Re: every byte mattered ...
I did very little assembly programming; in fact just some M68K on some programmable controller box thingy at college and that was it. Prior to that I was jealous of BBC Basic and its fancy-pants inline assembly and after that I was vaguely curious about Vax Macro and the System/3x0 assembler that the old beards at work used, but that's about it.
I only discovered the x86's weirdness (nomenclature because it was the 80286 by this time) as I was press-ganged into writing an email retrieval client for our salesentities' luggables. It was awful. I mean my code was awful: I've made many indiscretions in my time but I'd never programmed a PC before and the remit was vague, so I should've refused and said I'd rather eat my own shoes than get involved with it, but I was young and not sufficiently well-versed in being stroppy when it mattered. So yeah, someone else's remit was "we've been told we need to do this, all we need to do is find someone naïve or daft enough to blame. Preferably both." And there I was. In hindsight, though there's not a shortage of challengers, I'm fairly confident it's the worst code I've ever written.
Obviously going back to having only 64K to play with was a bit of a culture shock: I mean I grew up in the 8-bit world but that was then and I never had to do anything especially challenging with it. I know I could've designed it to use some sort of HDD-based indexing malarky but when you have a "by the end of the week, how hard can it be?" requirement etc.
So I looked into how to work around it. I was also very interested in operating systems design at the time and absorbed all sorts of stuff about virtual memory systems and so on, inasmuch as a laysloth's knowledge can suddenly be expanded, anyway.
With that as my context, I read about the 80286's memory addressing.
Argh.
Biting the hand that feeds IT
