ym8.vhd

1、正常的计时功能：即具有二十四小时计时功能 2、正常的显示功能 3、正常的调时功能 4、闹钟定时功能 5、整点报时功能

library ieee;
use ieee.std_logic_1164.all;
entity ym8 is
    port(a:in std_logic_vector(3 downto 0);
         y:out std_logic_vector(6 downto 0));
end ym8;
architecture ym of ym8 is
signal n:std_logic_vector(3 downto 0); 
begin
   n<=a(3)&a(2)&a(1)&a(0);
 process(n)
    begin
    case n is
      when "0000"=>y<="1111110";
      when "0001"=>y<="0110000";
      when "0010"=>y<="1101101";
      when "0011"=>y<="1111001";
      when "0100"=>y<="0110011";
      when "0101"=>y<="1011011";
      when "0110"=>y<="1011111";
      when "0111"=>y<="1110000";
      when "1000"=>y<="1111111";
      when "1001"=>y<="1111011";
      when "1111"=>Y<="0000001";
      when others=>y<="0000000";
    end case;
  end process;
end ym;