Indenpendent chip model.
http://www.bol.ucla.edu/~sharnett/ICM/ICM.html
there is tons of good stuff regarding this in old posts for more infomation. [img]/images/graemlins/smile.gif[/img]
Most of the posters know all the math, they just don't bother to explain them especially it's a very old question. Check archive more. [img]/images/graemlins/cool.gif[/img]