Grampa Simpson said:
Possibly. It does not need to be binary compatible. One would have to do a survey of developers to see how many are using extensive assembly in their software. I'm under the impression that it's mostly a lost art, but I could be wrong.
I'd agree with you, and I doubt any developers are using much assembly these days (even if it's easier on consoles' RISC CPUs than x86, it's still a lot of effort for little gain). I would say, though, that what I'm thinking of here is for developers to be able to say "If it runs on the XBox 360 it will run at least as well on the Café". Code that requires a lot of 64-bit precision calculations will run on a 32-bit processor, but considerably slower, all other things being equal.
Grampa Simpson said:
Not quite. It must be able to support 6 simultenous threads. That could be 1, 2, 3, or 6 cores.
Threads aren't quite the same as cores, and there are plenty of situations where code that runs smoothly on 4 cores would run like crap on a 4-thread single core processor. Worse still, it can be fairly difficult (unless you have a
very good understanding of the processor's architecture) to tell which code multi-threads well and which doesn't, so a (say) single core, 6-thread processor could require some fairly frustrating code rewrites, violating the "If it runs on XBox 360 it'll run on Café" paradigm. A single-thread 6 core processor could work, I'll admit.
Grampa Simpson said:
No. It needs to be able to process more operations per second per thread as the Xenon. That doesn't directly correlate to clock speed.
Yes, you're quite right, but we'd be looking at the same ballpark when it comes to clock speed, especially as rumours thus far have indicated as much.
Grampa Simpson said:
The POWER7 would certainly meet their computing needs, and would massively exceed them. It would not be at all appropriate from a cost or heat output standpoint.
Yeah, cost and heat are certainly an issue. If they did use a CPU based on it, it would have to be stripped down to 3.2-3.4Ghz, 3 cores, smaller cache, etc., to get anywhere near feasibility.
Grampa Simpson said:
The
PowerPC A2 is a 64 bit PowerPC that probably would fit the bill much better. I do not know what type of support architecture it would require though.
The A2 could be an option, but it seems to be designed for in-order execution (see
here, page 7).
Grampa Simpson said:
Titan is another 32bit PowerPC variant that is low power and extensible.
That's actually a possibility, I hadn't looked at non-IBM processors. Although I'm not sure they'd necessarily be able to ensure binary compatibility with Wii, depending on whatever customisations IBM may have made for Nintendo.
Grampa Simpson said:
If I were to bet, I would bet it would be one of these three, but I also think that they did a huge amount of the system design in 2009, and that would have me leaning more towards the 476FP - I just don't know if would meet the operations per thread per second requirements to allow for easy porting.
If they actually have been working on it since 2009, then there's also the possibility that it's not based on any existing chip, but rather an entirely custom design for Nintendo. It's not usually done, but with a production run of 30m-100m units, it's perfectly feasible if no existing processor suits.