i41CX+ vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i41CX+
This advanced RPN scientific calculator offers workstation-class Computer Algebra System (CAS) capabilities, going beyond traditional replicas. It provides access to an extensive library of modules and programs, enhanced with iOS features, customizable skins, and iCloud support for seamless data management.
- RPN logic with 4-element stack
- Extensive memory registers
- Over 400 built-in functions
- Computer Algebra System (CAS)
- Virtual thermal printer/plotter
- Access to HP-41 module library
- Customizable skins and keyboard overlays
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i41CX+ is an advanced programmable and expandable RPN scientific calculator with a virtual thermal printer/plotter and workstation-class CAS capabilities that is far beyond a mere replica of the original. In addition to being functionally equivalent to the world-renowned HP-41CX and providing access to its entire library of modules and programs, i41CX+ is enhanced with iOS and hardware features, keyboard overlays, rich set of import and export capabilities, traditional and upbeat diverse set of skins, complete color control, iCloud support, and much more. The i41CX+ CAS is a full implementation of REDUCE. It's like having Mathematica or the computational engine of Wolfram Alpha in your pocket and, best of all, it runs natively so no internet connection is required. The CAS is fully programmable and provides the ability to reuse previous results in computations. Moreover, the CAS has full access to the calculator registers so it is possible to combine RPN programs with CAS programs. This is the finest and most powerful scientific/engineering/financial calculator for iOS devices bar none. CALCULATOR FEATURES: • RPN logic with a 4 element deep memory stack • 319 main and 600 extended memory registers • Over 400 built-in functions, including over 100 functions created specifically for i41CX+ • Time, calendar, alarm, and stopwatch functions • Four module ports provide access to HP-41 expansion pacs • Rich set of functions and algorithms: numerical, mathematical, statistical, complex, matrix, numerical integration, curve fitting, solutions to equations, and much more • Powerful, flexible, and programmable Computer Algebra System (CAS) supporting symbolic, arbitrary precision, scalar, vector and matrix algebra calculations, 2D/3D plotting, and much more • Full-screen text editor with configurable font style and size, color scheme, a user configurable macro keyboard, and a numerical keyboard • Access to the entire HP-41 library of solutions for science, mathematics, statistics, engineering, business, financial, surveying, medicine, real estate, and many other domains • Programmable - virtually unlimited number of lines • User definable keyboard • Ability to operate the calculator using a Bluetooth keyboard • Device integration: external display mirroring, copy and paste, in-app mail, system keyboard, GPS, accelerometer, digital compass, time and date synchronization, AirPrint, and much more • Virtually unlimited data and program storage capacity using the device's flash memory for local storage • Import/export data, programs, overlays, modules, etc. via the web, email, and iTunes file sharing • iCloud syncing of files and preference settings • iOS 8 Notification Center widget • 43 available keyboard overlays and support for user created overlays • Sound support including synthetic tones and interface sounds • Support for calculator skins and optional mini stack display • Adjustable calculator speed, sound volume, and display colors • Usage & Examples table with usage tips and examples • Quick Reference Guide of all built-in functions • CAS Quick Reference with all built-in functions, operators, switches, and packages • Beautiful and clean user interface PRINTER FEATURES: • Support for printing, plotting, graphics, and special characters • User configurable and programmable print color • Export printer output via email, clipboard, or AirPrint • Ability to save a JPEG image of the paper roll to the device's photo album *********************************************************** A comprehensive FAQ and Mini-Manual are available at http://alsoftiphone.com/i41CXplus. Please don't hesitate to use the "Contact Us" link there if you cannot find the answers or information that you seek. Thank you.
RPN
This app is a faithful simulation of a legendary 1970s programmable calculator, offering advanced features for scientists and engineers. It allows users to run existing programs, manage virtual program cards, and even print listings, all on their iPad.
