PS/2 controller doesn't handle state changes or device type

[Gegy]

Device state should rather be accessed through a function, so it can be checked each time it is called. In the current state, a device could be unplugged, but this would go unnoticed by anything using PS/2.
The controller also doesn't check the device type, meaning you could end up using a keyboard as a mouse or a mouse as a keyboard. This is not ideal, and should be checked.