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Glossary

Terms used throughout these docs that assume PS1-specific or SplashEdit-specific background.

OT (Ordering Table)

A fixed-size array of buckets used to depth-sort GPU primitives before they're sent to the GPU. Each primitive is linked into the bucket matching its depth; the PS1 has no Z-buffer, so this is how the engine approximates depth sorting. See OT Size and Bump Size Tuning.

GTE (Geometry Transformation Engine)

The PS1 CPU's coprocessor 2, a fixed-function unit that does matrix/vector math - transforms, projection, lighting - in hardware instead of on the R3000A's integer core. SplashEdit's exported coordinates and rotations are scaled to suit GTE fixed-point input (see GTE Scaling).

SIO0

The PlayStation's first serial port, which drives controllers and memory cards. Distinct from SIO1, the link-cable port.

SIO1

The PlayStation's second serial port - the link-cable / "serial port" port, used for Networking. Distinct from SIO0.

splashpack

The binary format SplashEdit exports a scene into. The psxsplash runtime reads a .splashpack file to load a scene's objects, textures, nav data, UI, and everything else authored in Unity.

Bump allocator

A per-frame, reset-every-frame allocator used for the GPU command buffer. "Bump" because allocating just advances (bumps) a pointer; nothing is freed individually, the whole thing resets at the start of the next frame. See OT Size and Bump Size Tuning.

VRAM

The PS1 GPU's dedicated video memory: 1MB, addressed as a 1024x512 pixel grid. Framebuffers, textures, CLUTs, and fonts all live here. See Textures & VRAM.

CLUT (Color Look-Up Table)

A small palette stored in VRAM that 4-bit and 8-bit indexed textures point into. A 4-bit texture's CLUT has 16 entries, an 8-bit texture's has 256, each entry a 16-bit color.

SPU (Sound Processing Unit)

The PS1's audio chip, with 512KB of its own dedicated RAM (separate from main RAM and VRAM) and 24 simultaneous ADPCM voices.

PCdrv

A BIOS/emulator facility that exposes the host filesystem to the PS1 as a virtual drive over the debug link. SplashEdit's emulator and real-hardware builds use it to stream scene files instead of baking everything onto a disc image during development. See Build Targets.