First of all sorry for the off-the topic post and for making
advertisment, although it is for an open-source project.
h**p://usmartx.sourceforge.net
uSmartX is a non-preemptive, multitasking, priority based RTOS.
In my spare time I've made a H8-300H port for this kernel,
but it probably works well with 300L and also with H8S with
minor modification to the library makefile.
I studied the document and examples of this RTOS (for AVR micro),For small 8 bit micros it is very nice,safer and smaller (in RAM) from preemptive monsters.
I think this rtos is great,and have many features.