IBM Model M NKRO USB Upgrade Kit
Complete internal upgrade kit for IBM Model M keyboards featuring custom NKRO diode matrix membrane, STM32 QMK controller, and USB-C housing. Supports VIA/VIAL configuration. Requires bolt-mod. Compatible with IBM 1391401, 1390131. Install time: 2-3 hours.
Complete NKRO USB Mod Kit
Full electronics replacement for compatible IBM Model M variants: a modern MCU controller PCB with 3D-printed USB housing.
Technical Specifications
| Supported Models | IBM Model M 101/102-key (ANSI), part numbers 1391401, 1390131, 1390120, and similar variants |
| Controller | STM32-based MCU, USB-C connector, QMK firmware |
| Firmware Support | QMK, VIA, VIAL (pre-flashed with default layout) |
| Key Rollover | True N-key rollover (NKRO) via diode matrix |
| Polling Rate | 1000Hz (1ms) |
| Protection | ESD protection, common-mode choke filtering |
| Installation | Requires bolt-mod, 2-3 hours, basic tools (screwdrivers, hex keys) |
| Reversibility | Fully reversible (can restore original electronics) |
Modern USB-C controller with QMK firmware support and sensible defaults.
Diode matrix designed for reliable chording and consistent scan with true NKRO support.
What's Included
- ✓STM32-based USB-C controller PCB (pre-flashed with QMK)
- ✓Custom NKRO-Enabled Diode Matrix Membrane Assembly
- ✓Lock Keys LED PCB
- ✓3D-printed USB housing
- ✓4 pin JST Cable
- ✓Chassis Ground cable and screw
- ✓Chassis Screws
- ✓Installation guide with photos and troubleshooting
- ○Optional: 2× Super/Win keys upgrade (requires minor case trimming)
- ○Optional: Bolt-mod hardware kit (52× M2.5×8mm screws, 10× M2.2×6.5mm flat head screws, 52× M2.5 nuts)
Preorder
Ship estimate: 4 weeks. Processed Securely with Stripe.
Buy multiple kits and save! Bulk discounts automatically applied.
A bolt-mod is necessary for this upgrade. Confirm your status:
Requires a small case modification: remove ~3mm of plastic across ~3cm between Ctrl and Alt, then smooth the cut. The kit includes the membrane pad + new spring + barrel assembly.
Add a premium coiled braided USB cable to your order.
By purchasing you agree to the preorder policy and terms. International orders may be subject to import duties/taxes on delivery.
- STM32-based controller PCB (USB-C)
- Custom NKRO-Enabled Diode Matrix Membrane Assembly
- Lock Keys LED PCB
- 3D-printed USB housing
- 4 pin JST Cable
- Chassis Ground cable and screw
- Chassis Screws
- Confirm bolt-mod status (required).
- Disassemble and remove original controller.
- Install new controller and USB housing.
- Flash firmware (or use preloaded defaults).
- Test NKRO functionality.
Customer Reviews
This is one of the few Model M mods that feels properly engineered, not just "made to work." The per-key diode matrix, clean flex layout, and no-nonsense MCU design show someone who actually understands signal integrity and long-term reliability. It installs cleanly, NKRO is genuinely solid, and it feels like what IBM would've built if USB existed back then.
This upgrade makes my Model M feel modern without changing what I love about it. Installation was straightforward, everything fit perfectly, and the keyboard feels rock solid in daily use. It just works exactly the way you want it to.