My RCX has no power socket, I don't know why. it seems that all RCX 1.0 over #300000 have no power adapters. My ONLY link is Google pictures. why?
The LEGO Group removed the power adaptor on RCX bricks included in the Robotics Invention System 1.5 onwards - These are often referred to as 1.1 or 1.5 bricks.