RPN on an iPhone


Hello all. Yes, I already have 'rpn21' and 'Free42' on my iPhone 4S. I'm planning to get the other Bartosiak masterpiece classics and Spice models later. So, I would appreciate your recommendations of other iPhone apps based on our beloved HP calculators.


Edited: 20 Nov 2012, 5:31 p.m.


I'm somewhat biased, but I think i41CX+ is one of the best.


2nd that. And the latest release supports the iPhone 5 taller screen. It's perfect. Free42 is also great (I hope that it will also be upgraded for the taller screen).

m48/m48+ are good for RPL. The author is working on taller screen support.


Vicinno 15E


Hi there. Please advise because I just loaded this app on my iPhone 4S and it won't operate. The LCD digit section is blank. I've tried pressing the lower left 'MENU' key (where the 15C's ON key is) and this app still won't light the LCD display. Is this app incompatible with my iPhone 4S or iOS 6?



I've had it on my 3gs with IOS 4 and now on my 5 with IOS 6.1, I did have one update that acted up but a reinstall fixed it. Try deleting and reinstalling.


Well, I am on iOS 6.0.1 and I presume that is the latest for my iPhone 4S. I say this because when I went into Settings to update, I was notified that my OS is up to date. I've tried the 'remove/re-install' ping-pong five times now and the 15C LCD display is blank every time and the keys don't do anything. Any thoughts?

Edited: 21 Nov 2012, 4:11 a.m.


Contact the developer.


Well, I am on iOS 6.0.1 and I presume that is the latest for my iPhone 4S. I say this because when I went into Settings to update, I was notified that my OS is up to date. I've tried the 'remove/re-install' ping-pong five times now and the 15C LCD display is blank every time and the keys don't do anything. Any thoughts?

I don't have this particular 15C implementation, but I see that the one I have installed has an "On" key that can be used to turn off the display and disable all the keys (except the "On" key). Maybe you simply need to hit the "On" key?


Sometimes a hard restart is in order. Hold the iPhone Home and Power buttons down simultaneously, continue to hold while the Slide To Power Off screen shows, and release only when the screen goes blank. Press the power button again, boot normally, and see if that fixes your problem.

Just holding the Power button down until you see the Slide To Power Off screen is a soft reset, and doesn't always clear memory.


Sound like a hard reset will cause a loss of data. Will the hard reset erase anything?


A iPhone hard reset is just like choosing Shut Down on a Mac. A iPhone soft reset is like choosing Restart. No data is lost.


Thanks for the lesson. I'm new to the iPhone universe since I've been waiting for iPhone apps to catch up to all the apps I've had on my Palm T|X. So, that's why I needed a translation of iPhone Resets compared to PalmOS resets.


If your iPhone is responding to controls, no reason to do a hard reset - that is like pushing the reset button (or cutting power) to your PC. Just hold power button down, slide to turn off, wait for screen to be black, then turn on normally.


I agree, except when you have installed a new program. The installation process sometimes leaves the memory fragmented and a restart is needed to clear the problem. Restarting is listed as a recommended step for installing some large programs.


Any impact on memory will be exactly the same with a power cycle as with a hard reset, only without crashing iOS first.

A hard reset should only be used if the phone has stopped responding. It is like pulling power cord out of your Mac, or pushing the hard reset button on an (older) PC. Or holding the power switch in for ten seconds on a new PC. Not recommended for any normal situation.


I use "42s RPN Calculator" by Byron Foster daily. Unlike Eric, I am unbiased but also heartily recommend "i41CX+" by AL Software.


I have i41CX+, Free42, 42s, i48, FIN-12C and 12Cal. I don't need that many emulators/simulators, but I like collecting them. Since I use a real HP-42S as my primary calculator, I use Free 42 and 42s the most (I still don't have a preference). i41CX+ is my next most used calculator ap because of the modules you can load up. The CAS is very powerful, but I have only played with (I haven't actually NEEDED it).


I find myself using tangible calculators than using apps in practice. However, GO-25, GO-21, and ActiveRPN are my favorite RPN calculator apps.

Edited: 21 Nov 2012, 8:07 a.m.




Another vote for m48


I'd recommend ClassicRPN by AmeloConsulting, which is actually the Voyager series 11C, 12C, 15C and 16C (no 10C). It has the same keyboard layout of the original in landscape mode, and a modified layout with extra key functions in portrait mode. Added features are keystroke macro recording, display of the stack (Y,Z,T) above the main display of the X register, key click ON/OFF, key animate ON/OFF and different skins.

Also RPN-45 SD for only $1.99 from CuVee Software, which emulates either the standard HP 45 or an enhanced version with the timer fully implemented, hyperbolics, complex numbers, 18 storage registers, linear regression, date arithmetic, random numbers and much more.

Edited: 21 Nov 2012, 11:08 a.m.


This is probably the best thread to mention this app. I saw recently someone added an HP 50G emulator to the iTune store, for iphone and ipad.

I have not purchased it yet, so I cannot comment further.



Edited: 21 Nov 2012, 12:37 p.m.


Claims to be optimized for iPhone 5, but the skins are not.


Overall the app does not look as polished as m48, which is why I haven't purchased it yet. If the price comes down or the author teams up with a graphic artist I'll reconsider.

While we're in the subject (iphone apps) I can say I'm happy with PocketCas 3 and SymCalc, which are both good (no Internet needed) CAS platforms, but they are not emulators.



Overall the app does not look as polished as m48

The "About" credits the author of m48. At this point I'd have to label as a ripoff.

Got to buy my an iTunes gift card... to avoid the charge going on my credit card. That app looks good.

Edited: 21 Nov 2012, 7:00 p.m.


Did you know you can link a PayPal account to iTunes? So, you can sell junk on eBay, get paid through PayPal, pay for your apps, and never hit your credit card.

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