Comparison

Haihaisoft Reader vs RPN

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Haihaisoft Reader

A free PDF reader for iOS devices that offers fast launch speeds. It can also open PDF documents protected by DRM-X 3.0. Requires iOS 6 or later.

Highlights
  • Free PDF document reader
  • Fast launch speed
  • DRM-X 3.0 protected PDF support
  • iOS compatibility
Features
Read full description

Haihaisoft Reader for iPhone/iPad/iPod is a free PDF document reader, with fast launch speed. It is also for reading PDF document protected by DRM-X 3.0 platform. It requires iOS 6 or later.

About

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.

Highlights
  • 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
Features
Read full description

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

Haihaisoft Reader1 screens
RPN4 screens

Verdict

The call

The clearest difference is review sentiment: RPN at 93% against Haihaisoft Reader's 0%. RPN also leads on rating (4.6 vs 1.2) and ratings volume (17 vs 5). Haihaisoft Reader's advantage is price (Free vs $3.99) and iOS requirement (6.1 vs 12.0). On update cadence, ads, in-app purchases and device support 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

CostPrice · In-app purchases · Ads · Monetization

Haihaisoft Reader is free to download; RPN costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

RPN holds the better App Store score, 4.6 against 1.2. Both are backed by a comparable volume of ratings — 5 and 17 respectively. Written reviews point the same way: 0% of Haihaisoft Reader's written reviews are positive against 93% of RPN's.

UpkeepUpdate frequency

Haihaisoft Reader ships an update every 5 months, RPN every 3 months. The most recent releases landed on October 8, 2026 and October 12, 2026 respectively.

Scorecard6 real differences · 4 level
Haihaisoft Reader versus RPN: the parameters behind the verdict, then further details
ParameterHaihaisoft ReaderRPN
PriceFree — better$3.99
Rating1.2 (5 ratings)4.6 (17 ratings) — better
Positive reviews0.0% of reviews92.9% of reviews — better
Number of ratings517 — better
Update frequencyEvery 5 monthsEvery 3 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree — betterPaid
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS6.1 — better12.0
Further details — not scored
Size21 MB63 MB
Age rating4+4+
Developer海波 师CuVee Software

Customer experience

Haihaisoft Reader

All ratings5 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews5 reviews
Positive0.0%
Neutral20.0%
Negative80.0%

RPN

All ratings17 ratings
Positive94.1%
Neutral0.0%
Negative5.9%
Written reviews14 reviews
Positive92.9%
Neutral0.0%
Negative7.1%

In-app purchases

None

Haihaisoft Reader

No in-app purchases

None

RPN

No in-app purchases

Questions

Is Haihaisoft Reader free?
Haihaisoft Reader is free to download, with no in-app purchases.
Is RPN free?
RPN costs $3.99, with no in-app purchases.
Which has better reviews, Haihaisoft Reader or RPN?
RPN is rated higher. Haihaisoft Reader averages 1.2 out of 5 from 5 ratings, while RPN averages 4.6 from 17 ratings.
Do Haihaisoft Reader or RPN have ads?
Neither Haihaisoft Reader nor RPN shows ads.
Which is updated more often, Haihaisoft Reader or RPN?
Haihaisoft Reader ships an update every 5 months, and RPN every 3 months. Most recently, Haihaisoft Reader was updated on October 8, 2026 and RPN on October 12, 2026.

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