Why Can't The Pandora Emulate The Ps2?

[VRAndy]

Why is that?

Basically, imagine an an assembly instruction on the PS2. It's in assembly, so it takes "one tick" to run. (I'm simplifying here, so sue me.) But on an EMULATOR, that one instruction has to go through some logic to interpret it. Which may take many "ticks".

An emulator can't just send the instruction right to the CPU, it has to look at it and 'think' : "What kind of instruction is this, and what would the target machine do with it?".

Really, it's impressive that people can get that down to a 7:1 ratio.

 

[darionapole]

i use pcsx2 in my prescott 3GHz HT and it can barely run disgaea (and all those nippo ichi titles that are know to have very low cpu usage) with both HT cores at 100% at 54-60 fps with frame skip, and all the speed hacks. FF X runs at about 30fps with same setings. Now imagine the pandora, the cortex-A8 isn't as fast as a pentium 4 at same speed (as far as i know). well let's do the math, 60 / 3000 * 600 = 16FPS and 30 / 3000 * 600 = 6FPS, but as i said it isn't as fast at same speed so you would surely end up with 10 and 4 frames per second.

 

[Exophase]

in about 5-10 years i don't see why it couldn't. the newest ARM A9 cores run at 1Ghz and the site says that they can be put in a configuration of up to 4. i will admit to not knowing much of anything about emulation but if it was highly optimized and was running on a 1.5Ghz quad core it may run. (again i'm talking 5-10 years)

my laptop is running a 2.4Ghz Intel core 2 duo and most games (that can run on the emu) run at near full speed

Cortex-A9 would probably have to at least be beyond 3.5GHz before it can be competitive with your 2.4GHz Core 2, in integer performance. Much further to start matching it in floating point SIMD (where Core 2 can probably do a good 4x as much work per cycle) - this is quite relevant to VU emulation for PS2.

This of course says nothing about the GPU legwork involved.

Multi-core helps a little, but it can only do so much in emulation where several intensive pieces have to be well synchronized - unless things have changed a lot PCSX2 task switches its cores (R5900, two vector units, IOP) around every 512 instructions, which will never go over that spectacularly in multicore execution.

Of course, some games will require much much less CPU than full tilt, and this goes for emulating anything. There's almost always going to be some gross exception to the requirements, within reason.

But unlike many other emulators, PCSX2 really is pretty damn fast.

Not saying we won't be there in 5-10 years, but I don't really know what ARM's roadmap is like. Conventional speculation I've been hearing is that it'll be a while before they start investing in another major widening of the core. Of course, that won't stop third parties from coming up with more ARMs. There'll probably be more speedbumps - in 5 years I'm sure commodity handhelds will be running at least 2GHz 4-way Cortex-A9 or better, but I don't think that'll be enough for PS2 emulation. Mobile CPU development is really booming right now, but that doesn't mean it'll always be this way... the market was actually in something of a lull for a long time, when you consider that ~200MHz StrongARMs were out in like 1997 and 624MHz XScales in early 2000s, yet before Cortex-A8 a 533MHz ARM11 was actually still considered high end. So IMO we're only now seeing movement and there's no saying it'll last forever.

 

[VRAndy]

But unlike many other emulators, PCSX2 really is pretty damn fast.

Doesn't it achieve that speed by doing some amount of recompilation? Or am I completely making that up?

 

[Iorgy77]

PS3 doesnt have a PS2 emulator either.

 

[VRAndy]

PS3 doesnt have a PS2 emulator either.

What?

Some PS3s have PS2 hardware in them.
Some PS3s have a software PS2 emulator.
Some PS3s don't support PS2 software at all.

Why Sony didn't give them all the same features in this regard I'll never know.

 

[rabidpoobear]

PS3 doesnt have a PS2 emulator either.

What?

Some PS3s have PS2 hardware in them.
Some PS3s have a software PS2 emulator.
Some PS3s don't support PS2 software at all.

Why Sony didn't give them all the same features in this regard I'll never know.

They took out the PS2 hardware because it cost ~80-100 per unit IIRC.
xbox 360 came w/ software XBOX emulator and no one cared. PS3 tried to one-up them, realized at the last minute they made a costly error by over-speccing their system and making it too expensive, and are trying to play catch-up.

 

[VRAndy]

Ok, but why make a software emulator, and then not put it on all machines that don't have hardware back-compat?

 

[rabidpoobear]

Ok, but why make a software emulator, and then not put it on all machines that don't have hardware back-compat?

IDK, why have a camera with a proprietary a/v connector that uses proprietary memory?

It's Sony, they probably did it because some department head said it would increase PS2 sales. Who knows, I just see them making mistake after mistake this generation. Which is pretty sad considering how much the PS2 dominated last gen.

 

[Exophase]

Ok, but why make a software emulator, and then not put it on all machines that don't have hardware back-compat?

