Reckon 1.0 beta released


Hi, This is not about HP calculators, sorry, but it does have RPN!

As promised a while back, i've released Reckon, a free replacement calculator for the casio fx-9860g.

I've created a page where you can download the latest version and also the PDF manual. The manual explains how to operate it.

I'm quite pleased with the RPN mode. You can temporarily use ALG subexpessions from within RPN, just by opening a bracket "(". This is really handy for entering formulae.

Give it a go!


Excellent Hugh. I was intrigued about this earlier. Now I have to track down an appropriate Casio.



Mine arrived yesterday. Just in time :-)

Now to figure out how to download the new software.

Still, it is a reasonable little calculator although the complex support seems a bit patchy.

- Pauli


Paul, the extension g1a is only honored when you click on the right most icon in the toolbar to switch to the mass storage view. Then, you can import the file in the "Computer" panel and do a cut&paste to the calculator panel.


My comment was more to do with the fact that I run Windows nowhere and that I'd have to find non-Casio software to allow a download.

I've done this and am playing with Reckon. Look for xfer9860.

- Pauli



Fantastic! Great additional stack depth (in RPN) and super numeric precision and range. I love being about the compute 3000! then take the log of it and find out it's a 9131 digit number. There's a lot to try out in this calculator before I can comment on it.

Thank you so much for this wonderful alternative to the Casio calc and especially for RPN.



Thanks for your kind words,

Im trying some experimental ideas. For example the idea of using a notational operator to denote degrees rather than radians. This might seem a bit odd at first. It has been suggested already that, when i get around to the output format preferences, i implement a default rad/deg mode than can always be overridden by notation, but nevertheless allows for a default as is normally expected.

Whether to have modes and how many is something im experimenting in. Im planning to put output format preferences in the next release. FIX, SCI, ENG etc.



Do you have some site set up for bug reports, etc., should we email directly to you? This is probably not the best place to post them given the OT nature of this app (even if it is RPN).



Good idea, i’ll try to set up a forum that people can post bugs, suggestions and ideas.

A while back i had a forum, but very quickly it became overrun with spambot postings, so i disabled it. I’ll have to find out which one people now use that’s not going to get hijacked in 24 hours!


Thanks alot HUGH

Now I have to go out and purchase another calculator.....

I don't always get to London for Saturday anymore, usually during the week so how about a pint sometime.

I would need your phone number for that!

Cheers, Geoff


Hi Geoff,

I’ll send you some email. If you’re in London, give me a call. Also i can upgrade your calcwatch to the latest bugs!



Cheers and say hello to everyone at next saturdays meeting for me. Who know, I might make it...



Excuse me, Hugh,

may I ask a couple of (perhaps stupid) questions? I don't own an fx-9860g or an fx-9860g slim, but:

1) does Reckon run on both models?

2) Once you have uploaded Reckon, is the original OS lost forever, or Reckon runs upon it as a program, and thus it can be stopped anytime?

Thanks in advance.

-- Antonio


Reckon appears as an additional application. If you exit it (by selecting another app via the menu) and return later, you're back where you left off. I didn't find a proper EXIT function yet. You loose nothing except some free space. ;)


Thanks, very nice of you.

-- Antonio


Yes, marcus is correct. I quite like the fact that i can leave it running the app and power down and back again and im still there.


Hello. This seems to be interesting.

I suppose that it also works on the 9860 SLIM? I will get one to try it out.

HP, wake up !!! I started recommending the Casio fx-991ES to my high school students and most have bought one. Lost terrain for HP.


Absolutely it works on the "slim"!

Actually, i only have the slim so it's the only _real_ version i've tested. The SDK comes with a virtual version of the non-slim, so i was able to test it insofar as the emulator worked on the non-slim.

The keyboard matrix is different on the two machines. that is the only area that differs in the code. Also, the slim has the backlight and help button. if you push the HELP or F1 key. there is a popup with the current version. Unfortunately, i have to call the OS for this popup to appear and on the slim, you can "escape" into the help system for a while.

Good luck!


I installed your software on the Casio Graph 85 SD (the French version of the Fx-9860G SD). The RPN mode is beautiful!! I will install it on my other Casio Fx-9860G calculators.

Keep up the good work!



thanks for the comments. I've just posted a v1.01 BTW, it fixes a minor problem with DUP.


It comes up with 1.02. And I know which bug must have been fixed. ;)

(Try 69! ENTER F-D)


1.01 has the stack lift fixed, 1.02 there are no new features. but last night i was testing proot and discovered a rare problem with input parsing of vectors. embarrassingly, it would sometimes read 1 character off the end of the input and go bad.

proot is looking quite good tho. I know it wasn't on my list, but i had some half-finished code that didn't make it to the original release.

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