Characters: ASCII

Numbers are not the only kind of data to process.

Need letters, digits, punctuation, etc.

Assigning binary codes to characters is arbitrary.

Finite set, unlike numbers.

ASCII: American Standard Code for Information Interchange

Standard: can be used by many kinds of computers, regardless of architecture.

man ascii (in UNIX):

0 nul

16 dle

32 sp

48 0

64 @

80 P

96 `

112 p

1 soh

17 dc1

33 !

49 1

65 A

81 Q

97 a

113 q

2 stx

18 dc2

34 "

50 2

66 B

82 R

98 b

114 r

3 etx

19 dc3

35 #

51 3

67 C

83 S

99 c

115 s

4 eot

20 dc4

36 $

52 4

68 D

84 T

100 d

116 t

5 enq

21 nak

37 %

53 5

69 E

85 U

101 e

117 u

6 ack

22 syn

38 &

54 6

70 F

86 V

102 f

118 v

7 bel

23 etb

39 '

55 7

71 G

87 W

103 g

119 w

8 bs

24 can

40 (

56 8

72 H

88 X

104 h

120 x

9 ht

25 em

41 )

57 9

73 I

89 Y

105 i

121 y

10 nl

26 sub

42 *

58 :

74 J

90 Z

106 j

122 z

11 vt

27 esc

43 +

59 ;

75 K

91 [

107 k

123 {

12 np

28 fs

44 ,

60 <

76 L

92 \

108 l

124 |

13 cr

29 gs

45 -

61 =

77 M

93 ]

109 m

125 }

14 so

30 rs

46 .

62 >

78 N

94 ^

110 n

126 ~

15 si

31 us

47 /

63 ?

79 O

95 _

111 o

127 del

Kinds of symbols

control characters

punctuation/operator symbols

digits

uppercase alphabet

lowercase alphabet

Uppercase alphabet, lowercase alphabet, digits are each contiguous

Only 128 characters, but a byte is used to store, so msb of character is 0.

Sometimes extended (IBM PC) to 256 characters.