PS/2 keyboard subsystem

Provides (key) from a driver providing the PS/2 protocol. That
is, for a driver taking care of providing all key codes emanat-
ing from a PS/2 keyboard, this subsystem takes care of mapping
those keystrokes to ASCII characters. This code is designed to
be cross-compiled and loaded with drivers.

Requires PS2_MEM to be defined.

Load range: 411-414