VHLD实例双2－4译码器：74139

library IEEE;
use IEEE.Std_logIC_1164.all;


entity HCT139 is  
   port(A2, B2, G2BAR, A1, B1, G1BAR : in std_logic;
            Y20, Y21, Y22, Y23, Y10, Y11, Y12, Y13 : out std_logic);
end HCT139;

architecture VER1 of HCT139 is
begin
   Y10 <= '0' when (B1 = '0') and ((A1 = '0') and (G1BAR = '0')) else '1';  
   Y11 <= '0' when (B1 = '0') and ((A1 = '1') and (G1BAR = '0')) else '1';
   Y12 <= '0' when (B1 = '1') and ((A1 = '0') and (G1BAR = '0')) else '1';
   Y13 <= '0' when (B1 = '1') and ((A1 = '1') and (G1BAR = '0')) else '1';
   Y20 <= '0' when (B2 = '0') and ((A2 = '0') and (G2BAR = '0')) else '1';  
   Y21 <= '0' when (B2 = '0') and ((A2 = '1') and (G2BAR = '0')) else '1';
   Y22 <= '0' when (B2 = '1') and ((A2 = '0') and (G2BAR = '0')) else '1';
   Y23 <= '0' when (B2 = '1') and ((A2 = '1') and (G2BAR = '0')) else '1';
end 

本文关键字：译码器  DSP/FPGA技术，单片机-工控设备 - DSP/FPGA技术