How to write a keyboard driver for Mac, Win and Linux?

Question

Keyboard

There is a specific home-made piece of iron, with a keyboard. There is a desire to write a driver so that when typing text on this miracle keyboard, the text appears in the editor. Accordingly, to work in different OS.
Unfortunately, so far I have not found any information about the development of the keyboard, the keyboard driver for the OS.
It is not yet clear how to solve the issue with encoding, symbols, layout, and how the whole process occurs from pressing until a character appears on the screen.
I ask you to suggest what to read, to study and whether there are any developments.

Answer 1

One , two and three .