I guess every programmer has a genesis moment. One where everything starts to make sense and it's the true begining of their love of programming. This was mine. I was 14 and must have had my ZX81 for about 6 months or so when I bought this magazine. I was at my grans in reading this and suddenly all those HEX numbers I'd been typing in made sense. There in front of me was a true assembler listing. I suddenly realised what all the codes at the back of the manual meant, and how you used them. I poured over this article for days, playing with it, trying new values, changing little bits to see what would happen. Up until now I'd been doing ZX81 BASIC and was getting on okay. However when I got this article I saw the routine that drew the border and called it directly.
Unlike Basic, it popped up instantly. I was gob-smacked! It was SO quick. Basic would have taken over second to print that much! I played around with it, changing the character it drew and so on.
This showed me just what computers were capable of, and how these games I bought actually managed to do what they did. Now I could see how it all worked, I started to learn it all...
Put it simply... this is what got me hooked.