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Appendix A: RPN and the Stack 229
File name: hp 12c pt_user's guide_English_HDPMF123E27 Page: 229 of 275
Printed Date: 2005/8/1 Dimension: 14.8 cm x 21 cm
Now let’s see what happens in the stack during a chain calculation in RPN mode:
7
)65()43(
×
+
×
See how the intermediate results are not only displayed when they are calculated,
but also automatically stored and available in the stack at just the right time!
That’s basically how the stack operates. In the rest of this appendix, we’ll take a
more detailed look at how numbers are entered into and rearranged within the
stack, and the effect of the various hp 12c platinum functions on the numbers in the
stack.
Getting Numbers Into the Stack: The Key
As discussed in earlier sections, if two numbers are being keyed in for a
two-number function — such as
+
— you press
\
between the numbers to
separate them. The following diagram illustrates what happens in the stack when
you enter the numbers 10 and 3 (to calculate, for example, 10 ÷ 3). (Assume that
the stack registers have been already loaded with the numbers shown as the result
of previous calculations).
When a digit is keyed into the display, it is simultaneously entered into the
X-register. As additional digit keys are pressed, the corresponding digits are
appended (that is, added to the right of) those already in the displayed X-register
until
\
is pressed. As shown in the preceding diagram, pressing
\
does the
following:
1. It copies the number from the displayed X-register into the Y-register. This
process is part of the stack lift.
2. It tells the calculator that the number in the displayed X-register is complete:
that is, it terminates digit entry.