This is purely speculation, but my guess is that Sony is doing this to gradually phase out PS2 support so their next major console won't be expected to include it, since it's a pretty big headache.

If you look at Nintendo you might see a similar pattern:

GB Micro - drops GBC support
DSi - drops GBA support

(I'm guessing 3DS won't have GBA support, but I guess we'll have to see)

 

[quadomatic]

PS2 emulation didn't become playable until plugins for dual core support were made...it's really not going to happen

Keep your fingers crossed for Dreamcast though

 

[quadomatic]

Is that dance in green spandex involved in being a sex offender?

I only recognize that as Greenman from Always Sunny in Philadelphia, but maybe they were referencing it from somewhere else

 

[chole]

This is purely speculation, but my guess is that Sony is doing this to gradually phase out PS2 support so their next major console won't be expected to include it, since it's a pretty big headache.

I think the behind the scenes rationale was that leaving in PS2 compatibility might give third party developers incentive to keep producing PS2 games, which would slow down adoption of the PS3.

The real question is whether they put backwards compatibility for the PS3 in the PS4. The processor architecture was supposed to be strongly a long-term strategy, something that would service them for multiple generations (and it had better, because the cost of it has so far reset all their profits from previous consoles put together).

(I'm guessing 3DS won't have GBA support, but I guess we'll have to see)

More likely, Nintendo will have a portable equivalent to their Virtual Console. That way, they can resell their GBA games.

That's also why I skipped this generation. I got a GBA, which supports all their software from the original Game Boy on, and I figured all I needed to do was wait until they released the system that phased out GBA support for my next purchase.

 

[darionapole]

just curious, is it posible to put en arm cpu and a mips R3000/A compatible cpu both in the same board and be able to use both? So instead of using a soft cpu emulator we could use that chip to off load the main cpu. the ps2 cpu was a mips R3000A which was backward compatible with the R3000 from the psx,(ps2 = 200MHz, psx = 33MHz) Is it posible to get both recognised by linux or we would have to use some trick like the arm940 from the gp2x?
(arm being the main one for boot)

 

[Deyna]

in about 5-10 years i don't see why it couldn't. the newest ARM A9 cores run at 1Ghz and the site says that they can be put in a configuration of up to 4. i will admit to not knowing much of anything about emulation but if it was highly optimized and was running on a 1.5Ghz quad core it may run. (again i'm talking 5-10 years)

my laptop is running a 2.4Ghz Intel core 2 duo and most games (that can run on the emu) run at near full speed

Cortex-A9 would probably have to at least be beyond 3.5GHz before it can be competitive with your 2.4GHz Core 2, in integer performance. Much further to start matching it in floating point SIMD (where Core 2 can probably do a good 4x as much work per cycle) - this is quite relevant to VU emulation for PS2.

This of course says nothing about the GPU legwork involved.

Multi-core helps a little, but it can only do so much in emulation where several intensive pieces have to be well synchronized - unless things have changed a lot PCSX2 task switches its cores (R5900, two vector units, IOP) around every 512 instructions, which will never go over that spectacularly in multicore execution.

Of course, some games will require much much less CPU than full tilt, and this goes for emulating anything. There's almost always going to be some gross exception to the requirements, within reason.

But unlike many other emulators, PCSX2 really is pretty damn fast.

Not saying we won't be there in 5-10 years, but I don't really know what ARM's roadmap is like. Conventional speculation I've been hearing is that it'll be a while before they start investing in another major widening of the core. Of course, that won't stop third parties from coming up with more ARMs. There'll probably be more speedbumps - in 5 years I'm sure commodity handhelds will be running at least 2GHz 4-way Cortex-A9 or better, but I don't think that'll be enough for PS2 emulation. Mobile CPU development is really booming right now, but that doesn't mean it'll always be this way... the market was actually in something of a lull for a long time, when you consider that ~200MHz StrongARMs were out in like 1997 and 624MHz XScales in early 2000s, yet before Cortex-A8 a 533MHz ARM11 was actually still considered high end. So IMO we're only now seeing movement and there's no saying it'll last forever.

i see. thank you for the information ^_^
here's hoping that the mobile CPU development keeps going strong for a good long while *raises glass*

 

[Exophase]

I think the behind the scenes rationale was that leaving in PS2 compatibility might give third party developers incentive to keep producing PS2 games, which would slow down adoption of the PS3.

It's possible, but that doesn't really explain why it was removed. It's true that maintaining it is a cost, but it's probably better to leave it in and stop supporting it than to just scrap it. My only other guess is that since they've been selling PS3 Slim at quite a reduced price point that this time they want to be damn certain that people are buying it for PS3 games, and not so they ultimately just replace their PS2s.

The real question is whether they put backwards compatibility for the PS3 in the PS4. The processor architecture was supposed to be strongly a long-term strategy, something that would service them for multiple generations (and it had better, because the cost of it has so far reset all their profits from previous consoles put together).

