Super job.....finally an RPN calculator that follows the HP 'look and feel'.....I was very disappointed in the other two faux HP calcs in the Apps store.....they gave you 3/4's of the look and almost none of the retro feel of the 15c or 12c......key locations and such were not in their 'correct' locations.....the developer even added 'expansion keys' for future use.......what?, don't fix it if it ain't broke.....we love our old HP's just the way they are......as soon as i41CXp boots up, you are holding an HP 41 flavor calc in your hand.....the lack of an 'I love me' screen (as with the other two apps) is noticable also.....you can get right down to business......no dought every iPhone user that has (or still owns) an old school HP calculator will purchase this app.....I can only wish that AL software sees fit to give us a true 15c also......kudos......

Printer, 41CX emulation, user downloadable modules and code, execellent interface. What else could you ask for?

I've only used this program for a short while on my iphone, but so, far it performs to my expectations. Anyone who's ever used an HP-41C or RPN calculator before would certainly want to add this app to their toolbox.

I am very impressed. I owned a HP 41C many years ago and this is a very faithful replication of it.

This is a fantastic iPhone version of the legendary hp41cx. I have a complete Hp41cx series collection and the author has done an absolutely stunning implementation of this venerable HP classic. The level of detail and faithful implementation of all the functionality is truly incredible. Hats off to you!!!!!! Job well done!!! This calc stands out above all other RPN calcs in the app store. There's no comparison. Would gladly have paid much more. Marcus M.I.T. Class of 82

This is a very accurate simulation of the venerable 41CX. It sure does a great job of reproducing the experience of using that calculator, right down to pac loading, programming, and even printing! That’s great for that nostalgic feeling of reliving the “grand old days”, but it won’t be my day-to-day calculator. I just can’t remember all of those old functions (except, for some reason, the triangle functions, like SAS, SSS, etc), and no longer have the quick reference cards around. Nor would I want to use them even if I had them; I like the ease of use of modern calculators.

I'm a big HP RPN fan. I've tried a few of the RPN calculators on the App Store, and this is by far my favorite. It's basically a perfect copy of a 41CX. How could it be anything less than perfect? Great key response, good speed, and nice additions (like clock sync). Also, the printer functionality works great. I think this application is an effective balance between nostalgia factor (interface) and practicality.

This is truly a magnificent execution of a classic calculator interface. While remaining true to the integrity of the original design, selective enhancements to reflect the iphone environment are welcome. Well thought out, well executed, responsive. Simply makes all the other RPN calculators available (as of 9/3/08) pale in comparison.

I have been a lifelong user of an HP41C and this emulator works perfectly on my iPhone. Unlike the other HP RPN emulators available for the iPhone, this one works great and the buttons are laid out well, easy to press, and not prone to hitting the wrong key accidentally. The "print mode" gives a nice adding machine tape, just like an HP printer attached to an HP41c does - very handy. I wish that I had bought this app first, rather than wasting money buying every other RPN calculator offered on the app store.

I know that it would not be "true" to the original, but this app would match what I am looking for if it included a multi-line display.

This is a -perfect- emulation of the HP-41C calculator. If you used one of these "back in the day" and loved the calculator---as so many users did---then you'll love this. Others might find things to criticize. It doesn't have any features that the old 41c didn't, no multiline display, and the caculator and programming language use RPN. Oh, yes, it is fully programmable, because it is a complete implementation of the original.

Used to live on my HP-41C back in the good ol' days. Great to see an HP-41C app for the iphone. Even greater to see how good and complete an implemention it is! For example, there are lots of add-in modules for the physical calculator, and to use those in the emulator just go to the config screen, select the module you want, and it's contents are downloaded and added to the calculator. Also, all of the keyboard overlays (plastic things that go over the keyboard to show other features assigned to the keyboard by loaded programs) are virtually available to display on the screen. Runs programs, can be programmed, all like the real thing. Btw, if you load the "game" module and run "pinball", you'll see how to implement a pinball game with just one line of LCD display. To think some people (ahem) used to play games like that... :-)

If you're reading this, you're considering this app. Get it. Trust me, it's worth it. Beautiful, updated very regularly, and it's rock-solid to boot. The previous update was a big one and had a few bugs, but it looks like all have been fixed now. Totally worth it.

Few applications have gotten me as excited as this about switching phones and service providers. I am huge on device consolidation and this application takes the cake if you are or ever were an HP41 device user. I haven't tested every function of every add on ROM but my own applications thus far have operated flawlessly. It's an entire end user accessible programming platform right on my iPhone! The depth of coverage is mind boggling and the presentation is artistically stunning - true to the original image with enhancements that delight even the casual user. I can finally thrown away the box of old hardware that I've been hanging on to for decades. I hope to see enhancements that bridge the i41 environment to the iPhone's advanced capabilities. e.g. new i41 Functions that allow it to read current "GPS" positions, send text messages/email and perhaps an ability to query other elements of the iPhone's dataset (lookup contacts, etc).

