Programming the RPN-55

A program is nothing more than a sequence of keystrokes in the calculator and executed automatically with the press of a button – one keystroke replacing many. You can then execute the program as often as you like – typically with just one keystroke. The answer displayed at the end of execution is the same one you would have obtained by pressing the keys one at a time manually. No prior programming experience is necessary for RPN-55 calculator programming.

To get you started, try entering and executing the sample program shown on the Info screen of RPN-55 SD (double-tap the info button in the lower-right corner).


Entering and running a program

Reviewing your program

Debugging your program

Editing your program

Vintage Mode:
Editing programs is straight-forward in Vintage mode: by pressing keys, you simply overwrite whatever is stored at the current step.

You delete a step, say step 27, by overwriting it with a GTO 28 instruction.
To insert a step, replace the current step with a GTO instruction to a free memory location, reenter the replaced step there, then add the new step or steps, and finally enter a GTO command pointing back to the step just after the new GTO instruction.

To delete a prefix key (f or g):
Proceed as describted in the previous paragraph.

Extended Mode:
The extended mode of RPN-55 SD provides automatic insertion of a new step, as well as a delete command to remove a step.
In both cases, affected GTO commands are automatically adjusted to the changed target steps.

If the GTO's target lies in the unused program area after your last program step, no adjusting is needed.

If you insert GTO 19 after step 03 to branch to the instruction currently defined at step 19, what gets stored is GTO 20, since your GTO instruction is causing the rest of program memory to move down one line.
The display temporarily shows the corrected command followed by an asterisk (see below). Press BST, then SST to see how step 03 has been modified accordingly.

Entering GTO 19 after step 02:

Auto-corrected step 03:

Example program – Sum of 1 to x by Looping

Test case: Find the sum of all integers from 1 to 100.

Solution: Enter 100, tap R/S. Result: 5050

HP-55 Programming Trick

The problem:

The solution:

On RPN-55 SD, you can preserve all values on the stack:


Make sure to use f CL R, as g CL.R clears the stack of stacks.

HP-55 Programming Pad

  and print to make your programming life easier...

(Contributed by Roland K.)
      Managing programs on RPN-55
      Switch to PRGM mode.
Tap the display to open the program listing.

You can use a proportional or a non-proportional font in the description. Long-press any line of the listing to change.

Note that the current step is highlighted:
      Steps may be deleted by swiping left across the line:
      Tap Save to copy the changed program to the calculator.
To exit without changing the program, tap Cancel.

If you select a line before exiting, the line will be shown on the calculator display.

      Exporting a program
A program may be saved for later use or for archiving purposes.

Importing a program
To import a program from the Documents folder:

An empty program saved with registers will only replace the registers, leaving the program memory untouched.
This feature may be used to create pure data files.
Deleting the current program
A. To delete the currently stored program and all metadata:

B. To delete the currently stored program, but keep title and description:

Deleting an exported program



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