At the time of 6502 you were truly on command. I didn't do as much Z80 but I guess it was similar in this particular respect.
Things got really out of hand from AT on (80286). IMO that's not Personal Computing anymore, but rather Home Computer. You are mostly a consumer, even if you develop in ASM. You delegate control of your hardware completely.
I'd recommend anyone to learn Commodore 64 coding inside out. Or maybe Spectrum 48K. These are not the simplest machines of their time but they allow you to do a lot and were popular enough that almost everything that truly matters in computing exists for these architectures. And you can fathomably grok them inside out to such a level it will blow your mind.
Things got really out of hand from AT on (80286). IMO that's not Personal Computing anymore, but rather Home Computer. You are mostly a consumer, even if you develop in ASM. You delegate control of your hardware completely.
I'd recommend anyone to learn Commodore 64 coding inside out. Or maybe Spectrum 48K. These are not the simplest machines of their time but they allow you to do a lot and were popular enough that almost everything that truly matters in computing exists for these architectures. And you can fathomably grok them inside out to such a level it will blow your mind.