Page 75 - Computer science 868 Class 12
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HALF ADDER 1
A A⊕B
B
A.B HALF ADDER 2
C.(A⊕B)+AB
A⊕B⊕C
C
C.(A⊕B)
2.4 ENCODER
The computer works on binary numbers. We need to convert numbers from any base to their binary form so that
computer can process them. An encoder is the device that performs this conversion operation.
An Encoder is a combinational circuit that convert decimal, octal or hexa decimal numbers to
its equivalent binary from.
An encoder has a maximum of 2 n input lines and n output lines.
Encoders can be of three types:
1. Octal to Binary Encoder
2. Decimal to Binary Encoder
3. Hexadecimal to Binary Encoder
2.4.1 Octal to Binary Encoder
We recall, the base of an octal number is 8 and the digits are from 0 to 7. Octal numbers can be represented by 3 bits.
Thus an Octal to binary encoder has 8 input lines and 3 output lines.
The block diagram of an Octal to Binary encoder can be represented as follows:
0
1 B 2
2
3 Octal to
4 Binary Encoder B 1
5
6
B
7 0
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Computer Hardware 73

