that in non-arbitrary application one will be using an RTOS at some point in the chain. I have not run across an application that would be necessary to use an RTOS on the 8051. Dare I say, that using an RTOS on an 8051 would actually hinder ones processing performance. A much wiser solution is to split the power by combining multiple processors. With a hot processor, an RTOS makes sense because the processor has the capabilities and capacity to deal with all of the smaller low end functions of multiple processors gathering the data. Eventually, one has to deal with the data and an RTOS will come into play. In many non-arbitrary applications, an RTOS is absolutely necessary, but only in the higher end processing. Every time an MCU is connected to a PC, an O/S is being utilized. Anytime "real" processing is involved, an RTOS will be utilized.