According to the official Kawai website, as of September 2016, the last and most
current O/S firmware released for the K1r is V1.4

You can determine the firmware version by holding the SYSTEM button while turning on
the power or by reading the label on the EPROM (IC #7)

MODEL    UPDATE    VERSION #
-----    ------    ---------
 K1r     P163A*      V1.4

* The UPDATE number shown above usually appears on the label of the EPROM

Source: http://www.kawaius-tsd.com/pages/rom_a-k.html