(...) From what I've gathered: 1.0 to 1.5 Removed the power adapter board. Less components on the board. 1.0 to 2.0 from what I gathered a slightly newer board with a 32k ROM instead of the 16K in the 1.0. (The 1.0 is designed to hold a 32k ROM. As (...) (24 years ago, 26-May-00, to lugnet.robotics.rcx.legos, lugnet.robotics.rcx.nqc)