It was pretty much the set that really started many people on the path to having robotics as their major hobby. and introduced mindstorms. The set was a turning point and vastly lowered the barrier to entry.
It is set to be replaced by the NXT in Q3/4 2006.
There were four releases of the RIS (1.0(a and b), 2.0 and 3.0), each with slightly revised software and different bricks, multiplied by the locale/language specific versions of these. The earlier 1.0 set (of which there were actually two versions anyway) was sought after for its inclusion of a 9v power socket on the RCX brick itself, which was subsequently removed. The 1.0 version shipped with a serial port based tower.
The 2.0 Version shipped with a USB tower, revised firmware on the RCX brick and updated software, although the software updates were available for download separately for free on the Lego mindstorms website.
We try to keep this database of knowledge as up to date and correct as possible. If you have any corrections or additional information, please leave a comment.
Time to build your own robot! Using a Raspberry Pi with parts and some time, you can use my book to learn how to make and program a robot with automatic behaviours.