besteht aus zwei VHDL Dateien, der eigentlichen Schaltung und einer Testbench, mit der die Schaltung simuliert werden kann.

first.vhd

library ieee;
use ieee.std_logic_1164.all;
 
-- Simple module that connects the SW switches to the LEDR lights
entity first is 
port ( SW   : in      std_ulogic_vector(9 downto 0);
       LEDR : out     std_ulogic_vector(9 downto 0));  -- red LEDs
end first;
 
architecture structure of first is
begin
  LEDR <= SW;
end structure;

first_tb.vhd

library ieee;
use ieee.std_logic_1164.all;
 
-- Testbench for the first switch/led module
-- The switches are switched...
 
entity first_tb is
end; 
 
architecture beh of first_tb is
 
-- This is the component declaration 
  component first 
  port (
    SW:         in std_ulogic_vector(9 downto 0);
    LEDR:       out std_ulogic_vector(9 downto 0)
    );
  end component;
 
-- Signal declaration for the switches and the leds
  signal switch, ledr : std_ulogic_vector(9 downto 0); 
 
begin
 
-- Here the device under test is instantiated
  first_i0 : first
    port map (
      SW                  => switch,
      LEDR                => ledr);
 
-- This is the process where the switch is switched. Note that the process
-- always starts from the beginning. This process is not synthesizable because
-- of the wait statement. 
 
  schalter : process
  begin
    wait for 1 us; 
    switch <= "0000000001";
    wait for 3 us;
    switch <= "1000000000"; 
  end process schalter;
 
end; -- architecture