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 legendary 1970s programmable calculator, offering advanced features for scientists and engineers. It allows users to run programs, manage virtual cards, and access hundreds of free program cards from its website.

Highlights
  • Virtual program and data cards
  • Virtual paper tape printer
  • Database-driven card manager
  • Create, label, and organize unlimited cards
  • Effortless saving of card collections
  • Formatted program listings
  • Live display of stack and registers
Features
Read full description

A dream calculator of the 70's, priced at $3,200 in today's dollars, now affordable for everyone! RPN-97 Pro is the first complete simulation of Hewlett-Packard's legendary HP-97 programmable calculator for iOS. Produced from 1976 to 1984, the HP-97'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: “The most delightful app I possess. The magnet card reader emulation rocks. Would have paid much more for this." "As the owner of an actual working HP 97 calculator, I am blown away with this new simulator. Simply fabulous." "Whoever coded this my hat goes off to you - what a professional piece of work, incredible app." RPN-97 Pro is fully compatible with RPN-67 Pro, its companion simulator of the HP-67 calculator. Features: • Virtual program and data cards • Virtual paper tape printer • 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-97 • 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 HP-67 or HP-97 listings from other sources into RPN-97 and run them • "Live" display of stack, memory registers, program counter, flags • Show program usage notes • 30 selectable background images, even add your own • Much faster than a real HP-97 • Low-battery indicator (iPad charge 10% or less) • Compatible with RPN-67 Pro and RPN-67 SD, CuVee Software's HP-67 simulators • Supports hardware keyboard While RPN-97 Pro can work exactly like a real HP-97, changing a simple setting will turn the app into a super-charged HP-97: • 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 mode, hyperbolic functions • Non-volatile memory - stack, registers, program, flags, paper tape • Status indicators for prefix keys (EXT, f, LBL, GTO, 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-97 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-97/67 website: cuveesoft.ch/rpn67

Screenshots

Haihaisoft Reader1 screens

Verdict

The call

The clearest difference is review sentiment: RPN at 100% against Haihaisoft Reader's 0%. RPN also leads on rating (4.9 vs 1.2). Haihaisoft Reader's advantage is price (Free vs $4.99) and device support (3 vs 1). 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

CostPrice · In-app purchases · Ads · Monetization

Haihaisoft Reader is free to download; RPN costs $4.99 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, 4.9 against 1.2. Both are backed by a comparable volume of ratings — 5 and 11 respectively. Written reviews point the same way: 0% of Haihaisoft Reader's written reviews are positive against 100% of RPN's.

UpkeepUpdate frequency

Haihaisoft Reader ships an update every 5 months, RPN every 3 months. The most recent releases landed on September 21, 2026 and September 25, 2026 respectively.

Scorecard6 real differences · 4 level
Haihaisoft Reader versus RPN: the parameters behind the verdict, then further details
ParameterHaihaisoft ReaderRPN
PriceFree — better$4.99
Rating1.2 (5 ratings)4.9 (11 ratings) — better
Positive reviews0.0% of reviews100.0% of reviews — better
Number of ratings511 — better
Update frequencyEvery 5 monthsEvery 3 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree — betterPaid
DevicesiPhone, iPad, iPod — betteriPad
Requires iOS6.1 — better12.0
Further details — not scored
Size21 MB75 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 ratings11 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews12 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

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 $4.99, 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 4.9 from 11 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 September 21, 2026 and RPN on September 25, 2026.

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