Experiment 1  The 1bit Identity Comparator
You want to compare two binary numbers and know if they are identical?
This task is performed by an identity comparator.
In this experiment you compare two 1bit binary numbers.
Look at the truth table.
The result x=y
can only be equal to 1
if the inputs x
and y
are identical.
x 
y 
x=y 
0 
0 
1 
0 
1 
0 
1 
0 
0 
1 
1 
1 
Truth table of a 1bit identity comparator.

Circuit diagram of a 1bit identity comparator.

Circuit of a 1bit identity comparator.
(Enlarge)

This logical combination certainly sounds familiar to you.
It corresponds to the XNOR logic.
With a simple basic gate
you are able to set up a 1bit identity comparator.
You build the circuit
with only one of the four XNOR gates
on the CMOS IC 4077.
You want to compare two 2bit numbers...?
