On calcs with an internal ROM, U11 is not present and JP8 is closed. On calcs without an internal ROM, U11 is present and JP8 is open. Note that the 200000 and 400000 access are active low for an addressing range of 1FFFFF (2MB):



SORRY! This picture is (SOMETIMES) being cut off and I don't know why! (I have tried to resend it...) There is supposed to be a horizontal wire in the cut off section, and the box is JP8.