I don't feel confident that Cell will actually be a long term solution, it just hasn't paid off at all outside of PS3. But, I don't feel confident that it won't be either.

For what it's worth - and I admit this isn't even really related to anything but I feel like mentioning it - PS3 has been doing much better recently. In Japan it's not only outselling Wii in units sold but it's utterly dominating the top 10 games list, with Wii holding on to old first party titles. I don't know if this is enough to make them eligible to "win" this generation but it's definitely a massive turn around.

More likely, Nintendo will have a portable equivalent to their Virtual Console. That way, they can resell their GBA games.

Although they haven't shown signs of doing this yet, DSi practically feels designed for this. That is, if they did the smart thing and mirrored the entire RAM at 0x8000000 (where the cartridge port was) it'd allow them to easily load GBA ROMs into main memory then switch into the GBA mode that they probably didn't remove from the hardware. This would make supporting all games up to 16MB large (vast majority of GBA library) extremely simple, while still requiring people to purchase them again.

I'm still really interested to see how they accomplish DS backwards compatibility for 3DS.

just curious, is it posible to put en arm cpu and a mips R3000/A compatible cpu both in the same board and be able to use both? So instead of using a soft cpu emulator we could use that chip to off load the main cpu. the ps2 cpu was a mips R3000A which was backward compatible with the R3000 from the psx,(ps2 = 200MHz, psx = 33MHz) Is it posible to get both recognised by linux or we would have to use some trick like the arm940 from the gp2x?
(arm being the main one for boot)

PS2 isn't r3000a (okay, its IPU is, but that's more for PS1 compatibility), it's r5900. But it's also way more than a CPU - it has two powerful vector units, 3D hardware with its own particular low level interface, SPU hardware, various other things accessed at a low level.. lots of stuff that has to match right. You probably wouldn't even find an off the shelf CPU that implements the same core instruction set, much less with the same performance characteristics as Emotion Engine, much less with suitable power consumption characteristics for mobile... only Sony could really have something like that made and they'd probably struggle with it as well.

The whole "just use the same kind of CPU" mindset, ie virtualization, just doesn't really work when it comes to emulating consoles with lots of dedicated hardware running low level software. Virtualizing PSP would be more realistic, but even then you'd still be lacking the necessary vector unit support, which would be way too slow to emulate through traps.

 

[fearofshorts]

Although they haven't shown signs of doing this yet, DSi practically feels designed for this. That is, if they did the smart thing and mirrored the entire RAM at 0x8000000 (where the cartridge port was) it'd allow them to easily load GBA ROMs into main memory then switch into the GBA mode that they probably didn't remove from the hardware. This would make supporting all games up to 16MB large (vast majority of GBA library) extremely simple, while still requiring people to purchase them again.

Actually Exo, the GBA mode couldn't be removed from the hardware, because if it were no DS games would run on it.
The DS uses an ARM-9 and an ARM-7 processor. DS games use both, with the ARM-9 handling most of the grunt. The ARM-7 is usually reserved for just the simplest processing (though it is used quite well in some games, from what I understand). (Interestingly, the code used in each game's ARM-7 section pretty much never changes).

But the ARM-7 was also placed in there to enable GBA games to be played. The ARM-7 processor Nintendo used was, while not quite the same as the GBA's, close enough to it to virtualize GBA games.

And yes, there is a lot of talk about adding GBA games to the DSi's VC (believe me, everybody wants it), but Nintendo has been holding back. Perhaps for the 3DS?

Sorry if I missed something important in your post, but I thought that as a GBATemp forum-er I had to post here.

 

[Mr B]

The fact that the software PS2 emulation on the PS3 didn't really work, and was creating a big hassle for Sony could have something to do with them dropping it. A lot of titles never worked properly.
B!

 

[elwing]

Although they haven't shown signs of doing this yet, DSi practically feels designed for this. That is, if they did the smart thing and mirrored the entire RAM at 0x8000000 (where the cartridge port was) it'd allow them to easily load GBA ROMs into main memory then switch into the GBA mode that they probably didn't remove from the hardware. This would make supporting all games up to 16MB large (vast majority of GBA library) extremely simple, while still requiring people to purchase them again.

Actually Exo, the GBA mode couldn't be removed from the hardware, because if it were no DS games would run on it.
The DS uses an ARM-9 and an ARM-7 processor. DS games use both, with the ARM-9 handling most of the grunt. The ARM-7 is usually reserved for just the simplest processing (though it is used quite well in some games, from what I understand). (Interestingly, the code used in each game's ARM-7 section pretty much never changes).

hum, are you sure of this? as I was understanding it, commercial DS games (not speaking about homebrew...), use a nintendo furnished arm7 software and they only use it through some specific api (so it should be possible to remove the ARM7 and replace what's behind the fifo with anything else) am I mistaken?

 

[fearofshorts]

No, you are right. The ARM-7 part is provided by nintendo.
But it is also needed to run the games. Most of them simply won't work without it.