Digital Electronics interview questions

1. What is a Multiplexer ?
Multiplexer, also known as a data selector, is a device that selects between several analog or digital input signals and forwards it to a single output line. A multiplexer of inputs has select lines, which are used to select which input line to send to the output.

2. What is half adder ?
A half adder is a type of adder, an electronic circuit that performs the addition of numbers. The half adder is able to add two single binary digits and provide the output plus a carry value.

3. Explain a Logic gate ?
A logic gate is an idealized or physical electronic device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and unlimited fan-out, or it may refer to a non-ideal physical device. Most logic gates take an input of two binary values, and output a single value of a 1 or 0.

4. What is a half subtractor ?
The half subtractor is a combinational circuit which is used to perform subtraction of two bits. It has two inputs, the minuend X and subtrahend Y and two outputs the difference D and borrow out B out.

5. What is a Latch or Flip-flop ?
A flip-flop or latch is a circuit that has two stable states and can be used to store state information – a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs.The difference between a latch and a flip-flop is that a latch is level-triggered (outputs can change as soon as the inputs changes) and Flip-Flop is edge triggered (only changes state when a control signal goes from high to low or low to high).The major difference between latches and flip-flops is that a latch doesn’t contain any clock signal whereas flip-flops consist of a clock signal.

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