Real time Clock using AT89C4051

Hey everybody m a newbie ova here...i had a project for my college in which i had to design a real time clock..i was successful in making it work..n now i had to submit the whole report of it...which requires a VHDL simulation too..i dont have my VHDL concept so clear..so can anyone help me out for the VHDL thingy ????

Regards...!!