Home  www.playhookey.com  Thu, 08132020 

Direct Current

Alternating Current

Semiconductors

Digital

Logic Families

Digital Experiments

Computers

 Analog  Analog Experiments  Oscillators  Optics  HTML Test  

 Combinational Logic  Sequential Logic  Alternate FlipFlop Circuits  Counters  Registers  The 555 Timer   

Basic Gates

Derived Gates

The XOR Function

Boolean Algebra

Binary Addition

Negative Numbers and Binary Subtraction

 TwoInput Multiplexer  FourInput Multiplexer  OnetoTwo Line Decoder/Demultiplexer  TwotoFour Line Decoder/Demultiplexer  
Derived Logical Functions and Gates 

While the three basic functions AND, OR, and NOT are sufficient to accomplish all possible logical functions and operations, some combinations are used so commonly that they have been given names and logic symbols of their own.
We will discuss three of these on this page. The first is called NAND, and consists of an AND function followed by a NOT function. The second, as you might expect, is called NOR. This is an OR function followed by NOT. The third is a variation of the OR function, called the ExclusiveOR, or XOR function. As with the three basic logic functions, each of these derived functions has a specific logic symbol and behavior, which we can summarize as follows:
The three derived functions shown above are by no means the only ones, but these form the basis of all the others. On the next page we will look at how the XOR function is derived. Then we will begin our look at practical applications for logic gates in various combinations, to see just how these simple gates can be combined to perform every possible operation in a computer.


 
All pages on www.playhookey.com copyright © 1996, 20002015 by
Ken Bigelow Please address queries and suggestions to: webmaster@playhookey.com 