How to connect an external ROM over 4MB at the invalid extension of ROM?

Address A23 ~ A21 can't be outputed since PF7/A23(5ｐｉｎ) ~ PF5/A21(７ｐｉｎ) are set at input port right after reset. Please don't use the address at A23 ~ A21＝"１"(Ｈｉ) in the reset vector and add pull down resistors at A23 ~ 21 address pin s on a board.