Clover 1 graphics is used on Professional Iris systems only. It is almost impossible to find reliable information on the first systems of the 4D series - the early Professional Iris Series (4D/60, 4D/50, 4D/70).
The SGI FAQ documents two variants of the Professional Iris Series: One being called "B" and the other "G" (as in "4D/50G"). While the latter seems to be the common graphics option installed in these systems it is not clear what "B" is. It is possible that is the basic boardset and "G" the version with Z-Buffer option.
These graphics options predate OpenGL, the graphics language used is IRIS GL. They are not supported in IRIX 5.x or newer releases of the operating system.
The following boards belong to a this boardset:
- This seems to be what later was called Graphics Manager. It contains a Motorola 68020 CPU and possibly also the Geometry Engines (hidden under blue heatsinks).
- Raster subsystem?
- Optional Z-Buffer board.
- This board is the end of the Clover 1 graphics pipeline. This is where the monitor cable is attached.
The following shows the configuration of "G" graphics for a 12 slot TwinTower Professional Iris system:
|11||GFX||DE3||DE3 and TB2 are bridged using a card edge connector board.|