Be sure to click on "Projects>Add Circuit" before creating the
1-bit comparator. It will ask you for a name for the
circuit. Call it "one bit comparator".
2. Build a 3-bit comparator from 1-bit comparators.
Using Logisim, construct a circuit which has two 3-bit inputs, A = a2a1a0
and B = b2b1b0,
and one output, greater.
greater should be 1 if A > B when A and B are interpreted as unsigned binary
integers. The circuit should be built from 3 of your 1-bit
comparators, connected together with AND and OR gates. Save this
as the "main" part of your circuit (double-click on "main" before
entering this circuit).
To see how they should be combined, consider the simpler case of
2-bit inputs, A = a1a0
and B = b1b0.
Then greater should be 1 if a1>b1 OR ((a1=b1) AND (a0>b0)).
You should use the same approach, but extended to the 3-bit case.