Hi,
this is a question to the developers. I'm a quite competent programmer and getting interested in emulation. So basically, since the cpu architecture is the same wouldn't you only have to emulate the I\O and gpu?
That would defeat the purpose of the emulator. Nobody uses G4 anymore.
(06-23-2010, 07:14 AM)NaturalViolence Wrote: [ -> ]That would defeat the purpose of the emulator. Nobody uses G4 anymore.
Well that's a weird answer, so according to you there's no point developing emulators to less used platforms?
Why I'm asking is because I might get my hands on an old powerbook 1.5 GHz G4 and I am interested in emulation. I'm thinking of starting of emulating just the NES CPU and then go from there. This is just out of curiosity.
No, but it's a lot of work for practically zero benefit (little to no userbase).
An old 1.5ghz ppc g4 very likely can't handle the amount of floating point math per second and output & reading graphics card/random memory data like the ppc cpu inside the wii/gc.
Also, it uses an entirely different, IBM proprietary instruction set for cpu commands. Dolphin currently needs at least SSE2 to operate.
So dolphin can't be even used or compiled on Mac OS X if you don't have an AMD or intel cpu.
If you'd want to run dolphin on a computer with a PPC cpu, you would literally have to code everything from scratch. I don't think any coder is willing to take part in such a massive project just for maybe a dozen potential users. Dolphin is made for the x86 platform.
Also, gc/wii's PPC code will not run natively on your PPC iMac because it addresses RAM differently & has a lot of custom instructions which are not present at all on your home PPC. The broadway processor in wii is a significantly modded IBM 750CL with added support for paired single point calculation and additional altivec instructions. The JIT recompiler also compiles all the emulated code real-time when you run any game. This is very tolling on the cpu and a PPC g4 is with 100% certainty not powerful enough for emulating non-native code at such speeds to achieve anything playable.
(06-23-2010, 07:35 PM)Ocean Wrote: [ -> ]No, but it's a lot of work for practically zero benefit (little to no userbase).
An old 1.5ghz ppc g4 very likely can't handle the amount of floating point math per second and output & reading graphics card/random memory data like the ppc cpu inside the wii/gc.
Also, it uses an entirely different, IBM proprietary instruction set for cpu commands. Dolphin currently needs at least SSE2 to operate.
So dolphin can't be even used or compiled on Mac OS X if you don't have an AMD or intel cpu.
If you'd want to run dolphin on a computer with a PPC cpu, you would literally have to code everything from scratch. I don't think any coder is willing to take part in such a massive project just for maybe a dozen potential users. Dolphin is made for the x86 platform.
Also, gc/wii's PPC code will not run natively on your PPC iMac because it addresses RAM differently & has a lot of custom instructions which are not present at all on your home PPC. The broadway processor in wii is a significantly modded IBM 750CL with added support for paired single point calculation and additional altivec instructions. The JIT recompiler also compiles all the emulated code real-time when you run any game. This is very tolling on the cpu and a PPC g4 is with 100% certainty not powerful enough for emulating non-native code at such speeds to achieve anything playable.
Listen, I'm not talking about running dolphin on an G4, I want to discuss if it would be easier to make a more correct emulator for a G4 CPU (not running in full speed but being able to interpret the OP codes more natively) since it is also a PPC. I know you would have to make it from scratch, that is the point!
I'm not trying to be a smart ass, just want to make my question more clear.
but why would anyone not deemed clinically insane spend thousands/tens of thousands of hours recoding every aspect of dolphin just for a 'more correct emulator' when it's already very playable on x86 cpus
You'd have to consider the developers view realistically too. Put yourself in a devs shoes who works on dolphin for free in his spare time.
This project would make no sense compared to the amount of work/reward ratio of translating everything from sse instructions to powerpc.
Quote:I want to discuss if it would be easier to make a more correct emulator for a G4 CPU (not running in full speed but being able to interpret the OP codes more natively) since it is also a PPC
You have a point, but the PPC in a wii is different than a normal ppc. It has custom added instructions not seen in any other ppc processors, different way of mapping memory pages, improved algorithm for calculating floating point arithmetics, added support for paired single points calculation capability old ppc's don't have etc...
A typical PPC cpu in older iMac's has little in common with the broadway ppc chip in a wii.
and to dumb up what Ocean is saying:
Even if dolphin was ported to ppc it would still have to do a lot more emulation than that old prossesor could handle
He gets it. He's just talking about the potential for proper emulation regardless of performance (which I don't think he made clear in his first post).
It has nothing to do with Dolphin, forget about dolphin!
I, as a computer science student, am interested in the technology behind the gamecube/wii. We have studied the MIPS architecture and I've been thinking of trying some emulation of my own. This however is just a thought experiment, it will probably never come to light. BUT I am curious of how it would differ from a programming view from an x86 to a powerPC processor.
So, I'm not proposing dolphin for the powerpc or anything else. This is for my own amusement and learning.
We misunderstood. Especially since you posted this here.