V2200 Architecture

The V2200 integrates a 32-bit RISC processor, Triangle Engine, Pixel Engine, Fill Engine, PCI bus-master interface, VGA core, CRTC and RAMDAC. Local memory is shared by rendering, display refresh, the RISC and PCI accesses. The memory interface supports 2 to 16 MB of SGRAM or SDRAM on a 64-bit data bus.

Block Function Programming reference
RISC Executes microcode, reads command FIFO data and launches drawing operations. RISC programming
Triangle Engine Walks edges and spans; iterates vertex parameters and performs perspective correction. Triangle drawing
Pixel Engine Samples textures; applies visibility tests, blending, fog, dithering and plane masks. Pixel operations
Fill Engine Writes scan lines of solid, monochrome or color data. Memory fills
PCI interface Maps local memory and control registers; transfers command data by DMA. Host interface
CRTC / RAMDAC Reads the display surface and produces analog or digital video. Display control
VGA Provides text and graphics compatibility through mode 13 and mode X. VGA and VESA modes

The RISC launches work into the drawing engines. A launch can finish before the drawing operation finishes. Later instructions stall when they require a busy engine or a shared resource. Issue time, result delay and register hazards are separate quantities; see instruction hazards.

The chip has two drawing modes. V1000 compatibility mode uses step, parallel draw and parameterized draw instructions. V2000 mode enables Triangle Engine register shadowing with DrawCtl[3:0] = 0xB. It uses tri in place of the compatibility draw instructions. DrawCtl controls this distinction.

Sources: Technical Spec, p.4, Technical Spec, p.5, Technical Spec, p.16, Technical Spec, p.21, Technical Spec, p.38, Technical Spec, p.63