I got a reply from Geri, I guess the idea was ok, but technically, it is an outright no-go:
Quote:Hi Geri,
I've followed your driver development a bit on the background, but is it possible for you to rewrite 3dfx drivers so that multiple 5500's can be used in the same system??
I have been discussing this on the board and the problem is the initiation route, which vsa-100 is master etc etc.
http://www.falconfly.de/cgi-bin/yabb2/YaBB.pl?num=1355402726/0Could you let me know if it is possible?
kind regards
Pim
GERI:
there is a problem when using multiple v5 5500 would occur. the driver would require to sync the rendered image manually. the problem is that copying the frame buffer, and pasting it together would be probably slower, than just rendering the image on one simple card. copying and pasting back to gpu on a v5 would clamp the speed to probably somewhat around 5 fps. v5 is dead.
Quote:so in short, it would be possible, but the disred effect is not feasable?
But how does this work with the voodoo 2 then? Is it really cause of the hardware SLI connector that that does work and the 5500 would have to do it through software and pci bus?
GERI:
yes, when v2-s connected with sli bus, they sync the frame buffer directly, without requiring software texture transfer.
the same happens beethwen vsa100 chips when they are electronically connected, like voodoo5.
to make this with software assistance, it would need
-at least agp 8x transfer speed to be effective
-and support for virtual frame buffers and rendertotexture caps, OR support for hardware assisted quick framebuffer to texture copying.
3dfx cards dont have any of these requietments. this is only possible with some early cad cards, and above radeon 8500 / geforce3.
copying the frame buffer from voodoo5 to texture, takes 0.04-0.1 second.
copying the texture out from voodoo5 to system memory takes additional 0.05-0.1 second.
copying the half texture back to another voodoo5 would take ~0.02-0.05 second.
copying the frame buffer out from the chip decrases the performance below 4-8 fps.
and then you didnt even rendered anything, you just synchronized the images.
making this is possible with newer graphics cards, becouse they have enough bandwidth to move the images. but not with 3dfx.
and there is another problem with this too. since 3dfx cards cant do hardware vertex transformation and lighting, the voodoo5 need a lot of cpu power to process the vertices. the cpu just simply cant feed your voodoo5. and in this case, it would need to feed two of it.
to be short: voodoo5 is just a little improved voodoo1, that can render bigger textures in 32 bit, and have 2d functionalities. but its internal command set still looks back to somewhere around 1995. this is why voodoo5 is so slow.
Quote:Well that really sucks, since I remember reading not to very long ago, cpu's were finally so fast, they could do software rendering as a voodoo2 or 3 could hardware wise do oh so many years ago.
Reading your explenation, this would require something like a dualxeon based system, both at least core i7 based quadcores at 5Ghz, and 2 pci 5500's on a pci2pci-e connectors and then you'd might be able to emulate a 6000, right??
was a nice idea, can't the floppy like connector be used for it hardware wise??
GERI:
most modern software renderers, such as llvmpipe with mesa9.2 alreday perform around Radeon HD 5450/HD6450 on a moden 4 core i7 sysetm. (uncomparable faster than any voodoo).
also, you will still not be able to create a faster platform for two voodoo5 connection even if you put an 5 ghz cpu inside, since the communication is limited by the voodoo5 and the motherboard chipset itself. i dont think there is a possible way to connect two voodoo5 effectively.
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