[bitpak]

Hello everybody!

This is my first post here. I have no SGI machine at the moment, but looking for a few specific ones.
I love the aesthetic of the older 4D/VGX twin tower machines, which were used in the production of T2/JP/LM.
Unfortunately it's almost impossible to find such machine today, and if I would, I still couldn't afford it because of the size/weight.
So my question is what other graphics subsystem of a desktop SGIs have roughly the same performance of the VGX one? 

I2's Extreme?

[Raion]

Hello Bitpak,

The VGX/VGXT systems are a very early 3D accelerator and are pretty close to the RealityEngine, at least for non-textured routines. The Extreme Graphics set is based on a much more basic design -- frankly I'd say an IMPACT (i.e that in an Octane) would be a closer comparison because they do have texture capabilities on the VGX -- it's also a great example of how graphics hardware can be miniaturized. But that being said, there's no "mini-VGX" if that's your goal.

[bitpak]

Thanks, Raion

I am not an expert in any of SGI topic. I've just gathered some performance metrics for various graphics subsystems (from sgidepot and other sites and brochures). I'm aware that VGX has some hw texture capabilities which is not present on the Extreme Graphics (although someone noticed that VGX/VGXT systems are very slow when using textures). But flat-shaded polygons performance is more important for me. Also, I know VGX can be used with a multiprocessor R3K/R4K systems, and EG can be used only on a single CPU R4K-R10K system, if it's a desktop I2. Am I missing some point here with all these numbers? Maybe someone with both systems can make it clearer? Any input would be appreciated, really

---

To be more specific, I'm looking for an INDIGO2 machine, with a 4D/210VGX performance.
Can a 200Mhz R4K with Extreme Graphics be as good or slightly better than a 25Mhz R3K with VGX graphics in a non-textured polygons performance?

[jan-jaap]

Short history of SGI 'big iron' graphics:

• The original Geometry Engine, used in the 68K IRIS and 4D Professional IRIS was mostly used for wireframe geometry.
  
• The GT graphics (Professional IRIS) / GTX (PowerSeries) was the first to reliably do depth in hardware, so it could be used for solids.
  
• The VGX / VGXT (PowerSeries) have improved performance and limited texture capabilities. The total texture size is only a couple of hundred KB, and in VGX especially it's not possible for texture to cross a buffer iirc so it's not very efficient.
  
• Reality Engine was the first that could use texture memory without a speed penalty
  

A 4D/210 had a single R3000 @ 25MHz. It ran at best IRIX 5.3, but more likely IRIX 3.3 or 4.0. And that's a problem with a more modern system. It's still possible to run IRIX 4.05H on most R4000 Indigo2's with Extreme graphics, but IRIX 3.x only ran on the brown IRISes. IRIX 4 doesn't run many IRIX 3 apps because it switched from NeWS to X11 for graphics. IRIX 5 will still run IRIX 4 apps.

So, if you want to revive an old application you'll have to be careful. Also, especially in the days of GTX and VGX, application would often have logic of the type 'if graphics  == VGX : do something fancy ; else if graphics == GTX : do something basic ; else message "sorry, bye".

Otherwise, an R4400 Indigo2 Extreme runs circles around a 4D/210 in every possible way. Much faster CPU. Faster memory (and more of it). Faster disks. etc etc. Less things to break, less heat, less noise.

Still, I love my 4D/440 VGX. There's something about it -- if you can't have fast CPUs you've got to have many -- the low pitch hum of the fans and the fact that it still works even though it's 30+ years old. I've got a 4D/380 VGX as well, and I used to have a 4D/210 GTX.

[bitpak]

Thank you, jan-jaap! That's helpful.

I'll search for more info on the subject.

[bitpak]

It seems like I2 R4K Extreme would be faster than a 4D/210VGX and even 320VGX. After all, faster CPU should somehow compensate for lacking texturing capabilities.

[robespierre]

It seems like I2 R4K Extreme would be faster than a 4D/210VGX and even 320VGX. After all, faster CPU should somehow compensate for lacking texturing capabilities.

That depends heavily on what the applications require. The CPU and texture hardware are on opposite ends of the pipeline, after all.
Applications like MCAD don't need textures, but Vis/Sim relies on them.

[bitpak]

Sure thing. The plan is to learn some basic 3d modelling in Wavefront/Softimage. Why looking for 4D/VGX performance, then? Mostly because of what Angel team did on The Lawnmower Man. Those guys had a single 210VGX (with a couple of 3030s). I just want to do some similar low-poly modelling, on a system with similar performance. That's about it.

Thanks guys for replying and helping me out.