The "GC and Wii's GPUs" are exactly the same thing, they even contain the same bugs.
How did dolphin emulator become functional?
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09-03-2014, 08:42 AM
(09-02-2014, 10:12 PM)Shonumi Wrote: Reverse engineering. The "Flipper" GPU is still a GPU, so those who know how GPUs work can figure things out. You watch what commercial games do, what kind of commands they send where and at what time, you look for large scale behaviors and patterns and try to draw conclusions before examining smaller, individual processes, and above all you experiment (change things, even as small as a single bit, then view the results). (09-02-2014, 10:40 PM)tueidj Wrote: The "GC and Wii's GPUs" are exactly the same thing, they even contain the same bugs. WOW!!! (09-02-2014, 10:12 PM)Shonumi Wrote: Reverse engineering. The "Flipper" GPU is still a GPU, so those who know how GPUs work can figure things out. You watch what commercial games do, what kind of commands they send where and at what time, you look for large scale behaviors and patterns and try to draw conclusions before examining smaller, individual processes, and above all you experiment (change things, even as small as a single bit, then view the results). Actually truth be told I've been really curious about U emulation but, there is a stigmatism about it because so many people have asked. Yes I have read all about "why" it won't work but, that was far to vague for me. Plus i was curious about these things in general anyways. Puts ALOT more meaning behind why U emulation won't happen for some time. Don't the U and 360 share some similarities in the CPU or are they just related? I kind of really didn't expect PS3 and 360 emulation to happen so soon. Then I kind of got to wondering if under standings of these PPC CPUs could be used or have been to figure out emulation. (which you guys just mentioned did happen for GC/Wii) On top of all that I had a thread about N64 emulation and it VASTLY far behind other emulators/systems and that also got me to wondering how emulation works. 09-03-2014, 09:30 AM
(09-03-2014, 08:42 AM)cdoublejj Wrote: Actually truth be told I've been really curious about U emulation but, there is a stigmatism about it because so many people have asked. Yes I have read all about "why" it won't work but, that was far to vague for me. Plus i was curious about these things in general anyways. Puts ALOT more meaning behind why U emulation won't happen for some time. Yes, they both have a PPC based CPU, but the Wii U has one that several magnitudes faster being based on a newer architecture of PPC. Well, the developers behind N64 emulation lost interest in in, and development slowed. Now they only work on it when they're bored. Dolphin/PCSX2/PPSSPP/Citra/rPCS3 are based on relatively newish hardware, being still relevant in the public mindset, still has a lot of interest in it. 09-03-2014, 08:25 PM
Sure, if you think the Gekko CPU based on a 180 nm fab with 1 core at 486 Mhz similar to the Expresso in the Wii U with a 45 nm fab with 3 cores at 1.25 Ghz, then yes they are similar.
Yes, they're both PowerPC chips, probably even with a lot of similar code and instructions, but the Wii U CPU is a lot newer of a CPU. Even though it has full backwards compatibility with the Gekko and Broadway CPUs, it probably has more instructions unique to the chip 09-04-2014, 01:33 AM
It's not a new architecture and doesn't have any new instructions. It's basically broadway (which was almost identical to gekko) plus a bit of logic to handle three-core communication.
The big difference between wiiU and GC/wii software is that the new stuff actually runs on top of a proper OS using segmented memory, system calls, shared libraries etc. while the old stuff was static binaries which ran directly on the metal, so each game was more-or-less a complete self-contained operating system.
The GC ran the Dolphin OS. Sure, it was very limited to just the bios menu, but it was there to help the games talk to the hardware, just like any OS.
A smaller fab size, 45 vs 180, means there is new instruction sets to deal with the physically new hardware. (09-03-2014, 09:30 AM)KHg8m3r Wrote: Yes, they both have a PPC based CPU, but the Wii U has one that several magnitudes faster being based on a newer architecture of PPC. That just changed a little bit, https://www.indiegogo.com/projects/glide.../x/8492729 (09-04-2014, 01:33 AM)tueidj Wrote: It's not a new architecture and doesn't have any new instructions. It's basically broadway (which was almost identical to gekko) plus a bit of logic to handle three-core communication. There is a reason they have different names though, There are changes. However the similarities I might guess... if emulation was to be attempted would/could be be a starting point. (speculating of course)
The GC menu was not an OS, once it loaded a game it was gone from memory. It had nothing to do with "games talking to the hardware". Same with the wii menu.
Quote:A smaller fab size, 45 vs 180, means there is new instruction sets to deal with the physically new hardware.Absolute rubbish. The wii CPU has been shrunk a couple of times through its lifetime, do you think they also added new instructions to it? (09-04-2014, 03:32 AM)cdoublejj Wrote: There is a reason they have different names though, There are changes. However the similarities I might guess... if emulation was to be attempted would/could be be a starting point. (speculating of course) The main difference between gekko and broadway are more BAT registers (4->8), used to handle memory translation. They were used to map the wii's new MEM2 region. There were other differences like being able to prefetch data in larger sized chunks, but these features weren't used by the wii. The differences between espresso and broadway are a bit more extensive (mainly due to the new cores and variable L2 configurations) but from an application's point-of-view there's no real difference. (09-04-2014, 03:32 AM)cdoublejj Wrote: That just changed a little bit, https://www.indiegogo.com/projects/glide.../x/8492729 Yes, because he's looking for money to make the time to continue working (09-04-2014, 03:33 AM)tueidj Wrote: The GC menu was not an OS, once it loaded a game it was gone from memory. It had nothing to do with "games talking to the hardware". Same with the wii menu. The OS handles the function calls from the games to the hardware. A dev just programs a call for the OS to pull in the relevant data, and then they manipulate that. If the OS was purged from memory, then including the OS on each game really ups the chance of a bad game with a broken OS, rendering the game totally useless, where if the game doesn't contain the OS and has a bad write, it could still run, but maybe with a glitch here or there. edit: just dug around on the game isos I have, and I don't see any mentions of holding a full OS |
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