Desktop OSes just assume the vertical subtiles (at best with an option between RGB and BGR). TVs and mobile devices don't generally support subpixel rendering at all.
I've never seen this before, it's like a modern 2600 - deeply technical, scattered topics and depth, all very hacker-curious - and beautifully designed to boot.
Fun fact - the computiles piece is an uncredited rediscovery of Wang's work from the 1960's on computable tilings. Specifically, he went as far to show that the halting problem is equivalent to the 'domino problem' - can we tile the plane using a given finite set of dominoes (aka tiles) where we have infinitely many copies of each and the tiling must preserve edge-meet criteria. Every tiling is a computer program, every computer program is a tiling.
What do you mean? It's just simple beginner's examples in C. Should be easy enough to understand, C is famously very simple ('portable assembler' as they say!).