How it all started

Historically, the first computers were English-language. To encode symbolic information in them, it was enough to use only 7 bits of memory, while 1 byte consisting of 8 bits was allocated for this purpose. The number of characters understood by the computer in this case was 128. These characters included the English alphabet with its punctuation marks, numbers and some special characters. The English-language seven-bit encoding with the corresponding table (code page), developed in 1963, was called the American Standard Code for Information Interchange. Usually, the abbreviation “ASCII encoding” was and is still used to denote it.

Transition to multilingualism

Over time, computers became widely used in non-English speaking countries. In this regard, there was a need for encodings that allow the use national languages. It was decided not to reinvent the wheel and take ASCII as a basis. Encoding table in new edition has expanded significantly. The use of the 8th bit made it possible to translate into computer language already 256 characters.

Description

The ASCII encoding has a table that is divided into 2 parts. Only its first half is considered to be a generally accepted international standard. It includes:

Characters with serial numbers from 0 to 31, encoded in sequences from 00000000 to 00011111. They are reserved for control characters that control the process of displaying text on the screen or printer, sounding a sound signal, etc.
Characters with NN in the table from 32 to 127, encoded by sequences from 00100000 to 01111111 form the standard part of the table. These include space (N 32), letters of the Latin alphabet (lowercase and uppercase), ten-digit numbers from 0 to 9, punctuation marks, brackets of different styles and other symbols.
Characters with serial numbers from 128 to 255, encoded by sequences from 10000000 to 11111111. These include letters of national alphabets other than Latin. It is this alternative part of the ASCII table that is used to convert to computer form Russian symbols.

Some properties

Features of the ASCII encoding include the difference between the letters “A” - “Z” lower and uppercase only one bit. This circumstance greatly simplifies register conversion, as well as checking whether it belongs to a given range of values. In addition, all letters in the ASCII encoding system are represented by their own sequence numbers in the alphabet, which are written with 5 digits in the binary number system, preceded by 011 2 for lowercase letters and 010 2 for uppercase letters.

One of the features of the ASCII encoding is the representation of 10 digits - “0” - “9”. In the second number system they start with 00112 and end with 2 number values. So, 0101 2 is equivalent to the decimal number five, so the symbol “5” is written as 0011 01012. Based on the above, you can easily convert binary decimal numbers to an ASCII string by adding the bit sequence 00112 to each nibble on the left.

"Unicode"

As you know, thousands of characters are required to display texts in the languages of the Southeast Asian group. Such a number of them cannot be described in any way in one byte of information, so even extended versions of ASCII could no longer satisfy the increased needs of users from different countries.

Thus, the need arose to create a universal text encoding, the development of which, in collaboration with many leaders of the global IT industry, was undertaken by the Unicode consortium. Its specialists created the UTF 32 system. In it, 32 bits were allocated to encode 1 character, constituting 4 bytes of information. The main disadvantage was the sharp increase in volume required memory as much as 4 times, which entailed many problems.

At the same time, for most countries with official languages, belonging to the Indo-European group, the number of characters equal to 2 32 is more than excessive.

As a result further work Specialists from the Unicode consortium introduced the UTF-16 encoding. It became the option for converting symbolic information that suited everyone both in terms of the amount of memory required and the number of encoded characters. That is why UTF-16 was adopted by default and requires 2 bytes to be reserved for one character.

Even this fairly advanced and successful version of Unicode had some drawbacks, and after the transition from the extended version of ASCII to UTF-16, the weight of the document doubled.

In this regard, it was decided to use UTF-8 variable length encoding. In this case, each character of the source text is encoded as a sequence of length from 1 to 6 bytes.

Contact with American standard code for information exchange

All Latin characters in UTF-8 variable length are encoded into 1 byte, as in the ASCII encoding system.

A special feature of YTF-8 is that in the case of text in Latin without using other characters, even programs that do not understand Unicode will still be able to read it. In other words, the base ASCII text encoding simply becomes part of the new variable-length UTF. Cyrillic characters in YTF-8 occupy 2 bytes, and, for example, Georgian characters - 3 bytes. By creating UTF-16 and 8, the main problem of creating a single code space in fonts was solved. Since then, font manufacturers can only fill out the table vector shapes characters of text based on your needs.

Different operating systems prefer different encodings. To be able to read and edit texts typed in a different encoding, Russian text conversion programs are used. Some text editors contain built-in transcoders and allow you to read text regardless of encoding.

