Scientif Calculator (Help Needed!!!)

Hi,
     I need, to do a program using Turbo Pascal... It's a Scientific
calculator with the operation +-*/ ^ div and uses parentesis () {} []
and it's has capabilitys of using Variables ...

   My _BIG_ problem is to do the procedure, of putting in a Stack in
pos-fixed way (e.g. A+B       AB+  Pos-fixed)  because the prioraty of
parentesis and *,/,div,^...

    Can some one give me a help/hint, or if you have a similar
program/procedure send it to me...

Thanks in advance,

Ricardo Goncalves
Email: np9...@mail.telepac.pt