[sitkack]

This post has been hanging out with no comments for ages. I was like, I'll skim it later.

> It's almost burying the lede to announce that, though, because the real meat in this entry is how the Commodore 64 manages to emulate a very different 6502-based system. That piece is "6o6," for "6502-on-6502," and is a full virtualized software NMOS 6502 CPU that runs on a 6502 CPU — which I've open-sourced too. It has full control of guest code execution, including trapping undocumented and jam opcodes, and completely abstracts all memory access, making it possible to remap addresses, intercept illegal reads or writes, or even run entirely from virtual memory. On top of that, it's complete enough to not only pass a full functional test but also virtualize itself virtualizing itself:

This is incredible! Not just from a 6502 perspective, but from an everything perspective! Amazing work.

Also, it reminded me of this "The Zilog Z80 has a Protected Mode" https://www.youtube.com/watch?v=DLSUAVPKeYk posted to hn, but got no discussion.

[FLT8]

Also related: C64 booting Linux by emulating a RISC-V processor:

https://hackaday.com/2023/08/27/linux-on-a-commodore-64/

[sitkack]

Wow!

> There is a catch (rather: a couple) of course: It runs extremely slowly and it needs a RAM Expansion Unit (REU), as there is no chance to fit it all into just 64KiB.

> It even emulates virtual memory with an MMU.

https://github.com/onnokort/semu-c64

[userbinator]

That reminds me of this similar project using an ARM emulator instead: https://news.ycombinator.com/item?id=5581851

[elvis70]

> Also, it reminded me of this "The Zilog Z80 has a Protected Mode" https://www.youtube.com/watch?v=DLSUAVPKeYk posted to hn, but got no discussion.

Here is a thread with 138 comments: https://news.ycombinator.com/item?id=33229526