Simple Logic Gates

Over today’s Computer Science class, we learned how to use simple logic gates. Before going to the actual logic gates, I am first going to talk about Boolean Algebra, which is the operations involved when using logic gates. It is firstly introduced by George Boolean, who is an English mathematician. According to Mr. Pete, the Boolean Algebra is ideal for binary number system. (Mr. Pete) From to my own understanding, a logic gate is a basic building block of a circuit, it is operating with Boolean functions. We present the output and input in a table called Truth table.

Basic logic gates are listed as below:

1. NOT Gate

When you substitute a binary input signal (0 or 1), the output will, and always be the opposite as the input (Mr. Pete).

Picture from surrey.ac.uk

 

2. OR Gate

Different than the NOT gate, the OR gate can substitute two inputs. “If both are 0, the output is 0; otherwise, the output is 1.” Written by Mr. Pete.

Picture from surrey.ac.uk

 

3. AND Gate

If there are two inputs and both of them are 1, the output is 1, otherwise, the output is zero.

Picture from surrey.ac.uk

 

4. NAND Gate

Opposite than AND Gate, if there are two inputs and both of them are 1, the output is 0, otherwise, the output is 1.

Picture from surrey.ac.uk

 

5. NOR Gate

If two of the substitutes are zero, the output is 1, else, the output of the logic gate is zero.

Picture from surrey.ac.uk

 

6.  XOR Gate

The illustration diagram is shown below.

(“Talking with computers.” )

 

 

Logic gates can not only have one or two inputs; it can also have three inputs as well. All you have to do is do construct a four column truth table. As we all know that logic gates are used on electronic devices, here is a graph explaining the applications of each logic gate.

Picture from Mr. Pete’s Presentation Slide 

Before learning about logic gates, I never knew that a simple switch button can have such a complex but delicate mechanism. Learning about logic gates just give me more incentive to know more about computer science.

 

 

 

References:

“Basic logic gates.” surrey.ac.uk. n.d. Web. 24 Sept. 2016.

IYER, SRIRAM. “Death of Computer Science.” YourStory.com. 19 Dec. 2013. Web. 23 Sept. 2016.

“Talking with computers.” Brown.edu. n.d. Web. 24 Sept. 2016.

Mr. Pete. “Simple Logic Gates” Sept. 2016. Presentation.

“What is logic gate (AND, OR, XOR, NOT, NAND, NOR and XNOR)? – definition from WhatIs.com.” WhatIs.com. WhatIs.com, May 2015. Web. 23 Sept. 2016.