ASCII Table: An Essential Guide

The ASCII (American Standard Code for Information Interchange) table is a significant aspect of modern computing. Initially developed in the 1960s, ASCII was standardized to represent text-based information in computers, communications equipment, and other text-based devices. This article offers an in-depth look into the ASCII table, its structure, and uses.

Understanding the ASCII Table

ASCII is a character encoding standard that assigns unique numeric values to letters, digits, punctuation marks, space, control characters, and other symbols. The original ASCII standard uses 7 bits to represent each character, allowing 128 unique combinations (from 0 to 127). An extended version of ASCII uses an additional bit, expanding the range to 256 characters.

The Structure of the ASCII Table

The ASCII table is divided into two main sections:

1. Control Characters (0 – 31 and 127): These characters are not printable as they are intended to control hardware devices. Examples include carriage return (CR), line feed (LF), and escape (ESC).
2. Printable Characters (32 – 126): These characters include the common characters used in English writing. This section starts from space (32), goes through punctuation, numbers, uppercase letters, and more punctuation, and ends with lowercase letters.

An extended version of the ASCII table includes additional characters beyond 127, like foreign language characters, special symbols, and graphical elements.

Standard ASCII Table

DEC	HEX	OCT	BIN	CHAR	DESCRIPTION
0	00	000	00000000	NUL	Null char
1	01	001	00000001	SOH	Start of Heading
2	02	002	00000010	STX	Start of Text
3	03	003	00000011	ETX	End of Text
4	04	004	00000100	EOT	End of Transmission
5	05	005	00000101	ENQ	Enquiry
6	06	006	00000110	ACK	Acknowledgment
7	07	007	00000111	BEL	Bell
8	08	010	00001000	BS	Back Space
9	09	011	00001001	HT	Horizontal Tab
10	0A	012	00001010	LF	Line Feed
11	0B	013	00001011	VT	Vertical Tab
12	0C	014	00001100	FF	Form Feed
13	0D	015	00001101	CR	Carriage Return
14	0E	016	00001110	SO	Shift Out / X-On
15	0F	017	00001111	SI	Shift In / X-Off
16	10	020	00010000	DLE	Data Line Escape
17	11	021	00010001	DC1	Device Control 1 (oft. XON)
18	12	022	00010010	DC2	Device Control 2
19	13	023	00010011	DC3	Device Control 3 (oft. XOFF)
20	14	024	00010100	DC4	Device Control 4
21	15	025	00010101	NAK	Negative Acknowledgement
22	16	026	00010110	SYN	Synchronous Idle
23	17	027	00010111	ETB	End of Transmit Block
24	18	030	00011000	CAN	Cancel
25	19	031	00011001	EM	End of Medium
26	1A	032	00011010	SUB	Substitute
27	1B	033	00011011	ESC	Escape
28	1C	034	00011100	FS	File Separator
29	1D	035	00011101	GS	Group Separator
30	1E	036	00011110	RS	Record Separator
31	1F	037	00011111	US	Unit Separator
32	20	040	00100000	SP	Space
33	21	041	00100001	!	Exclamation mark
34	22	042	00100010	“	Quotation mark
35	23	043	00100011	#	Number sign
36	24	044	00100100	$	Dollar sign
37	25	045	00100101	%	Percent sign
