Deeply optimized MSX emulation on ESP32-S3 with VGA output

A developer has achieved a highly optimized implementation of MSX emulation on the ESP32-S3 microcontroller, supporting VGA output and audio capabilities. This advancement demonstrates the ESP32-S3’s potential for retro gaming projects, expanding its use beyond typical IoT applications.

The project involves using an ESP32-S3 with at least 8MB of PSRAM to run a modified version of the fMSX core, tailored for the Lx7 CPU cores. The emulation supports MSX1, MSX2, and MSX2+ standards, with software loaded via web interface or SD card. VGA output is achieved through a 2-bit R-2R DAC, while audio output requires custom wiring of PDM filters to GPIO pins. Significant performance enhancements were made by optimizing cache usage, aligning memory accesses for the Xtensa architecture, and reducing pipeline flushing, with the blessing of the original fMSX author. These modifications allow the ESP32-S3 to emulate Z80-based MSX systems effectively, leveraging the hardware’s multi-core capabilities.

Potential Impact on Retro Gaming Hardware

This development demonstrates that affordable, widely available microcontrollers like the ESP32-S3 can handle sophisticated emulation tasks typically reserved for more powerful systems like Raspberry Pi. It opens new possibilities for portable, low-cost retro gaming devices, making classic gaming more accessible. The improvements also showcase how optimizing software for specific hardware architectures can significantly enhance performance, encouraging further innovation in embedded emulation projects.

MSX Emulation and Hardware Advances

The MSX was a popular home computer standard based on the Z80 processor, known for its classic gaming and productivity software. Emulation of MSX on modern hardware has traditionally relied on single-board computers like the Raspberry Pi. The ESP32-S3, with its dual-core Xtensa architecture, has gained attention for applications beyond IoT, including gaming. Previous efforts on ESP32-based devices were limited by processing power and graphics capabilities. This project builds on the Retro-Go platform, which supports multiple retro consoles, and pushes its capabilities further by optimizing for the ESP32-S3’s unique architecture and resources, particularly targeting VGA output and audio integration.

“The optimizations targeted cache management and memory alignment, which are critical for achieving smooth emulation performance on the ESP32-S3.”

— an anonymous researcher

Remaining Technical Challenges and Limitations

It is not yet clear how this emulation performs under long-term use or with more demanding MSX software titles. Details about power consumption, stability over extended periods, and compatibility with various peripherals remain to be tested and confirmed.

Next Steps for Development and Community Testing

Further testing will determine the stability and compatibility of the emulation with a broader range of MSX titles. The developer plans to refine the software for better performance, expand peripheral support, and potentially integrate additional features like sound synthesis. Community feedback and open-source collaboration are expected to drive ongoing improvements.

Key Questions

How does the performance compare to other MSX emulators?

Preliminary results indicate that the optimized ESP32-S3 emulator can handle most MSX1 and MSX2 games smoothly, though performance varies with software complexity. Further benchmarking is ongoing.

What hardware is needed to replicate this setup?

An ESP32-S3 development board with at least 8MB PSRAM, a VGA output circuit (using a 2-bit R-2R DAC), and custom wiring for audio PDM filters are required. Additional peripherals like USB keyboards and SD cards are also used.

Can this be used for other retro systems?

Yes, the Retro-Go platform supports multiple consoles and computers. The same optimization techniques could potentially be applied to other systems, but specific adjustments are needed for each.

Is this project available for public use?

The project is currently in development, with code and schematics likely to be shared on open-source repositories once finalized. Keep an eye on community forums for updates.

Source: Hackaday