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Propeller 6502 emulator

Posted by EricBall, 08 October 2009 · 139 views

Propeller
Why is it people think that because the 2600 is "simple" (at least in terms of what level of graphics it can produce) that it will be easy to emulate?

The reason it isn't is because the 6507 and the TIA are "tightly coupled" - each can do things which have an immediate impact on the other. The 7800 and NES are loosely coupled unless interrupts are used. But In the 2600 the 6507 & TIA could almost be regarded as a single entity.

Anyway, occasionally people suggest creating a 2600 emulator for the Propeller. In their mind they assign a cog (processor) to each function - CPU, graphics, sound, input, etc. I typically scoff at them, citing the difficulty in emulating the 2600 - if for no other reason than the clock relationship between the 6507 and the TIA.

But earlier this week I started thinking - why not give it a shot. Put together a 6502 emulator with an eye to making it usable in a 2600 project. It might be fast enough or feature complete enough, but it will be an interesting exercise to see if it's even possible.




Scoffing sounds like less work. :)
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Good rant.

I think I understand where you are coming from regarding the VCS. I don't think anyone in that community really understands it.

Just FYI, my early efforts were more along the idea of things that could be done with a 6502. Starting down that road showed me quickly where I could learn some things. All good there. The memory foot print made the VCS early games an obvious target.

Watching the progress of the ZiCog progress has been informative. Some of the obvious ways of doing things with the COGs kind of fell flat. Other means ended up working well.

Very curious as to where you end up! Your other works have been great so far.

I'm rambling a bit. Really, the other target was an Apple. Memory is at issue, but speed and complexity are not. With the external RAM systems coming on line, having a working 6502 will open some interesting doors.
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potatohead, on Fri Oct 9, 2009 10:53 PM, said:

I think I understand where you are coming from regarding the VCS. I don't think anyone in that community really understands it.
I think many of the people who suggest emulating the 2600 (or the SNES) on the Propeller don't have in-depth knowlege of either platform.Although I am making progress on the 6502 core, I do not think it will run fast enough for the 2600.
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