-- M68008 Address Decoder
-- Address decoder for the m68008
-- asbar must be '0' to enable any output
-- csbar(0) : X"00000" to X"01FFF"
-- csbar(1) : X"40000" to X"43FFF"
-- csbar(2) : X"08000" to X"0AFFF"
-- csbar(3) : X"E0000" to X"E01FF"
library ieee;
use ieee.std_log_1164.all;
entity addrdec is
port(
asbar : in std_logic;
address : in std_logic_vector(19 downto 0);
csbar : out std_logic_vector(3 downto 0)
);
end entity addrdec;
architecture v1 of addrdec is
begin
csbar(0) <= '0' when
((asbar = '0') and
((address >= X"00000") and (address <= X"01FFF")))
else '1';
csbar(1) <= '0' when
((asbar = '0') and
((address >= X"40000") and (address <= X"43FFF")))
else '1';
csbar(2) <= '0' when
((asbar = '0') and
((address >= X"08000") and (address <= X"0AFFF")))
else '1';
csbar(3) <= '0' when
((asbar = '0') and
((address >= X"E0000") and (address <= X"E01FF")))
else '1';
end architecture v1;
