HotPaw Basic vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
HotPaw Basic
Experience retro computing by typing and running Basic programs on your iPhone or iPad. This app functions as a programmable calculator and can display simple line graphics, Morse code audio, and perform FFT analysis.
- Retro text-mode Basic interpreter
- Programmable calculator functionality
- Simple line graphics display
- Morse Code audio output
- FFT analysis
- GPS location support
- MQTT and BTLE communications
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Calling all early-personal-computing fans, remember typing Basic programs into your home computer? HotPaw Basic recreates the retro-experience of a text-mode Basic interpreter, and it runs right on your iPhone or iPad. You can also use HotPaw Basic as a programmable calculator, or for displaying simple line graphics. The HotPaw Basic interpreter supports the minimal Basic language, including: Commands: let if then else endif dim data read restore for to step next while wend goto gosub return ? print input open close end stop mat run new list del save load dir cls rem Functions: int() abs() sgn() rnd() sqr() exp() log() log10() sin() cos() tan() atn() len() val() asc() str$() chr$() hex$() mid$() timer() date$ time$ pi Operators: + - * / mod ^ = and or xor not Also includes new command and functions to support line graphics, Morse Code audio, FFT analysis, GPS location, MQTT and BTLE communications. Line numbers are required. Type in the text of your program and type "run" to run them. See: http://www.hotpaw.com/rhn/basic/iphone/ for a more complete description of the Basic language syntax, commands and functions which this Basic interpreter supports.
RPN
This app simulates a vintage programmable calculator from the mid-70s, offering enhanced features beyond the original. It allows users to run existing programs, manage virtual cards, and utilize advanced functions for scientific and engineering tasks.
- Virtual program and data cards
- Virtual paper tape printer
- Database-driven card manager
- Create, label, and organize unlimited cards
- Share cards via email, AirDrop, Dropbox
- Editable program listings
- Enhanced features for more program steps and registers
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A dream calculator of the mid-70's, priced at $2,500 in today's dollars (2025), right on your iPhone! RPN-67 SD is the iPhone version of RPN-67 Pro, the first complete simulation of Hewlett-Packard's legendary HP-67 programmable calculator for the iPad. Produced from 1976 to 1982, the HP-67 was a huge success among scientists, engineers and other professionals. Thousands of programs were written for it. Now you can run them right on your iPhone, with more ease and faster than ever before. To get you started quickly, run the built-in program cards, or choose from the large number of programs available as free downloads from our website. What users said: “This version permits you to use your virtual HP-67 just as you could the original – hand-held and highly portable. Congratulations to the developer for providing such an excellent and aesthetically pleasing software product." "This was my first scientific calculator in real life. It is great to have the simulator on my iPhone. The special features added make it into a HP-41 or 42S! It comes packaged with some great samples. Am having great fun with it." 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 • Editable listing shows labels, targets of branches, and errors • 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 listings into RPN-67 SD and run them • "Live" display of stack, memory registers, flags • Show and edit program instructions • Fast: 1.5 seconds vs. 6 minutes (program HM-05, determinant of 5x5 matrix) • Low-battery indicator (iPhone charge 10% or less) • Optional high-contrast mode for working in bright ambient light • Compatible with RPN-67 Pro and RPN-97 Pro While RPN-67 SD 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 simulated 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 names while entering or single-stepping a program • Change the duration of the PAUSE command • Compress constants in programs into a single step (reversible) RPN-67 SD 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 rating: RPN at 4.6 against HotPaw Basic's 3.9. RPN also leads on review sentiment (93% vs 52%) and price ($3.99 vs $4.99). On ratings volume, update cadence, ads and in-app purchases 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
HotPaw Basic costs $4.99 and RPN $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
RPN holds the better App Store score, 4.6 against 3.9. Both are backed by a comparable volume of ratings — 7 and 17 respectively. Written reviews point the same way: 52% of HotPaw Basic's written reviews are positive against 93% of RPN's.
HotPaw Basic ships an update every 5 months, RPN every 3 months. The most recent releases landed on September 21, 2026 and September 25, 2026 respectively.
| Parameter | HotPaw Basic | RPN |
|---|---|---|
| Price | $4.99 | $3.99 — better |
| Rating | 3.9 (7 ratings) | 4.6 (17 ratings) — better |
| Positive reviews | 52.4% of reviews | 92.9% of reviews — better |
| Number of ratings | 7 | 17 — better |
| Update frequency | Every 5 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 12.3 | 12.0 — better |
| Further details — not scored | ||
| Size | 1 MB | 63 MB |
| Age rating | 4+ | 4+ |
| Developer | HotPaw Productions | CuVee Software |
Customer experience
HotPaw Basic
RPN
In-app purchases
HotPaw Basic
No in-app purchases
RPN
No in-app purchases