38	26	046	00100110	&	Ampersand
39	27	047	00100111	‘	Apostrophe
40	28	050	00101000	(	Left parenthesis
41	29	051	00101001	)	Right parenthesis
42	2A	052	00101010	*	Asterisk
43	2B	053	00101011	+	Plus sign
44	2C	054	00101100	,	Comma
45	2D	055	00101101	–	Minus sign
46	2E	056	00101110	.	Period / dot
47	2F	057	00101111	/	Slash / divide
48	30	060	00110000	0	Digit 0
49	31	061	00110001	1	Digit 1
50	32	062	00110010	2	Digit 2
51	33	063	00110011	3	Digit 3
52	34	064	00110100	4	Digit 4
53	35	065	00110101	5	Digit 5
54	36	066	00110110	6	Digit 6
55	37	067	00110111	7	Digit 7
56	38	070	00111000	8	Digit 8
57	39	071	00111001	9	Digit 9
58	3A	072	00111010	:	Colon
59	3B	073	00111011	;	Semicolon
60	3C	074	00111100	<	Less than
61	3D	075	00111101	=	Equals sign
62	3E	076	00111110	>	Greater than
63	3F	077	00111111	?	Question mark
64	40	100	01000000	@	At symbol
65	41	101	01000001	A	Uppercase A
66	42	102	01000010	B	Uppercase B
67	43	103	01000011	C	Uppercase C
68	44	104	01000100	D	Uppercase D
69	45	105	01000101	E	Uppercase E
70	46	106	01000110	F	Uppercase F
71	47	107	01000111	G	Uppercase G
72	48	110	01001000	H	Uppercase H
73	49	111	01001001	I	Uppercase I
74	4A	112	01001010	J	Uppercase J
75	4B	113	01001011	K	Uppercase K
76	4C	114	01001100	L	Uppercase L
77	4D	115	01001101	M	Uppercase M
78	4E	116	01001110	N	Uppercase N
79	4F	117	01001111	O	Uppercase O
80	50	120	01010000	P	Uppercase P
81	51	121	01010001	Q	Uppercase Q
82	52	122	01010010	R	Uppercase R
83	53	123	01010011	S	Uppercase S
84	54	124	01010100	T	Uppercase T
85	55	125	01010101	U	Uppercase U
86	56	126	01010110	V	Uppercase V
87	57	127	01010111	W	Uppercase W
88	58	130	01011000	X	Uppercase X
89	59	131	01011001	Y	Uppercase Y
90	5A	132	01011010	Z	Uppercase Z
91	5B	133	01011011	[	Left square bracket
92	5C	134	01011100	\	Backslash
93	5D	135	01011101	]	Right square bracket
94	5E	136	01011110	^	Caret
95	5F	137	01011111	_	Underscore
96	60	140	01100000	`	Grave accent
97	61	141	01100001	a	Lowercase a
98	62	142	01100010	b	Lowercase b
99	63	143	01100011	c	Lowercase c
100	64	144	01100100	d	Lowercase d
101	65	145	01100101	e	Lowercase e
102	66	146	01100110	f	Lowercase f
103	67	147	01100111	g	Lowercase g
104	68	150	01101000	h	Lowercase h
105	69	151	01101001	i	Lowercase i
106	6A	152	01101010	j	Lowercase j
107	6B	153	01101011	k	Lowercase k
108	6C	154	01101100	l	Lowercase l
109	6D	155	01101101	m	Lowercase m
110	6E	156	01101110	n	Lowercase n
111	6F	157	01101111	o	Lowercase o
112	70	160	01110000	p	Lowercase p
113	71	161	01110001	q	Lowercase q
114	72	162	01110010	r	Lowercase r
115	73	163	01110011	s	Lowercase s
116	74	164	01110100	t	Lowercase t
117	75	165	01110101	u	Lowercase u
118	76	166	01110110	v	Lowercase v
119	77	167	01110111	w	Lowercase w
120	78	170	01111000	x	Lowercase x
121	79	171	01111001	y	Lowercase y
122	7A	172	01111010	z	Lowercase z
123	7B	173	01111011	{	Left curly bracket
124	7C	174	01111100	|	Vertical bar
125	7D	175	01111101	}	Right curly bracket
126	7E	176	01111110	~	Tilde
127	7F	177	01111111	DEL	Delete