Now you know how many characters are in the ASCII encoding and how and why it was developed. Of course, today the Unicode standard is most widespread in the world. However, we must not forget that it is based on ASCII, so the contribution of its developers to the IT field should be appreciated.

The set of characters with which text is written is called alphabet.

The number of characters in the alphabet is its power.

Formula for determining the amount of information: N=2b,

where N is the power of the alphabet (number of characters),

b – number of bits ( information weight character).

The alphabet with a capacity of 256 characters can accommodate almost all the necessary characters. This alphabet is called sufficient.

Because 256 = 2 8, then the weight of 1 character is 8 bits.

The unit of measurement 8 bits was given the name 1 byte:

1 byte = 8 bits.

The binary code of each character in computer text takes up 1 byte of memory.

How is text information represented in computer memory?

The convenience of byte-by-byte character encoding is obvious because a byte is the smallest addressable part of memory and, therefore, the processor can access each character separately when processing text. On the other hand, 256 characters is quite a sufficient number to represent a wide variety of symbolic information.

Now the question arises, which eight-bit binary code match each character.

It is clear that this is a conditional matter; you can come up with many encoding methods.

All characters of the computer alphabet are numbered from 0 to 255. Each number corresponds to an eight-bit binary code from 00000000 to 11111111. This code is simply the serial number of the character in the binary number system.

A table in which all the characters of the computer alphabet are assigned to each other serial numbers, is called an encoding table.

For different types Computers use different encoding tables.

The table has become the international standard for PCs ASCII(read aski) (American standard code for information exchange).

The ASCII code table is divided into two parts.

Only the first half of the table is the international standard, i.e. symbols with numbers from 0 (00000000), up to 127 (01111111).

ASCII encoding table structure

Serial number	Code	Symbol
0 - 31	00000000 - 00011111	Symbols with numbers from 0 to 31 are usually called control symbols. Their function is to control the process of displaying text on the screen or printing, sounding a sound signal, marking up text, etc.
32 - 127	00100000 - 01111111	Standard part of the table (English). This includes lowercase and capital letters Latin alphabet, decimal numbers, punctuation marks, all kinds of brackets, commercial and other symbols. Character 32 is a space, i.e. empty position in the text. All others are reflected in certain signs.
128 - 255	10000000 - 11111111	Alternative part of the table (Russian). Second half of the code ASCII tables, called a code page (128 codes, starting from 10000000 and ending with 11111111), may have various options, each option has its own number. The code page is primarily used to accommodate national alphabets other than Latin. In Russian national encodings, characters from the Russian alphabet are placed in this part of the table.

First half of the ASCII code table

I draw your attention to the fact that in the encoding table the letters (uppercase and lowercase) are located in alphabetical order, and the numbers are ordered in ascending order. This observance of lexicographic order in the arrangement of symbols is called the principle of sequential coding of the alphabet.

For letters of the Russian alphabet, the principle of sequential coding is also observed.

Second half of the ASCII code table

Unfortunately, there are currently five different encodings Cyrillic (KOI8-R, Windows. MS-DOS, Macintosh and ISO). Because of this, problems often arise with transferring Russian text from one computer to another, from one software system to another.

Chronologically, one of the first standards for encoding Russian letters on computers was KOI8 ("Information Exchange Code, 8-bit"). This encoding was used back in the 70s on computers of the ES computer series, and from the mid-80s it began to be used in the first Russified versions operating system UNIX.

From the early 90s, the time of dominance of the MS DOS operating system, the CP866 encoding remains ("CP" means "Code Page", "code page").

Computers Apple operating under operating room control Mac systems OS, use their own Mac encoding.

In addition, the International Standards Organization (ISO) has approved another encoding called ISO 8859-5 as a standard for the Russian language.

The most common currently is Microsoft encoding Windows, abbreviated CP1251.

Since the late 90s, the problem of standardizing character encoding has been solved by introducing a new international standard which is called Unicode. This is a 16-bit encoding, i.e. it allocates 2 bytes of memory for each character. Of course, this increases the amount of memory occupied by 2 times. But such a code table allows the inclusion of up to 65536 characters. The complete specification of the Unicode standard includes all the existing, extinct and artificially created alphabets of the world, as well as many mathematical, musical, chemical and other symbols.

