That’s the greatest manual I’ve ever touched. It taught me a huge chunk of what I know about hardware, from bitmap graphics to assembler and addressing modes, to IO. I knew that if you wanted to make your BASIC programs go faster, you wrote parts of them in assembly. Fortunately no one bothered to tell me that this was supposed to be harder so I charged ahead, soaking it up like a sponge.
In case anyone's wondering what makes HN so damn great