Question

what are logic gates? Write two names of universal logic gates.

Answer 1

Hint: A logic gate is an ideal or physical electronic device with a Boolean feature, a logical operation on one or more binary inputs which generates a single binary output. The term may refer to an ideal logical gate, for example, with zero rise time and unlimited fans, or a non-ideal physical structure, depending on its context.

Complete step-by-step answer:
Logic gates are mainly implemented through diodes or transistors that act as electronic switches but can also be built by means of vacuum tubes, electromagnetic relay systems (Relay Logic). Logic gates can be cascaded with amplitation in the same format as Boolean functions, allowing the building of a physical model of all Boolean logic, and thus all algorithms and the mathematics that can be represented by Boolean logic.
Universal logical gates are the logical gates to use any Boolean function. No other type of gate is required.
They are called as “Universal Gates” because-
1. They can realize all the binary operations.
2. All the basic logic gates can be derived from them.
They have the following properties-
1. Universal gates are not associative in nature.
2. Universal gates are commutative in nature.
There are following two universal logic gates-
Figure-

1. NAND Gate
2. NOR Gate

NAND Gate –
 1. A NAND Gate is constructed by connecting a NOT Gate at the output terminal of the AND Gate.
2. The output of a NAND gate is high (‘1’) if at least one of its inputs is low (‘0’).
3. The output of a NAND gate is low (‘0’) if all of its inputs are high (‘1’).
The logic symbol for NAND Gate is as shown below-
Figure-

2. NOR Gate-
1. A NOR Gate is constructed by connecting a NOT Gate at the output terminal of the OR Gate.
2. The output of the OR gate is high (‘1’) if all of its inputs are low (‘0’).
3. The output of the OR gate is low (‘0’) if any of its inputs is high (‘1’).
The logic symbol for NOR Gate is as shown below-
Figure-

Note- Logical circuits include such tools as multiplexers, registers, arithmetic logic units and computer memory that contain more than 100 million microprocessors. Most gates are made of MOSFETs in modern (metal–oxide–semiconductor field-effect transistors).