zero_detect.vhd

该芯片的功能是： ① 有一复位开关

library ieee;
use ieee.std_logic_1164.all;
entity zero_detect is
  port(a:in std_logic_vector(3 downto 0);
       zero:out std_logic);
end zero_detect;
architecture rtl of zero_detect is
begin
   zero<='1' when a="0000" else '0';
end rtl;