This is a fantastic emulation of the HP41CX. I use it daily and have not seen is crash once. The overlay feature and the ability to "insert" expansion modules Is pretty amazing. You can even get the PPC module, which is pretty amazing since the original module back in the '80s was something like $125, and here it's free.I still have my physical HP41CX running beautifully after all these years, but I almost always use this iphone emulator. My only wish is that the developer find an easier way to import programs. On my old Treo, the HP41 emulator I used let you bring in a program as a Palm note. With this emulator, you have to go find this wierd 3rd-party "compiler" or something like that, to prepare the program. I don't have time for a new hobby right now. I don't know about support for synthetic program steps. Other than the issue of importing of programs, I am very happy with this program.

I've tested this program and it is the best simulator of the HP41cx. It has been a long time since I've used a 41cx, but like riding a bike, it came back to me. It includes all the program pacs and they worked great. I could go on and on, but I'll just say, it is worth every penny and much more.

I've been a fan of HP calculators since before the 41. To have such an accurate emulation of the ultimate of the old-school HP calculators availble is amazing. It is now my default calculator on the iPhone. Is anybody working on anything that emulates the 48 series?

I have a broken hp 41cv with the survey pac.(paid $300) Now I can have it on my iphone with the survey pac ( paid $7.99) This is the best app........ Thank you

This is currently the best HP RPN scientific calculator app for the iPhone by far. Works just like the real thing except no tactile response (of course). The keyclick sounds and ease of hitting the intended button makes up for it. The virtual printer is a very cool bonus. You will not regret paying the very reasonable pricetag for this meticulously well done app.

I had been looking for an RPN calculator and I'm glad I waited! This is truly exceptional with it's complete simulation of every aspect of the 41cx, including plotter, module, and overlay support. The basics are there as well with the keys layed out nicely (gaps between) for accurate data entry. Great job!!

For years I have longed to have the 41C back that I used in college. It was a gigantic calculator in today's terms, but its functionality was superb. From the little bit I've tested this application, it is an excellent rendition of the original--only in a much more svelte package (the iPhone). I look forward to running all the functionality through its paces. Until then, I'm quite pleased with what I've seen. This is the second most money I've paid for an application, but at the price it's still a value.

As of today (Oct. 27, 2008), I enjoy using the i41CX+ calculator on my iPhone, but I'm thinking I'll try out a couple of others, for the following three reasons:

Thanks for bringing my hp-41 back to life. I wonder if I can find the old manuals.. The state of the art in 1983 running on the state of the art in 2008. Wonder if 20 years from now I'll be running an iPhone emulator running an hp-41 app.

This is absolutely flawless in terms of emulation and is helpful to have around with me for quick RPN calculations. The printer feature is also pretty neat when used to trace calculations done for longer expressions.

My HP41c has been an everpresent part of my real desktop for almost 30 years. Now I can have it everywhere I go with my iPhone without a nerdy belt case for it!

I used my HP 41CX w/ Math Pac through college. This app is excellent! I downloaded it and then pulled out my old 41CX manuals that came with my original 41CX so that I could brush up on programming, Math Pac, etc. Everything on the app has worked exactly like the 41CX performed. The only complaint I have is that the printer files (when saved to the camera roll) are blurred if the file is too long. Short print files are fine. I suspect this issue can be corrected easily. I still give it five stars. Will be 5++ if the printer issue is fixed. Also, is it possible to wi-fi the print files straight from the app?

This is an absolutely unbeatable c

I have owned nearly every HP calculator ever made. I was one of the first to own the HP-41. I still remember driving from Seattle to Corvallis, the day it was released, oh so many years ago, just to get one. I was just as egar to own i41CX, for the iPhone. It works nearly identical to the real HP-41. The ability to load nearly every module that was developed for the HP-41 makes it a truely excellent calculator. It's built-in dynamic overlay changer is awesome. It's built in printer, with ability to save printout and mail, works better than a real printer. Your ability to write your own programs offline and download to the i41CX via the internet, is a function that HP would have only dreamed of. But the best part of the i41CX is the accessibility of the author, to answer questions and tweak the program to make it better. If you have a question, just ask the author.

Great designs are always useful, and the HP-41C is a great design.

This calculator is not only an excellent emulation of the old RPN HP-41CX calculator with all its bells & whistles, it is also an excellent and truly "usable" calculator for the flat glass screen on the iPhone and iPod Touch. No other calculator can match the button feedback (key press glow & sound) and sleek visual interface - the spacing and size of the buttons is also well done. When you add all the programming and compatibility features of the old 41CX this becomes an unrivalled success.