marconelly!
Veteran
Would that memory help them prevent access to the Media CPU?
Official PSP Thread
- Thread starter ChryZ
- Start date
marconelly! said:
Well, according to what I'm told, thats the change. eDRAM reduced, external RAM added. I've got a figure of 16MB, but I don't know if thats the full count or just the external.
Panajev2001a
Veteran
DaveBaumann said:
Dave, PSP has the CPU, GPU, etc... all on a single SoC, there has never been one single mention of off-chip DRAM... all the 12 MB have always been embedded in the PSP SoC.
Where have you heard that there was going to be any external RAM ?
Also adding external RAM would not bee too expensive and reducing e-DRAM would lower PSP's performance more than if we did not add external RAM and kept the e-DRAM we had.
Panajev2001a
Veteran
DaveBaumann said:
That is soooo .... grrrrr.....
Thanks... I am depressed now...
marconelly!
Veteran
Hmm, if that is the full count, that would be 4MB more than PSP originally intended to have.
2MB video, 2MB media, 4MB VRAM (if it's halved like you said) and 8MB external. Sounds possible, but I hope that is not the case, but it's rather 2-2-4-16
Can anyone provide an educated guess as to how the memory would be utilized if one of these two cases pans out? What would be stored where and uploaded when?
Pana, I think having 8MB more memory (or even just 4) would do much more for PSP than than some extra performance. It already has crazy performance for a handheld, but with more memory, games would be able to actually utilize that performance to the fullest. Yes, I know that texture and vertex compression and tesselating could help a lot, but 8MB in this day and age is not much if you want to have large, detailed levels and complex code (= big exe file)
2MB video, 2MB media, 4MB VRAM (if it's halved like you said) and 8MB external. Sounds possible, but I hope that is not the case, but it's rather 2-2-4-16
Can anyone provide an educated guess as to how the memory would be utilized if one of these two cases pans out? What would be stored where and uploaded when?
Pana, I think having 8MB more memory (or even just 4) would do much more for PSP than than some extra performance. It already has crazy performance for a handheld, but with more memory, games would be able to actually utilize that performance to the fullest. Yes, I know that texture and vertex compression and tesselating could help a lot, but 8MB in this day and age is not much if you want to have large, detailed levels and complex code (= big exe file)
Which is actually still pretty damn impressive for a handheld if you ask me. Just not as impressive as the BS PR we should be used to by now.
As far as RAM is concerned.. I don't see the big deal. Maybe it could use more if it was to operate like a PDA.. but for games on that small screen? Should be fine IMO.
No, Im more worried about the ergonomics of the case itself. That control pad looks really akward. It is just a mock-up, and even then, you cant really judge without holding it.. but just the way it slants around the edge of the thing. I guess time will tell.
I'd agree with marconelly! - the extra RAM should be a good thing. The quanties that were spec'ed up seem to be very low for any kind of texturing and the addition of RAM should make dev's lives much easier in terms of texture usage. I don't think its going to necessarily suffer too much in terms or performance, dependant on external RAM speeds - if the VRAM remains untouched then thats still going to be pretty fast colour writes. Of course, this puts it closer to what MBX does.
marconelly!
Veteran
How does memory management works on MBX? Does it have VRAM + EDRAM (plus the main RAM on whatever device it's implemented) Also, what are it's polygon/texturing/fillrate specs?
Reality check... What quantifies "any kind of texturing?" The PSOne only has had 3MB (well 3.5 if you add audio) RAM all together, the N64 4.5MB, it's on part with a GP32 (with far better memory performance), and about half that of a DC (well main-mem that is) while rendering at less than half the resolution of the DC...
While I'd like 16MB of RAM myself, I'd rather not take it at the expense of segmenting my main memory into embedded and external pools...
marconelly! said:
Memory management is more or less the same as any other PowerVR tiler, however in this instance MBX is designed to reside on the same core as the CPU os they have a fully unified memory structure.
