Looks like you're doing something similar to what I wanted: given that the comparison operators are all in sequence, it ought to be possible to e.g. come up with a scheme that generates the correct bits to match the operator (or the operator offsets from the first) and eor to give zero if the match ...

This is very interesting. I wonder if more silicon could similarly have speed up the X and Y regs.

No doubt having modeled on a breadboard they were already pushing space limitations.
You would need more adders as well, inx/iny use the ALU, and you're already using the ALU to do indexed ...

It is interesting to create games on one platform (the Atari or the C64) and then take the development to the other system. I think it adds more to creative design than developing for either system alone.

How do you address the RAM limitation 8K vs 64K and the lack of 4 VIA ports (2 on the CPU ...

hmmm... good question.

We save cycles with zero page indexed addressing so a possible scenario that comes to mind would be to read and increment (write) the index register.

You can trace both halves of the master-slave sides of the stackpointer with an URL like this:
http://visual6502.org/JSSim/expert.html?graphics=f&a=0&d=ea9aea&steps=12&logmore=dpc7_SS,dpc6_SBS,s,-nots

The stack pointer is special, in the sense that it can be read and written in the same cycle, so ...

So, an emulator that emulates and Atari emulating a C64.

The AI was right. You can’t emulate a C64 on an Atari 2600.
This is related to your observation earlier "having only to address the audio and graphical limitations of the target device".

COSMAC-VIP games and RCA Studio 77 console games ...

Incidentally, the AI diatribe mistakenly implies the 6510 in the C-64 has more capability than the 6502. Both MPUs have the exact same instruction set.
The diatribe doesn't say that at all. The 6510 does have more capability than the "simpler '6502' variant" processor.

The Atari 2600 uses a 6507 ...

That’s not emulation, as the Atari 2600 doesn’t have the sound and graphics hardware of the C-64. At best, I might call it a simulation.

Incidentally, the AI diatribe mistakenly implies the 6510 in the C-64 has more capability than the 6502. Both MPUs have the exact same instruction set.

Agree ...

It is possible for the Atari 2600 to emulate complex Commodore 64 video games with advanced graphics and sound.
Here is a white paper with workstages from the Fjälldata 2025 competition:
https://relationalframework.com/Emulating_the_Commodore_64_on_the_Atari_2600.htm

This technique is similar to ...

6502 Chip-8 emulator with built-in ROMs

This Chip-8 Emulator for the C64 has an embedded Chip-8 program library you can replace to create standalone Chip-8 programs for the C64.

Try the emulator and step through the Chip-8 programs, some are quite impressive.

https://github.com/kschuetz/c64 ...

My first experience with programming was with Mr Coffee, BigTrek, Light-Brite and Fidelity Chess Challenger that had a Z80 CPU.

Chess Challenger helped tutor me in relational calculus early on; Chess and SQL both are forms of RC.

Lite-brite helped with designing and understanding multicolor pixel ...

That's something that has only human I/O, so the difference hardly shows up there. However, it definitely cannot take the place of the emulated computer where the latter has particular ports, pinouts, voltages, timings, signaling protocols, etc.; so it is a very narrow, limited view of emulation ...

I read the thread on emulation vs simulation and agree with the idea that cycle precise software emulation is real emulation.

Here's an example of Atari 2600 simulation and emulation in context:

The first Atari 2600 Flashback model used a NOAC Nintendo-on-a-chip with simulated Atari 2600 games ...

Just released this 6502 Atari 2600 emulator with a BASIC compiler for the Commodore 64:
http://relationalframework.com/GameLoader_C64_Atari_emulator_with_SuperCharger_BASIC.htm

Had a gander at your website, and I'm confused.

Is this a program that can be used natively on a real C64, or is it ...

It's an emulator, it runs these Atari ROM's with pixel perfect cycle precise emulation.

The VM emulates the TIA presenting a shadow register bus to the Atari 2600 program which runs unchanged just as if it were talking on the bus to a real TIA.