Skip to content

Glossary

Term Meaning
moby The game's own name for a movable world object: Spyro (sometimes), a gem, an enemy, a chest, a 3D HUD element.
class A moby's type, m_Class. It selects the model the moby draws with and the code that runs it, and it is the key most overrides and material selectors are written against.
tick One simulation step, 29.913 per second (NTSC 1125000/37609). Gameplay state advances only on a tick, so a mod that changes what the game does works in tick context.
VBL The PSX vertical blank, 59.826 Hz, two per tick. The CLI word "frame" means VBL: --frame-limit counts these.
present One drawn frame. How many presents a tick gets depends on the machine and on --render-fps, so a present count is never a contract.
canonical, sub-tick The scene extracted at the tick itself is canonical. Scenes drawn between two ticks are sub-tick and carry alpha, how far past the tick they sit, from 0 up to 1.
extraction The walk that turns guest state into draw data, once per scene. Refine callbacks run here.
guest RAM The game's 2 MB of PSX memory, held as a byte array in the process. Writing it changes gameplay; everything else a mod does cannot.
vaddr A PSX virtual address, the 0x80… form the game uses internally. api->guest(vaddr) turns one into a host pointer. Guest structs store vaddrs, never host pointers.
arena Guest memory a mod owns, from api->guest_alloc. It is timeline state: savestates, rewind and runahead carry and restore it like any other guest bytes, which host statics are not.
tick context, present context Where a call runs. Guest RAM writes, api->call, guest_alloc and registration are legal in tick context and refused in present context, which covers present hooks and UI section bodies.
override, base() A mod's function that replaces a game function, and the call that runs the next override in the chain and then the original. Where base() sits in the body makes the override a pre-hook, a post-hook or a replacement.
mutative A mod that writes guest RAM, declared as sim_mutative in the manifest. Memory cards are tagged with the mutative set that wrote them.
savestate, rewind, runahead Timeline features: capture and restore a moment, step backwards, speculatively run ticks ahead. Each needs the mod to declare how its own state behaves (state, runahead), and each is refused for an undeclared mod.