main controller on which context switching is required
Now that you (to your dismay) have realized that multitasking on a '51 is a bad idea, and stubbornly ask again, why do you not let us know why "context switching is required".

My best guess is that it is not, just that you think it is.

Moderators:

If, as in the last thread, no reply from the original poster comes forth (or the thread get started again), please delete all.

Erik