1. Which waveform is the result of the simulation below?

module design (input a, input b, output o);

    assign o = a & b;

endmodule

module tb;

    logic a, b, o;

    design design_inst (a, b, o);

    initial
    begin
        $dumpvars;
        $monitor ("%t a %b b %b o %b", $time, a, b, o);

        #10;
        a = 0; b = 0; #10;
        a = 1; b = 0; #10;
        a = 0; b = 1; #10;
        a = 1; b = 1; #10;
    end

endmodule

a)

<img width=100% src="and_wave.png">

b)

<img width=100% src="not_and_not_wave.png">

c)

<img width=100% src="not_or_not_wave.png">

d)

<img width=100% src="or_wave.png">

e)

<img width=100% src="xor_wave.png">


2. What is the result of synthesis of this module?

module design
(
    input  a,
    input  b,
    input  carry_in,
    output sum,
    output carry_out
);

    wire p = a ^ b;
    wire q = a & b;

    assign sum       = p ^ carry_in;
    assign carry_out = q | (p & carry_in);

endmodule

<img width=100% src="adders.png">