XOR Gate

An XOR (exclusive OR) gate is a fundamental binary logic gate with two inputs and one output. The output is 1 if only one input is 1. An XOR gate with more than two inputs gives an output of 1 if an odd number of inputs is 1. Some authors call the XOR gate with N inputs the odd function.

The following truth table gives the specification for a two input XOR gate with output X:

A	B	X
0	0	0
0	1	1
1	0	1
1	1	0

The schematic form of the XOR gate is:

Below is a Verilog structural model for the XOR gate. In the code, the first argument to xor is the gate output, the other arguments are inputs.

	    
module xor_gate(X, A, B);
   output X;
   input  A;
   input  B;

   xor(X, A, B);
endmodule
	    
	  

References

Mano, M. Morris, and Kime, Charles R. Logic and Computer Design Fundamentals. 2nd Edition. Prentice Hall, 2000.
Kleitz, W. Digital Microprocessor Fundamentals. 3rd Edition. Prentice Hall, 2000.