1. Computer codes
ASCII Codes, EBCDIC Codes
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2. Objective
On completion of this period, you would be able
to know
 ASCII Codes
 EBCDIC Codes
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3. Recap
 Conversion of binary number to hexa decimal
 Conversion of hexa decimal number to binary
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4. Prerequisite
 ASCII Codes
 EBCDIC Codes
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5. COMPUTER CODES
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6. 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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7. Character Sets
BCD - Binary Coded Decimal
ASCII - American Standard Code for
Information Interchange
EBCDIC - Extended Binary Coded Decimal
Interchange Code
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8. BCD CODE
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9. 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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10. 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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11. Standard BCD codes
Decimal number Standard BCD codes
0 0000
1 0001
2 0010
3 0011
4 0100
5 0101
6 0110
7 0111
8 1000
9 1001
10 00010000
11 00010001
12 00010010
13 00010011
56 01010110
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12. ASCII CODE
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13. 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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14. 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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15. 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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16. ASCII Codes for characters
Alphabetic ASCII-8 HEX Numeric ASCII-8 HEX
A 10100011 A1 0 01010000 50
B 10100010 A2 1 01010001 51
C 10100011 A3 2 01010010 52
D 10100100 A4 3 01010011 53
E 10100101 A5 4 01010100 54
F 10100110 A6 5 01010101 55
G 10100111 A7 6 01010110 56
H 10101000 A8 7 01010111 57
I 10101001 A9 8 01011000 58
J 10101010 AA 9 01011001 59
K 10101011 AB
L 10101100 AC
M 10101101 AD
N 10101110 AE
O 10101111 AF
P 10100000 B0
Q 10110001 B1
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