half adder

Half adder is a combinational arithmetic circuit that adds two numbers and produces a sum bit (S) and carry bit (C) as the output.

module halfadder(a, b, s, c);
input a;
input b;
output wire s;
output wire c;

assign {c,s}=a+b;

endmodule

module halfadder(a, b, s, c);
input a;
input b;
output s;
output c;

xor x1(s,a,b);

and a1(c,a,b);

endmodule

truth table

half adder gate level

data flow

module halfadder_test();

reg a,b;

wire s,c;

halfadder h1(a,b,s,c);

initial begin

a=1'b1; b=1'b1;

#20 a=1'b1; b=1'b0;

#20 a=1'b0; b=1'b1;

#20 a=1'b0; b=1'b0;

end

endmodule

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