I'll second the childhood memories comment. I also remember pouring over Z80 machine code and does anyone remember typing in individual numbers on a 1K ZX81 to run a blocky space invaders program (circa 1979)??
I remember forking an open source game library around 1985. Well, typing the source code in from the magazine so I could make my own game with sprites. I don't think I made it because of those awful rubber keys and it was not my computer anyway. The owner claimed he knew a guy who could replace the weird rubber keys with some plastic Commodore keyboard (though that would make typing BASIC code challenging -- the Spectrum keyboard had some strange mode where you could type just a single key to insert DIM or LIST).
Worse, it required that mode. It was memory-saving by using single character codes for the commands rather than 3 bytes for DIM or 4 bytes to store LIST as ASCII.
Still, love and upvoted you for also having a ZX81 and, like me, typing in insane machine code. Probably felt like travelling back 2 years in time!!!! :)