Guy - Showing the lazy points positions and making it possible to change them really helped me to follow the diagrams on www.cr31.co.uk/stagecast/trains/tt1_points.html
Being able to watch the moving train animations made it even easier. This is probably the best visual demonstration of digital computer processes I've ever seen.
Congratulations too to Peter Nolan on his Youtube video of a working duplo layout for the binary counter.
Would any of the science museums (or modelling exhibitions) be interested, I wonder?
Keslian