Which furthers supports the idea of the RAM being a unified pool addressable from either CPU or GPU.
Nintendo 3DS hardware thread
- Thread starter brain_stew
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Good points about non-physically unified memory but still visible to both CPU and GPU. That probably has performance implications that put it somewhere in between a non-unified address space and sharing a single (and single-ported) memory chip. Still different enough to not consider it the same class as the latter, IMO.
Although, I don't see how the video supports the notion of VRAM being directly CPU visible, could you clarify?
I liked DS's approach, which was to have both the CPU/2D and 3D engine capable of accessing VRAM, but only by mapping explicitly in software and during safe times. This removed the silicon overhead and non-determinant performance of having shared bus arbitration. But the 3D core didn't have any means of directly addressing main memory, and since it's a deferred renderer you couldn't stream textures. Its small (512KB) of memory visible for textures was arguably still typically enough for the small resolution target, but you get to a certain point where a tiny texture memory really has to act as a cache for the larger main memory and therefore have access to it. N64 was really hit hard by not having this, even though it did have decent DMA.
Although, I don't see how the video supports the notion of VRAM being directly CPU visible, could you clarify?
I liked DS's approach, which was to have both the CPU/2D and 3D engine capable of accessing VRAM, but only by mapping explicitly in software and during safe times. This removed the silicon overhead and non-determinant performance of having shared bus arbitration. But the 3D core didn't have any means of directly addressing main memory, and since it's a deferred renderer you couldn't stream textures. Its small (512KB) of memory visible for textures was arguably still typically enough for the small resolution target, but you get to a certain point where a tiny texture memory really has to act as a cache for the larger main memory and therefore have access to it. N64 was really hit hard by not having this, even though it did have decent DMA.
Hmm, is it safe to say that you know a little more official info about this than we do Faf?To be fair, PSP is closer to PS3 as a segmented-ram platform - ie. the two memory pools are functionally equivalent, storing any data. It also doesn't have the ultra-wide eDram others do, and coupled with the bus-configuration which wasn't meant to handle external DRam, it still suffers very similar to how N64 and XBox did in the end.
Anyway - who says 3DS doesn't have dedicated VRam?
In either case, from the pictures I suppose we can conclude that it has at least one 512mb of FCRAM, following the footsteps of the DSi. What kind of RAM did the DS/DS-lite originally have?
FCRAM as well, as far as I know. Fujitsu MB82DBS02163C-70L (32Mbit). Nintendo really seems to love pseudostatic RAM.Hmm, is it safe to say that you know a little more official info about this than we do Faf?
In either case, from the pictures I suppose we can conclude that it has at least one 512mb of FCRAM, following the footsteps of the DSi. What kind of RAM did the DS/DS-lite originally have?
Assuming the specs IGN published a while ago are mostly correct, I guess the RAM is clocked at 133MHz (same as the GPU). 2.1GB/s with 6ns access time sounds pretty good for a handheld as far as I can tell.
[Q
Two cycle access time for the CPU. As if a modern desktop processor would be running out of the L1 cache. Wouldn't you love it? Effectively removes concerns about the memory hierarchy and how to set up data structures and data access. Sweet. Then again, capacity is modest.
Two cycle access time for the CPU. As if a modern desktop processor would be running out of the L1 cache.
Wouldn't you love it? Effectively removes concerns about the memory hierarchy and how to set up data structures and data access. Sweet. Then again, capacity is modest.tongue_of_colicab
Veteran
I've been searching for a anwser to this for a while but couldn't find it. Does anybody know if you can switch the parallax barrier on/off on the fly?
Yes. 3DS has a slider on the side for 3D depth. Turn it all the way down and you get a 2D screen at twice resolution.
Well, you get a 2D image, but it's still rendering at 400*240. At least, I assume that's the case in games like SF4 that are 60fps in 2D mode. Have other games specifically announced they double the horizontal resolution in 2D mode?
Yes, the capacity isn't that impressive. FCRAM is much more expensive than LPDDR, though - Nintendo isn't completely stupid, they probably know what they're doing. Maybe the cards use MXSMIO or a similar interface. With nearly 300MB/s and features like XIP, going for speed instead of capacity might be more efficient.[Q
Two cycle access time for the CPU. As if a modern desktop processor would be running out of the L1 cache.
Good point. Perhaps they interlace vertically? That could make some sense. But from reading impressions, that slider is essential for getting a comfortable 3D experience - without it the 3DS would suck. Also, it is apparently pretty hard to keep your head in the right position, and any game that requires more than very gentle input is a problem. Weekend Confirmed podcast for this weekend has a pretty lengthy discussion on the 3DS and its games, apparently most of the press got to play it extensively last week.
