Difference between revisions of "VPro"

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== V6/V8 Pixel Clock Issues ==
 
== V6/V8 Pixel Clock Issues ==
  
The first generation of VPro boards -V6 & V8- have a design flaw that prohibits graphics modes in much of what might otherwise be considered the normal range for SGI desktop systems:  
+
The first generation of VPro boards (V6 & V8) have a design flaw that prohibits graphics modes in much of what might otherwise be considered the normal range for SGI desktop systems:  
 
* Modes in the 109-193MHz range cannot be selected at all on V6/V8.  
 
* Modes in the 109-193MHz range cannot be selected at all on V6/V8.  
 
* Modes that are close to the lower end of that range (like 1280x1024_59/60) are only allowed at 8 bytes/pixel framebuffer size and even at that setting some people reported display problems (noise, flickering).
 
* Modes that are close to the lower end of that range (like 1280x1024_59/60) are only allowed at 8 bytes/pixel framebuffer size and even at that setting some people reported display problems (noise, flickering).

Revision as of 17:56, 22 March 2008

General information

The VPro series (code name "Odyssey") is a a computer graphics architecture for SGI workstations. First released on the SGI Octane2, it was subsequently used on the SGI Fuel and SGI Tezro workstations. VPro provides some very advanced capabilities such as per-pixel lighting, also known as "phong shading", and 48-bit RGBA color.

There are currently four different VPro graphics board revisions, called: V6, V8, V10 and V12. The first series were the V6 and V8, with 32MB and 128MB of RAM respectively. The V10 and V12 had double the geometry performance of the older V6/V8, but were otherwise similar. The V6 and V10 can have up to 8MB RAM allocated to textures, while V8 and V12 can have up to 104MB RAM used for textures.


Features

  • "OpenGL on a chip"™ technology
  • Hardware implementation of specular shading with per-pixel normal interpolation (through the SGIX_fragment_lighting extension)
  • 48-bit (12-bit per component) RGBA
  • 96-bit hardware-accelerated accumulation buffer for depth of field, full-scene anti-aliasing, motion blurs and other effects
  • texture memory capacity 8MB (V6, V10) or 104MB (V8, V12), total memory 32MB (V6, V10) or 128MB (V8, V12)
  • Perspective-correct textures and colors
  • High-performance hardware clipping
Option: Color: RAM: Max. Texture Memory Geometry Speed
V6 48bit RGBA 32MB 8MB Original GE speed
V8 48bit RGBA 128MB 104MB Original GE speed
V10 48bit RGBA 32MB 8MB 2X Faster GE speed
V12 48bit RGBA 128MB 104MB 2X Faster GE speed


Graphics subsystem

The VPro graphics subsystem consists of an SGI proprietary chip set and associated software. The chip set consists of the buzz ASIC, the pixel blaster and jammer (PB&J) ASIC, and associated SDRAM.

The buzz ASIC is a single-chip graphics pipeline. It operates at 251 MHz and contains on-chip SRAM. The buzz ASIC has three interfaces:

  • Host (16-bit, 400-MHz peer-to-peer XIO link)
  • SDRAM (The SDRAM is 32 MB (V6 or V10) or 128 MB (V8 or V12); the memory bus operates at half the speed of the buzz ASIC.)
  • PB&J ASIC

All VPro boards support the OpenGL ARB imaging extensions, allowing for hardware acceleration of numerous imaging operations at real-time rates.


V6/V8 Pixel Clock Issues

The first generation of VPro boards (V6 & V8) have a design flaw that prohibits graphics modes in much of what might otherwise be considered the normal range for SGI desktop systems:

  • Modes in the 109-193MHz range cannot be selected at all on V6/V8.
  • Modes that are close to the lower end of that range (like 1280x1024_59/60) are only allowed at 8 bytes/pixel framebuffer size and even at that setting some people reported display problems (noise, flickering).

Pertinent nekochan.net discussions about these issues can be found here and here.