RPN-65 Pro – The first simulator of world's first pocket computer for iOS

Version 2.5.1

NOTE: Most of the descriptions on this site also apply to RPN-65 SD for the iPhone.

RPN-65 Pro is a photorealistic simulation of the first programmable handheld calculator ever produced. Introduced by Hewlett-Packard in 1974 at a price of $795 (more than $4000 in today's dollars), it was a tremendous success with engineers, scientists and hobbyists.

RPN-65 runs virtually all existing HP-65 programs. It sports a powerful program database and an array of import/export options.

RPN-65 in Plus mode is the HP-65 you wished you had back in the 70's: more program steps, more registers, more functions, more subroutine levels, much higher speed, comfortable program editing, printing without wasting paper tape, live view of all registers and flags, and a program library at your fingertips.

RPN-65 has been verified to run correctly all examples of many original HP Program Pacs, including:
HP Standard Pac, HP E.E. Pac I, HP Math Pac I, HP Math Pac 2, HP Stat Pac I.

RPN-65 comes with these Pacs built in and ready to explore.


Use RPN-65 just like the original HP-65 – or turn on advanced features, such as:

    More features the HP-65 never offered:



HP-65 with Paper Tape Printer and Program Usage Notes



HP-65 with Register View



RPN-65 Card Manager showing Standard Pac card



RPN-65 Card Manager – Creating a new Plus program card



RPN-65 Pro is available here:

RPN-65 Pro



RPN-65 for the iPhone is available here:




RPN-65 SD — What's different from the iPad version

Version 2.5.1

RPN-65 SD is the iPhone/iPod version of RPN-65 Pro.

While the user interface is – for obvious reasons – quite different from the iPad version,
the features are virtually the same.

Tap the "?" available on various screens for hints about using the app.

RPN-65 SD comes with the following HP Program Pacs already built-in:
HP Standard Pac, HP E.E. Pac I, HP Math Pac I, HP Math Pac 2, HP Stat Pac I.






The "Personal Computer"
The May 1974 issue of Hewlett-Packard Journal, covering the HP-65. Download

Download the program "Diode Current Iteration" shown on pages 10 & 11 for RPN-65 Pro.

HP-65 User's News
The first issue of "HP-65 User's News", published by Hewlett-Packard, Switzerland: Download


HP-65 User's News
The second issue of "HP-65 User's News", published by Hewlett-Packard, Switzerland: Download


HP-65 Brochure (Feb 1974)
12 pages, in German Download


RPN-65 on MacBreak Weekly, Episode 572
Andy Ihnatko's pick of the week, presented on Aug 22, 2017: Watch



Version History RPN-65

2.5.1 – Aug 19, 2019
  • New:
  • • Fixed an issue in vintage mode where in rare cases a random number would show instead of the result
  • • Fixed an issue in vintage mode where the step number was not correctly updated in W/PRGM mode

2.5 – Aug 16, 2019
  • New:
  • • Fixed a few inconsistencies occurring in vintage mode only
  • (iPad) In Settings, stepping through background pictures now wraps around at range limits
  • (iPhone) Card texts for vintage mode cards were not centered on some devices

2.4 – Jan 10, 2019
  • New:
  • • Backstepping all input digits is not logged as CLX in TRACE mode anymore
  • • Access RPN-65 homepage directly from info screen
  • • Many under-the-hood refinements

  • Bug Fix:
  • • D.MS operation didn't always convert 60 secs into 1 min

2.3 – Aug 17, 2018
  • New:
  • • Extended paper tape sharing (AirDrop, Notes, Dropbox, and more)

2.2 – Jun 25, 2018
  • New:
  • • Additional Stack View. Tap on the card slot to see the stack and a few other registers. (RPN-65 Pro only)
  • • Paper tape can be set to bold printing (press the printer's TXT button to see the option). (RPN-65 Pro only)
  • • Improved readability of register names in the calculator's stack view. (RPN-65 SD)
  • • Drag and Drop Support:
      – Drag numbers and program lines from other parts of RPN-65 to the calculator display
      – On RPN-65 Pro, you can also drag and drop numbers and program lines from other apps opened using Slide Over
      – Drag and Drop requires iOS 11 or later

2.1 – May 22, 2018
  • New (RPN-65 Pro only):
  • • On the calculator screen, tap the new "Prgm≷Inst" button to quickly switch between program listing and instructions
  • • In W/PRGM mode, copy and cut are supported in the program listing
  • • To insert the pasteboard content after the current step, paste into the listing or the display

  • Bug Fixes:
  • • In vintage mode, keys tapped in W/PRGM mode in power-off state would show in display
  • • Some display elements remained visible after power-off in W/PRGM mode (RPN-65 SD only)

2.0 – Apr 16, 2018
  • New:
  • • Improved pasting of values into display, e.g. by copying or dragging from paper tape
  • • Added green ribbon to printer (see Settings)
  • • Insert blank line on paper tape (swipe left, select "Space") (RPN-65 SD)
  • • Printer/Mail font changed to "bold" (RPN-65 SD)

  • Bug Fixes:
  • • Non-responsive confirmation dialogs after tapping "Cards" in Card Manager (RPN-65 Pro on iOS 11)

1.9 – Dec 11, 2017
  • New:
  • • Values containing blanks may be pasted into display
  • • More optimizations for iPhone X (RPN-65 SD)

