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You can reuse some classic ThinkPad keyboards as standalone USB keyboards, but there is no universal adapter: the keyboard matrix, flex-cable pinout, and TrackPoint interface vary by model. A documented IBM ThinkPad 380ED conversion shows what the project can involve: a Teensy 3.2 scans the keys and presents them over USB, while separate circuitry handles that model’s analog TrackPoint.
How the conversion works
A laptop keyboard is not automatically a USB device. A controller must connect to the keyboard’s flex cable, scan its key matrix, and translate key presses into USB input. If you also want the TrackPoint, the controller or supporting circuitry must handle that pointing device’s particular electrical interface as well.
Frank Adams and Brian Chan’s ThinkPad 380ED keyboard and TrackPoint to USB project uses a Teensy 3.2 to scan the keyboard and create a composite USB keyboard-and-mouse device. Hackaday’s May 26, 2020 overview describes the conversion. The project is a model-specific example, not a drop-in design for every ThinkPad keyboard.
Identify the keyboard and TrackPoint before choosing parts
Find the exact laptop or keyboard model, then confirm the flex-cable connector, pin count, and pinout against a design made for that hardware. Also decide whether you want only the keys or the TrackPoint and its buttons. Adding pointing-device support can mean additional wiring and electronics.
#1 Best Overall
- Compatible With: RJ45 Keyboard to USB Converter v1.0 cable Compatible with IBM Model M Terminal keyboards
- Applicable scenarios:RJ45 to USB Converter v1.0 uses Soarer’s Converter firmware so you can use your old IBM Model M Terminal and compatible keyboards on a modern computer with USB support
- Product Includes:1 x RJ45 Keyboard to USB Converter cable(Ethernet (RJ-45) Female, USB Male)Compatible with Windows, MacOS, and Linux.Scan code set 3.Realtime configuration using online
- Product Features:Remapping.Layers.Macros.On-the-fly Config Selection.Full NKRO, if the keyboard supports it Compatible with Windows, MacOS, and Linux.Scan code set 3.Realtime configuration using online
- No Power Required:Plug and play, more convenient connection
The difference between projects is substantial:
| Documented conversion | Keyboard and TrackPoint details | Controller or construction |
|---|---|---|
| IBM ThinkPad 380ED | The project scans the keyboard matrix. Its TrackPoint uses analog strain gauges requiring external signal conditioning. | Teensy 3.2; project firmware builds a composite USB keyboard and mouse device. Source |
| ThinkPad T61 | The guide describes a PS/2 TrackPoint interface and a dedicated Fn-key connection outside the matrix in that implementation. | Teensy-based controller; the guide discusses pull-ups for PS/2 clock and data. Source |
| L420 and related models | Separate flex-cable connections are specified for the keyboard and TrackPoint; the design lists a 30-pin keyboard FFC connector. | Custom PCB and a Teensy++ running QMK. The project lists L410/L412/L420/L421 and related models as compatible; verify the exact keyboard before relying on that claim. Source |
These designs are useful starting points only when your hardware matches their assumptions. Do not carry a pinout, controller choice, or wiring detail from one ThinkPad generation to another without checking it.
Why the 380ED TrackPoint needs extra circuitry
The 380ED project describes analog strain gauges rather than the PS/2 signaling used by the T61 design. In the 380ED build, the authors measured the strain-gauge resistors at about 352 Ω at rest and a change of about 1 Ω under hard directional force. With a 3.3 V divider, they calculated a change of only about ±4 mV, too small to detect reliably in their setup without amplification. Those figures are measurements and calculations for that project and keyboard, not universal TrackPoint specifications.
Rank #2
- [Package Contents] Includes four adapters (4.3*1.8 cm / 1.7*0.7 inch). These adapters are compatible with most PS/2 interface mice and keyboards. Only mice or keyboards with built-in chip converters will work; please check compatibility before purchasing.
- [USB to PS/2 Adapter] This USB to PS/2 adapter allows you to easily connect a USB mouse or keyboard to a computer with limited USB ports. Note that the resulting USB port can only be used to connect a mouse and keyboard; other USB devices cannot be connected.
- [Driver-Free Installation] This adapter features a plug-and-play design, requiring no software drivers. Simply plug your mouse or keyboard into a PS/2 port to use your device without any additional setup, ensuring a hassle-free and convenient experience.
- [Instructions] The PS/2 to USB adapter is not hot-swappable, so be sure to turn off your computer before connecting the adapter. After connecting, please restart your computer. If the middle mouse button becomes unresponsive, simply restart your computer for optimal performance.
- [Wide Application] This adapter is ideal for computers with insufficient USB ports or malfunctioning USB devices. By converting a USB port to a PS/2 connection, you can ensure stable use of your mouse or keyboard without taking up valuable USB ports, thereby enhancing the functionality of your device.
To read the small analog changes, the build uses an AD8236 instrumentation amplifier, a low-impedance reference, and careful offset adjustment. This is one reason a keyboard-only conversion may be much simpler than recreating the complete pointing-device experience.
