go41cx overlay Math module


My attempt at overlay files used with the Math module for the go41cx android app by Oliver de Smet

Math Overlay 01

Math Overlay 02

EDIT: I have purged the files on my drpbox due to changes in Oliver's program design.

Edited: 13 Feb 2012, 4:06 a.m. after one or more responses were posted


Nice, could I put them on my site ?


P.S. printer emulation and hepax support are almost finished ....
(next will be sound)


Great Olivier !
Can you tell me if you intend to extend te character set to halfnut, i.e lower case ? The sandbox module does not display correctly its names....
Also do you intend to support skins/existing modules overlay (graphically complex, cannot be done in pure text).
Thanks and cheers



Key entry now useable at speed greater than 1, even works very well at x32 or max speed (around x50 for my slow motorola defy), but PSE and CAT are accelerated too

Fullnut display is done (sandbox is ok), but with the same restriction as real hardware :)

Printer is done, just some limitation about the size of the paper ...

Hepax support (up to 32 KB : 4 8KB modules) with relocation of the rom is done

I added CV support to allow more modules if you don't need XF and Time. But you can still plug XF and Time modules in the CV if needed

I added a CCD-OSX with special addressabilities : look for free page from 3 to 7 then from 15 to 8 :) So you can have a CX with printer (page 6), Hepax (page 7), 3 8K modules (ports 1, 2 and 3), CCD page 15 and a 4K rom module in port 4 (page 14), only page 4 is free (as usual). it gives 48 KW rom, 24 KW hepax ram, 600 regs XF and a 4 KW application pac :)

For the graphical overlays, it's possible, but it is a major rework of the keypad part ...

I hope to post this v1.2 on market tomorrow.



Hi Olivier,

That's awesome work, thank you so much ! I think you'll be the primary reason why I will ditch my Iphone ! A bit more polishing in the graphics/skins/overlays, and you'll be on par with i41cx+ ! Well no, because Antonio also included a CAS in i41cx+, but I've always thought that was a bit too far off ;)

But thanks to all your emulators you 've made the Android plateform the primary one for HP calculators ! Just would need a 17Bi++ as on the iphone. If you get bored, you could port Emu42 from Christoph to Android ;))

I love your 15C too, the way you replaced the useless key codes with mnemonics is brillant, I would just would a bit more polishing (e.g. the size of the back help), and landscape mode to make it perfect.

And, of course, a 65... :)

Sorry to be that demanding, but that's your awesome work that triggered this in the first place :)




Emu42 from Christoph to Android ;))

Try Free42 from Thomas Okken.


Emu42 --- so that one can also run the HP28s ROM which works well as a landscape orientation emulated calculator.


Edited: 7 Feb 2012, 7:21 a.m.


I'm well aware of wonderful Free42 :)

The reason why I'm asking Emu42 is not for the 42 (although the hardware emulation is also interesting, 100% compatibility), but for the 17BII, 27S and 28S (I would love to say 32II but I don't have the ROM and there is no way to dump it).




V1.2 is now on the market. The format of the save state changed. Please save your work in xmem, save and export it to be safe on restart after the Memory Lost.



New release 1.3.0 with graphics for skins and overlay will be soon in the market, now you could customize your overlays. For skins, send them back to me, I will include them.



Very nice! I'm thinking about throwing out my hardware 41c's...

The only problem I'm having (and had since earlier versions): ADV doesn't work on the printer.

I wish though you had kept the text only overlays as a second option. They would be handy for a quick and dirty user program overlay as they are so much easier to make.


I fully agree about this overlay.
I feel guilty, because I suggested Olivier (probably I was not the only one) to make graphical overlays because the text ones were too limited; but these text ones had the big advantage to be quickly and easily done. What about a code like:

if (file_extension_is_ovl)

or is it too naive ? ;)




Nice, could I put them on my site?

Sure, that's why I posted them here. Grab them and host them on your site, I will eventually purge them from my dropbox. Everyone is free to change and improve the overlays.

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