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)
Some Other Question :
- Explain the Common Bus System with its diagram.
- Explain the register transfer language with example.
- What is high impedance state in three-state buffer? Explain three state gate in designing bus system.
- Explain 4-bit Arithmetic Circuit with its Function Table
- Discuss the phases of Instruction Cycle with flowchart.
- Explain the basic working principle of the Control Unit of basic computer using diagram.