Extended ASCII Table

Dec	Hex	Oct	Binary	Character	Description
128	80	200	10000000	Ç	Majuscule C-cedilla
129	81	201	10000001	ü	Minuscule u-umlaut
130	82	202	10000010	é	Minuscule e-acute
131	83	203	10000011	â	Minuscule a-circumflex
132	84	204	10000100	ä	Minuscule a-umlaut
133	85	205	10000101	à	Minuscule a-grave
134	86	206	10000110	å	Minuscule a-ring
135	87	207	10000111	ç	Minuscule c-cedilla
136	88	210	10001000	ê	Minuscule e-circumflex
137	89	211	10001001	ë	Minuscule e-umlaut
138	8A	212	10001010	è	Minuscule e-grave
139	8B	213	10001011	ï	Minuscule i-umlaut
140	8C	214	10001100	î	Minuscule i-circumflex
141	8D	215	10001101	ì	Minuscule i-grave
142	8E	216	10001110	Ä	Majuscule A-umlaut
143	8F	217	10001111	Å	Majuscule A-ring
144	90	220	10010000	É	Majuscule E-acute
145	91	221	10010001	æ	Minuscule ae
146	92	222	10010010	Æ	Majuscule AE
147	93	223	10010011	ô	Minuscule o-circumflex
148	94	224	10010100	ö	Minuscule o-umlaut
149	95	225	10010101	ò	Minuscule o-grave
150	96	226	10010110	û	Minuscule u-circumflex
151	97	227	10010111	ù	Minuscule u-grave
152	98	230	10011000	ÿ	Minuscule y-umlaut
153	99	231	10011001	Ö	Majuscule O-umlaut
154	9A	232	10011010	Ü	Majuscule U-umlaut
155	9B	233	10011011	¢	Cent sign
156	9C	234	10011100	£	Pound sign
157	9D	235	10011101	¥	Yen sign
158	9E	236	10011110	₧	Peseta sign
159	9F	237	10011111	ƒ	Florin sign
160	A0	240	10100000	á	Minuscule a-acute
161	A1	241	10100001	í	Minuscule i-acute
162	A2	242	10100010	ó	Minuscule o-acute
163	A3	243	10100011	ú	Minuscule u-acute
164	A4	244	10100100	ñ	Minuscule n-tilde
165	A5	245	10100101	Ñ	Majuscule N-tilde
166	A6	246	10100110	ª	Feminine ordinal
167	A7	247	10100111	º	Masculine ordinal
168	A8	250	10101000	¿	Inverted question mark
169	A9	251	10101001	⌐	Reversed not sign
170	AA	252	10101010	¬	Not sign
171	AB	253	10101011	½	One half
172	AC	254	10101100	¼	One quarter
173	AD	255	10101101	¡	Inverted exclamation
174	AE	256	10101110	«	Left angle quote
175	AF	257	10101111	»	Right angle quote
176	B0	260	10110000	░	Light shade
177	B1	261	10110001	▒	Medium shade
178	B2	262	10110010	▓	Dark shade
179	B3	263	10110011	│	Box drawings light vertical
180	B4	264	10110100	┤	Box drawings light vertical and left
181	B5	265	10110101	╡	Box drawings vertical single and left double
182	B6	266	10110110	╢	Box drawings vertical double and left single
183	B7	267	10110111	╖	Box drawings down double and left single
184	B8	270	10111000	╕	Box drawings down single and left double
185	B9	271	10111001	╣	Box drawings double vertical and left
186	BA	272	10111010	║	Box drawings double vertical
187	BB	273	10111011	╝	Box drawings double up and left
188	BC	274	10111100	╜	Box drawings up single and left double
189	BD	275	10111101	╛	Box drawings up double and left single
190	BE	276	10111110	┐	Box drawings light down and left
191	BF	277	10111111	└	Box drawings light up and right
192	C0	300	11000000	┴	Box drawings light up and horizontal
193	C1	301	11000001	┬	Box drawings light down and horizontal
194	C2	302	11000010	├	Box drawings light vertical and right
195	C3	303	11000011	─	Box drawings light horizontal
196	C4	304	11000100	┼	Box drawings light vertical and horizontal
197	C5	305	11000101	╞	Box drawings vertical single and right double
198	C6	306	11000110	╟	Box drawings vertical double and right single
199	C7	307	11000111	╚	Box drawings double up and right
200	C8	310	11001000	╔	Box drawings double down and right
201	C9	311	11001001	╩	Box drawings double up and horizontal
202	CA	312	11001010	╦	Box drawings double down and horizontal
203	CB	313	11001011	╠	Box drawings double vertical and right
204	CC	314	11001100	═	Box drawings double horizontal
205	CD	315	11001101	╬	Box drawings double vertical and horizontal
206	CE	316	11001110	╧	Box drawings up single and horizontal double
207	CF	317	11001111	╨	Box drawings up double and horizontal single
208	D0	320	11010000	╤	Box drawings down single and horizontal double
209	D1	321	11010001	╥	Box drawings down double and horizontal single
210	D2	322	11010010	╙	Box drawings up single and right double
211	D3	323	11010011	╘	Box drawings up double and right single
212	D4	324	11010100	╒	Box drawings down single and right double
213	D5	325	11010101	╓	Box drawings down double and right single
214	D6	326	11010110	╫	Box drawings vertical double and horizontal single
215	D7	327	11010111	╪	Box drawings vertical single and horizontal double
216	D8	330	11011000	┘	Box drawings light up and left
217	D9	331	11011001	┌	Box drawings light down and right
218	DA	332	11011010	█	Full block
219	DB	333	11011011	▄	Lower half block
220	DC	334	11011100	▌	Left half block
221	DD	335	11011101	▐	Right half block
222	DE	336	11011110	▀	Upper half block
223	DF	337	11011111	α	Alpha
224	E0	340	11100000	ß	Sharp S or Beta
225	E1	341	11100001	Γ	Gamma
226	E2	342	11100010	π	Pi
227	E3	343	11100011	Σ	Sigma
228	E4	344	11100100	σ	Sigma minuscule
229	E5	345	11100101	µ	Micro
230	E6	346	11100110	τ	Tau
231	E7	347	11100111	Φ	Phi majuscule
232	E8	350	11101000	Θ	Theta
233	E9	351	11101001	Ω	Omega
234	EA	352	11101010	δ	Delta minuscule
235	EB	353	11101011	∞	Infinity
236	EC	354	11101100	φ	Phi minuscule
237	ED	355	11101101	ε	Epsilon
238	EE	356	11101110	∩	Intersection
239	EF	357	11101111	≡	Identical to
240	F0	360	11110000	±	Plus-minus
241	F1	361	11110001	≥	Greater-than or equal to
242	F2	362	11110010	≤	Less-than or equal to
243	F3	363	11110011	⌠	Top half of integral
244	F4	364	11110100	⌡	Bottom half of integral
245	F5	365	11110101	÷	Division sign
246	F6	366	11110110	≈	Almost equal to
247	F7	367	11110111	°	Degree sign
248	F8	370	11111000	∙	Bullet operator
249	F9	371	11111001	·	Middle dot
250	FA	372	11111010	√	Square root
251	FB	373	11111011	ⁿ	Superscript n
252	FC	374	11111100	²	Superscript two
253	FD	375	11111101	■	Black square
254	FE	376	11111110		NBSP in DOS, Unicode
255	FF	377	11111111		Undefined in DOS, y with diaeresis in Unicode

