2: ASCII Encoding

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2: ASCII Encoding

Standing for "American Standard Code for Information Interchange", this was the first attempt to provide a character exchange standard. When it was invented in the 1960’s, computing limitations limited the set to 2⁷ or 128 characters. For more information on how ASCII was developed, you can read this CNN article.

ASCII Chart

Characters number 1-31 are old control characters designed for teletype machines.

ASCII Numeric Values 32-127

32-47

Num	Char
32
33	!
34	"
35	#
36	$
37	%
38	&
39	‘
40	(
41	)
42	*
43	+
44	,
45	–
46	.
47	/

48-63

Num	Char
48	0
49	1
50	2
51	3
52	4
53	5
54	6
55	7
56	8
57	9
58	:
59	;
60	<
61	=
62	>
63	?

64-79

Num	Char
64	@
65	A
66	B
67	C
68	D
69	E
70	F
71	G
72	H
73	I
74	J
75	K
76	L
77	M
78	N
79	O

80-95

Num	Char
80	P
81	Q
82	R
83	S
84	T
85	U
86	V
87	W
88	X
89	Y
90	Z
91	[
92	\
93	]
94	^
95	_

96-111

Num	Char
96	`
97	a
98	b
99	c
100	d
101	e
102	f
103	g
104	h
105	i
106	j
107	k
108	l
109	m
110	n
111	o

112-127

Num	Char
112	p
113	q
114	r
115	s
116	t
117	u
118	v
119	w
120	x
121	y
122	z
123	{
124	|
125	}
126	~
127	DEL

 

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Properties of ASCII

ASCII is structured as followed

• Characters #0-31 are old teletype command or control codes
• Character #32 is a blank space
• Characters #48-57 are numerals
• Characters# 65-90 are capital letters
• Characters #97-122 are lower case letters
• The rest are different types of punctuation
• Numeric position determines alphabetic order

  NOTE: Sometimes the character number in an encoding scheme is called a code point.

Additional charts can be found at the following Web sites, among others.

• Fincher.org
• Memorial University of Newfoundland
• University of Wisconsin

NOTE: Some charts may list the decimal number (base-10) as well the hexadecimal (base-16) number and octal (base-8) number. In most cases, you would use the decimal number.

Deficiencies of ASCII

ASCII is notoriously U.S.centric and did not provide for common Western European symbols such as the British £ symbol, accented letters (e.g. ñ, é, ü), or even the ¢ symbol. In addition, it is a 7-bit code restricted to 128 (2⁷) characters, which is too few characters for the many languages which use accents in their spelling.

However, ASCII has been a core standard since its inception, and is an encoding standard available to almost all modern computers all over the world.

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