Let's try using an ASCII table to imagine what words will look like in the computer's memory. Internal representation of words in computer memory

Sometimes it happens that a text consisting of letters of the Russian alphabet received from another computer cannot be read - some kind of “abracadabra” is visible on the monitor screen. This happens because computers use different character encodings for the Russian language.

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In this article: Insert an ASCII or Unicode character into a document

If you only need to enter a few special characters or symbols, you can use keyboard shortcuts. List ASCII characters see the following tables or the article Inserting letters from national alphabets using keyboard shortcuts.

Notes:

Inserting ASCII characters

To insert an ASCII character, press and hold the ALT key while entering the character code. For example, to insert a degree symbol (º), press and hold the ALT key, then type 0176 into numeric keypad.

To enter numbers, use the numeric keypad rather than the numbers on the main keyboard. If you need to enter numbers on the numeric keypad, make sure the NUM LOCK indicator is on.

Inserting Unicode Characters

To insert a Unicode character, enter the character code, then press ALT keys and X. For example, to insert a dollar symbol ($), enter 0024 and press ALT and X in sequence. For all Unicode character codes, see .

Important: Some programs Microsoft Office, such as PowerPoint and InfoPath, do not support converting Unicode codes to characters. If you need to insert a Unicode character in one of these programs, use .

Notes:

If the wrong Unicode character appears after you press ALT+X, select the correct code, and then press ALT+X again.

In addition, you must enter "U+" before the code. For example, if you enter "1U+B5" and press ALT+X, the text "1µ" will be displayed, and if you enter "1B5" and press ALT+X, the symbol "Ƶ" will be displayed.

Using the symbol table

A symbol table is a program built into Microsoft Windows, which allows you to view the characters available for the selected font.

Using a symbol table, you can copy individual symbols or a group of symbols to the clipboard and paste them into any program that supports displaying those symbols. Opening the symbol table

In Windows 10, enter the word "symbol" in the search box on the taskbar and select the symbol table from the search results.

In Windows 8, enter the word "character" at home screen and select symbol table from the search results.

In Windows 7, click the Start button, select All Programs, Accessories, System Tools, and then click Character Map.

Characters are grouped by font. Click the font list to select the appropriate character set. To select a symbol, click it, then click the Select button. To insert a symbol, click right click mouse over the desired location in the document and select Paste.

Frequently used character codes

Full list characters, see on your computer, ASCII character code table, or Unicode character tables organized by set.

Glyph

Currency

Legal symbols

Mathematical symbols

Fractions

Punctuation and dialect symbols

Shape symbols

Commonly used diacritics codes

For a complete list of glyphs and corresponding codes, see.

Glyph

Non-printing ASCII control characters

Signs used to control some peripheral devices, such as printers, are numbered 0–31 in the ASCII table. For example, the page feed/new page character is number 12. This character tells the printer to move to the beginning of the next page.

Table of non-printing ASCII control characters

Decimal number	Sign	Decimal number	Sign
		Freeing the data channel
Start of title		First device control code
Beginning of text		Second device control code
End of text		Third device control code
End of transmission		Fourth device control code
	five-pointed	Negative confirmation
Confirmation		Synchronous mode transfers
Beep		End of transmitted data block

Horizontal tabulation		End of media
Line feed/new line		Replacement symbol
Vertical tab			exceed
Page translation/new page	Twelve	File separator
Carriage return		Group separator
Shift without storing bits		Record separator
Bit-preserving shift	fifteen	Data separator

