A yellow icon appears at toggle of signal in ncsim. Cant make out what is it?

Question

I can see a yellow icon appearing at the toggle of a signal in my simulations. The icon shows a square wave like image. I tried to look up for an explanation, closest enough was "zero pulse width" but I am still unsure. No documentation explains what it is exactly and what causes it. Its not causing me any problem but I am just curious. Does anyone have any idea ?

Answer 1

This indicates that multiple transitions happened on the signal in the same simulation time step. This can be expanded to show the intermediate values. See this discussion on the Cadence forum: http://community.cadence.com/cadence_technology_forums/f/30/t/26894

Some example code which shows the behavior:

module test;

   logic [1:0] bus;

   initial begin
      bus  = 2'b00;
      #10;
      for(int i = 0; i<8; i++) begin
         bus     = bus + 1;
      end
      #10;
      bus  = 2'b11;
      #10;
      $finish();
   end

endmodule

Simvision screenshots without and with the time expanded. To expand the time select "Expand Sequence Time->All Time" from the "View" menu.