四选一libraryieee;useieee.std_logic_1164.all;entitymux41aisport(d3,d2,d1,d0,a1,a0:instd_logic;y:outstd_logic);endentitymux41a;architectureone1ofmux41aisbeginy<=d0whena1='0'anda0='0'elsed1whena1='0'anda0='1'elsed2whena1='1'anda0='0'elsed3;endarchitectureone1;八选一libraryieee;useieee.std_logic_1164.all;entitymux81aisport(d7,d6,d5,d4,d3,d2,d1,d0,a2,a1,a0,en:instd_logic;y:outstd_logic);endentitymux81a;architectureone2ofmux81aissignalQ:std_logic_vector(3downto0);beginQ<=en&a2&a1&a0;y<=d0whenQ="0000"elsed1whenQ="0001"elsed2whenQ="0010"elsed3whenQ="0011"elsed4whenQ="0100"elsed5whenQ="0101"elsed6whenQ="0110"elsed7whenQ="0111"else'Z';endarchitectureone2;三八译码器libraryieee;useieee.std_logic_1164.all;entitydecoder38aisport(s1,s2,s3:instd_logic;a2,a1,a0:instd_logic;y:outstd_logic_vector(7downto0));enddecoder38a;architectureone1ofdecoder38aissignals:std_logic_vector(5downto0);begins<=s1&s2&s3&a2&a1&a0;withsselecty<="11111110"when"100000","11111101"when"100001","11111011"when"100010","11110111"when"100011","11101111"when"100100","11011111"when"100101","10111111"when"100110","01111111"when"100111","11111111"whenothers;endone1;共阳极七段显示译码器（低电平有效）libraryieee;useieee.std_logic_1164.all;entityqiduan7aisport(a3,a2,a1,a0:instd_logic;dout:outstd_logic_vector(6downto0));endqiduan7a;architectureone2ofqiduan7aissignals:std_logic_vector(3downto0);begins<=a3&a2&a1&a0;withsselectdout<="0000001"when"0000","1001111"when"0001","0010010"when"0010","0000110"when"0011","1001100"when"0100","0100100"when"0101","0100000"when"0110","0001111"when"0111","0000000"when"1000","0000100"when"1001","1111111"whenothers;endone2;备注：0000001表示0即0000；1001111表示1即0001；0010010表示2即0010；0000110表示3即0011；1001100表示4即0100；0100100表示5即0101；0100000表示6即0110；0001111表示7即0111；0000000表示8即1000；0000100表示9即1001；其余的不显示用1111111表示；