how to interface 8255 IC with 8051 microcontroller.
"Note that the 8255 is obsolete, and has been obsolete for many years." "You could in all fairness say the same thing about the 8051." Yes, the actual Intel 8051 chip itself is obsolete; but the 8051 architecture is most certainly alive and well, with many current derivates, and new products being introduced all the time.