HP -28S Manual page 179

Moving Stack Objects. These commands rearrange the objects on
the stack; the number of objects doesn't change. Commands preceded
by
"n"
require a real-number argument.
Command Description
SWAP Moves the object in level 2 to level 1.
ROT Moves the object in level 3 to level 1.
n
ROLL Moves the object in level
n
to level 1.
n
ROLLD
Moves the object in level 1 to level
n.
The command names ROT
(rotate),
ROLL, and ROLLD
(roll down)
are
descriptive of the motion of objects as a block. ROT moves the object
in level 3 to levell, rotating a block of three objects; ROLL and
ROLLD roll blocks of
n
objects.
Copying Stack Objects. These commands return a copy of one or
more stack objects. Copying only one object returns the copy to level
1 and lifts the other objects on the stack (including the original object)
to a higher level. When you copy more than one object, they're copied
as a block in a similar manner. Commands preceded by
"n"
require a
real-number argument.
Command Description
DUP Copy the object in level 1. (When no command line is
present, you can execute DUP by pressing
I
ENTER
I.)
OVER Copy the object in level 2.
n PICK Copy the object in level n.
DUP2 Copy the objects in levels 1 and 2.
n DUPN Copy the objects in levels 1 through n.
178 19: The Stack