The whole thing started as a want: the maker felt the famous Korg M1 belonged in the PicoVintageSynthCollection, a growing set of vintage synth recreations, and set out to build it. The result is PicoFaceM1, a DIY synth running on a stock RP2350 board with 8 MB or more of flash, wearing a green PCB and a small color screen, with three rotary knobs marked SW1, SW2 and SW3.
What stands out to me is how faithful the engine is. It was written from scratch by disassembling the original M1 operating system, with no borrowed code. The filter path mirrors the real hardware with four single-pole sections split across two chips, hitting a 24 dB/oct slope from the genuine tables. Amplitude is handled multiplicatively, with linear ramps stepping every 20.8 ms. Every one of the 33 original effect types came over as an algorithm, and it holds 16-voice polyphony. Samples stream straight forward out of 4 MB of PCM in flash.
To keep audio blocks on schedule, the core runs overclocked at 444 MHz and 1.60 V. That seems a sensible budget to me, and the maker has said the true bottleneck is not the clock speed itself but pulling samples out of slow flash quickly enough, which takes block transfers.
The demo runs through patch presets and combination banks while playing audio, with names like Universe, Piano 16', Brass 1, Solo Sax, Drums #1 and FilmScore appearing on screen, and the unit reproduces both the synth sounds and multi-timbral sequences convincingly. One thing still unclear is the exact board sitting under the assembly. Note that users must supply their own legally obtained PCM data and OS ROMs, which the build system picks up automatically from the roms/ directory.