4-bit adders

A 4-bit adder accepts two 4-bit numbers and a carry input and outputs a 4-bit sum and a carry.
The logic circuitry for a 4-bit adder is shown in the following figure. As you can see, the adder is constructed using 1-bit adders. Every 1-bit adder accepts a bit from each number. The last module accepts also the carry input.

These are the instructions to play with the circuit:

• Click on the 1's and 0's in green (the inputs) to change their value. To run the simulation with these new values, click on the "Continue" value. The first 4 inputs are the first number, the next 4 inputs are the last number , and the last input is the carry.

• The "Reset" button will clear all the input values.

Last modified 2/1/2000 by Juan de Lara ( Juan.Lara@ii.uam.es, http://www.ii.uam.es/~jlara) need help for using this courses?.