Experiment 4 - The 1-bit Magnitude-Comparator

A magnitude comparator has three outputs. It also compares whether two numbers are identical. In addition, it tells you which number is bigger.

First look at a 1-bit comparator. The truth table has been expanded by two results and therefore the circuit diagram becomes much more complicated.

x y x<y x=y x>y 0 0 0 1 0 0 1 1 0 0 1 0 0 0 1 1 1 0 1 0 Truth table of a 1-bit magnitude comparator.

Circuit diagram of a 1-bit magnitude comparator.

With the circuit shown you build the 1-bit magnitude comparator.

Circuit of a 1-bit magnitude comparator. (Enlarge)

As you can see, a 1-bit magnitude comparator is significantly more complicated than the corresponding one-bit identity comparator.

Next, you look at the 2-bit magnitude comparator.