The hands on reports I've seen say there's a 3D sweet spot, but that its reasonably forgiving. I haven't seen any reports of having to keep your head still in one specific position or youll lose the effect.
tongue_of_colicab
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I know that but what I ment was if a game could turn it on or off by itself. Because I was thinking what if you want to show a 2d menu for example? Do you still have to render 2 seperate images? Or can you just output the same image to both eyes (I suppose that would be the case) and end up with a 2d image without having to render things twice? Because I thought otherwise it might be nice if you could switch 3d on or off when you don't need it and save some extra power by not having to render things twice. But now i'm thinking about it what I'm saying probably just doesn't make any sense.
Certainly in principle, althugh we don't know how the inner workings and dev tools deal with 3D; whether it's left to the developer to create two independent frontbuffers (or one stereoscopic one) and read the slider rating for their own camera setups, or if developers set up one camera in a somewhat fixed engine and this is divided into two viewing positions. The former is most likely, and I expect devs have a lot of freedom except the TRCs will ensure compatibility with the 3D viewing, in which case rendering one eye and copying to the other would be possible.
Mod: Moved from NGP thread...
I recall there were rumors that 3DS would be more powerful than Wii and on a similar level to XBox 360 and PS3. Strange that people would be hung up over comments regarding NGP and not these..
I don't believe Sony ever said "more powerful than PS3." You can't really directly compare the two so easily when it comes to what kind of results you'll see, but I think the demos so far are doing a good job speaking for themselves.
I recall there were rumors that 3DS would be more powerful than Wii and on a similar level to XBox 360 and PS3. Strange that people would be hung up over comments regarding NGP and not these..
I don't believe Sony ever said "more powerful than PS3." You can't really directly compare the two so easily when it comes to what kind of results you'll see, but I think the demos so far are doing a good job speaking for themselves.
archangelmorph
Veteran
But you loose all the benefits of that power when you realise you're getting raped on load/store latencies & can't get data in/out of the VFPU fast enough to process it..
Exophase said:
The Wii rumour is probably true which by any feat isn't particularly surprising (especially given that it's also more expensive
)...As for PS360..?
Lol!
Linear transform is n^2, matrix multiply is n^3, operations like vertex shading are very data linear and easy to prefetch for and therefore hide latency of (PSP does have prefetch)... and you think that memory latency is making it impossible to realize the arithmetic capabilities of the VPFU?
Store latencies are hidden by a write buffer which I think in PSP's case is write combining.
The Wii rumour is probably true which by any feat isn't particularly surprising (especially given that it's also more expensive
As for PS360..?
Lol!
Is 3DS more powerful than Wii? If the 2x ARM11 @ 266MHz rumor is true then it certainly isn't on the CPU front, and all signs point to less raw GPU power with perhaps fancier pixel shading and of course programmable vertex shading.
3DS would be more expensive for all sorts of other reasons, like including 2 LCDs where one is 3D and another has a touchscreen, batteries, speakers... That, and it's pretty well established by this point that Nintendo sells at prices they can get away with and not necessarily the tiny or even reverse margins that other console manufacturers sell at.
The RE4 Progenitor Virus trailer running on GC hardware looks better than anything coming out for 3DS. The Wii has more memory and a faster CPU than GC. From what I've seen, 3DS has lower realworld polygon pushing power which makes the graphics kinda ugly despite fancy lighting.
The 3DS appears to have a similar relation to the Wii as the NGP to the PS3 or the PSP to the PS2. The Conduit guys said they got the Wii version running on 3DS looking similar to the Wii version but it took quite a bit of tweaking. With Epic already having stated that UE3 games can run on both HD consoles and NGP, for all intents and purposes the NGP seems close enough to be able to share the brunt of development costs, being Art assets.
Memory architecture is the single biggest bottleneck of PSP, it limits everything the CPU does not just the VFPU. Maybe if the scratch-pad wasn't co##ed-up things could have been different for the latter at least.Exophase said:
Pica200 is rated at 4Pixels/clock, and if it has more then 1shader-op/clock(or fixed-function equivalent) it could comfortably outperform Flipper at similar clock speeds. And programmable vertex-operations should easily make-up for slightly lower peak-vertex throughput.
I get that. But that doesn't mean that the VFPU's ALU capabilities are completely wasted or unrealizable. Some Cortex-A8 platforms have pretty awful memory latency too, although L2 cache helps make up for it a lot compared to on PSP.
That's a pretty big if. Of course, we don't know what clock speed it'll be at either.
