# RPN-55 SD

> Classic HP Calculator w/Timer

Canonical page: [https://chrome-stats.com/d/id1469907917](https://chrome-stats.com/d/id1469907917)

## Overview

- **ID:** `id1469907917`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** CuVee Software
- **Category:** Productivity
- **Rating:** 5.00 / 5 (8 ratings)
- **Version:** 3.3
- **Last updated:** 2025-10-17
- **First published:** 2019-07-03
- **Size:** 17 MB
- **Data as of:** 2026-09-06
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/rpn-55-sd/id1469907917)
- **Website:** [https://www.cuveesoft.ch](https://www.cuveesoft.ch/)
- **Privacy policy:** [http://www.cuveesoft.ch/privacy/index.html](http://www.cuveesoft.ch/privacy/index.html)

## Description

RPN-55 SD is the first photo-realistic simulation for the iPhone of Hewlett-Packard's low-cost alternative to the famous HP-65 programmable scientific calculator. Produced from 1975 through 1977, it was the "Merlin" member of the classic HP calculator series, priced at $395. HP claimed that it featured "(...) more pre-programmed functions than any other scientific pocket calculator in the world."

A main feature of the HP-55 was a crystal-controlled 100-hr digital timer with the ability to store times while the timer was running and later recall them. On RPN-55 SD the timer may also act as a 12-hr or 24-hr clock, including date and weekday display.

While the simulator works just like the original calculator – except being much faster and having twice the program memory – you can turn on extended features to make it even more enjoyable to use.

RPN-55 SD comes complete with original HP programs built in.

Features:

• Photo-realistic look-and-feel
• Vintage mode or Extended mode
• Programmable (99 steps), conditional branching
• Insert and delete steps with automatic address correction
• Delete range of steps
• Subroutines (4 levels)
• 20 registers, "continuous", with unrestricted store/recall arithmetic
• "Live" register view
• Program listing view
• Program library view
• Store and retrieve any number of programs
• 100-hr timer supporting 10 split times and 12/24-hr clock mode with date
• Swap unit conversions with additional functions, e.g. hyperbolics
• Sharing: e-mail, AirDrop, Dropbox, copy, paste, print
• 112 programs pre-installed

Calculator functions:

• Statistics (linear regression, mean, standard deviation, correlation coefficient, x- and y-estimates)
• Trigonometric functions (degrees, radians, grads)
• Polar/rectangular conversions
• Inverse, square root, logarithm, exponential, pi
• Storage arithmetic (store and recall)
• Percent, absolute, integer, fractional value, round
• Factorial
• Random number
• Unit and hours conversions

Details: cuveesoft.ch/rpn55

## Rankings

- #350,855 — Overall

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Source: [Chrome-Stats](https://chrome-stats.com/d/id1469907917)