Page 57 - ComputerScience_Class_11

Example 2: Write the decimal representation of 1001100001100011.
Answer: Grouping in 4 bits and writing the decimal equivalent of each group:

1001 1000 0110 0011
9 8 6 3
So, the equivalent decimal number is 9863.

Application of BCD:
• BCD systems are used in electronic counters, digital clocks and pocket calculators.
Limitations of BCD:
• BCD codes are inefficient as compared to binary codes. For example, 12 in binary is 1100 but in BCD notation it is
written as 0001 0010.
• Arithmetic operations become more complex as compared to binary notation.
• As BCD is a 4-bit code, it can only represent numbers and is incapable of handling non-numeric characters.

To represent alphabets in BCD, a 6-bit coding system was developed which could represent numbers, letters and
some special characters. It contains 2 zone bits and 4 numeric bits and can be represented using octal equivalents.
Internally, however, it appears as a 7-bit code, the leftmost bit called the check bit or parity bit is added as shown below:

Check bit Zone bits Numeric bits
B A 8 4 2 1
The following table represents a 6-bit BCD code:
Character Zone bit Numeric bit Octal value
A 11 0001 61
B 11 0010 62
C 11 0011 63
D 11 0100 64
E 11 0101 65
F 11 0110 66
G 11 0111 67
H 11 1000 70
I 11 1001 71
J 10 0001 41
K 10 0010 42
L 10 0011 43
M 10 0100 44
N 10 0101 45
O 10 0110 46
P 10 0111 47
Q 10 1000 50
R 10 1001 51
S 01 0010 22
T 01 0011 23
U 01 0100 24
V 01 0101 25
W 01 0110 26
X 01 0111 27
Y 01 1000 30

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