Logic Circuits Questions and Answers

Logic Circuits Questions and Answers

Q1. What is a combinational circuit?


In a combinational circuit, the output depends upon present input(s) only i.e, not dependant on the previous input(s). The combinational circuit has no memory element. It consists of logic gates only.

Q2. Write two characteristics of combinational circuits.

The two characteristics of combinational circuits are:

  • In combinational circuits, the output exists as long as the input exists.
  • A combinational circuit will always respond in the same fashion to the input function, when we apply signal to the input terminal of the combinational logic circuit.

Q3. What is a half-adder?

A logic circuit, that can add two 1-bit numbers and produce outputs for sum and carry, is called a half-adder.

Q4. What is a full-adder?

A binary adder, which can add two 1-bit binary numbers along with a carry bit and produces outputs for sum and carry is called a full-adder.

Q5. What is a flip-flop?

A flip-flop is a basic memory element that is made of an assembly of logic gates and is used to store 1-bit of information.

Q6. What is a latch?

It is a D-type of flip-flop and stores one bit of data.

Q7. What is an excitation table?

Excitation table gives an information about what should be the flip-flop inputs if the outputs are specified before and after the clock pulses.

Q8. What is a state table?

State table consists of complete information about present state, next state, and outputs of a sequential circuit.