GPU of the Day: SGI GE7 Geometry Engine

SGI Extreme 4GE7MCM 256 MFLOPS 320,000 Gates

At 2.6oz (75 grams) and 2.25 inches square (6cm) the SGI 4GE7MCM is a beast of a graphics chip.  More properly called a Geometry Engine was, the GE7 was responsible for all the graphics processing in SGI Indigo² workstations.  The Indigo² Extreme graphics option consisted of a pair of these MCMs (Multi-Chip-Module).  Each one contains 4 GE7 Geometry Engines providing 32MFLOPS of performance each.  Each GE7 consists of a custom 80,000 gate array from LSI (for a total of 320,000 gates and 128MFLOPS per MCM).  This performance level was, ironically, better then the main system CPU (35MFLOPs for the 200MHz R4400 option).

Each of the black ‘caps’ on the chip covers a single GE7 Engine.  A similar design was used for the XZ Graphics system that had only 4 total GE7 cores.  This was either implemented with 2 of the large MCMs that had only 2 GE7s in them (same package however) that were marked 2GE7MCM, or, later, a single surface mount MCM containing 4 GE7 engines.  All were manufactured by LSI.  In total the Extreme Graphics subsystem had no less then 31 custom gate arrays from LSI for a total of over 1.2 million gates.   At an average of 2 transistors per gate that works out to around 2.5 million transistors, a considerable amount for a graphics system in 1993.  Today’s graphics chips pack in transistors numbering in the billions, the Geforce GTX 680 has a total of 3.54 billion transistors, and performance measured in TFLOPS, again for the GTX 680, 3.09TFLOPS.  Today’s graphics chips cannot, however, compete with the magnificent looks of the GE7’s giant MCM package.

Sources:
Indigo² Product Guide (PDF)
Indigo² Technical Report