Graphic Options

There are two different types of graphic boards in the Iris Indigo, the Entry (or starter) and the Express graphics.

Server

Some Indigos were sold as headless server. They were called 'Data Station' if they were an IP12, or simple 'Server 4000' with the IP20 cpu board ( 1 ). In the graphic slot was just a metal dummy.

Entry graphics

The Entry graphics is a cheap 2D frame buffer ( 1 2 3 4 ). It is capable of 1024x768 Pixels at 60Hz with 8 Bit color depth. The only advantage is, that it have a VGA style connector and a 13W3 connector, so you can connect it to any decent PC monitor. SGI sold also dualheaded systems with two Entry graphics, but they are very rare. The entry was sold in two different flavors, the LG1 and the LG2, but I can't see any difference between them (maybe the logo is it). Some of them have a nifty logo along with credits on it ( 1 2 3 4 ).

Express graphics

The Express graphics is a modular board set ( 1 2 3 4 5 ). It was used from the Personal Iris to the Indigo2/Indy in different form factors and configurations. The main board of the graphics hold zero to four Geometry Engines (GE7). Each GE7 has 32 MFlops. It also holds one to three propietary frame buffer memory Simms (VM2), the Raster Engine (RE3 at 50MHz) and the 'Head Quarter' (HQ2) as well as some smaller chips. On the upper side is a daughter board with the RAMDac and support chips. It has a 13W3 connector for the monitor and a genlock connector. On the lower side can be the Z-Buffer board (ZB1) which provides a 24 Bit Z-Buffer. For a very good description of the Express graphics read the Indigo2 and POWER Indigo2 Technical Report from Ian's very good web site. The following table show the configuration which were sold by SGI in the Indigo:
# of GE7# of VM2Z-Buffer
XS11no
XSZ11yes
XS24 13no
XS24Z 13yes
XZ 23yes
XSM (can someone confirm these?) 43no
Elan 43yes

The following table gives an overview about the capabilities off the Express graphics, and if its done in Hardware.
Feature Done in HW?
Blending yes
Anti-Aliasing Point (Size 1), Line (Linewidth 1)
Light Sources up to eight
Surface Properties yes
Two-Sided Lighting yes
Local Light yes
Fog and Haze yes (not per-fragment fog modes)
Texture Mapping no
Stencil Planes 4 Bit
Clipping Planes 6 (Minimize clipping for better performance)
Alpha Blending yes
Depth Buffer if ZB1 installed

Benchmarks and technical data

Pictures