- Virtual program and data cards
- Virtual paper tape printer
- Database-driven card manager
- Save card collections to Mac/PC
- Formatted program listings
- Print listings via AirPrint
- Live display of stack and registers
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A dream calculator of the 70's, priced at $1,900 in today's dollars, now on your iPad! RPN-67 Pro is the first complete simulation of Hewlett-Packard's legendary HP-67 programmable calculator for iOS. Produced from 1976 to 1982, the HP-67's features coupled with its capability to store programs on magnetic cards made it a huge success among scientists, engineers and other professionals. Thousands of programs were written for it. Now you can run them right on your iPad, with more ease and faster than ever before. To get you started quickly, download hundreds of program cards from our website for free. What users said: "I am a collector of HP emulators on my iPad. The HP-67 is beyond spectacular!" "What an application! Perfect visual experience, perfect emulation, even the clicks are pleasant." "In many ways, the app is even better than the original - much faster, better and easier programming". RPN-67 Pro is fully compatible with RPN-97 Pro, its companion simulator of the HP-97 calculator. Features: • Virtual program and data cards • Virtual paper tape printer supports all HP-97 printer modes • Powerful database-driven card manager • Create, label, and organize a virtually unlimited number of cards • Use iTunes to effortlessly save entire card collections on your Mac/PC • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • Formatted listing clearly showing labels and targets of branches • E-mail listings and let the recipient paste the text right into RPN-67 • Print listings on any AirPrint-compatible printer • Program listing on paper tape shows subroutine nesting • Edit paper tape • E-mail paper tape, or print it via AirPrint • Cut/copy/paste displayed value or program steps • Paste existing HP-67 or HP-97 listings into RPN-67 and run them • "Live" display of stack, memory registers, program counter, flags • Show program usage notes • 30 selectable background images, even add your own • Fast: 0.8 secs vs. 6 mins (iPad Pro vs. HP-67, determinant of 5x5 matrix) • Low-battery indicator (iPad charge 10% or less) • Compatible with RPN-67 SD and RPN-97 Pro, CuVee Software's HP-97 simulation • Supports external hardware keyboard While RPN-67 Pro works like a real HP-67, changing a simple setting will turn the app into a super-charged HP-67: • Up to 999 program steps, 8 subroutine levels, 6 additional flags (F4...F9) • 100 additional registers • 100 additional labels • 100 built-in constants and conversions • More than 150 additional powerful operations and functions Plus: • 15 commands to print and manipulate any range of extended registers • Unrestricted register arithmetic • Exchange x with any register • Complex numbers, hyperbolic functions • Non-volatile memory - stack, registers, program, flags, paper tape • Status indicators for prefix keys (f, g, h, STO, RCL, etc.) • Display showing thousands separators (optional) • Text output on paper tape in 10 colors, even simple plotting • Stack-of-stack: push/pop the entire stack on internal stack (4 levels) • Single-step into subroutines (optional) • Powerful debugging aids, including 10 breakpoints with counters • Keycodes translated to command name while entering or single-stepping a program • Change the duration of the PAUSE command • Cancel SST or BST operation by simply sliding your finger off the depressed key • Compress constants in programs into a single step (reversible) • Use existing programs in text format by a simple paste operation RPN-67 Pro comes with more than 130 programs pre-installed, including HP Standard Pac, HP Business Decisions Pac, HP Math Pac I, HP Stat Pac I, and HP Surveying Pac I. The simulator has been verified to correctly run the examples given in HP Civil Engineering Pac I, HP Clinical Lab Pac, HP E.E. Pac I, HP Games Pac I, HP M.E. Pac I, HP Navigation Pac I, as well as large number of programs published in Users' Library Solutions. For more information and free program downloads visit the RPN-67 website: cuveesoft.ch/rpn67
Screenshots
Verdict
The clearest difference is price: RPN at $4.99 against i41CX+'s $24.99. i41CX+'s advantage is rating (4.8 vs 4.3) and ratings volume (106 vs 6). On review sentiment, ads, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
i41CX+ costs $24.99 and RPN $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
i41CX+ holds the better App Store score, 4.8 against 4.3. That said, the two scores are not equally well evidenced: i41CX+ has 106 ratings behind it against 6, so its average is the more settled of the two. Written reviews point the same way: 91% of i41CX+'s written reviews are positive against 90% of RPN's.
i41CX+ ships an update every 5 weeks, RPN every 3 months. The most recent releases landed on September 25, 2026 and September 21, 2026 respectively.
| Parameter | i41CX+ | RPN |
|---|---|---|
| Price | $24.99 | $4.99 — better |
| Rating | 4.8 (106 ratings) — better | 4.3 (6 ratings) |
| Positive reviews | 91.3% of reviews — better | 90.0% of reviews |
| Number of ratings | 106 — better | 6 |
| Update frequency | Every 5 weeks — better | Every 3 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod — better | iPad |
| Requires iOS | 13.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 123 MB | 78 MB |
| Age rating | 4+ | 4+ |
| Developer | Antonio Lagana | CuVee Software |
Customer experience
i41CX+
RPN
Bugs and requests
i41CX+
Reported bugs
2 issues- Issues with the 41Z math module producing garbled output
- Scaling problems with overlays
Requested features
4 requests- Landscape mode for better button size
- Haptic feedback for button presses
- Ability to load and save programs/modules via cloud/email
- Macros or scripting support
RPN
Not enough reviews yet to summarise bugs or requests.
In-app purchases
i41CX+
No in-app purchases
RPN
No in-app purchases









