LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; use ieee.std_logic_arith.all; USE IEEE.STD_LOGIC_UNSIGNED.ALL; ENTITY YMQ IS PORT(AIN4 : IN STD_LOGIC_VECTOR(3 DOWNTO 0); DOUT7 :OUT STD_LOGIC_VECTOR(6 DOWNTO 0)); END YMQ; ARCHITECTURE ART OF YMQ IS BEGIN PROCESS(AIN4) BEGIN CASE AIN4 IS WHEN "0000"=>DOUT7<="1111110"; WHEN "0001"=>DOUT7<="0110000"; WHEN "0010"=>D0UT7<="1101101"; WHEN "0011"=>DOUT7<="1111001"; WHEN "0100"=>D0UT7<="0110011"; WHEN "0101"=>DOUT7<="1011011"; WHEN "0110"=>DOUT7<="1011111"; WHEN "0111"=>D0UT7<="1110000"; WHEN "1000"=>DOUT7<="1111111"; WHEN "1001"=>DOUT7<="1111011"; WHEN OTHERS=>DOUT7<="0000000"; END CASE; END PROCESS; END ART;

代码中存在一个拼写错误，将DOUT7写成了D0UT7。这个错误会导致CASE语句中的第三个和第五个分支的赋值语句出现错误，应该把D0UT7改成DOUT7。修改后的代码如下：

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY YMQ IS
   PORT(AIN4 : IN STD_LOGIC_VECTOR(3 DOWNTO 0); 
        DOUT7 : OUT STD_LOGIC_VECTOR(6 DOWNTO 0));
END YMQ;

ARCHITECTURE ART OF YMQ IS
BEGIN
   PROCESS(AIN4)
   BEGIN
      CASE AIN4 IS
         WHEN "0000" => DOUT7 <= "1111110";
         WHEN "0001" => DOUT7 <= "0110000";
         WHEN "0010" => DOUT7 <= "1101101";
         WHEN "0011" => DOUT7 <= "1111001";
         WHEN "0100" => DOUT7 <= "0110011";
         WHEN "0101" => DOUT7 <= "1011011";
         WHEN "0110" => DOUT7 <= "1011111";
         WHEN "0111" => DOUT7 <= "1110000";
         WHEN "1000" => DOUT7 <= "1111111";
         WHEN "1001" => DOUT7 <= "1111011";
         WHEN OTHERS => DOUT7 <= "0000000";
      END CASE;
   END PROCESS;
END ART;

经过修改后，代码中的语法错误已经被修正。