What do logic gates do and why are they needed in computers?

[courtrigrad]

Hello all

Just refreshing for computer science midterm, and need to review logic gates. What exactly are logic gates? I know that they include AND OR XOR etc... but why is it really needed? Could you please provide some examples of their effiiciency in the real world?

Thanks a lot

 

[Curious3141]

Those are called Boolean logic operations. Essentially such an operation acts on two bits (1 or 0) and produces a binary output (1 or 0). The relationship between all possible values the input(s) can take and the output can be reflected in a truth table.

The basic Boolean operations you have to know are NOT, AND, OR and XOR. Then you have derived operations like NAND, NOR and XNOR.

Boolean logic is useful both in software and in hardware.

In software (programming), Boolean logic is important in making decisions to direct program flow. Like IF (condition A) AND (condition B) THEN (output C), etc.

In hardware (electronics), you can get ICs (integrated circuits) that carry out these basic operations in digital logic circuits. For example, the 7404 chip is an inverter (NOT) chip. An extremely basic example of logic usage in hardware is for example when you put two switches in series to turn on (1) or off (0) a light. The light only comes on (1) when switch 1 is ON 'AND' switch 2 is ON. Or you could design a circuit that turns on a water sprinkler when the ambient light reaches a certain level 'OR' the relative humidity falls below a certain level, using the relevant transducers for detecting each of those conditions.

The XOR operation has slightly more esoteric use, the simplest use I am aware of is in computing the bit in a binary addition (compare the XOR truth table to the following : 0 + 0 = 0, 1 + 0 = 1, 0 + 1 = 1, 1 + 1 = 0 [carry 1]).

 

[wais]

for your help

Hi there,

Logic gates are fundamental building blocks of digital circuits and are used to perform logical operations on binary inputs. They are represented by symbols and can be combined to create complex circuits that can perform various tasks.

As you mentioned, some common logic gates include AND, OR, and XOR gates. These gates take in two binary inputs and produce a single binary output based on the logical operation being performed. For example, an AND gate will only produce a "1" output if both inputs are "1", otherwise it will produce a "0" output.

Logic gates are essential in computing because they allow us to manipulate and process information in a digital form. They are used in various applications such as computer processors, memory units, and even in simple everyday devices like calculators.

One example of their efficiency in the real world is in computer processors. The logical operations performed by logic gates are used to create complex instructions that allow the processor to perform calculations and process data. Without logic gates, computers would not be able to function as they do today.

I hope this helps to clarify what logic gates are and why they are important. Good luck on your midterm!