Bookmarked this to read about optimizers, because it looks great.
That said, I clicked on the link because it had "6502" in the title. And... this isn't very interesting as a retrocomputing activity. To be blunt: there's absolutely no way in hell a compiler architecture like that is ever going to be self-hosting in 64k of memory space.
I don't think of retro-computing as an activity limited solely to the hardware and software that existed at a given time, that's far too restrictive for me.
6502 is an architecture, not a specific machine, nor even the set of machines that supported that architecture in the past. The architecture is and remains interesting on its own! (6502 assembly remains a really good intro to assembly, for instance, even for people that have never even seen a C64.)
There is absolutely scope for people to do fun things with 6502 that could never run on a C64 or an Apple II. The vast majority of 6502 code today runs in emulation, so there's really no reason to artificially gimp it to ape the limitations of any given machine. (Unless emulating that specific machine of course!)
> The vast majority of 6502 code today runs in emulation
Emulating a 6502 isn’t that popular, so _if_ there’s even a single commercial product still using a 6502, I would guess that could easily run more 6502 cycles in total than are getting emulated.
- It was true during the Tamagotchi craze (https://hackaday.com/2013/05/24/tamagotchi-rom-dump-and-reve...: “it was a huge chore just to figure out what processor this uses. It turned out to be a 6502 core with a few other things built in”), but that’s over 20 years ago.
So, where, if anywhere, are these things being used?
> 6502 assembly remains a really good intro to assembly
It... really is not, though. It doesn't teach you macro assemblers as they exist in the modern world. It doesn't teach you interaction with the linker except in the simplest ways.
And while the instruction set is "simple" in the sense that it can be understood on a page of paper, lots of critically important ideas don't exist in a meaningful way. Modern techniques like register assignment aren't possible given the limitations and non-orthogonality of the CPU state. There's no "ABI" equivalent you can use to call a standard function, and even something as foundational as "passing arguments" to a function isn't directly expressible, because the "stack pointer" isn't actually a pointer. In point (heh) of fact, no pointers are pointers because the 6502 doesn't actually have an abstraction for a memory address!
Everyone should learn to hack on an Apple II (and good grief, not a Commodore unless you are trying to learn VIC-II or SID hardware), but not to teach themselves "assembly" as a skill they might apply elsewhere.
In fact it's almost the same argument used for why we teach new kids Python and not BASIC. The latter just isn't a useful tool for expressing the concepts you need to learn.
I was almost with you, because much as I love the 6502, it is kind of weird by modern "standards". But then: the Apple II? Like, wtf man. C'mon. The Apple II is shit. Is it just because you like that sweet double density disk throughput? Well, fair enough, but then why not go for the BBC Micro. 2 MHz, plus 80 columns. OK, so it only has 32 KB RAM... meanwhile, you are still American.
In summary, please tell us how many shades of mucky greyish brown you get with the Apple II. Because with the C64, you get 13.
> Well, fair enough, but then why not go for the BBC Micro
Because the Apple shipped four years earlier? The question isn't what machine is better. Obviously later hardware builds on the advances of its ancestors. The idea behind valuing history is understanding where the changes happened.
Acorn (and Commodore) shipped an excellent machine given the constraints of the time. Both devices were worth purchasing.
Apple shipped an absolutely groundbreaking work of genius that no one had forseen and that no one would duplicate for years. AAA games were shipping in 1988 (c.f. Ultima V and Prince of Persia) designed directly to a framebuffer design architected in the spring of 1977.
If you can't see the difference there and perceive which device is more important to understand and study, I don't know what to say.
> It... really is not, though. It doesn't teach you macro assemblers as they exist in the modern world. It doesn't teach you interaction with the linker except in the simplest ways.
What does the processor/instruction set have to do with the available tooling?!
FYI back in the day much of Acorn's (BBC Micro = 6502) software was written using a very capable macro assembler (source: I worked there).
Yes! I learned 6502 assembly from the Apple ][ system manual. You got the op code tables, the schematics and Woz‘s monitor incl. listing and a disassembler. It motivated me to learn English, forced me to carefully calculate relative jumps and taught me to think first then code. Two of the three still useful skills.
> Wow you really are into telling people what they should do.
Saying "6502 is not a good platform for learning assembly" is simply not the same thing as saying "you should not learn assembly language with a 6502 assembler", and I don't understand how you're interpreting it that way.
It's just giving you my opinion and advice. By your own logic, you are now trying to censor my ability to give that opinion and advice. That's bad too, right? Why are you "telling me what to do"?
Chill. Opinions are OK. If you don't agree, that's fine. But a better response is a reasoned counter argument and not "don't say that".
Not interesting to you, but other people may differ! A cross-compiler targeting the 6502 is still interesting to some. As the article notes, these compiler techniques weren’t invented in the 70s because computers weren’t powerful enough to make good use of them. What’s wrong with exploring what the original hardware is capable of when freed from those restrictions?
It is my understanding the the GEOS system was developed on a more powerful machine than the C64/Atari computers it was used on. This let then have the entire code in memory and then processed for common functions. They could not do this on the the 64K-8 bit computers at the time.
There's nothing "wrong" with it. I'm just saying that if I'm going to read an article about fun 6502 activities, I want to see it hosted on an Apple II. If I want to read about compiler techniques, I'd prefer to see it targetting a more orthogonal (or less weird, anyway) architecture.
Okay, here's an article about calculating e to 116,000 digits on an Apple ][: <https://archive.org/download/Apple_2_Woz_e_Calc_1981/Apple_2...> (warning, PDF!). I found it interesting to read, even though I never owned an Apple ][, nor did I ever own a 6502-based computer (well, except for the Atari 2600). I was, however, able to apply the techniques to computers I did own (6809 and 8088 based).
That waa me. My 6502 "IDE" was a BBC Micro, with it's excellent BBC BASIC ROM that had inline 6502 assembler built-in to the BASIC language.
It was so good and accessible, and documented in the Advanced User Guide, that after learning BASIC starting age 10, I learned 6502 a few months later and was able to reverse engineer and modify other people's games not long after that.
I had the luxury of floppy drives which my contemporaries did not have
The floppies helped immensely with self-hosted development of larger programs. Imagine losing all your assembler work due to a crash running it because it was tempting to skip rhe time of several minutes saving to tape. Floppies were reasonably fast for saving before running things, but few people I knew had them.
It also gained a Z80 second processor (an add-on; and later a 68000), so rhe Z80 helped with development of 6502 code, as a RAM disk and editing scratchpad that survived 6502 crashes. And for running Wordstar, which was a decent editor.
Eventually I had someone else's ZX Spectrum hooked up to the BBC with a kind of home-made bit-banging serial port. That's when things started getting fancy, as my BBC's Z80 second processor's flavour of BBC BASIC could assemble Z80 code for the Spectrum, and run some Z80 binaries from other people's Spectrum software, with the BBC's 6502 providing display and sound emulation.
Yup, that was me too. The BBC Micro was a great 6502 dev environment (for the time).
Several years after I moved on from the Beep to a PC, I again had the opportunity to use my knowledge of 6502 assembly. A rally-driving friend asked me to look into changing the fuel curves in their Toyota's ECU. Turns out that many early 90s ECUs used 6502s. I whipped up a 6502 disassembler (in Turbo Pascal) and was able to reverse engineer the ROM dump and make the required adjustments. Fun times.
That said, I clicked on the link because it had "6502" in the title. And... this isn't very interesting as a retrocomputing activity. To be blunt: there's absolutely no way in hell a compiler architecture like that is ever going to be self-hosting in 64k of memory space.