Appendix B: Stack Lift and the LAST X Register 211
T
y y y y
Z
x x x x
Y 4.0000
53.1301
53.1301
53.1301
X 3
5.0000
0.0000
7
Keys:
| :
| `
7
Stack
enabled.
Stack
disabled.
No stack
lift.
Imaginary X-Register. All enabling functions provide for a zero to be
placed in the imaginary X-register when the next number is keyed or
recalled into the display.
Neutral Operations
Stack Lift. Some operations, like •, are neutral; that is, they do not
alter the previous status of the stack lift. Thus, if you disable the stack lift
by pressing v, then press ´ • n and key in a new number, that
number will write over the number in the X-register and the stack will not
lift. Similarly, if you have previously enabled the stack lift by executing,
say ¤, then execute a • instruction followed by a digit entry
sequence, the stack will lift.
*
The following operations are neutral on the HP 15c:
•
g
U
¦
i t ” nnn
CLEAR u
¥
^ ‚
CLEAR Q %
†
D Â
CLEAR ∑
R W ©
Imaginary X-Register. The above operations are also neutral with
respect to clearing the imaginary X-register.
*
All digit entry functions are also neutral during digit entry. After digit entry termination,
” and “ are lift enabling; − is disabling.
†
That is, the ´ % sequence used to view the imaginary X-register.