--
-- generate chip selects for 8/16 bit operation
--
chip_selects: process(cs0, bhe, a0)
begin
	ce0 <= '1';
	ce1 <= '1';
	if cs0='0' and a0='0' then 
	ce0 <= '0';
	end if;
	if cs0='0' and bhe='0' then
	ce1 <= '0';
	end if;
end process chip_selects;

--
-- generate read and write strobes 
--
read_strobes: process(rd, a11)
begin
	oe <= '1';
	iord <= '1';
	if rd='0' and a11='0' then
	oe <= '0';
	end if;
	if rd='0' and a11='1' then
	iord <= '0';
	end if;
end process read_strobes;

write_strobes: process(wr, a11)
begin
	we <= '1';
	iowr <= '1';
	if wr='0' and a11='0' then
	we <= '0';
	end if;
	if wr='0' and a11='1' then
	iowr <= '0';
	end if;
end process write_strobes;