Dec	Hex	Symbol	Dec	Hex	Symbol
000	00	specialist. NOP	128	80	Ђ
001	01	specialist. SOH	129	81	Ѓ
002	02	specialist. STX	130	82	‚
003	03	specialist. ETX	131	83	ѓ
004	04	specialist. EOT	132	84	„
005	05	specialist. ENQ	133	85	…
006	06	specialist. ACK	134	86	†
007	07	specialist. BEL	135	87	‡
008	08	specialist. B.S.	136	88	€
009	09	specialist. TAB	137	89	‰
010	0A	specialist. LF	138	8A	Љ
011	0B	specialist. VT	139	8B	‹ ‹
012	0C	specialist. FF	140	8C	Њ
013	0D	specialist. CR	141	8D	Ќ
014	0E	specialist. SO	142	8E	Ћ
015	0F	specialist. S.I.	143	8F	Џ
016	10	specialist. DLE	144	90	ђ
017	11	specialist. DC1	145	91	‘
018	12	specialist. DC2	146	92	’
019	13	specialist. DC3	147	93	“
020	14	specialist. DC4	148	94	”
021	15	specialist. N.A.K.	149	95
022	16	specialist. SYN	150	96	–
023	17	specialist. ETB	151	97	—
024	18	specialist. CAN	152	98
025	19	specialist. E.M.	153	99	™
026	1A	specialist. SUB	154	9A	љ
027	1B	specialist. ESC	155	9B	›
028	1C	specialist. FS	156	9C	њ
029	1D	specialist. G.S.	157	9D	ќ
030	1E	specialist. R.S.	158	9E	ћ
031	1F	specialist. US	159	9F	џ
032	20	clutch SP (Space)	160	A0
033	21	!	161	A1	Ў
034	22	"	162	A2	ў
035	23	#	163	A3	Ћ
036	24	$	164	A4	¤
037	25	%	165	A5	Ґ
038	26	&	166	A6	¦
039	27	"	167	A7	§
040	28	(	168	A8	Yo
041	29	)	169	A9	©
042	2A	*	170	A.A.	Є
043	2B	+	171	AB	«
044	2C	,	172	A.C.	¬
045	2D	-	173	AD
046	2E	.	174	A.E.	®
047	2F	/	175	A.F.	Ї
048	30	0	176	B0	°
049	31	1	177	B1	±
050	32	2	178	B2	І
051	33	3	179	B3	і
052	34	4	180	B4	ґ
053	35	5	181	B5	µ
054	36	6	182	B6	¶
055	37	7	183	B7	·
056	38	8	184	B8	e
057	39	9	185	B9	№
058	3A	:	186	B.A.	є
059	3B	;	187	BB	»
060	3C	<	188	B.C.	ј
061	3D	=	189	BD	Ѕ
062	3E	>	190	BE	ѕ
063	3F	?	191	B.F.	ї
064	40	@	192	C0	A
065	41	A	193	C1	B
066	42	B	194	C2	IN
067	43	C	195	C3	G
068	44	D	196	C4	D
069	45	E	197	C5	E
070	46	F	198	C6	AND
071	47	G	199	C7	Z
072	48	H	200	C8	AND
073	49	I	201	C9	Y
074	4A	J	202	C.A.	TO
075	4B	K	203	C.B.	L
076	4C	L	204	CC	M
077	4D	M	205	CD	N
078	4E	N	206	C.E.	ABOUT
079	4F	O	207	CF	P
080	50	P	208	D0	R
081	51	Q	209	D1	WITH
082	52	R	210	D2	T
083	53	S	211	D3	U
084	54	T	212	D4	F
085	55	U	213	D5	X
086	56	V	214	D6	C
087	57	W	215	D7	H
088	58	X	216	D8	Sh
089	59	Y	217	D9	SCH
090	5A	Z	218	D.A.	Kommersant
091	5B	[	219	D.B.	Y
092	5C	\	220	DC	b
093	5D	]	221	DD	E
094	5E	^	222	DE	Yu
095	5F	_	223	DF	I
096	60	`	224	E0	A
097	61	a	225	E1	b
098	62	b	226	E2	V
099	63	c	227	E3	G
100	64	d	228	E4	d
101	65	e	229	E5	e
102	66	f	230	E6	and
103	67	g	231	E7	h
104	68	h	232	E8	And
105	69	i	233	E9	th
106	6A	j	234	E.A.	To
107	6B	k	235	E.B.	l
108	6C	l	236	E.C.	m
109	6D	m	237	ED	n
110	6E	n	238	E.E.	O
111	6F	o	239	E.F.	n
112	70	p	240	F0	r
113	71	q	241	F1	With
114	72	r	242	F2	T
115	73	s	243	F3	at
116	74	t	244	F4	f
117	75	u	245	F5	X
118	76	v	246	F6	ts
119	77	w	247	F7	h
120	78	x	248	F8	w
121	79	y	249	F9	sch
122	7A	z	250	F.A.	ъ
123	7B	{	251	FB	s
124	7C	\|	252	F.C.	b
125	7D	}	253	FD	uh
126	7E	~	254	F.E.	yu
127	7F	Specialist. DEL	255	FF	I

ASCII code table Windows characters.
Description of special (control) characters It should be noted that initially control characters of the ASCII table were used to ensure data exchange via teletype, data entry from punched tape and for simple control of external devices.
Currently, most of the ASCII table control characters no longer carry this load and can be used for other purposes. Code Description

