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3 Supplementary Material

3.1 Verilog

In the previous lab you have defined a half adder by instantiating primitive gates. As the design becomes more and more complex, it is convenient to create separate modules and then combine them in one file. For example, in the previous lab you have created a half adder module and in this lab you will create a full adder/subtractor which can be designed by using the half adder module. So, in this lab you will instantiate two half adders to form the full adder, then instantiate four full adders to create the 4-bit adder/subtractor. Program 1 illustrates this concept.

% latex2html id marker 86\begin{verbatim}module sample_mod...
...im}\caption{An example of a module instantiating
other modules.}
In this sample program the module sample_moduleA is instantiated twice as SA1 and SA2 in the higher level module sample_moduleB.

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Last Modified 2009-09-23