3 ms·
As the proud owner of a ZX-81 I remember staring at the Z80 instruction reference at the end of the user's manual without the faintest clue of what any of that
by YZF 3mo ago
As the proud owner of a ZX-81 I remember staring at the Z80 instruction reference at the end of the user's manual without the faintest clue of what any of that meant. It took me some while before I managed to wrap my head around how CPUs actually run programs (vs. the high level abstractions like BASIC or other languages).
- Scubabear68 3mo agoThat machine was my intro to computers too, and I was fascinated by “fast mode” blanking the screen and the interesting tradeoffs between hardware and software.
- xcf_seetan 3mo agoAnother proud ZX-81 owner, my first computer bought as kit. It made me the TI pioneer in my little city. So cool times, everything was complex and simple at the same time. I had a flight simulator in only 1Kb ram :D
- TheOtherHobbes 3mo agoThe ZX81's 1k chess - actually 672 bytes - was, and still is, legendary.
- sedatk 3mo agoActually, BASIC’s flat structure helped me a lot in understanding Z80 assembly when I was 12. You see, memory addresses were line numbers, registers were variables, JP was GOTO, CALL was GOSUB. CP was IF, JP, Z was THEN GOTO, and LD was LET, and so forth.
- lelanthran 3mo ago> You see, memory addresses were line numbers, registers were variables, There was only a single[1] register though, the accumulator. [1] Okay, there was the PC as well. Maybe a flags register too? But only one used for variables, IIRC.
- sedatk 3mo agoYou seem to be confusing Z80 with 6502.
- lelanthran 3mo ago> You seem to be confusing Z80 with 6502. You're quite correct, I did confuse the two. Too late to edit it now, but at least your response will stand as a correction.