Choose a build route that matches your goal
- Keyboard only: Look for a conversion documented for the exact keyboard model and flex-cable pinout. You avoid TrackPoint-specific circuitry and signaling.
- Keyboard plus TrackPoint: Confirm the TrackPoint interface for that model first. The 380ED’s analog signal conditioning and the T61’s PS/2 wiring are not interchangeable.
- Integrated desktop keyboard: A custom PCB and enclosure can make salvaged parts easier to use on a desk. The L420 build describes layered acrylic or wood panels and a custom PCB; enclosure fabrication is optional, not a requirement of every conversion.
Controller boards and firmware are likewise project-specific. The 380ED example uses a Teensy 3.2; the L420 design uses a Teensy++ with QMK. Treat these as documented choices for those builds, not as a universal bill of materials. Check the project’s instructions and board compatibility before buying components.
Rank #3
- PS/2 to USB ADAPTER: Premium computers accessories - PS2 to USB adapter - compatible for PS2 Keyboard/ PS2 Mouse/ Windows/ Mac/ Linux/ Bar Code Scanner
- CABLES INTERCONNECTS FUNCTIONAL: USB to ps2 adapter with two PS2 female ports, PS2 mouse and keyboard through USB port on any computer
- USAGE: PS2 adapter to usb is compliant with the Standard Specification of USB 1.0 and 1.1. Purple port for keyboard and green one for mouse
- CONVENIENCE: PS/2 to USB converter converts two PS/2 devices (Keyboard and Mouse) to the USB Interface
- COMPATIBILITY: PS2 USB adapter keyboard converts the PC PS/2 port of KVM switch to USB port (PC or SUN platforms
Parts and project checks
For a 380ED-style build, the project identifies a Teensy 3.2 and AD8236 instrumentation amplifier as key components. A model-specific build may also call for suitable flex-cable connectors, resistors, and other supporting electronics. The L420 project, for example, specifies a custom PCB, separate keyboard and TrackPoint connections, resistors, a capacitor, and M2 screws.
- Match the keyboard’s exact model and connector to a documented design.
- Check whether its TrackPoint is analog, PS/2, or another interface before wiring it.
- Follow that project’s schematic and firmware notes rather than substituting values from another model.
- Confirm present-day board and connector availability and compatibility before ordering; the project documentation does not guarantee current stock.
For a different approach, Lenovo’s legacy support page for the ThinkPad USB Keyboard with TrackPoint describes a prebuilt USB keyboard and historical driver support. Its listed operating-system support is period-specific, not a guarantee of compatibility with current systems. TEX Electronics’ seven-row keyboard history discusses its design and production goals but does not establish current availability.
Rank #4
- PS/2-to-USB ADAPTER: Adapter for those who like to continue using their PS/2 devices. Connect mouse and keyboard to your computer by using only one USB port
- SUITABLE FOR PS/2 DEVICES: Two PS2 female ports, purple for keyboard and green for mouse, and one USB male port.
- BUILT-IN USB-IC: You can use PERIPRO-401 to connect your keyboard and mouse with PS2 interface to USB 2. 0 port at PC or laptop. It also supports PS/2 Port of KVM Switch.
- UNIVERSAL PURPOSES: Fits with industrial and professional needs
- PACKAGE INCLUDES: Perixx PERIPRO-401 adapter, manual; 12-month limited
What to expect from the finished keyboard
A successful conversion can give an old laptop keyboard a standalone USB connection, and a suitably designed build can expose its TrackPoint as a USB mouse. The amount of work depends on the exact model and whether you want pointer support, a custom PCB, or an enclosure. Frank Adams described the appeal of older ThinkPad keyboards as their full-size keys and feel; that is his subjective rationale, not a measured ergonomic finding.
A separate ThinkPad keyboard reuse project may provide another model-specific reference. Compare its hardware and wiring to the keyboard in hand rather than assuming that the word “ThinkPad” means the designs are interchangeable.
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Best Value
- 【USB to Dual PS/2 Adapter】 Convert a single USB port into two PS/2 ports. This adapter allows connection of one PS/2 keyboard and one PS/2 mouse to a computer that only has USB ports.
- 【Connect Keyboard and Mouse】 Designed with two PS/2 female ports (purple for keyboard and green for mouse), allowing connection of legacy PS/2 input devices to modern computers with USB ports.
- 【Broad OS Compatibility】 Works with most operating systems including Windows, Linux, and other systems that support standard USB keyboard and mouse devices.
- 【Ideal for Legacy Peripherals】 A practical solution for using older PS/2 keyboards and mice with PCs or laptops that lack PS/2 ports. Suitable for home, office, and legacy hardware setups.
- 【Passive Adapter – Compatibility Notice】 This is a passive adapter and requires devices that support both USB and PS/2 protocols (dual-mode devices). It will not convert PS/2-only devices to USB.
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