Imported from GitHub: rh1tech/frank · commit cf176cb · license GPL-3.0
Description
RP2350 Based Hardware Emulation Platform
README
FRANK
FRANK is a hardware emulation platform built around the Raspberry Pi RP2350 (Pico 2 modules and RP2350A QFN). RP2040 / Pico still works in FRANK's socket, but in practice only a handful of firmware (mainly the older ZX Spectrum cores) still targets RP2040. Everything modern (IBM PC, NES, SNES, Genesis, the DOOM / id Tech 1 ports, FRANK OS, and so on) is RP2350-only.
It started as a fork of the Murmulator project by Alex Ekb. Over time it picked up extra video outputs, audio paths, USB and WiFi support, and several form factors.
The name comes from "Frankenstein". The board is stitched together from parts of different projects, so the name stuck.
Looking for an older board?
This repository now ships only the boards under hardware/ that are actively maintained. The accessories/ and archive/ directories are gone. Older revisions, retired boards, and accessory adapters such as HDMI2VGA and USB2PS2 live in rh1tech/frank-archive.
Experimental and work-in-progress designs live in rh1tech/frank-lab.
The boards in this repo
Seven maintained boards, each with its own KiCad project, gerbers, BOM and assembly drawings, plus two add-on modules (TurboSound and Hecate).
| Board | Render | PCB size | Compute | Best for |
|---|---|---|---|---|
| MegaFRANK | 149.9 × 99.5 mm | Pimoroni PGA2350 (RP2350B module) | Maximal board — every output plus on-board dual-AY TurboSound, DS3231 RTC and dual power input. | |
| FRANK PGA | 99.5 × 83.1 mm | Pimoroni PGA2350 (RP2350A module) | Every output on one PCB, native USB host with multiplexer, ESD-protected. | |
| FRANK | 99.5 × 83.1 mm | Raspberry Pi Pico / Pico 2 (socket) + RP2040-Zero | Socketed alternative. Easiest to solder, swap Pico modules at will, USB-to-PS/2 helper on board. | |
| MiniFRANK | 85.6 × 53.98 mm | RP2350A QFN, on-board | Compact full-feature board with WiFi, VGA, HDMI and one gamepad port. | |
| MicroFRANK | 32 × 74 mm | RP2350A QFN, on-board | Smallest board. HDMI only, no hardware PS/2 or DB9 gamepad. Keyboards, mice and gamepads connect over the stacked USB host. | |
| ZeroFRANK | 65 × 25 mm | RP2350A QFN, on-board | Smallest RP2350A board. HDMI only, USB host for input, on-board flash + PSRAM + I²S audio. | |
| Nyx | 51 × 21 mm | RP2350B QFN, on-board | Open-source Pico 2 clone with built-in PSRAM. Drop-in replacement for Pico Plus 2 in the FRANK socket. |
The full-size and compact boards use the M2 GPIO layout, so any firmware build for M2 runs on them (subject to the feature differences below). Nyx is a compute module — it plugs into the FRANK socket and provides the RP2350B, flash and PSRAM; the FRANK motherboard provides all the I/O.
Comparison table
| Feature | MegaFRANK | FRANK PGA | FRANK | MiniFRANK | MicroFRANK | ZeroFRANK |
|---|---|---|---|---|---|---|
| Compute module | Pimoroni PGA2350 | Pimoroni PGA2350 | Pico / Pico 2 (socket) | RP2350A QFN on-board | RP2350A QFN on-board | RP2350A QFN on-board |
| On-board flash | via module | via module | via module | W25Q128 (16 MB) | W25Q128 (16 MB) | W25Q128 (16 MB) |
| On-board PSRAM | via module | via module | via module | 8 MB | 8 MB | 8 MB |
| HDMI output | Yes | Yes | Yes | Yes | Yes | Yes |
| VGA output | Yes | Yes | Yes | Yes | — | — |
| Composite (RCA) | Yes | Yes | Yes | — | — | — |
| TFT display header | Yes | Yes | Yes | — | — | — |
| Hardware PS/2 port | Yes | Yes | Yes | Yes | — | — |
| USB-emulated PS/2 (RP2040-Zero) | — | — | Yes | — | — | — |
| Gamepad ports (DB9) | 2 | 2 | 2 | 1 | — | — |
| Stacked USB Type-A host | Yes | Yes | Yes | Yes | Yes | — (USB-C PIO host) |
| MW7211A USB hub | Yes | Yes | Yes | Yes | Yes | — |
| USB host multiplexer | 74HC4052D | 74HC4052D | — | TS3USB221 | TS3USB221 | — |
| USBLC6 ESD protection | Yes | Yes | — | Yes | Yes | Yes |
| ESP-01S WiFi socket | Yes | Yes | Yes | Yes | — | — |
| Tape input (3.5mm) | Yes | Yes | Yes | Yes | — | — |
| Audio output | 3.5mm jack | 3.5mm jack | 3.5mm jack | 3.5mm jack | 3.5mm jack | 3.5mm jack |
| TDA1387 DAC | Yes | Yes | Yes | Yes | Yes | Yes |
| PAM8403 speaker amp | Yes | Yes | Yes | — | — | — |
| Power input | DC barrel jack (×2) | DC barrel jack | DC barrel jack | USB-C | USB-C | USB-C |
| Voltage regulator | MP1584 buck + AMS1117 LDO | MP1584 buck + AMS1117 LDO | MP1584 buck + AMS1117 LDO | AMS1117 LDO | ME6211 LDO | AMS1117 LDO |
| Power switch | Slide | Slide | Slide | Slide | Slide | — |
| Mounting holes | 4 × 2.7 mm | 4 × 2.7 mm | 4 × 2.7 mm | 4 × 2.7 mm | 4 × 2.7 mm | 4 × 2.7 mm |
On-board TurboSound (dual YM2149), a DS3231 real-time clock and a DS2401 silicon serial number are unique to MegaFRANK.
