module latch(output reg q,input d,input clk); always begin wait (clk) #100 q=d; end endmodule module simlat; reg D,CLK; wire Q; initial D=1'b1; initial CLK=0'b1; latch l1(Q,D,CLK); //always #10 CLK=~CLK;//if this is included my simulator hangs completely initial #16 D=~D; initial #200 $finish; endmodule //without that statement prgram works just fine. please tell me why?? // thanks in advance.