HP HP-21 - Reviewing the Stack

20 How the VWOTrk
When a number is keyed in, its contents are written into the
displayed X-register, and the other registers remain unchanged.
For example, if you keyed in the number 314.32, your stack
registers would look like this:
Name Register
T 0.00
Z 0.00
Y 0.00
X 314.32 Display.
Reviewing the Stack
The I8 (roll down) key lets you review the entire stack con-
tents at any time. Each time you press the key, the stack
contents shift downward one register.
So the number as you’ve keyed it in will be rotated around to the
T-register by pressing [X8.
When you press the key the stack contents are rotated
from this . . . to this:
T [0.00 T 314.32
Z 10.00 Z 10.00
Y 10.00 Y 10.00
X |314.32 Display. X |0.00 Display.
Notice that the contents of the registers are shifted. The
registers themselves maintain their positions. The X-register
is always displayed, so you can see now.
Pressing the [iXll key again rotates the contents once more.
Press [[X again and the stack contents are shifted
from this . . . . .. to this.
T 314.32 T 0.00
Z 0.00 Z 314.32
Y 10.00 Y 0.00
X 0.00 Display. X |0.00 Display.