NAND Gate Behavioral Style

Two-Input NAND Function in Behavioral Style

Design Code

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module NAND_function(output f, input a, b);

  wire f = a~&b; // Equivalent form

endmodule

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Test Bench

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module NAND_test;

  reg x, y;

  wire z;

  NAND_function F1 (.a(x), .b(y), .f(z));

  initial

    begin

      $monitor("a=%b b=%b \t f=%b", x,y,z); // Tab format

      x = 1'b0; y = 1'b0;

      #5 x = 1'b0; y = 1'b1;

      #5 x = 1'b1; y = 1'b0;

      #5 x = 1'b1; y = 1'b1;

      $finish;

    end

endmodule

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Output
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a=0 b=0                 f=1

a=0 b=1                 f=1

a=1 b=0                 f=1

a=1 b=1                 f=0

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1. Continuous assignment (assign)

• There are two ways of defining continuous assignment
• assign net = net or register; e.g. assign f = a&b;
• net <Variable name> = net or register; e.g. wire f = a&b; It is equivalent to wire f; f= a&b;

2. Strings

• \t : Tab
• \n : new liner
• \\ : \
• \" : "
• %%: %
• \ddd : Octal digits