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 
t    z    y    y 
Z 
z    y    x    x 
Y 
y    x   
4.0000
  4.0000
X 
x   
4 
 
4.0000
  3 
Keys:
 
4 
v 
3 
 
 
(Assumes 
stack 
enabled.)
  Stack 
lifts. 
  Stack 
disabled.
  No stack 
lift. 
   
 
*
 Refer to footnote, page 36.