Ah, this reminds me of my first computer, the Vic 20. I was fascinated by all this. unfortunately I didn't apply myself and learn what all of this meant at that time.
If I remember correctly, the system calls where indirect jumps where the address of the jump was in ram (it had been copied from the rom on startup): it was designed to you could hijack system calls and modify their behavior. This blew my mind as a teenager.
I wish modern system where still designed like that...
There were a handful of pointers to the routines to use for BASIC execution in RAM starting at address $300, which could be pointed elsewhere for BASIC extenders or to redirect IRQs. Apart from that, most syscall addresses where in ROM.
It allowed disabling parts of the ROM though to access the full RAM. That way you could rewrite the real jump addresses, bypassing the ROM completely.
I shd dig through this sometime. I remember the Basic Rom to be 8kb and the whatever it is called IO? Also 8kb. A command takes 2-3 bytes so in less then about 7000 commands it is possible to implement a full operating systen with basic. I still (and more and more so) find this unbelievably efficient.
There's no horizontal scrollbar for me on Safari, which kind of makes comparing different takes on each address impossible unless you have four monitors to stretch this across. Or Firefox or Chrome, now that I check it on them. (OSX 10.14.6, Safari 13.1, FF 76.0.1, Chrome 81.0.4044.13)
You can uncheck some of the sources to reduce the amount of horizontal space needed (for example, I immediately took out the German ones, and then took out the ones that appeared to have a lot of gaps, to the point where I'm down to "Mapping the Commodore 64", "Programmer's Reference Guide", and "64map").
But yeah, hopefully this becomes more of a starting point for a combined reference, since that seems to be more useful as an actual development resource than having to decide which source references to show side-by-side.
Whenever I find a site with good information but horrible readability, I turn off the CSS. That often makes it look bland, but it becomes far more readable --- more like a book. Some browsers have a "reader mode" which does a similar thing. Sometimes I may send the author an email about it.
What a blast from the past. It was always difficult to access the RAM underneath the ROM above 48K. You could but you'd have no system calls available.
> You could but you'd have no system calls available.
True, but to be fair though, games developers had little (if any) need for system calls into the kernel, and we'd often make use of that RAM.
Not that I recall exactly what we were using it for, it varied game to game — disclaimer: several published C64 games, but I've not messed with any of this since the early 90s!
When I submitted this yesterday the 'Ultimate' at the beginning of the title was also automatically removed. I thought I had made a copy-and-paste error at first. Weird.
HN has a long history of de-sensationalizing link titles, both through automated substitutions and manual changes from moderators. Some aspects of this are in the "News Guidelines" at https://news.ycombinator.com/newsguidelines.html:
> Please don't do things to make titles stand out, like using uppercase or exclamation points, or saying how great an article is. It's implicit in submitting something that you think it's important.
> If the title includes the name of the site, please take it out, because the site name will be displayed after the link.
> If you submit a video or pdf, please warn us by appending [video] or [pdf] to the title.
> If the title begins with a number or number + gratuitous adjective, we'd appreciate it if you'd crop it. E.g. translate "10 Ways To Do X" to "How To Do X," and "14 Amazing Ys" to "Ys." Exception: when the number is meaningful, e.g. "The 5 Platonic Solids."
> Otherwise please use the original title, unless it is misleading or linkbait; don't editorialize.
I sometimes wish the guidelines were a bit more transparent, e.g. confirming with the submitter that the meaning of the title hasn't been harmed by an overzealous replacement. The edits are clearly a net positive, but they're confusing when they go wrong.
A few months ago @petercooper made an app for tracking live changes to HN headlines, which gives a sense of how frequent they are: https://hackernewstitles.netlify.app/
HN's software debaiter changed it. If it gets it wrong, you can always click 'edit' to edit the title. In this case I'd say it probably got it right though.
