HP 15c Scientific manual Disabling Operations, Enabling Operations

210 Appendix B: Stack Lift and the LAST X Register

Disabling Operations

Stack Lift. There are four stack-disabling operations on the calculator.* These operations disable the stack lift, so that a number keyed in after one of these disabling operations writes over the current number in the displayed X-register and the stack does not lift. These special disabling operations are:

v ` z w

Imaginary X-Register.A zero is placed in the imaginary X-register when the next number following v, z, or w is keyed or recalled into the display (real X-register). However, the next number keyed in or recalled after − or ` does not change the contents of the imaginary X- register.

Enabling Operations

Stack Lift. Most of the operations on the keyboard, including one-and two- number mathematical functions like x and *, are stack-enabling operations. This means that a number keyed in after one of these operations will lift the stack (because the stack has been ―enabled‖ to lift). Both the real and imaginary stacks are affected. (Recall that a shaded X-register means that its contents will be written over when the next number is keyed in or recalled.)

T

Z

Y

X

Keys:

t

z

y

x

4

(Assumes

stack

enabled.)

z	y
y	x

x4.0000

44.0000

	v
Stack	Stack
lifts.	disabled.

y

x

4.0000

3

3

No stack

lift.

*Refer to footnote, page 36.