Bino, At 09:02 13.10.2006 +0700, you wrote: >Anyway ... any clue on RAM extender Circuit is verry appreciated :) You may check the Ethernut 1.3 schematic. This is the most simple board. http://www.ethernut.de/en/hardware/enut1/ Page 2, IC3 and IC4 Also check the ATmega128 datasheet. Harald