Modules
Two add-on modules ship alongside the boards:
| Module | Render | PCB size | What it is |
|---|---|---|---|
| TurboSound | 42 × 79.5 mm | Dual YM2149 / AY-3-8910 sound expansion (socketed DIP-40). Currently supported only by MiniFRANK via its expansion header. | |
| Hecate | 53 × 29 mm | Standalone RP2040 USB-to-PS/2 bridge board. Runs the Hecate firmware; presents USB keyboards and mice as PS/2 devices. |
Supported software
Over thirty emulators and native ports run on FRANK boards.
Console emulators
| Firmware | Platform | Repository | PSRAM required |
|---|---|---|---|
| frank-nes | NES / Famicom (Dendy) | frank-nes | Yes (8 MB) |
| frank-snes | SNES / Super Famicom | frank-snes | Yes (8 MB) |
| frank-genesis | Sega Genesis / Mega Drive | frank-genesis | Yes (8 MB) |
| frank-c64 | Commodore 64 | frank-c64 | Yes (8 MB) |
| frank-apple | Apple IIe | frank-apple | Optional |
| frank-msx | MSX / MSX2 / MSX2+ (fMSX core) | frank-msx | Yes (8 MB) |
PC emulation
| Firmware | Platform | Repository | PSRAM required |
|---|---|---|---|
| frank-386 | IBM PC i386 (DOS, Windows 3.x/95, Linux) | frank-386 | Yes (8 MB) |
Game engine ports
| Firmware | Game | Repository | PSRAM required |
|---|---|---|---|
| frank-idtech1 | DOOM, Heretic, Hexen, Strife (all-in-one) | frank-idtech1 | Yes (8 MB) |
| frank-doom | DOOM (standalone) | frank-doom | Yes (8 MB) |
| frank-heretic | Heretic | frank-heretic | Yes (8 MB) |
| frank-wolf3d | Wolfenstein 3D | frank-wolf3d | Yes (8 MB) |
| frank-duke3d | Duke Nukem 3D | frank-duke3d | Yes (8 MB) |
| frank-prince | Prince of Persia | frank-prince | Yes (8 MB) |
| frank-digger | Digger Remastered | frank-digger | No |
| frank-quest | ScummVM (AGI, SCI, SCUMM v1–v7, GOB, KYRA — King's Quest, Monkey Island, Day of the Tentacle, Full Throttle, Gobliiins, Kyrandia and more) | frank-quest | Yes (8 MB) |
OS and utilities
| Firmware | Description | Repository | PSRAM required |
|---|---|---|---|
| frank-os | Full desktop OS (Windows 95-style GUI, apps, built-in emulators) | frank-os | Yes (8 MB) |
| frank-kickstart | UF2 firmware launcher with SD card browser | frank-kickstart | Optional |
| frank-manul | Text-mode web browser (HTTP/HTTPS via ESP-01 WiFi) | frank-manul | Yes (8 MB) |
| frank-netcard | AT modem firmware for the ESP-01 WiFi module | frank-netcard | No |
Murmulator firmware
The original Murmulator project provides additional firmware that runs on FRANK boards as well:
ZX Spectrum cores: ZX Spectrum 48K / 128K / +3e (tecnocat, pico-spec, frut-bat, ZX Speccy P, murmulator), ZX Elf (pico-alf).
Other cross-platform emulators: MS-DOS IBM PC XT 8088, BK-0010 / BK-0011M, Radio 86RK, Macintosh, Atari 800, NES / Famicom / Dendy, Sega Master System / Game Gear, NEC PC Engine / TurboGrafx-16, Nintendo GameBoy / GameBoy Color, Watara Supervision, Atari Lynx, Bandai Wonderswan / Wonderswan Color, NeoGeo Pocket Color, Gamate, Game & Watch / Elektronika.
Tools and applications: MurmulatorOS, Picomite MMBasic, VersaTerm, the original Murmulator bootloader.
