2015101402 1X2=2位元多工器

module top;

wire A1, A0, SEL, B1, B0,out1 ,out0

system_clock #1600 clock1(A1);
system_clock #800 clock2(A0);
system_clock #400 clock3(SEL);
system_clock #200 clock4(B1);
system_clock #100 clock5(B0);

mux M1(out1, A1, B1, SEL);
mux M0(out0, A0, B0, SEL);
endmodule



module mux(OUT, A, B, SEL);

output OUT;

input A,B,SEL;

not I5 (sel_n, SEL) ;

and I6 (sel_a, A, SEL);

and I7 (sel_b, sel_n, B);

or I4 (OUT, sel_a, sel_b);

endmodule



module system_clock(clk);
parameter PERIOD=100;
output clk;
reg clk;

initial clk=0;

always
 begin
#(PERIOD/2) clk=~clk;
 end

always@(posedge clk)
 if($time>1600)$stop;

endmodule