# Platforms

OS⁴ is built on FreeBSD and supports x86_64 and AArch64 architectures. The Harmonia stack compiles natively on each target.

## Architecture Matrix

| Architecture | Hardware Examples |
|-------------|-------------------|
| **x86_64 / amd64** | Standard PCs, servers, cloud VMs |
| **AArch64 / ARM64** | Raspberry Pi, server-class ARM, embedded boards |

## Constrained Runtimes

Constrained runtimes run a subset of the Harmonia stack — orchestration and key capabilities, without full OS-level integration.

| Platform | Notes |
|----------|-------|
| **iOS** | Harmonia as embedded framework |
| **Android** | Harmonia as native library |
| **OpenXR** | VR/AR agent runtime |

## Cross-Architecture Evolution

Agents on different architectures share genomic evolution through Git:

- **Genomic layer** (S-expressions) — architecture-neutral source code, pushed to Git daily
- **Epigenetic layer** (runtime state) — architecture-specific snapshots, backed up to persistent storage hourly

Each agent recompiles locally for its target. An improvement discovered on x86 can propagate to ARM agents automatically.

## Next Steps

- [Self-Improvement](/docs/harmonia/self-improvement) — genomic/epigenetic sync details
- [Getting Started](/docs/os4/getting-started) — download and boot OS⁴
- [What is OS⁴](/docs/os4/what-is-os4) — why a dedicated agent OS