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42s RPN Calculator

By Byron Foster

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42s is an iPhone port of Thomas Okken's excellent and stable Free42, a complete re-implementation of the highly praised HP-42S RPN calculator. There are no ROMs or emulators involved allowing 42s to run natively and fast. This calculator provides all the functionality of the original 42S with several hundred functions, programability, printer output, etc. Additionally, several enhancements have been made over the original calculator such as additional precision and the ability to import and export programs.

Features include:

* Import and Export programs to and from the 42s with an easy to use web interface.
* Programmable for custom functionality. Packages are available for additional functionality including Engineering, Scientific, Financial, Statistical, etc. Backward compatible with 41CX programs.
* Internally stores values and performs operations in 25 digit decimal precision.
* Use the iPhone keyboard for entering character data, or variable names.
* Runs several orders of magnitude faster then the original calculator, including program execution, solving, integration, matrix operations, etc...
* Swipe LCD vertically to get up to 7 lines of display.
* Double tap LCD to cut and paste one or more numbers from the stack, or paste one or more numbers to the stack
* swipe LCD vertically on the right hand side to roll stack contents, or to scroll a program in program mode.

Recently added features:

* Key clicks work with 1st generation iPods.
* Sound tones mimic those of the original HP-42S
* Double tap print output view to copy print contents
* Display last x register in the upper right hand corner of LCD
* Tap LCD in alpha entry mode to toggle the display of the iPhone keyboard.

* Added option for a dynamically sized stack. Choose between the traditional (X, Y, Z, T) style stack, or a fully dynamic stack.
* Added option for no stack lift on Enter.
* Added DROP command, executed by doube tapping the back key
* Added option to remove device status bar for a larger LCD
Added additional lines to LCD modes, now supports up to 6 lines of stack, or 7 lines of program.
* Added scroll bar to program mode.
* Program mode can now be scrolled with the menu active.

Added in 3.0:

* Compatibility with iOS4 including application switching and compatibility bugs
* Added hi-rez (retinal) key pad image for iPhone 4
* Added Undo and Redo functions for the stack. Swiping the LCD left or right performs these operations.
* Added display option to show flags 0-4 at the top of the display if they are set.

What's New in Version 3.2.1

* Added Unit conversions (under CONVERT menu)
* Added new full screen LCD view in program mode, (Swipe down twice while in program mode)
* Added NEWPG command which is really just a short cut for creating programs, Enter PGN.FCN menu then SHIFT->LBL
* Added ability to type in all 25 digits of a number.
* Added register 11 functionality (Works when program comes up from a cold start, not backgrounded)
* Allow opening the printer view while printing is active.
* Moved printer watermark/button to upper right hand corner. watermark becomes dark when there is new unseen print output.
* Bug fixes

iPhone Screenshots

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Customer Reviews

What a Great App!

I've used a 42S for over 20 yrs in my engineering work, and have come to depend on it and the programs I've written for it over the years. I was so happy to see the 42S adaptation to the iOS platform, and even happier with its fidelity to the calculator itself. I loaded my programs into my iPhone & iPad without any difficulty and they ran perfectly!! Being able to save the programs away to a file for safe keeping is a huge enhancement.

I highly recommend this one !!!

My favorite RPN calc ever!

I've used RPN Calculators off and on again since my father introduced me to an old HP back in the 70's. Now, I'm a contractor engineer at NASA and this is my "go-to" app for making calculations of all kinds. I'll admit that when I need to do more complex analysis there are better tools, but that requires a computer and more sophisticated applications. When I want to make quick "sanity check" calculations, THIS app is my app of choice. Brilliantly done!

Love this app!

Update March 16, 2015:

I knocked this down a star because its form factor needs to be modified to fit the larger screens of the iPhone 6 and 6 plus. My only complaint!

I have an HP 42s and I hardly ever use it anymore since this is such an excellent rendition of this calculator. I have tried several of the other RPN calculators in the app store, and this one is by far the best. Also, Mr. Foster offers excellent support and prompt answers to questions and problems.

BTW, there is a knock off of this on the app store, called RPNCalc 42s. It is a copy of an earlier version, and offers no support--I have visited the web site for this. Buyer Beware.

But you cannot go wrong with Mr. Foster's implementation of the 42s!

42s RPN Calculator
View In iTunes
  • $4.99
  • Category: Utilities
  • Updated:
  • Version: 3.2.1
  • Size: 1.0 MB
  • Language: English
  • Seller:

Compatibility: Requires iOS 3.1 or later. Compatible with iPhone, iPad, and iPod touch.

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