Toshiba T9P40YH GE11 REVC – geometry/image engine for SGI IMPACT graphics on Indigo2 and Octane

Definition

The Toshiba T9P40YH GE11 REVC is an ASIC used as GE11 (geometry/image engine) within the IMPACT graphics subsystems of Silicon Graphics, used on workstations such as SGI Indigo2 and SGI Octane. In practice, the GE11 is one of the core blocks of the pipeline: it handles 3D geometry processing and (in part) imaging operations, working alongside other dedicated ASICs (raster, pixel pipe, texture) to provide full hardware acceleration.

In the stated context, the component is associated with Silicon Graphics workstations based on MIPS R4000-family CPUs (and related derivatives), and is placed in the 1996–1998 timeframe as part of “IMPACT” graphics configurations.

GE11’s role in the IMPACT pipeline: why it is an “engine” and not a general-purpose CPU

Even if it is often called a “processor” in collector terminology, GE11 is not a general-purpose CPU: it is a specialized accelerator. In a typical IMPACT pipeline:

• The command processor (e.g., HQ3/HQ4, depending on the platform) dispatches commands and primitives.

• One or more GE11 devices perform transformations and geometry/imaging-related operations.

• The raster engine (RE4), pixel pipe (PP1), and (when present) the texture engine (TE/TRAM) complete frame generation.

Practically, the presence of a GE11 (or two GE11s in higher-end configurations) strongly influences the subsystem’s ability to handle complex scenes and OpenGL streams with significant geometry load.

Platforms: Indigo2 and Octane with IMPACT graphics (MGRAS)

IMPACT solutions are known for being offered on Indigo2 and, in a “repackaged” form integrated into the newer system bus, also on Octane (where technical documentation clearly describes graphics based on the Indigo2 IMPACT chipset).

At the configuration level, Octane documentation reports explicit block counts (GE11/RE4/PP1/TE/TRAM) for variants such as SI/SSI/MXI, showing that GE11 is a repeated building block used to scale performance.

Video output and 1280 × 1024 resolution

In the stated usage context, the IMPACT subsystem is associated with a typical 1280 × 1024 resolution, very common on SGI workstations of the era (24-bit framebuffers and professional monitors with dedicated refresh rates).

Sketch of the most important connections

                 system bus / workstation interconnect
        ┌──────────────────────────────────────────────────────┐
        │     platform interface + command processor            │
        │     (command/primitive dispatch into the pipeline)    │
        └───────────────────────────┬──────────────────────────┘
                                    │
                                    ▼
                         ┌────────────────────────┐
                         │  Toshiba T9P40YH GE11   │
                         │  GE11 geometry/image    │
                         │  engine (3D pipeline)   │
                         └───────────┬────────────┘
                                     │
                                     ├────────► RE4 raster engine (pixel fill)
                                     ├────────► PP1 pixel pipe (blend/depth/dither)
                                     └────────► TE/TRAM (texture, if present)
                                                │
                                                └────────► video output (e.g., 1280×1024)

Table 1 – Identification data and specifications

Table 2 – Operational and design considerations