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Computer codes ASCII Codes, EBCDIC Codes

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Objective

On completion of this period, you would be able to know

ASCII Codes

EBCDIC Codes

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Recap

Conversion of binary number to hexa decimal

Conversion of hexa decimal number to binary

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Prerequisite

ASCII Codes

EBCDIC Codes

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COMPUTER CODES

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Why codes are used?

• Codes are used to represent the letters and special characters (such as +,-,*,$,&) in terms of 0’s and 1’s

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Character Sets

BCD - Binary Coded Decimal

ASCII - American Standard Code for Information Interchange

EBCDIC - Extended Binary Coded Decimal Interchange Code

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BCD CODE

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BCD (Binary Coded Decimal)

BCD code is the simplest code to represent decimal numbers

In BCD code a decimal number is represented by four binary bits

For example, 3 is represented as 0011

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BCD Code (Binary Coded Decimal) contd

If a decimal number consists of two or more than two digits, each digit is individually represented by its four bit binary equivalent

For example, 56 is represented by 0101 0110

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Standard BCD codes

Decimal number Standard BCD codes

0

1

2

3

4

5

6

7

8

9

10

11

12

13

56

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

00010000

00010001

00010010

00010011

01010110

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ASCII CODE

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ASCII

ASCII is pronounced as “ask-ee”

It stands for American Standard Code for Information Interchange

It is widely used in micro computers

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ASCII (contd)

Micro computers using 8-bit word length use

7-bit to represent the basic code

The 8th bit is used for parity or it may be permanently 0 or 1

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ASCII CODE (contd) :

In this code a character is represented by two parts

They are a zone portion and numeric portion

Each digit has 0101 as the zone portion and its binary representation as the numeric portion

Alphabetical characters are divided into two groups having 1010 or 1011 as the zone portion

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ASCII Codes for characters

Alphabetic ASCII-8 HEX A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

10100011

10100010

10100011

10100100

10100101

10100110

10100111

10101000

10101001

10101010

10101011

10101100

10101101

10101110

10101111

10100000

10110001

A1

A2

A3

A4

A5

A6

A7

A8

A9

AA

AB

AC

AD

AE

AF

B0

B1

Numeric ASCII-8 HEX0

1

2

3

4

5

6

7

8

9

01010000

01010001

01010010

01010011

01010100

01010101

01010110

01010111

01011000

01011001

50

51

52

53

54

55

56

57

58

59

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