I have created a PS/2 keyboard and mouse interface chip that works
with the BX-24 and similar microcontrollers. The interface can be
either serial or TWI/I2C. The same device supports either a keyboard
or a mouse or both simultaneously.
If you have an interest in using such a device and providing feedback
on it or if you have other questions, please send me a private email
via dkinzer AT easystreet DOT com.
I don't have specific plans to productize this at present but that
may be the eventual outcome. I'm also working on some ideas for
interface chips for other types of functions that are too complicated
or too time-critical for the BX-24 to handle directly.