Thanx Jan for the great idea, I will try it.

Just to the KISS (Keep-Interrupt-as-Short-as poSsible) problem as Erik said in one his threads - this is still the project with the API for the ASIC. So the APP is linked together with the API library, therefore most of the parallel processing (like data packet decoding, and placing to SW buffers) etc) takes place in the ISR.

And because the API is a closed library there is no other way to do the processing (as far as I know - ANY CREATIVE IDEAS ARE WELCOME) in the main loop of the program. I have to add that the our requirement philosophy says - our know-how is encoded in the API so we should hide everything from the user.
+ the API should be simple enough so that also a cleaning lady could write a software even without any programming knowledge
+ it should be fast enough so that it can run low-power applications
+ it should be effective enough so that it can do Mamut tasks like routing
+ it should be small enough to fit to 8051 architecture (with 256 IDATA) & with 2kB XRAM

Like a perfect Woman beautyfull + good in Bed + can cook + drive a car + and be very smart + hates shopping.

Sorry for thet of off-topic text but I wanted to scream out what's already long time on my heart just to see what requirements are put sometimes on a SW running on 8051.

But everything is possible just have to fight with it.