Experiment 1 - The 1-bit 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 1-bit 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 1-bit identity comparator.

Circuit diagram of a 1-bit identity comparator.

Circuit of a 1-bit 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 1-bit identity comparator.

You build the circuit with only one of the four XNOR gates on the C-MOS IC 4077.

You want to compare two 2-bit numbers...?

Experiment 2 - 2-bit Identity Comparator