---
id: LSN-0014
ticket: legacy-runtime-learn-import
title: Portability and Cross-Platform Execution
created: 2026-03-27
tags: [migration, tech-debt]
---

# Portability and Cross-Platform Execution

Status: pedagogical
Companion spec: [`../specs/11-portability-and-cross-platform-execution.md`](../../specs/11-portability-and-cross-platform-execution.md)

PROMETEU treats portability as an architectural property of the machine, not as an after-the-fact adaptation.

## Core Idea

The main point is simple:

- the machine defines the semantics;
- the host performs presentation and physical integration;
- the cartridge does not negotiate behavior with the operating system.

That avoids the common notion that each platform has "its own version" of game logic.

## Why This Matters

When time, memory, input, audio, and graphics are defined by the machine, the following become easier:

- deterministic replay;
- reproducible certification;
- execution on desktop, mobile, and DIY hardware;
- clean separation between semantics and adaptation.

## Practical Separation

A useful way to think about it is:

- the cartridge carries program and assets;
- the VM/runtime executes the logic;
- the host shows pixels, delivers audio, and collects physical input;
- the host does not redefine the game's rules.

## What Portability Does Not Mean

PROMETEU does not promise:

- the same physical latency;
- the same power consumption;
- the same raw host throughput.

It promises logical consistency. That is what matters to the machine's identity.

## Teaching Value

This model helps teach:

- the difference between logic and presentation;
- why modern engines often lose determinism;
- how to design portable software without relying on luck.