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Home Digital Combinational Logic HalfAdder  
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HalfAdderAs a first example of useful combinational logic, let's build a device that can add two binary digits together. We can quickly calculate what the answers should be:
0 + 0 = 0 0 + 1 = 1 1 + 0 = 1 1 + 1 = 10 (binary!) So we well need two inputs (a and b) and two outputs. The low order output
will be called The truth table is
Simplifying boolean equations or making some Karnaugh map will produce the
same circuit shown below, but start by looking at the results. The
or in ladder logic


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