NUL, 00	Null, empty
SOH, 01	Start Of Heading
STX, 02	Start of TeXt, the beginning of the text.
ETX, 03	End of TeXt, end of text
EOT, 04	End of Transmission, end of transmission
ENQ, 05	Enquire. Please confirm
ACK, 06	Acknowledgment. I confirm
BEL, 07	Bell, call
BS, 08	Backspace, go back one character
TAB, 09	Tab, horizontal tab
LF, 0A	Line Feed, line feed. Nowadays in most programming languages it is denoted as \n
VT, 0B	Vertical Tab, vertical tabulation.
FF, 0C	Form Feed, page feed, new page
CR, 0D	Carriage Return, carriage return. Nowadays in most programming languages it is denoted as \r
SO,0E	Shift Out, change the color of the ink ribbon in the printing device
SI,0F	Shift In, return the color of the ink ribbon in the printing device back
DLE, 10	Data Link Escape, channel switching to data transmission
DC1, 11 DC2, 12 DC3, 13 DC4, 14	Device Control, device control symbols
NAK, 15	Negative Acknowledgment, I do not confirm.
SYN, 16	Synchronization. Synchronization symbol
ETB, 17	End of Text Block, end of the text block
CAN, 18	Cancel, canceling previously transferred
EM, 19	End of Medium
SUB, 1A	Substitute, substitute. Placed in place of a symbol whose meaning was lost or corrupted during transmission
ESC, 1B	Escape Control Sequence
FS, 1C	File Separator, file separator
GS, 1D	Group Separator
RS, 1E	Record Separator, record separator
US, 1F	Unit Separator
DEL, 7F	Delete, erase the last character.

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In order to use ASCII correctly, it is necessary to expand your knowledge in this area and about coding capabilities.

What is it?

ASCII is an encoding table of printable characters (see screenshot No. 1) typed on computer keyboard, to transmit information and some codes. In other words, the alphabet and decimal digits are encoded into corresponding symbols that represent and carry the necessary information.

ASCII was developed in America, so the standard character set usually includes the English alphabet with numbers, for a total of about 128 characters. But then a fair question arises: what to do if encoding of the national alphabet is required?

Other versions of the ASCII table have been developed to address similar issues. For example, for languages with a foreign language structure, letters of the English alphabet were either removed or added additional characters in the form of a national alphabet. Thus, the ASCII encoding may contain Russian letters for national use (see screenshot No. 2).

Where is the ASCII coding system used?

This coding system is necessary not only for dialing text information on the keyboard. It is also used in graphics. For example, in the ASCII Art Maker program graphic images various extensions consist of a range of ASCII characters (see screenshot No. 3).

As a rule, such programs can be divided into those that perform the function graphic editors, inverting an image into text, and those that convert an image into ASCII graphics. The well-known emoticon (or as it is also called “smiling human face”) is also an example of an encoding symbol.

This encoding method can also be used during writing or creation HTML document. For example, you enter a specific and necessary set of characters, and when viewing the page itself, the symbol corresponding to this code will be displayed on the screen.

Among other things this type encoding is necessary when creating a multilingual website, because characters that are not included in a particular national table will need to be replaced with ASCII codes. If the reader is directly connected with information and communication technologies (ICT), then it will be useful for him to familiarize himself with such systems as:

Portable character set;

Control characters;

EBCDIC;

VISCII;

YUSCII;

Unicode;

ASCII art;

KOI-8.

ASCII Table Properties

Like any systematic program, ASCII has its own characteristic properties. So, for example, the decimal number system (numbers from 0 to 9) is converted to binary system calculus (i.e. each decimal digit is converted to binary 288=1001000 respectively).

The letters located in the upper and lower columns differ from each other only by a bit, which significantly reduces the level of complexity of checking and editing the case.

With all these properties, ASCII encoding works as eight-bit, although it was originally intended to be seven-bit.

Application of ASCII in Microsoft programs Office:

If necessary this option information encoding can be used in Microsoft Notepad and Microsoft Office Word. Within these applications, the document can be saved in ASCII format, but in this case, you will not be able to use some functions when typing text.

In particular, bold and bold fonts will not be available because encoding only preserves the meaning of the typed information, and not general view and shape. You can add such codes to a document using the following software applications.