4-bit adder simulation example

- [Instructor] Now let's take a look at my implementation … of the FourBitAdder. … This is Quartus Prime, … where I'll use the ModelSim simulator. … If you take a look at the code, … the first thing I want you to notice is in line one … where we have the timescale directive … indicating that each time step takes one nanosecond … and that the resolution of the simulation … will be in steps of 100 picoseconds. … Now, if you look at line eight, … you'll see the instantiation of a FourBitAdder named adder, … and it has the usual connections, … two registers, A and B, as the inputs, … and the Sum wire array and the Cout wire as its outputs, … and looking at the simulation, … you will see that starting at line 12, … we have zero plus zero assigned to A and B. … Then after five nanoseconds, … we have to add one plus three, … then four plus eight, … and finally, 12 plus 10. … We are interested in seeing how our system behaves … and what results it yields from those input values. … The stop command in line 17 …