RPN: The Automatic Memory Stack 2–7
During program entry,
b
deletes the currently–displayed program line and
cancels program entry.
During digit entry,
b
backspaces over the displayed number.
If the display shows a labeled number (such as
/)
), pressing
or
b
cancels that display and shows the X–register.
When viewing an equation,
b
displays the cursor at the end the equation
to allow for editing.
During equation entry,
b
backspaces over the displayed equation, one
function at a time.
For example, if you intended to enter 1 and 3 but mistakenly entered 1 and 2, this
is what you should do to correct your error:
T
Z
1
1
11
X
11
2
03
123
4
5
1. Lifts the stack
2. Lifts the stack and replicates the X–register.
3. Overwrites the X–register.
4. Clears x by overwriting it with zero.
5. Overwrites x (replaces the zero.)
The LAST X Register
The LAST X register is a companion to the stack: it holds the number that was in the
X–register before the last numeric function was executed. (A numeric function is an
operation that produces a result from another number or numbers, such as
#
.)
Pressing
{
returns this value into the X–register.
This ability to retrieve the "last x" has two main uses:
1. Correcting errors.
