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.


Features

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

• 999 program steps


• 111 additional registers, with full store and recall register arithmetic


• 105 additional labels


• Nested subroutines supported by 8-level stack


• Additional flag commands


• Run programs at much higher speed than the HP-65


• Use virtual program and data cards.


• Powerful card database manager lets you organize your cards in predefined categories.


• Title and label your own cards right in the app, even cut off the card corners to write-protect them.


• Save entire card collections on your Mac or PC (using iTunes).


• Import/export single program or data cards, or send them by e-mail.


• E-mail program listings or print them on any AirPrint-compatible printer.


• Print on a virtual paper tape printer. E-mail the paper tape, or send output to a real printer.


• Select the ribbon color (black or blue).


• Optionally show negative results in red.


• Print any text on the paper tape.


• Follow subroutine nesting on the paper tape.


• See target step number of branches right in the program listing.


• Low-battery warning in the calculator's display when iPad battery charge drops below 10%.
  In TRACE mode, a message will be printed on the paper tape.


• Watch the stack, the memory registers, the program step counter and the flags in real-time.


• Paste text representations of HP-65 programs right into the calculator and run them.


• Enter program steps by simply typing commands into the program listing.


• Copy/paste values and program steps directly in the display.


• Correct input typing errors by swiping left across the display.


• Select any of 30 background images. Or import your own.


More features the HP-65 never offered:


• Non-volatile memory.


• High-precision calculations, not limited to display capacity.


• Display country-specific thousand separators.


• Visual status indicators of prefix keys.


• Program steps shown in plain-text in the display area.


• Cancel SST and BST by simply dragging your finger off the key.


• Register arithmetic works with RCL command.


• Reads data cards created by RPN-65/67/97.

RPN-65 Pro

RPN-65 SD

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.



Extras

• Stack display. Simply tap the card slot to turn the stack display on or off.


• High-contrast mode. Triple-tap the display to turn high-contrast mode on or off.
  High-contrast mode applies to the main display, stack display and register display.
  Use the settings to define your preferred mode.


• Haptics. Set level of desired haptic feedback in settings.


• Full-screen program editing. Tap display in W/PRGM mode.
  Tap the listing, type a command, like GTO A, or even xy.
  Tap any label name to see its location.
  Tap LBL: to switch label sets.
  Unused labels appear dimmed.


• Easy access to program instructions and description.
  Swipe display right to see program instructions.
  Swipe right again to see the program description.
  Both views are editable. To store changes permanently, copy the text, then
  paste it into the appropriate field in the card manager.

Restrictions

• No background images


• No TXT option on printer

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

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 at HHC 2015, Nashville, TN
Namir Shammas presents RPN-65 at the HP Handheld Conference: Watch

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

• New:
• • (RPN-65 SD) The program listing view supports two fonts. Long-press the listing to switch. (iOS 13 or later)
• • (RPN-65 SD) Visual adjustments to iPhone 16 Pro and iPhone 16 Pro Max
• • (RPN-65 Pro)
    In the Cards view:
         Tap Steps/Max repeatedly to see the first, current, and last program steps.
         Tap the green text below the title to see the current program step.

• New:
• • Non-LED display supports thousand separators.
• • LED display may toggled on and off in Settings -or- by tapping the f key, then double-tapping the display.
• • Thousand separators may be toggled on and off in Settings -or- by tapping the f key, then triple-tapping the display.
• • The Card Manager may be called up by swiping the card slot left. – [SD only]: the card slot must be empty.
• • The action of swiping a card out of the card slot may now be cancelled.
• • In order to unclutter the display, the default angular mode indicator DEG goes out after 2 seconds.

• New:
• • [Vintage mode] Loading an empty card will blink 0.00 and program memory will be cleared to NOPs, like on a real HP-65.
• • Some fonts changed from Courier to Menlo for better legibility.
• • [SD] Screens Paper Tape Printer, Program Usage, and Program Description may be dismissed by dragging them down,
    in addition to swiping them horizontally.

