_primary.vhd

用Verilog实现8255芯片功能

library verilog;
use verilog.vl_types.all;
entity top_8255 is
    port(
        rst_n           : in     vl_logic;
        cs_n            : in     vl_logic;
        a1              : in     vl_logic;
        a0              : in     vl_logic;
        wr_n            : in     vl_logic;
        rd_n            : in     vl_logic;
        data_bus        : inout  vl_logic_vector(7 downto 0);
        a_bus           : inout  vl_logic_vector(7 downto 0);
        b_bus           : inout  vl_logic_vector(7 downto 0);
        c_bus           : inout  vl_logic_vector(7 downto 0)
    );
end top_8255;