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Model H

This conversion kit allows you to replace your IBM Model M's original internal controller board with a modern USB board. This aims to match the footprint of the original controller and plugs into the original keyboard matrix, but exposes a USB port through the original SDL connector.

Thanks to QMK, the keyboard is fully programmable. It ships with a DFU-style bootloader, which can be programmed over USB.

Features​

  • Non-destructive upgrade - just swap the boards
  • Native USB (with type B connector), no adapter required
  • Doesn't require original controller
  • STM32 ARM Processor @ 72MHz with 64kb flash
  • Remappable keys (using QMK configurator)
  • Uses open source QMK firmare
  • Open source hardware
  • Reprogrammable through USB or ARM SWD
  • Lower power (50 mA typical)
  • Genuine "TE Connectivity Trio-mate" connectors, as used on the original Model M

Compatibility​

The Model H comes in two variants to match different internal connectors. Please check to make sure you order the right one.

Specifications​

  • Purpose: Drop-in replacement controller for IBM Model M keyboards.
  • Common Microcontrollers: Often STM32-based (e.g., STM32F103, STM32F303) or ATmega32U4 for older designs. This guide assumes a modern STM32-based version.
  • Connectivity: USB (typically Type-C or Type-B on the controller) to connect to a modern computer.
  • Firmware: QMK Firmware is standard, allowing for extensive customization.
  • Bootloader: DFU (Device Firmware Upgrade) for STM32-based versions.

For specific Model M variants supported, see the Model H Variants page.

Frequently Asked Questions (FAQ)​

This page addresses frequently asked questions regarding the Model H Controller for IBM Model M keyboards.

General Questions​

  • What is the Model H Controller?

    The Model H is an aftermarket replacement controller designed to upgrade original IBM Model M keyboards with modern USB connectivity and customizable firmware, typically QMK. This allows users to use these classic keyboards on modern computers and tailor their functionality.

  • Why would I need a Model H Controller?

    • Original Model M keyboards use older interface (like AT or PS/2) not directly compatible with modern USB ports.
    • To add programmability and custom layouts/macros using QMK.
    • To replace a faulty original controller.

Firmware and Flashing (QMK)​

  • How do I flash QMK firmware onto my Model H Controller?

    Assuming an STM32-based Model H, flashing involves DFU mode:

    1. Obtain your .bin or .hex firmware file: Build this using QMK, configured for the Model H and its specific STM32 chip.
    2. Disconnect the Model H from your computer.
    3. Locate the BOOT0 button/pin and RESET button on the Model H PCB. The method to enter DFU can vary slightly by design (e.g., a single button press, or jumper). Consult the Model H documentation.
    4. Typically, you'll press and hold BOOT0 (or set a jumper) and then press and release RESET, or plug in USB while BOOT0 is active.
    5. The controller should enter DFU mode.
    6. Use a DFU programming tool (e.g., dfu-util, STM32CubeProgrammer) to flash the firmware.
      • Example dfu-util command: dfu-util -a 0 -s 0x08000000:leave -D your_firmware.bin (address might vary).
    7. After flashing, the controller will reset with the new firmware.

    Refer to the Entering the Bootloader troubleshooting page for general tips, but always prioritize Model H specific instructions.

  • My computer doesn't recognize the Model H in DFU mode.

    • Ensure correct DFU drivers are installed (e.g., Zadig for Windows).
    • Verify the sequence for entering DFU mode for your specific Model H version.
    • Try a different USB cable and port.

  • My Model M doesn't work after flashing.

    • Ensure you flashed firmware specifically built for the Model H and your Model M variant.
    • Double-check your QMK configuration.
    • Verify internal connections between the Model H and the Model M's membrane/PCB.

Hardware and Installation​

  • Is the Model H compatible with my specific IBM Model M?

    Refer to the Model H Variants page or the documentation provided by the Model H manufacturer. Different Model M versions have different internal connectors and controller form factors.

  • Installation difficulties.

    • Carefully follow the installation guide for your Model H.
    • Ensure all internal ribbon cables or connectors from the Model M are securely and correctly attached to the Model H.
    • Avoid damaging the Model M's membranes during installation.

  • Some keys are not working or are behaving erratically.

    • This could be an issue with the Model M's membrane, a bad connection to the Model H, or a QMK configuration error.
    • Reseat all connections.
    • Clean the Model M's membranes if they are dirty.
    • Verify your QMK matrix and pin configuration.

Layout and Configuration (QMK)​

  • How do I customize the layout for my Model M using Model H and QMK?

    Use QMK's standard keymap customization. You can remap keys, add layers, and create macros. The default Model H QMK firmware usually provides a standard Model M layout as a base.

Community and Support​

  • Where can I get help with my Model H Controller?

    • The QMK Discord server.
    • Forums and communities dedicated to IBM Model M keyboards (e.g., Deskthority, r/ModelM).

Always consult the documentation specific to your Model H version for the most accurate installation and flashing instructions.