This code will not compile as its been stipped down. Its purpose is serve as an example for your own developement of a simple multi-tasking kernel. It was originally written for a z180 using an embedded c compiler. The register requirements for that compiler dictated which registers were saved in the stack image. You most likely will need to modify which registers are saved. For a completely general purpose kernel, you will have to save all registers but the result will be a slower context switch. �