If you had stuck with the standard register usage / calling conventions as required, and you kept the calculator stack in registers, then the only function that could possibly know how the stack is implemented is your main function, which would satisfy the abstraction requirement to limit knowledge about the stacks implementation to a few functions.
NOTE: PCs are little-endian machines, whereas the Suns are big-endian machines. If your code has endian dependencies, then you will definitely have problems getting it to work on the Suns if you first get it to work on a PC.
bsy@cse.ucsd.edu, last updated