FRANK Digger

Official page: frank.rh1.tech — hub for all FRANK boards and firmware.

Digger Remastered for RP2350 (Raspberry Pi Pico 2) with HDMI display, PS/2 or USB keyboard, and I2S audio.

Screenshots

Title Screen	Gameplay

About

Digger is a classic arcade-style PC game created by Windmill Software in 1983 for the IBM PC. Players control a digger collecting emeralds and gold while avoiding monsters called Nobbins and Hobbins.

In 1998, Andrew Jenner reverse-engineered the original x86 binary and created Digger Remastered — a portable C reimplementation that preserved the original gameplay. Maksym Sobolyev (sobomax) later extended the project with SDL support, Linux compatibility, and various improvements.

FrankDigger is a bare-metal port of Digger Remastered to the RP2350 microcontroller, using CGA 4-color graphics mode for a minimal flash footprint (~347 KB UF2). It outputs video over HDMI via PIO, reads input from a PS/2 or USB keyboard, and plays audio through an I2S DAC — all without an operating system.

Note on Title Screen

The original CGA implementation in sobomax/digger had cgatitle() as a stub — it returned immediately without drawing anything. The VGA version had full title graphics including the Windmill Software copyright text. Since this port uses CGA mode, that copyright text was never part of the source code we inherited. The title screen with the red border, high score table, and game character descriptions was added as part of this port.

Supported Boards

This firmware is designed for the following RP2350-based boards with integrated HDMI, PS/2, USB, and I2S:

• FRANK — A versatile development board based on RP Pico 2, HDMI output, and extensive I/O options.
• Murmulator — A compact retro-computing platform based on RP Pico / Pico 2, designed for emulators and classic games.

Both boards provide all necessary peripherals out of the box — no additional wiring required.

Hardware Requirements

• Raspberry Pi Pico 2 (RP2350) or compatible board
• HDMI connector (directly connected via resistors, no HDMI encoder needed)
• PS/2 keyboard (directly connected) and/or USB keyboard (via native USB port)
• I2S DAC module (e.g., TDA1387 or PCM5102)

Pin Tables

Two GPIO layouts are supported: M1 and M2.

HDMI (via 270 ohm resistors)

Signal	M1 GPIO	M2 GPIO
CLK-	6	12
CLK+	7	13
D0-	8	14
D0+	9	15
D1-	10	16
D1+	11	17
D2-	12	18
D2+	13	19

PS/2 Keyboard

Signal	M1 GPIO	M2 GPIO
CLK	0	2
DATA	1	3

I2S Audio

Signal	M1 GPIO	M2 GPIO
DATA	26	9
BCLK	27	10
LRCLK	28	11

Controls

Both PS/2 and USB keyboards are supported simultaneously in release builds.

Single Player

Key	Action
Arrow keys	Move digger
F1	Start one-player game
Space	Fire
F7	Toggle music
F9	Toggle sound
F10	Exit game

Two Players

Key	Action (Player 2)
W	Up
A	Left
S	Down
D	Right
F2	Start two-player game

Building

Prerequisites

1. Install the Raspberry Pi Pico SDK (version 2.0+)
2. Set environment variable: export PICO_SDK_PATH=/path/to/pico-sdk
3. Install ARM GCC toolchain

Build

# Clone the repository
git clone https://github.com/rh1tech/frank-digger.git
cd frank-digger

# Default build: M2 board, 252 MHz
./build.sh

# Build for M1 board
./build.sh -b M1

# Build with custom CPU speed
./build.sh -c 378

Release Build

Release builds enable USB HID keyboard support and produce UF2 files for both board variants:

./release.sh

Output files are placed in the release/ directory.

Flash

# With device in BOOTSEL mode:
picotool load build/frank-digger.uf2

# Or with device running:
./flash.sh

License

The RP2350 port code is licensed under the GNU General Public License v3.0 or later — see LICENSE for details.

The original Digger Remastered source code by Andrew Jenner and Maksym Sobolyev retains its original BSD-2-Clause and GPL-2.0 licenses, as noted in the individual file headers.

Author

Mikhail Matveev <xtreme@rh1.tech>, https://rh1.tech

Acknowledgments

Windmill Software

• Digger (1983) — The original IBM PC game.

Andrew Jenner

• Digger Remastered (1998-2004) — Reverse-engineered portable C reimplementation of the original x86 binary.

Maksym Sobolyev / Sippy Software

• sobomax/digger — SDL port, Linux support, and ongoing maintenance.
• License: BSD-2-Clause

Michael Knigge

• Code cleanup and bug fixes for the sobomax/digger codebase.

Raspberry Pi (Trading) Ltd.

• pico-extras — Audio I2S PIO library.
• License: BSD-3-Clause

Ha Thach / tinyusb

• tinyusb — HID keycode definitions.
• License: MIT

PS/2 PIO Keyboard Driver

• PS/2 keyboard PIO code for RP2040/RP2350.
• License: GPL-2.0-or-later