Other compatible boards
Most firmware also runs on:
- Murmulator (M1 and M2)
- Olimex PICO-PC (some firmware)
- Waveshare RP2350-PiZero (some firmware)
Getting started
- Order or fab the PCB (gerbers are in each board's
gerbers/directory). - Source the components using the BOM (
hardware/<board>/docs/<rev>/bom.html). - Solder following the board-specific guide, starting with the smallest passives and working outwards.
- Flash firmware: hold BOOTSEL on the RP chip, plug USB, release, copy a
.uf2file to the drive that appears (or usepicotool load). - Insert an SD card with ROMs, WADs or disk images.
- Plug in a display (HDMI or VGA), keyboard (PS/2 or USB) and gamepad.
For quick switching between firmware, flash frank-kickstart first. It gives you a graphical launcher that re-flashes from SD without touching BOOTSEL again.
PSRAM
Most modern firmware (frank-os, frank-quest, frank-386, frank-genesis, frank-snes, frank-msx, frank-idtech1, frank-doom and so on) needs 8 MB of PSRAM. Some firmware refuses to boot without it: frank-quest installs a custom dlmalloc backed entirely by external PSRAM (drivers/psram_init.c, drivers/dlmalloc.c), because the runtime (heap-allocated game state, decoded resources, mixer ring buffers, font caches) does not fit in the RP2350's 520 KB of SRAM.
How you get PSRAM depends on the board:
- MiniFRANK and MicroFRANK: PSRAM is already on-board (8 MB ESP-PSRAM64H). Nothing to do.
- FRANK PGA: the Pimoroni PGA2350 module already includes 8 MB PSRAM. Nothing to do.
- FRANK: the socketed Pico 2 has no PSRAM by default. Three ways to fix this:
- Pimoroni Pico Plus 2 (recommended). A ready-made Pico 2 with 8 MB PSRAM. Drop it into the socket and you are done.
- Build a Nyx, an open-source RP2350B board with integrated 16 MB flash and 8 MB PSRAM. Same form factor as Pico 2, drops straight into the socket.
- Solder a PSRAM chip on top of the flash chip of an RP2350 clone. SOP-8 flash chips are mostly only on clones (typically the black boards), not on a genuine Pico 2.
Repo layout
hardware/ Board KiCad projects (megafrank, frank_pga, frank, minifrank,
microfrank, zerofrank, nyx) plus the turbosound and hecate modules
docs/ Shared component datasheets and assembly notes
software/ Pre-built UF2s. Currently ships Hecate, the USB-to-PS/2 bridge
firmware for FRANK's on-board RP2040-Zero. Once flashed, a USB
keyboard or mouse appears on the hardware PS/2 lines.
Source: https://github.com/rh1tech/hecate
Documentation
Each board and module has its own assembly and usage guide:
- MegaFRANK assembly and usage guide
- FRANK PGA assembly and usage guide
- FRANK assembly and usage guide
- MiniFRANK assembly and usage guide
- MicroFRANK assembly and usage guide
- ZeroFRANK assembly and usage guide
- Nyx assembly and usage guide
- TurboSound module guide
- Hecate (USB-to-PS/2 bridge) guide
The hardware/<board>/docs/ directories also contain auto-generated BOMs (bom.html) and assembly drawings (assembly.pdf, schematics.pdf) for each PCB revision.
Links
- rh1.tech/projects/frank — project website
- rh1tech/frank-archive — older boards and accessories
- rh1tech/frank-lab — experimental designs
Firmware repositories
Console emulators:
- frank-nes — NES / Famicom (Dendy)
- frank-snes — SNES / Super Famicom
- frank-genesis — Sega Genesis / Mega Drive
- frank-c64 — Commodore 64
- frank-apple — Apple IIe
- frank-msx — MSX / MSX2 / MSX2+
PC emulation:
- frank-386 — IBM PC i386 (DOS, Windows 3.x/95, Linux)
Game engine ports:
- frank-idtech1 — DOOM, Heretic, Hexen, Strife (all-in-one)
- frank-doom — DOOM (standalone)
- frank-heretic — Heretic
- frank-wolf3d — Wolfenstein 3D
- frank-duke3d — Duke Nukem 3D
- frank-prince — Prince of Persia
- frank-digger — Digger Remastered
- frank-quest — ScummVM (AGI, SCI, SCUMM, GOB, KYRA)
OS and utilities:
- frank-os — Full desktop OS with built-in emulators
- frank-kickstart — UF2 firmware launcher
- frank-manul — Text-mode web browser
- frank-netcard — AT modem firmware for ESP-01
- hecate — USB-to-PS/2 bridge for the RP2040-Zero
Author
Mikhail Matveev — software engineer and hardware developer based in Thessaloniki, Greece. Background in software architecture, QA and open-source development. Builds retro computing hardware and writes firmware for fun. More projects at rh1.tech.
License
© 2026 Mikhail Matveev, [email protected]
GPL v3. See LICENSE.
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