Why are you still using the 8051 for god's sake?
It's 20 years old. The H8 pisses over it, so does a pic, and a avr. and an st, and a 166, and lodes of others!
Mind you, it's good for washing machine's.
8)
I think the 8051 is popular because it's the one used in schools and colledges. Stick to what you know to be safe. It has undergone continuous development with hundreds of variants and super speed varieties.
I'm not realy knocking it, it does the business.
As for cost, ST make some powerful micros that cost as little as 48p in quantities.
do you think that 8051 needs a RTOS ? I am thinking of buying Keil's RTOS. But, how can I decide if my application needs RTOS or I can just write a big-loop progarm ?