Little did I know that the Japanese have been using the same idea for ages. In fact these boards as old as I am!
https://en.wikipedia.org/wiki/Thumb-shift_keyboard
This one is from 1980:
https://www.fujitsu.com/global/about/corporate/history/products/computer/wordprocessor/keyboard.html
I am cleaning up the firmware for all the keyboards. Two biggest changes are switch to the current QMK version 0.22.14 and enabling the VIA/REMAP support for all the keyboards. Look for the banners fo
My split boards have a controller in each half. That is they can be used separately as keypads. Also they can be programmed separately: one half can contain the default layout while the other contain