Difference between revisions of "Half Adder / Full Adder"

From TRCCompSci - AQA Computer Science
Jump to: navigation, search
(Full Adder)
Line 16: Line 16:
  
 
[[File:Full Adder Blocks.png]]
 
[[File:Full Adder Blocks.png]]
 +
 +
==4 Bit Adder==
 +
The 4 bit adder is 4 full adders connected together to allow you to add 2 4 bit binary numbers together. A1, A2, A3, A4 represent 1 binary number, and B1, B2, B3, B4 represent the other binary number.
 +
 +
[[File:4-bit-adder.jpg]]

Revision as of 08:48, 16 March 2017

Half Adder

The half adder circuit will do half of a binary addition of 2 1 bit binary numbers. A & B are the 2 1 bit binary values, remember the rules of binary addition:

  • 0 1's sum is 0
  • 1 1's sum is 1
  • 2 1's sum is 0 carry is 1
  • 3 1's sum is 1 carry is 1

The most common half adder is made up of two logic gates, an AND gate and a XOR gate. It has two inputs and two outputs. The two inputs are the two bits you are adding together and the two outputs are the result and a carry-on for when the output value is not large enough to display the answer.

Halfadder1.gif

Full Adder

The full adder is 2 half adders connected together, this will allow you to add 2 1 bit binary numbers together.


Full Adder Blocks.png

4 Bit Adder

The 4 bit adder is 4 full adders connected together to allow you to add 2 4 bit binary numbers together. A1, A2, A3, A4 represent 1 binary number, and B1, B2, B3, B4 represent the other binary number.

4-bit-adder.jpg