What is Primary Logic Gates?
According to Wikipedia, In electronics, a logic gate is an idealized or physical device implementing a Boolean function; that is, it performs a logical operation on one or more logical inputs, and produces a single logical output.
The common use of logic elements is to act as switches, although they have no moving parts. They open to pass on a pulse of electricity or close to shut it off. This is why they are known as gates. The primary gates are OR, AND, NOT.
OR Gate
An OR gate has an output 1 if any of its inputs are 1. The diagram and truth table for two input OR gate are shown in Fig 5.1. Ideal output, Y = A + B, where + denotes OR operation.
Figure 5.2 Illustrates, the close relationship between 2-input OR gate and electrical switching circuits. Such a circuit normally contains some source of energy (a battery), an output device (a lamp), and one or more switches - all connected by wires. A switch is a two-state device that is either closed (on) or open (off). In Figure 5.2 switch A and B, are connected in parallel. The lamp will light if switch A is closed, or if switch B is closed, or if both switches are closed. But this is the property described by the truth table for the OR gate, where 1 denotes that the switches or lamp is on and 0 indicates that it is off.
AND Gate
An AND gate has an output 1 if all of its inputs are 1. The diagram and truth table for a two input AND gate are shown in Figure 5.3. Here output, Y= A.B, where '.' denotes AND operation.
NOT Gate
A NOT gate has one input and one output. It has the effect of reversing the input signal and is sometimes called an inverter. The diagram and truth table for a NOT gate are shown in Fig 5.5. Here output Y= A where '-' indicates NOT operation.
Basic gates (AND, OR, NOT) and universal gates (NAND, NOR) can be used in combination to make up digital computer circuits.
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