Arithmetic circuits can perform seven different arithmetic operations using a single composite circuit.
It uses a full adder (FA) to perform these operations. A multiplexer (MUX) is used to provide different inputs to the circuit in order to obtain different arithmetic operations as outputs.
4-bit Arithmetic Circuit :
Consider the following 4-bit Arithmetic circuit with inputs A and B. It can perform seven different arithmetic operations by varying the inputs of the multiplexer and the carry (C0).
Truth Table for the above Arithmetic Circuit :
S0 |
S1 |
C0 |
MUX Output |
Full Adder Output |
0
|
0
|
0
|
B
|
A + B
|
0
|
0
|
1
|
B
|
A + B + 1
|
0
|
1
|
0
|
B’
|
A + B’
|
0
|
1
|
1
|
B’
|
A + B’ + 1 = A – B
|
1
|
0
|
0
|
0
|
A
|
1
|
0
|
1
|
0
|
A + 1
|
1
|
1
|
0
|
1
|
A – 1
|
1
|
1
|
1
|
1
|
A – 1 + 1 = A
|
Hence, the different operations for the inputs A and B are –
- A + B (adder)
- A + B + 1
- A + B’
- A – B (subtracter)
- A
- A + 1 (incrementer)
- A – 1 (decrementer)
Last Updated :
15 Feb, 2021
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