• New:
• • [Vintage mode] Pressing a user-definable key A..E ignores and resets the prefix key g.
• • [Pro] Selecting a card other than the top card in a filtered list of programs would cause a crash.

• New:
• • [Vintage mode] Typing GTO.digit and LBL.digit would not start a number entry with digit.
• • [Vintage mode] Single-stepping an instruction like LBL 5 would not be executed as on a real HP-65 when the mode switch
    was flipped to W/PRGM and back to RUN between steps LBL and 5.
• • [UI and Plus modes] Backstepping from step 001 to 000 is now supported. In addition, step 000 is labeled as "[TOP]".

• New:
• • [Vintage mode] Enhanced compatibility with a real HP-65.
• • In "Fast" mode, the program step is shown in W/PRGM mode. Tap it to show or hide.
• • In "UI" mode, step 100 may be addressed by "GTO.00"
• • In modes "UI" and "Plus", you can quickly backstep your program without leaving the RUN mode. Press g, then BST repeatedly. Press g again to end.
• • "Print Labels" (f1 LBL) is programmable in Plus mode.
• • "Cued Stops" are now supported (see HP-65 Owner's Handbook, Jan. 1974 p.77 or July 1974 p.95).
• • Refined appearance and working of the Save/Done button on the card description screen.

• Bug Fixes:
• • Fixed a crash on trying to load a card with register data protected by Touch ID or Face ID.
• • Fixed a number of graphical issues.

• Website:
• • Enjoy the new section on HP-65 Peculiarities.

• New:
• • Enable or disable the flashing of pressed keys in the Settings ("Flash Keys").
• • In enhanced modes ("UI" and "Plus"), the trigonometric mode indicator DEG appears only when "Large Display Digits" is on.
    No indicators are shown in vintage modes ("Off" and "Fast").


• • (RPN-65 Pro) Long-press the circled info button to call up the "What's New" screen.

• Bug Fixes:
• • [Vintage mode] Entering a merged code instruction (e.g. g NOP) at step 100 now works correctly.
• • [Vintage mode] Single-stepping (SST) from step 100 in W/PRGM mode now shows 00 00, not step 01.

• Bug Fix:
• • In W/PRGM mode, changes applied to a program didn't enable the button "Write Card" in the Card Manager.

• New:
• • Improved handling of program cards saved with registers:
    - In Card Manager, the switch "With Regs" is set if the program card contains registers.
    - If the calculator has different register values, you may modify the card by tapping "Write Card".
    - If all calculator register values are 0, tapping "Write Card" removes all registers from the program card.
  
  • (RPN-65 Pro) Added external keyboard command cmd-T to edit program title in Card Manager.
  
  • (RPN-65 SD) Haptics
    Set the haptic feedback level in the calculator's settings.
    Make sure that on your iPhone in "Settings / Sounds & Haptics" the option "System Haptics" is enabled.
    Note that iPads have no haptics engine.

• Bug Fixes (RPN-65 Pro):
• • When using an external keyboard, some keys were unresponsive in iOS 15.
• • External keyboard command opt-L (for LSTx) didn't work.

• Bug Fixes:
• • With registers shown in landscape mode, rotating the iPad portrait mode, then closing and restarting the app
     would display part of the register view behind the calculator.
• • Sound volume returned to the default value after restarting the app.

• New:
• • Improved compatibility of Data Cards across the different Enhancements settings.
• • Clearing registers now affects register R0 in Plus mode only.
• • (RPN-65 SD) Minor cosmetic changes.

• Bug Fix:
• • Fixed wrong step 75 in MATH 1-15A in the default database from 99 to 03.

• New:
• • (RPN-65 HD) iPad mini (2021) compatibility
• • The What's New screen may now be called up anytime from the Info screen.

• Bug Fix:
• • Fixed issue on pre-iOS 13 devices where running the app in vintage mode set to DSP 9 would round to 8 digits.

