also do premptive type sheduling. program timer to interrupt every n seconds, read the status on every T seconds, decide a quanta you provide to a task. switch to next task as quanta expires, by this way you will always have the statust and every program will feel.

switching involves all the registers saved. its time consuming. calculate if you can affodrd to do so. better use i386 structure which supports task switchin despite of MCS-51 which are designed for small controls


abhishek