History

I have recently built a neo retro computer that uses PS/2 as its keyboard interface. While searching for a PS/2 solution, I decided to take matters in my own hands and build the missing link in keyboard interface - reusing vintage keyboards but with a modern twist.

Purpose

PCB to interface vintage 8bit keyboard with a Raspberry Pi pico to run as a Keyboard controller.

Meant to take a C16 or C64 keyboard matrix (different firmware) and map it, to enable USB -or- PS/2 connectivity (selectable by jumper)

The device is VIAL compliant and can be fully remapped at https://vial.rocks/

Hardware

This PCB has been developped on KiCad v10

It has two 20-pin connectors, only one to be used depending on firmware. (The C16 & C64 matrix are not compatible.)

The hardware has provisions for keyboard leds but they currently are non-functionnal - this will be resolved as a firmware upgrade.

There is also provision for an added caps lock switch - meant mainly for C64 while using a mechboard.

Firmware

Sources

Compatible QMK/Vial firmware is present on my fork of Vial

see https://github.com/wereallgeek/vial-qmk

Precompiled firmware

precompiled variants are available there:

C16: https://github.com/wereallgeek/vial-qmk/blob/vial/binaries/commodore_8bit_c16-vial.zip

C64: https://github.com/wereallgeek/vial-qmk/blob/vial/binaries/commodore_8bit_c64-vial.zip

More information

More information can be obtained on my blog.

see https://wereallgeeks.wordpress.com/2026/10/14/ps2keyboardpcb/