[mikelabatt]

My oldest son is 5, and I am having some of the same thoughts.

What system did you do the demos on in the 1990s? Might a "classic" system like that not be the "contained" environment you are looking for as a learning environment? And you are even good at that! Systems like the C64, Amiga 500 and Amiga 1200 are still references for current demoscene competitions. They are timeless, you can find them on eBay or emulate them, and your son will be able to show his skills on those even 10 years from now.

If you are afraid that these are not cool enough for your son, fear not. At retro events like VCF, Pixel Heaven, or in the dedicated area at Gamescom, children line up to play on those systems, and for some it is an element of great pride to be experts in them.

My answer to your question looks like this at the moment: I will start with a CBM 8032, after showing him how arcade games of the 1980s were. Then I will add a bit of color, sound, and maybe sprites, via a VIC-20 or C64. And then, if things go well, we can add multitasking and more OS and chipset features by exploring one of the last cool systems where you could try to master every secret: the Amiga.

It doesn't have to be "retro for life". But I think that learning with a "simple" past like this, also makes you better appreciate the present and the future.