This was very nicely done and a really enjoyable time travel video. I learned to program on a ZX81 at a young age. With the manual (shown), the Usborne 1980s programming books that actually taught kids how to do machine code (all now released free: https://usborne.com/browse-books/features/computer-and-codin... ) and then also the Rodney Zak's Z80 book (also available free somewhere). What a great start to a career as a hacker! Cost my parents something like a hundred bucks down here in New Zealand, but I also had to mow my neighbour's lawn to get my hands on an old black and white TV set to plug it into. How I loved that machine, but also hated it (they keyboard was terrible, and the 16kb "RAM pack" would crash the machine if you wobbled it). I envied the more feature-rich Commodore 64s etc that other kids had, but they tended to use them in a more passive way: playing games only. I think the austerity of the ZX81 either produced or at least selected for a curiosity about how code works.