Uses of ASCII

Since its inception, ASCII has become a fundamental standard in the computing world. Here are a few of its essential uses:

1. Communication between devices: ASCII is widely used for data transmission between devices. Many protocols, like HTTP and SMTP, use ASCII for formatting and data exchange.
2. Text files: ASCII is commonly used for plain text files. Notepad and other basic text editors primarily use ASCII.
3. Programming: Many programming languages use ASCII values for character processing. For example, in C and Python, you can use ASCII values to perform arithmetic on characters.
4. Art and design: ASCII is used in creating text-based art and design, known as ASCII art.

ASCII and Unicode

While ASCII is incredibly useful, it has one notable limitation—it is unsuitable for languages other than English. That’s where Unicode comes in.

Unicode is a character encoding standard that aims to represent all characters from all languages. It includes ASCII as a subset, meaning all ASCII characters have the same values in Unicode. Unlike ASCII, which uses 7 or 8 bits, Unicode can use 8, 16, or 32 bits, representing a much larger range of characters.

In conclusion, the ASCII table is a foundational standard in the digital world. Despite being several decades old, ASCII continues to be an essential tool for digital communication and data processing. Unicode has extended its usefulness by providing a comprehensive and inclusive character encoding system. ASCII and Unicode together form a crucial part of our digital communication infrastructure.