将RAM存储器的数据输入改为系统键盘输入的VHDL代码

下面是将RAM存储器的数据输入改为系统键盘输入的VHDL代码：

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity keyboard_ram is
    port(
        clk : in std_logic;
        rst : in std_logic;
        data_in : in std_logic_vector(7 downto 0);
        address : in std_logic_vector(7 downto 0);
        write_en : in std_logic;
        data_out : out std_logic_vector(7 downto 0)
    );
end entity;

architecture rtl of keyboard_ram is
    type ram_type is array (0 to 255) of std_logic_vector(7 downto 0);
    signal ram : ram_type := (others => (others => '0'));
begin
    process(clk)
    begin
        if rising_edge(clk) then
            if rst = '1' then
                ram <= (others => (others => '0'));
            elsif write_en = '1' then
                ram(to_integer(unsigned(address))) <= data_in;
            end if;
            data_out <= ram(to_integer(unsigned(address)));
        end if;
    end process;
end architecture;

在这个代码中，我们添加了一个名为`data_in`的新端口，它接收来自系统键盘的输入数据。在`process`过程中，我们检查`write_en`信号，如果为1，则将`data_in`写入RAM中的`address`地址。最后，我们从RAM中读取`address`地址处的数据，并将它输出到`data_out`端口。