Short presentation of ExistOS/KhiCAS for the HP39GII

The HP39gii is a monochrom graphing calculator that was released by HP in 2012. It is using internally Giac/Xcas as computing kernel. Historically, it's the first port of Giac/Xcas to a calculator but the CAS was never exposed to the public, because it would have been banned by some countries. Later HP released the HP Prime where the CAS is exposed. But the Prime is more expensive than the HP39gii was, and the Prime port of Giac/Xcas is not free software, some Xcas commands are not available and you can not update your Prime when I release new versions of Giac/Xcas. That's a little frustrating for me to see that I can not expose the CAS on the 39gii and I can not release enhanced versions of the Prime CAS.
Then in November 2022, I discovered on tiplanet (thanks to critor!) that some very smart people have implemented an alternative OS for the 39gii: this OS is called ExistOS and it is free software. Yes, it is really free, under the GPL 3 license, it's not a pseudo open source OS with such a restrictive license that you can not do anything useful with it, like Numworks does now. And it has already a port of KhiCAS inside! I'm not a specialist, but it seems to me that the OS is very well done. Add that to my frustration not to be able to release enhanced versions of KhiCAS for the hp39gii and Prime, I have decided to enhance the KhiCAS port from the 39gii, despite the fact that the number of hp39gii owners is small,

Up to date version of KhiCAS for ExistOS

The current version is still in alpha devel stage. Binary releases : The binaries should be transfered to the calculator using the Windows updater. If you do not have a physical calculator, you can try the OS with the hp39gii emulator available for Windows
The latest source code of KhiCAS for the 39gii, to be used in conjunction with ExistOS.
These files are licensed under the GPL3 license.


A quick introduction is available here in English or Chinese. For a more complete documentation, you can refer to the Casio KhiCAS manual, available here in English or French. The Views key replace the Casio EXIT key.
Bernard Parisse, Institut Fourier (CNRS UMR 5582), 100 rue des Maths, Université Grenoble Alpes, CS 40700, 38058 Grenoble cedex 9
Tel: ( 33 ou 0 ) 4 76 51 43 14. bernard.parisse at