  • Bug Fixes:
  • • "STO ." commands are now correctly ignored in vintage mode
  • • +,-,*,/ operations didn't work after pressing the g prefix key
  • • Top of paper tape would not move in some situations (RPN-65 SD)
  • • Incorrect app icon shown when installed on iPad (RPN-65 SD)

1.8 – Oct 25, 2017
  • New:
  • Card Manager (iPad only):
      – On opening or changing card, the currently addressed program step scrolls into view automatically
      – Tap label "Next:" to scroll the currently addressed program step into view
      – Tap label "Steps:" to see the top of the listing
      – Tap the value following "Steps:" to see the bottom of the listing
  • • Improved handling of data cards
  • • Speed improvements
  • • Improved trig functions for extremely small angles
  • • Support for iOS 11 and iPhone X

  • Bug Fixes:
  • • In vintage mode, switching to W/PRGM mode doesn't skip to the last executed step anymore
  • • INT and FRAC didn't print result in the correct line in mode TRACE

1.7.1 – Mar 14, 2017
  • New:
  • • Improved visual feedback on tapping keys (display blanking)

  • Bug Fix:
  • • In vintage mode, after switching to W/PRGM, the code of the last tapped key in RUN mode did not disappear on the next key press

1.7 – Mar 8, 2017
  • New:
  • • Swipe loaded card left to see the current program as stored on the card
  • • Repeatedly pressing prefix key g in vintage mode works as on real HP-65

  • Bug Fix:
  • • Fixed issues regarding Touch-ID-protected registers

1.6 – Mar 1, 2017
  • New:
  • • Enjoy the genuine HP-65 card reader sound in vintage mode!

  • Bug Fix:
  • • Toggling the W/PRGM-RUN switch disabled showing the last key entered in place of the current program step (vintage mode only)

1.5 – Feb 7, 2017
  • New:
  • • Search: Now faster and more powerful than ever. Search in program titles or descriptions.
  • • On Touch-ID-enabled devices, access to calculator registers stored on program cards may be restricted
  • • New flag commands:
      DSP f SF toggles the flag, then tests if it's set
      DSP f1 SF toggles the flag, then tests if it's cleared
      DSP f TF toggles the flag
      DSP f1 TF1 tests if both flags are in the same state
      DSP f1 TF2 tests if the two flags are in different states
  • • Step number display may be toggled in vintage mode
  • • Added card category "My Programs"

  • Bug Fixes:
  • • In rare cases, DSP.9 format would show 10 fractional digits
  • • In Card Manager, listing was not selectable on write-protected card
  • • In vintage mode, CLX could not be entered after a NOP command
  • • When entering a program in vintage mode, key fronts were not shown on pressing the g key (RPN-65SD only)
  • • Key status indicators appeared in vintage mode (RPN-65SD only)

1.4 – Nov 16, 2016
  • New:
  • Program cards with registers
  • New commands: STO STK and RCL STK (press STO ENTER and RCL ENTER)
  • • Commands f1 LBL (= Print labels and flags) and f1 CLX (= Print program) are now programmable
  • • In all operation modes, absolute values between 0 and 1 are not interpreted as zero by the DSZ command
  • • Long-press a line on the paper tape to copy it to the pasteboard
  • • Long-press and drag a line from the paper tape to the display to copy/paste it
  • • Double-tap card in card list to load it
  • • Red progress bar shows fill status of program memory (in W/PRGM mode)
  • • Next step display (tap above "OFF" to toggle)
  • • Tapping f1 key reveals names of inverse functions
  • • Paper tape capacity increased to 2000 lines
  • • Improved results for SIN, COS, TAN with very large arguments
  • • Decimal addition/subtraction for higher precision
  • • Calculator sounds mix with background audio and have their own volume control
  • • Speed optimizations
  • • Expanded help screens

  • Bug Fix:
  • • NOP command could not be pasted into display

1.3 – May 21, 2016
  • New:
  • • Localized number grouping
  • • Display looking closer to real HP-65

  • Bug Fix:
  • • Fixed syntax error count not suppressed for data cards (with possible crash when touched)

1.2 – Feb 17, 2016
  • New:
  • • Exchange data cards with RPN-67 and RPN-97 via copy/paste
  • • Import cards directly from e-mail
  • • Import cards from our website without using iTunes
  • • Save cards to Dropbox; import cards from Dropbox
  • • Print card texts or save as PDF in iBooks
  • • Exchange cards via AirDrop
  • • Tap "Errors" to scroll to next syntax error in listing

  • Bug Fix:
  • • If no mail app active, no warning appears until trying to e-mail

1.1 – Nov 17, 2015
  • New:
  • • 18 new functions (beep, date/time, swap registers, matrix operations, etc.)
  • • Comparisons with zero added to standard comparisons with y
  • • Auto-execute subroutine 99 on loading new card
  • • Registers A..E and a..e are now shown in the register display
  • • Register operations with A..E or a..e are now programmable
  • • The "Write Data Card" command (W/DATA) is now programmable
  • • RCL 0 and STO 0 changed to merged command format
  • • RCL.nn and STO.nn changed to merged command format
  • • In vintage mode, round ->D.MS to DDDDD.MMSS as the HP-65 does (only 4 trailing digits)
  • • Much improved program input using command mnemonics
  • • Print preview (requires iOS 9)

  • Bug Fixes and Other Changes:
  • • Starting a number with DP or EEX didn't enable automatic stack lifting
  • • Pressing user-defined function didn't clear single-step mode in vintage mode
  • • Executing A..e in a program now correctly begins search at step 001

1.0 – September 2, 2015
  • First public version.

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