HP HP-21 - Page 35

In addition to the automatic stack lift after a calculation, the
stack automatically drops during calculations involving both X-
and Y-registers. It happened in the above example, but let’s
do the problem differently to see this feature more clearly.
First press [fBj to clear the X-register.
Press Stack Contents
0.00
0.00 16 is keyed into the displayed
0.00 X-register.
16.
.
16
X
<
N
-
- 0.00 |
0.00
16.00
16.00
16 is copied into Y.
X
<
N
=
0.00
0.00
16.00
30.
30 30 is written over the 16 in X.
X
<N
0.00 |
16.00 30 is entered into Y. 16 is
30.00 lifted up to Z.
30.00
X
=<
N
-
0.00
16.00 11 is keyed into the displayed
30.00 register.
11.
X
<
N -
16.00
30.00
11.00
11.00
11 is copied into Y. 30 and 16
are lifted upto Zand T
respectively.
X
<
N
-