ASCII (American Standard Code for Information Interchange)

The ASCII code is a table or list that contains all the letters in the alphabet, both upper and lower case together with punctuation marks, parentheses and other additional characters. In this code each character is always represented by the same number of bits. For example, in ASCII code the capital letter A is always represented by the binary representation of the decimal number 65, ie. 01000001 (assuming an 8 bit code).

The standard ASCII code defines 128 character codes (from 0 to 127), of which, the first 32 are control codes (non-printable), and the other 96 are representable characters:

 

*

0

1

2

3

4

5

6

7

8

9

A

B

C

D

E

F

0

NUL

SOH

STX

ETX

EOT

ENQ

ACK

BEL

BS

TAB

LF

VT

FF

CR

SO

SI

1

DLE

DC1

DC2

DC3

DC4

NAK

SYN

ETB

CAN

EM

SUB

ESC

FS

GS

RS

US

2

!

"

#

$

%

&

'

(

)

*

+

,

-

.

/

3

0

1

2

3

4

5

6

7

8

9

:

;

<

=

>

?

4

@

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

5

P

Q

R

S

T

U

V

W

X

Y

Z

[

\

]

^

_

6

`

a

b

c

d

e

f

g

h

i

j

k

l

m

n

o

7

p

q

r

s

t

u

v

w

x

y

z

{

|

}

~

* This panel is organized to be easily read in hexadecimal: row numbers represent the first digit and the column numbers represent the second one. For example, the A character is located at the 4th row and the 1st column, for that it would be represented in hexadecimal 41 conventionally written as 0x41.

The extended 8-bit ASCII code  is not unique with different sets of characters for the extra 128 characters.

The two most used extended ASCII character sets are the one known as OEM, that comes from the default character set incorporated in the IBM-PC and the other is the ANSI extend ASCII which is used by recent operating systems.

The OEM character set, is included in the majority of PC compatibles when started before loading any operating system or under MS-DOS. It includes diverse foreign signs, some marked characters and line drawiung characters. Unfortunately it is usually redefined regionally to incorporate certain special symbols in different countries.