Reviewing the stack – HP 33s User Manual
Page 43
RPN: The Automatic Memory Stack
2–3
Reviewing the Stack
R¶ (Roll Down)
The
(roll down) key lets you review the entire contents of the stack by
"rolling" the contents downward, one register at a time. You can see each
number when it enters the X–register.
Suppose the stack is filled with 1, 2, 3, 4. (press 1
2
3
4)
Pressing
four times rolls the numbers all the way around and back to where
they started:
T
1
4
3
2
1
Z
2
1
4
3
2
Y
3
2
1
4
3
X
4
3
2
1
4
What was in the X–register rotates into the T–register, the contents of the T–register
rotate into the Z–register, etc. Notice that only the contents of the registers are
rolled — the registers themselves maintain their positions, and only the X– and
Y–register's contents are displayed.
Rµ (Roll Up)
The
|
(roll up) key has a similar function to
except that it "rolls" the
stack contents upward, one register at a time.
The contents of the X–register rotate into the Y–register; what was in the T–register
rotates into the X–register, and so on.
T
1
2
3
4
1
Z
2
3
4
1
2
Y
3
4
1
2
3
X
4
1
2
3
4