Workboy

WorkBoy — a modern, buildable recreation

An open recreation of Nintendo's unreleased Game Boy WorkBoy keyboard accessory (Source R&D / Fabtek / Montague‑Weston, 1992): a QWERTY keyboard that plugs into the Game Boy Link Port and turns the console into a PDA, plus a software cartridge.

This repo contains a complete, buildable and CI‑verified design — firmware, a clean‑room ROM, a DRC‑clean PCB, a 3D‑printed case, and an assembly‑ready BOM.

Status: python tests/run_ci.py is green — 16 protocol checks + ROM, firmware, and case builds. The PCB autoroutes to 0 DRC violations.

What's here

Build & test

python tests/run_ci.py     # runs every check whose toolchain is installed

Toolchains: GBDK‑2020 (ROM), PlatformIO + avr‑gcc (firmware), build123d (case), KiCad 10 + Freerouting (PCB). See BUILD_PLAN.md and kicad/PCB_README.md for the full pipelines.

How it works (one paragraph)

The Game Boy is the serial master on the link port; the WorkBoy keyboard is a passive slave that returns one scan‑code byte per poll. So the "custom PCB" is a small 5 V ATmega328P keyboard‑matrix controller that speaks the documented WorkBoy serial protocol — no level shifter needed. The protocol/scan‑codes were reverse‑engineered by shonumi (GBE+) and re‑verified here against the real ROM.

Console compatibility

One 5 V design covers every console that can run a Game Boy / Game Boy Color cartridge — including the GBA and GBA SP, whose link port switches to 5 V when an 8‑bit cartridge is inserted. Only the cable plug varies.

Full table, cable choices, and why this is not split into per‑console repos: COMPATIBILITY.md.

⚠️ GBA/SP support is documented behaviour that this project has not yet verified on a bench. Measure before trusting it.

What you'll need to build one

Nothing here is exotic. Rough 2026 USD; the board is most of the cost.

Console side

The keyboard board

Ordering 10 boards costs $86.50 all-in ($8.65/board) versus $59.75 for 5 — 28 % cheaper per board, because the engineering fee and shipping don't scale.

Tools

• An ISP programmer. An Arduino Uno running the stock ArduinoISP sketch is the cheapest route and doubles as the breadboard prototype MCU (it's a 5 V ATmega328P, so it talks to the DMG link directly). A USBasp works too. ⚠️ An ST-Link will not work — it speaks SWD/JTAG/SWIM, and the ATmega needs ISP. firmware/platformio.ini already ships a commented stk500v1 block for the Arduino-as-ISP path.
• A logic analyzer (any cheap 8-channel 24 MHz sigrok/PulseView clone, ~$10) — verifying the SPI handshake and clock edge is the single most useful bring-up check.
• Soldering iron, solder, flux · breadboard + dupont wires · 3D printer + PETG/PLA.

The link connector — the one part with no catalog option There is no reliably-purchasable bare DMG link plug. Either cut a third-party link cable (most reliable — keep the 4 used wires SO/SI/SC/GND, and meter them before soldering: the two ends are deliberately cross-wired, so one end's SO is the other's SI), or 3D-print the plug — e.g. svender's DMG link cable plug, which uses 6 pins harvested from female USB sockets. Breakout PCBs exist but still need a cable.

Suggested order of purchase. Buy the logic analyzer and a link cable first and run the P0/P1 protocol test on a breadboard — prove the handshake before spending on the PCB. Order boards, switches and inserts only once that works.

Licence

MIT — see LICENSE. Attribution, scope, and what is deliberately not in this repo are recorded in NOTICE.

Legal

This is an independent, unofficial recreation. It is not affiliated with, endorsed by, or connected to Nintendo, Source R&D, Fabtek, or Montague‑Weston. "WorkBoy" and "Game Boy" are used descriptively to identify the device being recreated and the consoles it attaches to.

The original WorkBoy ROM is leaked, copyrighted Nintendo‑licensed code — it is not included here and must not be committed or distributed. The cartridge software in rom/ is clean‑room, written from the documented wire protocol. Use the leaked ROM only for private bench reference.

The WorkBoy trademark (USPTO 74239332, filed 1992) was abandoned in 1994 without ever registering, and both original companies are defunct — see NOTICE.