The MK84 tar files contain the sources for the MK84 micro-kernel. This
is the first version of the micro-kernel to contain real-time support.
This version of the kernel is somewhat unstable under a normal workstation
workload so it is not replacing the default tar files which are MK82.

To enable the real-time functionality you need to build with the "realtime"
option added to your configuration. e.g. CONFIG=STD+WS+realtime.