-- not in book
entity computer_system is
end entity computer_system;
-- end not in book
architecture abstract of computer_system is
subtype word is bit_vector(31 downto 0);
signal address : natural;
signal read_data, write_data : word;
signal mem_read, mem_write : bit := '0';
signal mem_ready : bit := '0';
begin
cpu : process is
variable instr_reg : word;
variable PC : natural;
-- . . . -- other declarations
begin
loop
address <= PC;
mem_read <= '1';
wait until mem_ready = '1';
instr_reg := read_data;
mem_read <= '0';
wait until mem_ready = '0';
PC := PC + 4;
-- . . . -- execute the instruction
end loop;
end process cpu;
memory : process is
type memory_array is array (0 to 2**14 - 1) of word;
variable store : memory_array := (
-- . . .
-- not in book
0 => X"0000_0000",
1 => X"0000_0004",
2 => X"0000_0008",
3 => X"0000_000C",
4 => X"0000_0010",
5 => X"0000_0014",
others => X"0000_0000"
-- end not in book
);
begin
wait until mem_read = '1' or mem_write = '1';
if mem_read = '1' then
read_data <= store( address / 4 );
mem_ready <= '1';
wait until mem_read = '0';
mem_ready <= '0';
else
-- . . . -- perform write access
end if;
end process memory;
end architecture abstract;
<div align="center"><br /><script type="text/javascript"><!--
google_ad_client = "pub-7293844627074885";
//468x60, Created at 07. 11. 25
google_ad_slot = "8619794253";
google_ad_width = 468;
google_ad_height = 60;
//--></script>
<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script><br /> </div>