Calculator Functionsandthestack; Two-Number Functions - HP -11C Owner's Handbook Manual

Section 2: Memory Stack, LAST X, and Data Storage 29
Calculator Functions and the Stack
When you want to key in two numbers, one after the other, you
press between entries of the numbers. However, when you
want to key in a number when the number already in the displayed
X-register is the result of a previous calculation or other function
(like [(x=y], [R#], etc.), you do not need to use [ENTER]. Why?
Executing almost any HP-11C function has two results:
1. The specified function is executed.
2. The automatic memory stack is enabled; that is, the stack
will lift automatically when the next numberis keyed in.
For example, with 4 already keyed into the X-register:
/ lost
Yo / \
X= / ]—-»
Keys 5 (+]
There are four functions— [ENTER], (CLy], [2+], and [=-]—which
disable the stack.* They do not provide for the lifting of the stack
when the next number is keyed in. Following the execution of one
of these functions, keying in a new number will simply write over
the currently displayed number instead of causing the stack to lift.
(Although the stack lifts when is pressed, it will not lift
when the next number is keyed in. The operation of
illustrated on pages 27 and 28 shows how thus disables the
stack.) In most cases, the above effects will come so naturally that
you won't even think about them.
Two-Number Functions
An important aspect of two-number functions is the positioning of
the numbers in the stack. To execute an arithmetic function, the
numbers should be positioned in the same way that you would
* When pressing [«]clears the entire displayit operates the same as and disables the
stack. Otherwise, [«] is neutral; that is, it does not affect the stack. For a further
discussion of the stack, refer to appendix B, Stack Lift and LAST X.