Hi,


Why disappears the transaction marked with (*) in the simulation? I
have got '0' (0-20ns) after running this.


----------------------------

library ieee;
use ieee.std_logic_1164.all;

entity test2_tb is
end test2_tb;

architecture TB_ARCHITECTURE of test2_tb is
signal a : std_logic;
signal b : std_logic;
signal c : std_logic;
begin
STIMULUS: process
begin
a <= '0';
wait for 0 ns;

a <= '1' after 2 ns; -- (*)
a <= '0' after 4 ns;
wait for 20 ns;

wait;
end process;
end TB_ARCHITECTURE;

---------------------------


When I change the STIMULUS process to this one:

STIMULUS: process
begin
a <= '0';
wait for 0 ns;

a <= '1' after 2 ns;
a <= '1' after 4 ns;
wait for 20 ns;

wait;
end process;


It seems all transaction executed. The waveform is '0' in (0-2ns) and
'1' after 2 ns.


Thanks for any help
Attila