The Automatic Memory Stack; What The Stack Is - HP -32S Owner's Manual

The Automatic Memory
Stack
2
This chapter explains how calculations take place in the automatic
memory stack and why this method minimizes the number of key
strokes for complicated calculations. You do not need to read and
understand this material to use the calculator. However, you will find
that understanding this material greatly enhances your use of the cal
culator, especially when programming.
In part 2, Trogramming*, you will see that the stack helps manipulate
and organize data for programs.
What the Stack Is
Automatic storage of intermediate results is the reason that the HP-32S
easily processes the most complex calculations, and does so without
parentheses. The key to automatic storage is the automatic, RPNmem
ory stack*
The memory stack consists of four storage locations, called registers,
which are 'stacked' on top of each other. It is a work area for calcula
tions. These registers—labeled X, Y, Z, and T—store and manipulate
four current numbers. The 'oldest' number is the one in the T- (top)
register.
1HP's operating logic is based on an unambiguous, parentheses-free mathematical logic
known as "Polish Notation,' developed by the Polish logician Jan Lukasiewicz (1878—
1956).While conventional algebraic notation placesthe operators between the relevantnum
bers or variables, -Lukasiewicz's notation places them before the numbers or variables. For
optimal efficiencyof the stack,we have modified that notation to specify the operators after
the numbers. Hence the term Reverse Polish Notation, or RPN.
2: The Automatic Memory Stack 35