[TUHS] Any good 6502 assembly references?

[Alexis via TUHS]

Aiden Thomas via TUHS <tuhs at tuhs.org> writes:

> Hello!
> I'm fairly new here (just got on the mailing list). You guys got 
> me
> really excited about continuing the legacy of computing. I'm 
> planning
> out an interpreter onto my website, most likely 6502 based. So 
> if
> anyone knew any good manuals or open sourced design documents of 
> the
> 6502 CPU I'd love to hear! I'm also open to other architectures 
> that
> would be fun to write interpreters for.

Well, this list is about _Unix_ history, not about computing 
history in general, so your request as it stands might be 
considered off-topic (but i'm not a mod).

That said, i'm interested in 6502 myself - as someone who actually 
used 6502 machines at the time, e.g. the BBC Micro B - and would 
be interested in a discussion about historic attempts to have a 
Unix-ish system on the 6502. The Wikipedia page for GeckOS, which 
is:

> a multitasking operating system for MOS 6502, and compatible 
> processors such as the MOS 6510 ... [and] one of the few 
> successful attempts to implement a Unix-like operating system on 
> the 6502 architecture

has a section titled "Unix on 6502 architecture":

> While early versions of Unix ran on for example early model 
> PDP-11
> computers that were comparable to Commodore 64 in terms of 
> memory and
> processor performance there were architecture differences in 
> terms of
> lack of a kernel mode, only 3 8-bit registers versus eight 
> 16-bit
> general registers, and a fixed stack. These architectural 
> limitations
> make implementing a Unix-like operating system on the 6502
> challenging.
>
> The possible non-exhaustive list of other viable Unix-like
> implementations on 6502 are LUnix, Asterix (Chris Baird) and ACE
> (Chris "Polar" Baird). GeckOS arguably is more complete in some
> respects, with ACE being stronger in terms of standard Unix 
> utilities
> but weaker in the operating system area.


Alexis.