This information is not official

It is subject to change at any time

Use at your own risk


Graphics Configuration Information:

Due to the Integrated Visual Computing (IVC) architecture of the Visual Workstation, all the graphics resources are allocated out of the system resource pool. In order for the system resources to be available, they must be obtained from the system *before* the operating system has access to them. After all, you wouldn't want your screen's frame buffer to be swapped to disk, would you?

Therefore, it is very important to properly configure the Visual Workstation graphics and display settings for your application. Some of these settings have no direct affect on the applications, but make the system work better in general. Others can have a 10X impact on performance (either + or -), others perhaps +/- 10%. All these settings are contained on the "Display Properties" dialog of the NT Control Panel.

  1. First, be sure the Enable SGI and DCC Video Modes option is enabled in the Silicon Graphics Display panel.
    1. This enables additional video modes and resolutions with SGI monitors.
    2. In fact, all SGI-PC monitors I've tested seem to support the 1920x1200 mode, which gives amazing desktop real estate.
    3. Be aware, however, that this means your system has to update significantly more pixels than at lower resolutions.
      1. For benchmarking purposes, be sure to set a resolution to something comparable to the competition.
  2. Next, go the the "Silicon Graphics Settings" panel and select the "CAD Design" profile from the list of pre-defined graphics profiles and then select the "Copy" button. You can rename the resultant profile as you like, but the important thing is that this makes the settings modifiable by you. Now hit the Properties button and you can see what the settings are.
    1. The Screen Area controls the size of the video display based upon the monitor's capabilities (see #1 above).
    2. Refresh Rate is tied to the video monitor capabilities as well.
    3. Color Palette controls the "depth" of the video frame buffer.
      1. For AutoCAD and Mechanical desktop, use either 32768 Colors or TrueColor for best performance.
      2. If you are not using the AccelGraphics OpenGL viewer or Mechanical Desktop (which includes the AccelGraphics viewer) you might try the 256 color option to save memory if desired.
    4. The Depth Buffer setting should be set to either 16 or 24 bits for Mechanical Desktop (or AutoCAD w/ AccelGraphics viewer) otherwise, it can be turned off to save memory.
    5. Graphics Options should be set to Use Back Buffer if using the AG viewer or Mechanical Desktop, otherwise, both can be turned off to save memory.
    6. Graphics Memory Allocation can be set to 0 for Autodesk CAD products, as they use no texture mapping features that require additional graphics memory.
  3. These steps must be done for each and every user account on the system who will be using the software. This is because this information is stored on a per-user basis.
    1. The default system configuration is not ideal for running interactive software, it must be changed.


  1. You must base your changes off of the CAD Design profile.
    1. If you are unsure what you have based your profile from, delete it and make a copy of the CAD Design setting.
  2. You must reboot your system after making these changes.
  3. You must do this for each user account on the system that wishes to run interactive applications.

Since the Visual Workstation makes use of the IVC architecture , all the graphics memory needs are supplied from the total memory installed in the system. Thus, going from 32768 colors (which uses 2 bytes of memory per pixel) to TrueColor (which uses 4 bytes per pixel) doubles the amount of RAM used for the frame buffer. Likewise, enabling back buffer support doubles memory use again (a copy for the front buffer and a second copy for the back buffer). Increasing the screen resolution increases the memory use as well. So there is always a tradeoff in how much memory to allocate to the graphics and how much to allocate for the system. It is best to allocate as little as needed to the graphics to allow the hardware to support the application(s) needs. Otherwise, if the hardware can't support a given mode, a much slower software path will be used. For example, if the application request double-buffer graphics, but the hardware double-buffer support is disabled, the software rendering engine will provide a second buffer but speeds will be perhaps 1/20th that of the hardware path.

Conversely, allocating too much memory to graphics such that the application begins to page to disk, is not a good idea either. If no applications use texture mapping, then allocating memory for texture storage is a waste. If you are running multiple applications, then choose the graphics settings required by the most demanding application. The settings set an "upper limit" of capabilities that the hardware driver can provide. Setting capabilities too low, results in a much slower software path, setting too high wastes memory.

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Graphics Settings 101:

If you are faced with configuring a Visual Workstation for an unknown graphics application(s), then it is best to proceed in a logical, top-down manner to detemine the ideal setting in the shortest amount of time. The following steps will take you through the process:

  1. Does the application use OpenGL?
    1. Does it use GDI as well?
      1. If yes, choose "CAD Design" to start with.
      2. If no, choose another configuration profile.
  2. Does the application use a lot of colors?
    1. If yes, select TrueColor, otherwise, 32768.
  3. Does the application use smooth double-buffered animations?
    1. If yes, then enable the hardware backbuffer support, otherwise leave it off to save memory.
  4. Does the application use overlay graphics?
    1. Usually it will display a diagnostic message if this feature is required, enable it if so., otherwise off.
  5. Does the application use texture-mapped graphics?
    1. If yes, determine how much memory might be needed.
      1. If you see objects showing up with "white" textures, this is a clue that you have run out of texture memory.
    2. If no, set this to 0, to free this memory for your application to use.

If you plan to run multiple applications, perhaps with different graphics requirements, choose a setting that takes the maximum of the combined application's needs. For example if one app is happy with 32768 colors and the other needs TrueColor, use TrueColor. Likewise if one needs texture RAM and the other doesn't, allocate enough for the app that needs it. More resources is generally better unless it begins to take memory from the operating system which results in paging.

A word on rebooting: Often after changing settings, you'll be prompted to reboot your system for the changes to take affect, other times you will not. The underlying logic seems to be that a reboot is asked for when memory needs increase. For example going from 1024x768 to 1280x1024 resolution needs more memory, you must reboot to allocate it. Going down in resolution uses less memory, a reboot is not required, but the memory formerly used is not given back to the system until a reboot is done. When in doubt, the best bet it to reboot after changing settings. When I am investigating changes, I find if I max out the settings and reboot, then I can play with dropping individual settings down to see what impact they have without needing to reboot. Once I get the setting I want, I save it and reboot.

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Inside the box:

Here's some information on the inner workings of the system that I have assembled here for your convenience. All this information could be determined by using simple tools and visual inspection (which is how I did it).

The IVC workstations differ from typical PCs, in that they do not have a traditional BIOS ROM. Rather thay have an ARC PROM, which gives a much higher level of interface to boot level options, etc. Users of SGI MIPS workstations will immedeatly recognize the look and feel of the ARC PROM, because it has been used on most SGI MIPS workstations since the Indigo2.

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[Last updated: 21.JAN.2000]