PowerVR tilers don't have "VRAM" or "EDRAM" in the traditional sense, (along with the normal caches) they have an area of silicon which is the "tile". Tile size can vary dependant on the implementation (and does so even between versions of MBX), but IIRC they have previously implemented a 32x16 pixel tile and possible a 32x32 (I can't remember). Due to the binning/regionalised nature of the the architecture the tile can effectively act as a full mini "on chip" frame buffer for each tile that its operating on - not until every operation that is going to be carried out in that region has been carried out will the contents of the tile be passed to the external frame buffer. The advantage here is that as the sytem is regionalised it can quite neatly hide the fact that anything is being passed out to an external frame buffer as the operations on the next tile are already being carried out at thise point and this rendering is usually going to take more time than 32x16 pixels worth of bandwidth. Another advantage is that the tile depth is usually 32bits, so that even if the frame buffer is of a lower depth (which its highly likely to be on small devices) all the blends and other colour operations are carried out at 32bit and only dithered lower after all the ops are carried out (although this may the the same for PSP is the VRAM is stores at 32bit and the full screen size fits in, which I assume it must).
Note sure about fillrates as these vary upon implementation and specification of MBX. All (IIRC) MBX's have Dot3 capabilities, making polybump practical, and the full MBX even has the "VGP" which is a programmable vertex pipeline.
I'm sure Simon will be able to clear any issues and specs that I've got incorrect. If you want to read more about the principals of PowerVR's tiling, much/most of which will apply to MBX, and MBX then we have numerous articles, reviews and interviews that go into the tech:
http://www.beyond3d.com/articles/tilebasedrendering/index1.php
http://www.beyond3d.com/reviews/videologic/neon250/index1.php
http://www.beyond3d.com/reviews/videologic/vivid/index1.php
http://www.beyond3d.com/previews/videologic/vividxs/
http://www.beyond3d.com/interviews/pvrmbx/
archie4oz said:
PS One was point sampling with no mip-maps wasn't it?
DaveB said:
Yes, always.
gurgi said:
What someone once told me was that mip-mapping is done on PS2 (obviously you can tell in newer titles) but that it doesn't follow the standard "du/dv" SGI formula but instead the developer has to implement a distance method to calculate mip maps. I assume that's true by the fact that textures don't seem to blur correctly at sharp angles (as on DC), but it could still be wrong.
Panajev2001a
Veteran
DaveBaumann said:
External RAM adds to the cost of the console, a cost that will not decrease ultra fast over time.
When they shrink the PSP SoC to 65 nm the external RAM is still going to take the same amount of PCB and cost about the same...
I really really dislike this idea... cutting the e-DRAM used by the R4000i, the VFPU and the GPU, etc... is a bad idea.
You are going to waste time transferring tons of data back and forth from the e-DRAM and the external RAM: 8 MB of e-DRAM is already a not huge amount... cutting it to 4 MB or something like that makes no sense.
Ask GCN developers if they would have rather had 32-34 MB of 1-T SRAM or 24 MB of 1-T SRAM and 16 MB of 80 MB/s A-RAM.
I know which solution I would have pushed the management towards...
This is going to be something that will backfire on developers...
I do not think they will put ultra fast and low latency external RAM...
They would also have to add a Memory Controller on the PSP SoC not to make latency a huge problem.
4 MB of e-DRAM would not be too horrible if the external RAM is around 2.6-3 GB/s and we have an embedded memory controller like PlayStation 2 with its Direct RAMBUS solution as the 4 MB of e-DRAM would help a lot to reduce the latency as seen by the in-order R4000i CPUs.
I do not believe external memory will be that fast nor that we will see an embedded in the SoC Memory Controller.
archie4oz said:
Well, assuming PSP does have mip-maps this is going to require more RAM than PS One did for an equivelent number of textures.
What was the fill-rate of PS One as well? Generally speaking, RAM (and texture quantity/quality) has scaled with fill-rate as well, and I'm not sure the correlation is purely circumstancial - PSP's fill-rate isn't insubstancial.
Yes it would.
We'll wait and see what happens, I still have doubts that Sony is even concidering dropping some of the e-DRAM let alone add External memory.
Personally I don't think of PSP's ram to be limiting at all, I think of it as not a shortage, but that it's more ram than we have ever had in a portable before.
