prometeu-runtime/docs/runtime/learn/mental-model-audio.md

Audio Mental Model

Status: pedagogical Companion spec: ../specs/05-audio-peripheral.md

The right mental model for audio in PROMETEU is an active peripheral with a budget, not "automatic sound".

Philosophy

Sound:

• consumes time;
• consumes memory;
• uses finite channels;
• depends on explicit commands.

That brings PROMETEU closer to classic consoles and arcades where the game "talks" to an audio block with its own rules.

Audio CPU Metaphor

A useful metaphor is:

[Game CPU] -> sends commands at 60 Hz -> [AUDIO Peripheral]
                                         |
                                         v
                                   Voices + Mixer
                                         |
                                         v
                                     PCM Output

This metaphor does not require a dedicated thread. It only separates responsibilities:

• the machine defines the logical model;
• the host decides how to deliver continuous buffers;
• the game speaks in commands, not direct backend manipulation.

Good Habits

• reuse samples;
• limit simultaneous voices;
• treat sound as an intentional event;
• separate music and effects;
• avoid triggering the same sound every frame.

Historical Direction

The main influences here are:

• NES, for the clarity of limited channels;
• SNES, for sample playback and mixing;
• CPS-2 and Neo Geo, for the feeling of headroom and sample presence.

PROMETEU abstracts those references. It does not try to reproduce any of those systems literally.