• New:
• • Improved accuracy in extreme cases of y^x.
    Example: For 1.0000001^{2^27} RPN-65 now shows the correct value 674530.4707.
    (A real HP-65 returns 674530.8761)
• • The What's New screen may now be called up anytime from the Info screen.

• Bug Fix:
• • (SD) Display issues when iPhone is set to DISPLAY ZOOM mode.

• New:
• • Changed search scope in Card Manager: finding text in "Plus" cards has been replaced with finding text in "Instructions"
• • In vintage mode, the RPN-65 stores the same numbers in R9 as the real HP-65 after performing the operations SIN, COS, TAN and their inverse on arguments 0 or ±1.
• • f REG now clears the extra registers RA, RB, ..., Rd, Re
• • f CLx now clears only the extended registers R00...R99
• • The current program step is always displayed in the editable listing, even when it is located in unused program memory.

(HD only):
• • Added two extra commands missing on the original HP-65. Available via external keyboard only:
    – % : find percentage X of a number Y
    – ⌥% : find percent increase or decrease from Y to X
    – ⌃ right Arrow: skip to next label
    – ⌃ left Arrow: skip to previous label
• • New external keyboard commands:
    – >: swaps registers R0…R9 and RA…Re
    – ⇧⌘ S: thousand's separators on/off
    – ⌃ right Arrow: skip to next label
    – ⌃ left Arrow: skip to previous label
• • Extended support for external keyboard in Card Manager:
    – ⌘ upArrow: address previous card
    – ⌘ downArrow: address next card
    – ⌘ leftArrow: address previous category
    – ⌘ rightArrow: address next category
    – ⌘ return: select currently addressed card
    – ⌘ F: enter search mode
    – ⌘ return: exit search mode with currently addressed card
• • Press ⇧⌃⌥ N to automatically turn on the calculator, eject any card, set W/PRGM mode and clear the program memory.

• New:
• • (Pro) Simplified installation of user background image via Files app (see "Background Image")
• • Delete a range of program steps by entering the range on the stack (X,Y), then pressing h DEL in RUN mode
• • The command "clear extended registers" (f CLx) brings up a warning dialog
  
• • Improved single-stepping when using an external keyboard
  
• • Key flashing may be turned off and on:
    – Store 19390101 in R1 to turn off
    – Recall 19390101 from R1 to turn on
      (Hewlett-Packard Company was founded on Jan 1, 1939)
• • (Pro) Additional commands for external keyboard:
    – ⇧K: stack display on/off
    – ⌥P: π
    – ⌃$: NOP

• Bug Fix:
• • Labels of a user program card were not editable

• New:
• • Hardware keyboard support on iPad version!
    Use your iPad's Smart Keyboard, or any Bluetooth keyboard, to do calculations, run programs, change views, adjust settings, control the printer, and much more – without ever touching the iPad screen. Press and hold the cmd-key to see the most important commands. Type cmd-? to see which key does what.
• • Added comparison instructions x < y and x < 0 in Plus mode
• • Improved listing in Vintage mode
• • Reenabled portrait mode on RPN-65 Pro

• Bug Fix:
• • Using scientific notation could crash the app in some regions, i.e. Australia, Sweden, Slovenia.

• New:
• • Improved compatibility of vintage mode with a real HP-65
• • Supports Slide Over on iPadOS. For example, you can store program snippets in a Notes file, then simply drag them into the listing in Card Manager. Or even into the calculator display.
• • iOS 13 support: Dark Mode, file sharing
• • The rarely used portrait mode has been dropped
• • iOS 11 or later

• Bug Fix:
• • A change introduced in iOS 13 caused results in vintage mode to be reduced to 6 significant digits

• 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

• 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

• 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

• New:
• • Extended paper tape sharing (AirDrop, Notes, Dropbox, and more)

• 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

• 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)

• 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)

• 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)

• 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

• 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

• 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

• 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)

• 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)

• 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

• 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)

• 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

• 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

• First public version.