New Amiga emulator skips Linux and runs straight on Raspberry Pi hardware

Bellatrix takes a very different route to Amiga emulation. It doesn’t run inside Linux. It doesn’t sit on top of a desktop. Instead, it boots directly on a Raspberry Pi 3B and takes control of the hardware itself. That changes the feel of the whole project. Rather than treating the Raspberry Pi as a general-purpose computer that happens to run an emulator, Bellatrix turns it into a dedicated Amiga-style system. The software handles processor emulation, chipset timing, USB input, storage access and video output without relying on a conventional operating system underneath. It’s a much more direct setup.

What bare-metal emulation really means

Bare-metal emulation sounds more complicated than it is. On a normal Raspberry Pi, Linux manages the processor, memory, USB ports, storage and display. An emulator then runs as one program among many, sharing the machine with background services and other system tasks. Bellatrix removes that layer.

It talks to the Raspberry Pi hardware directly and takes responsibility for the jobs an operating system would usually handle. That includes reading input devices, managing storage, scheduling processor work and sending graphics to the display. Why bother? Control.

The Amiga’s processor, graphics chips, audio hardware and memory system all need to stay closely synchronised. A general-purpose operating system can interrupt that timing with background tasks or scheduling delays. Bellatrix decides exactly when each part of the emulated machine runs. That doesn’t mean bare-metal software is automatically faster or more accurate. It isn’t magic. But it gives the developers much tighter control over the Raspberry Pi’s resources. The downside is obvious. Bellatrix has to do far more work itself.

Rebuilding the Amiga in software

At the centre of Bellatrix sits the Rigel library, which emulates the Amiga’s main custom chips. These include Agnus, Denise, Paula and the CIA components. Those names will be familiar to long-time Amiga users. Together, they handle much of the machine’s graphics, sound, timing and input behaviour. The Motorola processor side uses two different backends.

Musashi works as a traditional M68K interpreter. It reads the original Motorola instructions and executes them one by one. Emu68 takes a more ambitious route by translating those instructions into AArch64 code that the Raspberry Pi’s ARM processor can run directly. In theory, that can deliver much better performance. In practice, it’s still the experimental option.

Bellatrix currently comes in six kernel versions. Musashi 68000, Musashi 68040 and Emu68 are each available in single-core and multicore builds. For actual use on a Raspberry Pi 3B, the Musashi 68040 multicore version offers the safest mix of speed, stability and compatibility. Kickstart 1.3, Workbench 1.3, AROS and USB HID input already work. Emu68 can reach the AROS boot screen on real hardware, but it still needs more testing before it becomes the everyday choice.

Four cores, four clear jobs

The Raspberry Pi 3B has four ARM processor cores, and Bellatrix divides the workload between them. Core 0 manages the system and handles physical input and output. Core 1 runs the emulated Motorola processor. Core 2 looks after the Amiga chipset. Core 3 stays available for future work, such as RTG graphics or more advanced audio processing. That separation matters.

A typical emulator may ask one processing thread to handle the CPU, graphics, sound and input in quick succession. Bellatrix spreads those jobs across different cores and keeps them in sync with queues, interrupts and scheduling controls.

The Host Reactor on Core 0 checks hardware at around 1 kHz. That means it runs roughly once every millisecond. In measured tests, the dispatch time stayed comfortably inside that window. Storage can still cause delays, though. Some file operations run synchronously, so the launcher may pause while it waits for a task to finish.

A launcher built for disk images

Bellatrix includes its own launcher, which appears before the emulated Amiga starts. It can scan a FAT32 USB drive for ADF floppy images and ISO files. It also looks inside subdirectories, so users don’t have to place everything in one folder. A USB keyboard or HID-compatible joystick handles menu selection. No USB drive? That’s fine.

The launcher can also read files from the SD card’s boot partition. It makes the machine feel closer to a dedicated retro system than a Raspberry Pi running a standard emulator package.

Setup still takes some effort. The available downloads are Raspberry Pi kernel files, not complete SD card images. Users need the usual Raspberry Pi firmware files, a suitable configuration and a legally obtained Kickstart ROM. AROS also works, although its separate ROM files need to be combined into one image first.

What still needs work

Bellatrix works, but it isn’t finished. Direct booting from an Amiga RDB-partitioned SD card doesn’t work yet. ISO boot support through the planned CD-ROM system also remains incomplete.

Bluetooth support can scan for devices, but it can’t yet complete the full pairing and connection process. RTG graphics are still at an early stage too. The software can load parts of the graphics card system, but accelerated output and the VC4 backend need more development. Audio tells a similar story.

Direct HDMI sound has worked on real hardware, but full Paula audio still needs tuning and broader testing. Emu68 also needs more compatibility work before it can take over from Musashi as the main processor engine. None of this makes Bellatrix unusable. It simply shows where the project stands.

A different kind of Raspberry Pi emulator

Bellatrix isn’t trying to replace every established Amiga emulator. It has a narrower goal. It wants to turn the Raspberry Pi 3B into a dedicated Amiga platform, with direct hardware access and a clearly divided multicore design. That makes it more complex than a normal emulator, but also more interesting from an engineering point of view.

The Musashi builds already provide a workable base. Emu68, RTG graphics, improved audio and better storage support point towards what comes next. It’s still a developing system. But the core idea already works, and it gives the Raspberry Pi 3B a role that feels much closer to a self-contained Amiga than a small Linux computer running emulation software.